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FABIO BISCARINI
Professore Ordinario
Dipartimento di Scienze della Vita sede ex Chimica V.Campi 103
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Pubblicazioni
2024
- Dynamic studies of antibody-antigen interactions with an electrolyte-gated organic transistor
[Articolo su rivista]
Manco Urbina, P. A.; Paradisi, A.; Hasler, R.; Sensi, M.; Berto, M.; Saygin, G. D.; Dostalek, J.; Pinti, M.; Greco, P.; Borsari, M.; Knoll, W.; Bortolotti, C. A.; Biscarini, F.
abstract
Affinity-based biosensors employing surface-bound biomolecules
for analyte detection are important tools in clinical diagnostics
and drug development. In this context, electrolyte-gated organic
transistors (EGOTs) are emerging as ultrasensitive label-free biosensors. In this study, we present an EGOT sensor integrated
within a microfluidic system. The sensor utilizes the cytomegalovirus (CMV) phosphoprotein 65 as a biorecognition element to
detect the pathological biomarker human anti-cytomegalovirus
antibody in solution. The biorecognition element is grafted onto
the gate electrode by exploiting the polyhistidine-tag technology.
Real-time monitoring of the EGOT response, coupled with a twocompartment kinetic model analysis, enables the determination
of analyte concentration, binding kinetics, and thermodynamics
of the interaction. The analysis of the relevant kinetic parameters
of the binding process yields a reliable value for the thermodynamic equilibrium constant and suggests that the measured
deviations from the Langmuir binding model arise from the co-existence of binding sites with different affinities toward the antibodies.
2024
- How Biorecognition Affects the Electronic Properties of Reduced Graphene Oxide in Electrolyte‐Gated Transistor Immunosensors
[Articolo su rivista]
Sensi, Matteo; de Oliveira, Rafael Furlan; Berto, Marcello; Paradisi, Alessandro; Greco, Pierpaolo; Bortolotti, Carlo Augusto; Samorì, Paolo; Biscarini, Fabio
abstract
Ambipolar electrolyte-gated transistors (EGTs) based on reduced graphene oxide (rGO) have been demonstrated as ultra-sensitive and highly specific immunosensors. However, the physics and chemistry ruling the device operation are still not fully unraveled. In this work, the aim is to elucidate the nature of the observed sensitivity of the device. Toward this aim, a physical–chemical model that, coupled with the experimental characterization of the rGO-EGT, allows one to quantitatively correlate the biorecognition events at the gate electrode and the electronic properties of rGO-EGT is proposed. The equilibrium of biorecognition occurring at the gate electrode is shown to determine the apparent charge neutrality point (CNP) of the rGO channel. The multiparametric analysis of the experimental transfer characteristics of rGO-EGT reveals that the recognition events modulate the CNP voltage, the excess carrier density Δn, and the quantum capacitance of rGO. This analysis also explains why hole and electron carrier mobilities, interfacial capacitance, the curvature of the transfer curve, and the transconductances are insensitive to the target concentration. The understanding of the mechanisms underlying the transistor transduction of the biorecognition events is key for the interpretation of the response of the rGO-EGT immunosensors and to guide the design of novel and more sensitive devices.
2024
- Investigation of transcription factor–DNA binding with electrolyte-gated organic transistors
[Articolo su rivista]
Sensi, Matteo; Ricci, Andrea; Rigillo, Giovanna; Paradisi, Alessandro; Berto, Marcello; Gnesutta, Nerina; Imbriano, Carol; Biscarini, Fabio; Bortolotti, Carlo Augusto
abstract
Nuclear transcription factor Y (NF-Y) is a CCAAT-binding trimeric protein. The overexpression of the DNA-binding subunit A (NF-YA) results in deregulation of many CCAAT-dependent pro-growth genes in multiple tumor types. Exon 3 alternative splicing of NF-YA results in two different isoforms, NF-YAs (short) and NF-YAl (long), which can promote tumor proliferation or metastasis, respectively. In this work, we developed an electrolyte-gated organic transistor (EGOT) biosensor to study the binding of a NF-YAl-composed NF-Y complex to its consensus sequence. We show that by using the target DNA sequence as a probe, the device detects NF-Y in the range of 1 pM to 10 nM. Control experiments performed with oligonucleotide probes mutated in the consensus sequence exhibit weaker, though not fully hindered, binding to NF-Y compared to the response to unmutated DNA. This behavior confirms that the base pairs near the CCAAT-box also have a role in the transcription factor recognition. Furthermore, we contributed to the advancement of the present state of the art by demonstrating the ability of the EGOT biosensor to detect NF-Y in cell lysate, a fundamental step towards the development of point-of-care (POC) devices for the analysis of biopsies.The first electrolyte-gated organic transistor biosensor for the detection of a transcription factor (NF-Y) in buffer and cell lysate.
2023
- Nanoscale Quantized Oscillations in Thin-Film Growth Greatly Enhance Transconductance in Organic Transistors
[Articolo su rivista]
Drakopoulou, S; Murgia, M; Albonetti, C; Benaglia, S; Borgatti, F; Di Lauro, M; Bianchi, M; Greco, P; Papo, D; Garcia, R; Alessandrini, A; Biscarini, F
abstract
A growth mode of pentacene thin films deposited by high vacuum sublimation where the morphology versus thickness h "rings" back and forth between rough 3D films with pyramid islands and smooth 2D films with ziqqurat islands is discovered. The roughness & sigma; versus h exhibits seamless coherent oscillations whose amplitude and wavelength increase as integer multiples of 1.5 ML thickness. The quantized oscillations are reconducted to dynamic wetting/dewetting transitions involving the upper layers of pentacene film. Importantly, the transconductance of organic field effect transistors, either in solid state or electrolyte-gated, exhibits antiphase oscillations with one-decade swing. Charge mobilities in the wetting regime reach 0.1 cm(2) V-1 s(-1), in line with high-end values reported for thin-film pentacene transistors. Controlling this growth mode enables the limitations of charge transport imposed by the roughening transition to be overcome, a universal feature of high vacuum growth to date.
2023
- Pre-synaptic DC bias controls the plasticity and dynamics of three-terminal neuromorphic electrolyte-gated organic transistors
[Articolo su rivista]
Rondelli, Federico; Salvo, Anna De; Sebastianella, Gioacchino Calandra; Murgia, Mauro; Fadiga, Luciano; Biscarini, Fabio; Lauro, Michele Di
abstract
The role of pre-synaptic DC bias is investigated in three-terminal organic neuromorphic architectures based on electrolyte-gated organic transistors—EGOTs. By means of pre-synaptic offset it is possible to finely control the number of discrete conductance states in short-term plasticity experiments, to obtain, at will, both depressive and facilitating response in the same neuromorphic device and to set the ratio between two subsequent pulses in paired-pulse experiments. The charge dynamics leading to these important features are discussed in relationship with macroscopic device figures of merit such as conductivity and transconductance, establishing a novel key enabling parameter in devising the operation of neuromorphic organic electronics.
2023
- Reduced Graphene Oxide Electrolyte-Gated Transistor Immunosensor with Highly Selective Multiparametric Detection of Anti-Drug Antibodies
[Articolo su rivista]
Sensi, M.; de Oliveira, R. F.; Berto, M.; Palmieri, M.; Ruini, E.; Livio, P. A.; Conti, A.; Pinti, M.; Salvarani, C.; Cossarizza, A.; Cabot, J. M.; Ricart, J.; Casalini, S.; Gonzalez-Garcia, M. B.; Fanjul-Bolado, P.; Bortolotti, C. A.; Samori, P.; Biscarini, F.
abstract
The advent of immunotherapies with biological drugs has revolutionized the treatment of cancers and auto-immune diseases. However, in some patients, the production of anti-drug antibodies (ADAs) hampers the drug efficacy. The concentration of ADAs is typically in the range of 1-10 pm; hence their immunodetection is challenging. ADAs toward Infliximab (IFX), a drug used to treat rheumatoid arthritis and other auto-immune diseases, are focussed. An ambipolar electrolyte-gated transistor (EGT) immunosensor is reported based on a reduced graphene oxide (rGO) channel and IFX bound to the gate electrode as the specific probe. The rGO-EGTs are easy to fabricate and exhibit low voltage operations (& LE; 0.3 V), a robust response within 15 min, and ultra-high sensitivity (10 am limit of detection). A multiparametric analysis of the whole rGO-EGT transfer curves based on the type-I generalized extreme value distribution is proposed. It is demonstrated that it allows to selectively quantify ADAs also in the co-presence of its antagonist tumor necrosis factor alpha (TNF-alpha), the natural circulating target of IFX.
2022
- A Novel Biasing Scheme of Electrolyte-Gated Organic Transistors for Safe In Vivo Amplification of Electrophysiological Signals
[Articolo su rivista]
Di Lauro, M.; Zucchini, E.; De Salvo, A.; Delfino, E.; Bianchi, M.; Murgia, M.; Carli, S.; Biscarini, F.; Fadiga, L.
abstract
Successful translation of organic transistors as sensors and transducers to clinical settings is hampered by safety and stability issues. The operation of such devices demands driving voltages across the biotic/abiotic interface, which may result in undesired electrochemical reactions that may harm both the patient and the device. In this study, a novel operational mode is presented for electrolyte-gated organic transistors that avoid these drawbacks: the common-drain/grounded-source configuration. This approach reverts the standard common-source/common-ground configuration and achieves maximum signal amplification while applying null net bias across the electrolyte, with no parasitic currents. The viability of the proposed configuration is demonstrated by recording in vivo the somatosensory evoked activity from the barrel cortex of rats. The main inherent advantage of transistors with respect to passive electrodes is preserved in the proposed scheme: a superior signal-to-noise ratio is achieved which enables the detection of evoked activity at the single-trial level. Then, common-drain/grounded-source organic transistors are proposed as ideal candidate devices for a harmless translational recording platform.
2022
- Detection of Neurofilament Light Chain with Label-Free Electrolyte-Gated Organic Field-Effect Transistors
[Articolo su rivista]
Solodka, K.; Berto, M.; Ferraro, D.; Menozzi, C.; Borsari, M.; Bortolotti, C. A.; Biscarini, F.; Pinti, M.
abstract
Neurofilaments are structural scaffolding proteins of the neuronal cytoskeleton. Upon axonal injury, the neurofilament light chain (NF-L) is released into the interstitial fluid and eventually reaches the cerebrospinal fluid and blood. Therefore, NF-L is emerging as a biomarker of neurological disorders, including neurodegenerative dementia, Parkinson's disease, and multiple sclerosis. It is challenging to quantify NF-L in bodily fluids due to its low levels. This work reports the detection of NF-L in aqueous solutions with an organic electronic device. The biosensor is based on the electrolyte-gated organic field-effect transistor (EGOFET) architecture and can quantify NF-L down to sub-pM levels; thanks to modification of the device gate with anti-NF-L antibodies imparted with potentially controlled orientation. The response is fitted to the Guggenheim–Anderson–De Boer adsorption model to describe NF-L adsorption at the gate/electrolyte interface, to consider the formation of a strongly adsorbed protein layer bound to the antibody and the formation of weakly bound NF-L multilayers, an interpretation which is also backed up by morphological characterization via atomic force microscopy. The label-free, selective, and rapid response makes this EGOFET biosensor a promising tool for the diagnosis and monitoring of neuronal damages through the detection of NF-L in physio-pathological ranges.
2022
- Flexible Neural Interfaces Based on 3D PEDOT:PSS Micropillar Arrays
[Articolo su rivista]
Lunghi, A.; Mariano, A.; Bianchi, M.; Dinger, N. B.; Murgia, M.; Rondanina, E.; Toma, A.; Greco, P.; Di Lauro, M.; Santoro, F.; Fadiga, L.; Biscarini, F.
abstract
Multi-electrode arrays with 3D micropillars allow the recording of electrophysiological signals in vitro with higher precision and signal-to-noise ratio than planar arrays. This is the result of the tight interaction between the 3D electrode and the cell membrane. Most 3D electrodes are manufactured on rigid substrates and their integration on flexible substrates is largely unexplored. Here, a straightforward approach is presented for fabricating soft interfaces featuring 3D poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) micropillars on a soft flexible substrate made of polydimethylsiloxane (PDMS). Large-area isotropic arrays of PEDOT:PSS micropillars with tailored geometric area, surface properties, and electrochemical characteristics are fabricated via a combination of soft-lithography and electrodeposition. A 60% increase in capacitance is achieved for high density micropillars compared to planar electrodes and this is found to be correlated with the increased electroactive surface area. Furthermore, 3D PEDOT:PSS micropillars support adhesion, growth and differentiation of SH-SY5Y cells, and influence the direction of neurite outgrowth. Finally, by virtue of their elasticity, soft micropillars act as excellent anchoring loci for elongating neurites, facilitating their bending and twisting around the micropillar, increasing the number of contact points between the cells and the electrode, a key requirement to obtain high performance neural interfaces.
2022
- Laser Assisted Bioprinting of laminin on biodegradable PLGA substrates: Effect on neural stem cell adhesion and differentiation
[Articolo su rivista]
Tortorella, S.; Greco, P.; Valle, F.; Barbalinardo, M.; Foschi, G.; Lugli, F.; Dallavalle, M.; Zerbetto, F.; Bortolotti, C. A.; Biscarini, F.
abstract
Laser Assisted Bioprinting (LAB) is recognized to be an enabling and versatile microfabrication technology for regenerative medicine and artificial tissue engineering. Current bioprinting concentrates on a layer-by-layer approach to print cells in consecutive stacks or nets, to recreate specialized tissue functions with a top-down approach. This synthering of proximal cells however reduces the long range correlation of tissue parenchyma and stroma given by natural development, as result of cells mobility and signaling. In this work, laminin, one of the main components of brain extracellular matrix is deposited by LAB on a biodegradable scaffold made of poly(lactic-co-glycolic acid) (PLGA), providing chemical cues for the adhesion and differentiation of neural stem cells NE-4C induced by retinoic acid. Surface roughness and LAB induced aggregates promote the initial adhesion of neuronal stem cells to the PLGA substrate and influence the formation of clusters and interconnection between them. The amount of laminin delivered inside the spot area may be controlled down to sub-monolayer coverage and a positive correlation between the laminin spots and soma of trafficking cells is demonstrated, also by computational modelling. Anisotropic orientation of neurite outgrowth is induced upon differentiation, up to 70% of processes protruding from stem cell clusters. The comparative analysis shows that the topological cue plays a major role in enhabling cluster formation on the scaffold, but the bioprinted laminin spots appear to be regulating the strength of connection between them, opening the way to control the functional morphology of artificial neural tissue constructs.
2022
- Monitoring DNA Hybridization with Organic Electrochemical Transistors Functionalized with Polydopamine
[Articolo su rivista]
Sensi, M.; Migatti, G.; Beni, V.; D'Alvise, T. M.; Weil, T.; Berto, M.; Greco, P.; Imbriano, C.; Biscarini, F.; Bortolotti, C. A.
abstract
Organic electrochemical transistors (OECTs) are finding widespread application in biosensing, thanks to their high sensitivity, broad dynamic range, and low limit of detection. An OECT biosensor requires the immobilization of a biorecognition probe on the gate, or else on the channel, through several, often lengthy, chemical steps. In this work, a fast and straightforward way to functionalize the carbon gate of a fully screen-printed OECT by means of a polydopamine (PDA) film is presented. By chemical immobilization of an amine-terminated single-stranded oligonucleotide, containing the HSP70 promoter CCAAT sequence, on the PDA film, the detection of the complementary DNA strand is demonstrated. Furthermore, the specificity of the developed genosensor is assessed by comparing its response to the fully complementary strand with the one to partially complementary and noncomplementary oligonucleotides. The developed sensor shows a theoretical limit of detection (LOD) of 100 × 10−15 m and a dynamic range over four orders of magnitude.
2022
- Multifunctionally-doped PEDOT for organic electrochemical transistors
[Articolo su rivista]
Carli, S; Bianchi, M; Di Lauro, M; Prato, M; Toma, A; Leoncini, M; De Salvo, A; Murgia, M; Fadiga, L; Biscarini, F
abstract
Organic Electrochemical Transistors (OECTs) are suitable for developing ultra-sensitive bioelectronic sensors. In the organic electrochemical transistors architecture, the source-drain channel is made of a conductive polymer film either cast from a formulated dispersion or electrodeposited from a monomer solution. The commercial poly(3,4-ethylenedioxidethiophene)/poly(styrene sulfonate) (PEDOT:PSS) water dispersion is the workhorse of organic bioelectronics for its high conductance, low impact and ease of processability. In this study, a hybrid organic electrochemical transistors channel fabrication strategy is presented, where electrochemical deposition of a PEDOT/X (with X indicating the counterion) is performed on a dispersion-cast PEDOT:PSS film. Six different counterions where used: X = PSS, Nafion, Hyaluronate, Dextran sulfate, Dexamethasone phosphate and tauroursodeoxycholic acid, each potentially endowing organic electrochemical transistors with additional functions such as ion exchange and pharmacological activity upon release of X. The PEDOT/X-PEDOT:PSS bilayers were characterized by means of electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and focused ion beam tomography combined with scanning electron microscopy (FIB-SEM). In addition, their respective organic electrochemical transistorss were characterized and compared to PEDOT:PSS organic electrochemical transistors. Our results show that the hybrid bilayer strategy is viable to fabricate multifunctional organic electrochemical transistorss with biologically-relevant function, thereby retaining the outstanding figures of merit of commercial PEDOT:PSS.
2022
- PEDOT: PSS promotes neurogenic commitment of neural crest-derived stem cells
[Articolo su rivista]
Pisciotta, A.; Lunghi, A.; Bertani, G.; Di Tinco, R.; Bertoni, L.; Orlandi, G.; Biscarini, F.; Bianchi, M.; Carnevale, G.
abstract
: Poly (3,4-ethylendioxythiophene) polystyrene sulphonate (PEDOT:PSS) is the workhorse of organic bioelectronics and is steadily gaining interest also in tissue engineering due to the opportunity to endow traditional biomaterials for scaffolds with conductive properties. Biomaterials capable of promoting neural stem cell differentiation by application of suitable electrical stimulation protocols are highly desirable in neural tissue engineering. In this study, we evaluated the adhesion, proliferation, maintenance of neural crest stemness markers and neurogenic commitment of neural crest-derived human dental pulp stem cells (hDPSCs) cultured on PEDOT:PSS nanostructured thin films deposited either by spin coating (SC-PEDOT) or by electropolymerization (ED-PEDOT). In addition, we evaluated the immunomodulatory properties of hDPSCs on PEDOT:PSS by investigating the expression and maintenance of the Fas ligand (FasL). We found that both SC-PEDOT and ED-PEDOT thin films supported hDPSCs adhesion and proliferation; however, the number of cells on the ED-PEDOT after 1 week of culture was significantly higher than that on SC-PEDOT. To be noted, both PEDOT:PSS films did not affect the stemness phenotype of hDPSCs, as indicated by the maintenance of the neural crest markers Nestin and SOX10. Interestingly, neurogenic induction was clearly promoted on ED-PEDOT, as indicated by the strong expression of MAP-2 and β -Tubulin-III as well as evident cytoskeletal reorganisation and appreciable morphology shift towards a neuronal-like shape. In addition, strong FasL expression was detected on both undifferentiated or undergoing neurogenic commitment hDPSCs, suggesting that ED-PEDOT supports the expression and maintenance of FasL under both expansion and differentiation conditions.
2022
- Poly(3,4-ethylenedioxythiophene)-Based Neural Interfaces for Recording and Stimulation: Fundamental Aspects and In Vivo Applications
[Articolo su rivista]
Bianchi, M.; De Salvo, A.; Asplund, M.; Carli, S.; Di Lauro, M.; Schulze-Bonhage, A.; Stieglitz, T.; Fadiga, L.; Biscarini, F.
abstract
Next-generation neural interfaces for bidirectional communication with the central nervous system aim to achieve the intimate integration with the neural tissue with minimal neuroinflammatory response, high spatio-temporal resolution, very high sensitivity, and readout stability. The design and manufacturing of devices for low power/low noise neural recording and safe and energy-efficient stimulation that are, at the same time, conformable to the brain, with matched mechanical properties and biocompatibility, is a convergence area of research where neuroscientists, materials scientists, and nanotechnologists operate synergically. The biotic–abiotic neural interface, however, remains a formidable challenge that prompts for new materials platforms and innovation in device layouts. Conductive polymers (CP) are attractive materials to be interfaced with the neural tissue and to be used as sensing/stimulating electrodes because of their mixed ionic-electronic conductivity, their low contact impedance, high charge storage capacitance, chemical versatility, and biocompatibility. This manuscript reviews the state-of-the-art of poly(3,4-ethylenedioxythiophene)-based neural interfaces for extracellular recording and stimulation, focusing on those technological approaches that are successfully demonstrated in vivo. The aim is to highlight the most reliable and ready-for-clinical-use solutions, in terms of materials technology and recording performance, other than spot major limitations and identify future trends in this field.
2022
- Substrate roughness influence on the order of nanografted Self-Assembled Monolayers
[Articolo su rivista]
Scaini, D.; Biscarini, F.; Casalis, L.; Albonetti, C.
abstract
Adjacent patches of alkanethiol molecules whose chain lengths range from 11 to 15 carbon atoms are fabricated by nanografting within a Self-Assembled Monolayer matrix. Atomic Force Microscopy and Electrostatic Force Microscopy are employed to investigate their structural and electronic properties, highlighting the key role of the substrate roughness. In particular, the topographic phase signal allows to establish an odd–even dependence of the local stiffness versus the alkyl chain length, while the electrostatic force signal provides evidence that the conformational order versus the alkyl chain length follows an asymmetric parabolic trend induced by the substrate roughness.
2022
- Unravelling molecular disorder at SAM-functionalized charge injection interfaces in organic field-effect transistors
[Articolo su rivista]
Albonetti, C.; Olivieri, G.; Shehu, A.; Quiroga, S. D.; Murgia, M.; Biscarini, F.
abstract
Charge injection in Organic Field Effect Transistors is investigated by monitoring in real-time the electrical conduction, while in situ growing pentacene films. The source and drain electrodes are made of gold functionalized with alkanethiol Self-Assembled Monolayers (SAMs), whose number of carbon atoms ranges from 5 to 10. Measuring the current flowing into the channel allows us to establish a correlation between the charge injection and the pentacene film growth. In particular, the thickness dependence of both the charge mobility and the charge carrier accumulation can be explained in terms of the molecular order at the interface between the pentacene films and the SAMs. Specifically, the threshold voltage, contact resistance and temperature-dependent constant exhibit parabolic trends for increasing alkanethiol chain length. Conversely, both the band mobility and the charge mobility are characterized by oscillations that follow an odd–even trend with a linear decay for increasing number of the carbon atoms. These results corroborate the theoretical interpretation, previously proposed by Stoliar et al., that the odd–even effect is ascribable to the order degree and orientation of the pentacene molecules interacting with the SAMs, while the parabolic trend depends on the chain length of the alkanethiol SAMs.
2021
- Anti-drug antibody detection with label-free electrolyte-gated organic field-effect transistors
[Articolo su rivista]
Sensi, Matteo; Berto, Marcello; Gentile, Sara; Pinti, Marcello; Conti, Andrea; Pellacani, Giovanni; Salvarani, Carlo; Cossarizza, Andrea; Bortolotti, Carlo Augusto; Biscarini, Fabio
abstract
The efficacy of immunotherapy can be undermined by the development of an immune response against a drug/antibody mediated by anti-drug antibodies (ADAs) in treated patients. We present the first label-free EGOFET immunosensor that integrates a biological drug, Nivolumab (Opdivo©), as a specific recognition moiety to quantitatively and selectively detect ADAs against the drug. The limit of detection is 100 fM. This demonstration is a prelude to the detection of ADAs in a clinical setting in the treatment of different pathologies, and it also enables rapid screening of biological drugs for immunogenicity.
2021
- Contents list
[Abstract in Rivista]
Biscarini, F.; Coronado, E.; Painelli, A.; Yamshita, T.
abstract
2021
- Electrolyte-gated transistors for enhanced performance bioelectronics
[Articolo su rivista]
Torricelli, Fabrizio; Adrahtas, Demetra Z.; Bao, Zhenan; Berggren, Magnus; Biscarini, Fabio; Bonfiglio, Annalisa; Bortolotti, Carlo A.; Frisbie, C. Daniel; Macchia, Eleonora; Malliaras, George G.; Mcculloch, Iain; Moser, Maximilian; Nguyen, Thuc-Quyen; Owens, Róisín M.; Salleo, Alberto; Spanu, Andrea; Torsi, Luisa
abstract
Electrolyte-gated transistors (EGTs), capable of transducing biological and biochemical inputs into amplified electronic signals and stably operating in aqueous environments, have emerged as fundamental building blocks in bioelectronics. In this Primer, the different EGT architectures are described with the fundamental mechanisms underpinning their functional operation, providing insight into key experiments including necessary data analysis and validation. Several organic and inorganic materials used in the EGT structures and the different fabrication approaches for an optimal experimental design are presented and compared. The functional bio-layers and/or biosystems integrated into or interfaced to EGTs, including self-organization and self-assembly strategies, are reviewed. Relevant and promising applications are discussed, including two-dimensional and three-dimensional cell monitoring, ultra-sensitive biosensors, electrophysiology, synaptic and neuromorphic bio-interfaces, prosthetics and robotics. Advantages, limitations and possible optimizations are also surveyed. Finally, current issues and future directions for further developments and applications are discussed.
2021
- Green Fabrication of (6,5)Carbon Nanotube/Protein Transistor Endowed with Specific Recognition
[Articolo su rivista]
Berto, M.; Di Giosia, M.; Giordani, M.; Sensi, M.; Valle, F.; Alessandrini, A.; Menozzi, C.; Cantelli, A.; Gazzadi, G. C.; Zerbetto, F.; Calvaresi, M.; Biscarini, F.; Bortolotti, C. A.
abstract
A general single-step approach is introduced for the green fabrication of hybrid biosensors from water dispersion. The resulting device integrates the semiconducting properties of a carbon nanotube (CNT) and the functionality of a protein. In the initial aqueous phase, the protein (viz., lysozyme [LZ]) disperses the (6,5)CNT. Drop-casting of the dispersion on a test pattern (a silicon wafer with interdigitated Au source and drain electrodes) yields a fully operating, robust, electrolyte-gated transistor (EGT) in one step. The EGT response to biorecognition is then assessed using the LZ inhibitor N-acetyl glucosamine trisaccharide. Analysis of the output signal allows one to extract a protein-substrate binding constant in line with values reported for the free (without CNT) system. The methodology is robust, easy to optimize, redirectable toward different targets and sets the grounds for a new class of CNT-protein biosensors that overcome many limitations of the technology of fabrication of CNT biosensors.
2021
- Implantable Organic Artificial Synapses Exhibiting Crossover between Depressive and Facilitative Plasticity Response
[Articolo su rivista]
Calandra Sebastianella, G.; Di Lauro, M.; Murgia, M.; Bianchi, M.; Carli, S.; Zoli, M.; Fadiga, L.; Biscarini, F.
abstract
Organic neuromorphic devices mimic signal processing features of biological synapses, with short-term plasticity, STP, modulated by the frequency of the input voltage pulses. Here, an artificial synapse, made of intracortical microelectrodes, is demonstrated that exhibits either depressive or facilitative STP. The crossover between the two STP regimes is controlled by the frequency of the input voltage. STP features are described with an equivalent circuit where an inductance component is introduced in parallel with the RC circuit associated with poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS)||electrolyte interface. The proposed RLC circuit explains the physical origin of the observed STP and its two timescales in terms of charge build up in PEDOT/PSS.
2021
- Label free detection of miRNA-21 with electrolyte gated organic field effect transistors (EGOFETs)
[Articolo su rivista]
Selvaraj, M.; Greco, P.; Sensi, M.; Saygin, G. D.; Bellassai, N.; D'Agata, R.; Spoto, G.; Biscarini, F.
abstract
We report a dual gate/common channel organic transistor architecture designed for quantifying the concentration of one of the strands of miRNA-21 in solution. The device allows one to measure the differential response between two gate electrodes, viz. one sensing and one reference, both immersed in the electrolyte above the transistor channel. Hybridization with oligonucleotide in the picomolar regime induces a sizable reduction of the current flowing through the transistor channel. The device signal is reported at various gate voltages, showing maximum sensitivity in the sublinear regime, with a limit of detection as low as 35 pM. We describe the dose curves with an analytical function derived from a thermodynamic model of the reaction equilibria relevant in our experiment and device configuration, and we show that the apparent Hill dependence on analyte concentration, whose exponent lies between 0.5 and 1, emerges from the interplay of the different equilibria. The binding free energy characteristic of the hybridization on the device surface is found to be approximately 20% lower with respect to the reaction in solution, hinting to partially inhibiting effect of the surface and presence of competing reactions. Impedance spectroscopy and surface plasmon resonance (SPR) performed on the same oligonucleotide pair were correlated to the electronic current transduced by the EGOFET, and confirmed the selectivity of the biorecognition probe covalently bound on the gold surface.
2021
- Long-range selective transport of anions and cations in graphene oxide membranes, causing selective crystallization on the macroscale
[Articolo su rivista]
Quintano, V.; Kovtun, A.; Biscarini, F.; Liscio, F.; Liscio, A.; Palermo, V.
abstract
Monoatomic nanosheets can form 2-dimensional channels with tunable chemical properties, for ion storage and filtering applications. Here, we demonstrate transport of K+, Na+, and Li+ cations and F- and Cl- anions on the centimeter scale in graphene oxide membranes (GOMs), triggered by an electric bias. Besides ion transport, the GOM channels foster also the aggregation of the selected ions in salt crystals, whose composition is not the same as that of the pristine salt present in solution, highlighting the difference between the chemical environment in the 2D channels and in bulk solutions.
2021
- Materials for molecular electronics and magnetism
[Articolo su rivista]
Biscarini, F.; Coronado, E.; Painelli, A.; Yamashita, M.
abstract
Functional molecular materials exhibiting, in particular, electrical, magnetic or optical properties have been an active focus of research over the last 50 years. These materials have been a source of inspiration in two interrelated areas of research, namely, molecular electronics and molecular magnetism, with important implications in biomedical areas. This themed issue highlights recent progress and perspectives in these important areas of materials science. The issue covers topics from the chemical design and manipulation of novel molecular materials with unprecedented control over their properties, even at the single-molecule level, to exciting applications of these special molecular systems in emerging fields, including bioelectronics and molecular spintronics.
2021
- Physical insights from the Frumkin isotherm applied to electrolyte gated organic transistors as protein biosensors
[Articolo su rivista]
Manco Urbina, Pamela Allison; Berto, Marcello; Greco, Pierpaolo; Sensi, Matteo; Borghi, Simone; Borsari, Marco; Bortolotti, Carlo Augusto; Biscarini, Fabio
abstract
2021
- Sensing Inflammation Biomarkers with Electrolyte-Gated Organic Electronic Transistors
[Articolo su rivista]
Burtscher, B.; Manco Urbina, P. A.; Diacci, C.; Borghi, S.; Pinti, M.; Cossarizza, A.; Salvarani, C.; Berggren, M.; Biscarini, F.; Simon, D. T.; Bortolotti, C. A.
abstract
An overview of cytokine biosensing is provided, with a focus on the opportunities provided by organic electronic platforms for monitoring these inflammation biomarkers which manifest at ultralow concentration levels in physiopathological conditions. Specifically, two of the field's state-of-the-art technologies—organic electrochemical transistors (OECTs) and electrolyte gated organic field effect transistors (EGOFETs)—and their use in sensing cytokines and other proteins associated with inflammation are a particular focus. The overview will include an introduction to current clinical and “gold standard” quantification techniques and their limitations in terms of cost, time, and required infrastructure. A critical review of recent progress with OECT- and EGOFET-based protein biosensors is presented, alongside a discussion onthe future of these technologies in the years and decades ahead. This is especially timely as the world grapples with limited healthcare diagnostics during the Coronavirus disease (COVID-19)pandemic where one of the worst-case scenarios for patients is the “cytokine storm.” Clearly, low-cost point-of-care technologies provided by OECTs and EGOFETs can ease the global burden on healthcare systems and support professionals by providing unprecedented wealth of data that can help to monitor disease progression in real time.
2020
- A Bacterial Photosynthetic Enzymatic Unit Modulating Organic Transistors with Light
[Articolo su rivista]
Di Lauro, M.; la Gatta, S.; Bortolotti, C. A.; Beni, V.; Parkula, V.; Drakopoulou, S.; Giordani, M.; Berto, M.; Milano, F.; Cramer, T.; Murgia, M.; Agostiano, A.; Farinola, G. M.; Trotta, M.; Biscarini, F.
abstract
The photochemical core of every photosynthetic apparatus is the reaction center, a transmembrane enzyme that converts photons into charge-separated states across the biological membrane with an almost unitary quantum yield. A light-responsive organic transistor architecture, which converts light into electrical current by exploiting the efficiency of this biological machinery, is presented. Proper surface tailoring enables the integration of the bacterial reaction center as photoactive element in organic transistors, allowing the transduction of its photogenerated voltage into photomodulation of the output current up to two orders of magnitude. This device architecture, termed light-responsive electrolyte-gated organic transistor, is the prototype of a new generation of low-power hybrid bio-optoelectronic organic devices.
2020
- A minimal model of hospital patients’ dynamics in COVID-19
[Articolo su rivista]
Papo, D.; Righetti, M.; Fadiga, L.; Biscarini, F.; Zanin, M.
abstract
Italy has been one of the countries hardest hit by the coronavirus disease (COVID-19) pandemic. While the overall policy in response to the epidemic was to a large degree centralised, the regional basis of the healthcare system represented an important factor affecting the natural dynamics of the disease induced geographic specificities. Here, we characterise the region-specific modulation of COVID dynamics with a reduced exponential model leveraging available data on sub-intensive and intensive care unit patients made available by all regional councils from the very onset of the disease. This simple model provides a rather good fit of regional patient dynamics, particularly for regions where the affected population was large, highlighting important region-specific patterns of epidemic dynamics.
2020
- Amphiphilic cationic cyclodextrin nanovesicles: A versatile cue for guiding cell adhesion
[Articolo su rivista]
Valle, F.; Tortorella, S.; Scala, A.; Cordaro, A.; Barbalinardo, M.; Biscarini, F.; Mazzaglia, A.
abstract
It is well known that amphiphilic cationic β-cyclodextrins (amβCDs) form nanovesicles able to release their cargo in aqueous solution upon applying different stimuli. In addition they can be selectively positioned onto substrates by unconventional soft lithography. This makes them a powerful tool for designing environments where different cues can be externally supplied to the cells helping to achieve good control of their fate. Lithographically controlled wetting (LCW) of amβCD nanovesicles loaded with fluorescein isothiocyanate (FITC), amβCD/FITC, has been used here to fabricate geometrically functionalized surfaces, thus achieving multiscale control of the cell environment. The amβCD functionalization was strongly influenced by the surface energy of the underlying substrates that, according to their hydrophobicity, orient the amβCD in a different way, thus "offering"different portions to the cells. The structure of the pattern was characterized both over large scales exploiting the FITC fluorescence and at the nanoscale by atomic force microscopy. Cell guidance and aCD/FITC cell internalization were demonstrated in human neuroblastoma SHSY5Y cells. This journal is
2020
- Flexible Printed Organic Electrochemical Transistors for the Detection of Uric Acid in Artificial Wound Exudate
[Articolo su rivista]
Galliani, M.; Diacci, C.; Berto, M.; Sensi, M.; Beni, V.; Berggren, M.; Borsari, M.; Simon, D. T.; Biscarini, F.; Bortolotti, C. A.
abstract
Low-cost, minimally invasive sensors able to provide real-time monitoring of wound infection can enable the optimization of healthcare resources in chronic wounds management. Here, a novel printed organic electrochemical transistors (OECT) biosensor for monitoring uric acid (UA), a bacterial infection biomarker in wounds, is demonstrated in artificial wound exudate. The sensor exploits the enzymatic conversion of UA to 5-hydroxyisourate, catalyzed by Uricase entrapped in a dual-ionic-layer hydrogel membrane casted onto the gate. The sensor response is based on the catalytic oxidation of the hydrogen peroxide, generated as part of the Uricase regeneration process, at the Pt modified gate. The proposed dual membrane avoids the occurrence of nonspecific faradic reactions as, for example, the direct oxidation of UA or other electroactive molecules that would introduce a potentially false negative response. The biosensor is robust and its response is reproducible both in phosphate buffer saline and in complex solutions mimicking the wound exudate. The sensor has a high sensitivity in the range encompassing the pathological levels of UA in wounds (<200 μm) exhibiting a limit of detection of 4.5 μm in artificial wound exudate. All these characteristics make this OECT-based biosensor attractive for wound monitoring interfaced to the patient.
2020
- Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor
[Articolo su rivista]
Parkula, Vitaliy; Berto, Marcello; Diacci, Chiara; Patrahau, Bianca; Di Lauro, Michele; Kovtun, Alessandro; Liscio, Andrea; Sensi, Matteo; Samorì, Paolo; Greco, Pierpaolo; Bortolotti, Carlo A; Biscarini, Fabio
abstract
Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 μL microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNFα, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics.
2020
- Label-free immunodetection of α-synuclein by using a microfluidics coplanar electrolyte-gated organic field-effect transistor
[Articolo su rivista]
Ricci, S.; Casalini, S.; Parkula, V.; Selvaraj, M.; Saygin, G. D.; Greco, P.; Biscarini, F.; Mas-Torrent, M.
abstract
The aggregation of α-synuclein is a critical event in the pathogenesis of neurological diseases, such as Parkinson or Alzheimer. Here, we present a label-free sensor based on an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) integrated with microfluidics that allows for the detection of amounts of α-synuclein in the range from 0.25 pM to 25 nM. The lower limit of detection (LOD) measures the potential of our integrated device as a tool for prognostics and diagnostics. In our device, the gate electrode is the effective sensing element as it is functionalised with anti-(α-synuclein) antibodies using a dual strategy: i) an amino-terminated self-assembled monolayer activated by glutaraldehyde, and ii) the His-tagged recombinant protein G. In both approaches, comparable sensitivity values were achieved, featuring very low LOD values at the sub-pM level. The microfluidics engineering is central to achieve a controlled functionalisation of the gate electrode and avoid contamination or physisorption on the organic semiconductor. The demonstrated sensing architecture, being a disposable stand-alone chip, can be operated as a point-of-care test, but also it might represent a promising label-free tool to explore in-vitro protein aggregation that takes place during the progression of neurodegenerative illnesses.
2020
- Morphological Transitions in Organic Ultrathin Film Growth Imaged by in Situ Step-by-Step Atomic Force Microscopy
[Articolo su rivista]
Chiodini, S.; Straub, A.; Donati, S.; Albonetti, C.; Borgatti, F.; Stoliar, P.; Murgia, M.; Biscarini, F.
abstract
In situ atomic force microscopy (AFM) allowed us to investigate the evolution at the early stages of the growth of organic thin films. An ultrahigh-vacuum atomic force microscope, integrated with a Knudsen effusion cell for the sublimation of α-sexithiophene (6T), continuously scans the same region during the deposition of sublimed molecules on native silicon oxide as a function of the substrate temperature. Noncontact AFM images acquired sequentially provide snapshots of the time evolution of the film morphology that is monitored up to the deposition of five monolayers. At all substrate temperatures, a Stranski-Krastanov growth mode of organic films is observed: the first two monolayers grow layer-by-layer (two-dimensional - 2D), then films evolve into islands (three-dimensional - 3D). Despite the apparent similarity, we find an anomalous dynamic scaling characterized by the abrupt change of the growth exponent β vs substrate temperature. This novel transition, induced by the substrate temperature, is ascribed to the morphological transition from ziggurat islands to large terraces. The analysis of the evolution of the root-mean-square (RMS) roughness based on the distributed growth model underlines the role of down-hill mass transport for the growth of the first two monolayers, transport that is progressively hindered for the next monolayers.
2020
- Nanodecoration of electrospun polymeric fibers with nanostructured silver coatings by ionized jet deposition for antibacterial tissues
[Articolo su rivista]
Pagnotta, G.; Graziani, G.; Baldini, N.; Maso, A.; Focarete, M. L.; Berni, M.; Biscarini, F.; Bianchi, M.; Gualandi, C.
abstract
Silver-based nanomaterials are used as antibacterial agents in a number of applications, including wound dressing, where electrospun materials can effectively promote wound healing and tissue regeneration thanks to their biomimicry, flexibility and breathability. Incorporation of such nanomaterials in electrospun nonwovens is highly challenging if aiming at maximizing stability and antibacterial efficacy and minimizing silver detachment, without neglecting process straightforwardness and scalability. In this work nanostructured silver coatings were deposited by Ionized Jet Deposition (IJD) on Polylactic acid, a medical grade polyester-urethane and Polyamide 6,6 nanofibers. The resulting materials were thoroughly characterized to gain an in-depth view of coating morphology and substrate resistance to the low-temperature deposition process used. Morphology of silver coatings with well-cohesive grains having dimensions from a few tens to a few hundreds of nanometers was analyzed by SEM, TEM and AFM. TGA, DSC, FTIR and GPC showed that the polymers well withstand the deposition process with negligible effects on their properties, the only exception being the polylactic acid that resulted more susceptible to degradation. Finally, the efficacy against S. aureus and E. coli bacterial strains was demonstrated, indicating that electrospun fibers decorated with nanostructured silver by IJD represent a breakthrough solution in the field of antibacterial devices.
2020
- Neuromorphic Organic Devices that Specifically Discriminate Dopamine from Its Metabolites by Nonspecific Interactions
[Articolo su rivista]
Giordani, M.; Sensi, M.; Berto, M.; Di Lauro, M.; Bortolotti, C. A.; Gomes, H. L.; Zoli, M.; Zerbetto, F.; Fadiga, L.; Biscarini, F.
abstract
Specific detection of dopamine (DA) is achieved with organic neuromorphic devices with no specific recognition function in an electrolyte solution. The response to voltage pulses consists of amplitude-depressed current spiking mimicking the short-term plasticity (STP) of synapses. An equivalent circuit hints that the STP timescale of the device arises from the capacitance and resistance of the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) in series with the electrolyte resistance. Both the capacitance and resistance of PEDOT:PSS change with solution compositions. Dose curves are constructed from the STP timescale for each DA metabolite from pM to mM range of concentrations. The STP response of DA is distinctive from the other metabolites even when differences are by one functional group. Both STP and sensitivity to DA are larger across the patho-physiological range with respect to those to DA metabolites. Density functional theory calculations hint to a stronger hydrogen bond pattern of DA ammonium compared to cationic metabolites. The exponential correlation between STP and the binding energy of DA metabolites interacting with PEDOT:PSS indicates that the slow dynamics of ionic species in and out PEDOT:PSS is the origin of the neuromorphic STP. The sensing framework discriminates differences of nonspecific interactions of few kcal mol−1, corresponding to one functional group in the molecule.
2020
- Neuromorphic Organic Devices: Neuromorphic Organic Devices that Specifically Discriminate Dopamine from Its Metabolites by Nonspecific Interactions (Adv. Funct. Mater. 28/2020)
[Altro]
Giordani, Martina; Sensi, Matteo; Berto, Marcello; Di Lauro, Michele; Bortolotti, Carlo Augusto; Gomes, Henrique Leonel; Zoli, Michele; Zerbetto, Francesco; Fadiga, Luciano; Biscarini, Fabio
abstract
2020
- Photovoltage generation in enzymatic bio-hybrid architectures
[Articolo su rivista]
Di Lauro, M.; Buscemi, G.; Bianchi, M.; de Salvo, A.; Berto, M.; Carli, S.; Farinola, G. M.; Fadiga, L.; Biscarini, F.; Trotta, M.
abstract
Most of the photochemical activity of bacterial photosynthetic apparatuses occurs in the reaction center, a transmembrane protein complex which converts photons into charge-separated states across the membrane with a quantum yield close to unity, fuelling the metabolism of the organism. Integrating the reaction center from the bacterium Rhodobacter sphaeroides onto electroactive surfaces, it is possible to technologically exploit the efficiency of this natural machinery to generate a photovoltage upon Near Infra-Red illumination, which can be used in electronic architectures working in the electrolytic environment such as electrolyte-gated organic transistors and bio-photonic power cells. Here, photovoltage generation in reaction center-based bio-hybrid architectures is investigated by means of chronopotentiometry, isolating the contribution of the functionalisation layers and defining novel surface functionalization strategies for photovoltage tuning.
2020
- Quantitative phase-mode electrostatic force microscopy on silicon oxide nanostructures
[Articolo su rivista]
Albonetti, C.; Chiodini, S.; Annibale, P.; Stoliar, P.; Martinez, R. V.; Garcia, R.; Biscarini, F.
abstract
Phase-mode electrostatic force microscopy (EFM-Phase) is a viable technique to image surface electrostatic potential of silicon oxide stripes fabricated by oxidation scanning probe lithography, exhibiting an inhomogeneous distribution of localized charges trapped within the stripes during the electrochemical reaction. We show here that these nanopatterns are useful benchmark samples for assessing the spatial/voltage resolution of EFM-phase. To quantitatively extract the relevant observables, we developed and applied an analytical model of the electrostatic interactions in which the tip and the surface are modelled in a prolate spheroidal coordinates system, fitting accurately experimental data. A lateral resolution of ∼60 nm, which is comparable to the lateral resolution of EFM experiments reported in the literature, and a charge resolution of ∼20 electrons are achieved. This electrostatic analysis evidences the presence of a bimodal population of trapped charges in the nanopatterned stripes.
2020
- Scaling of capacitance of PEDOT:PSS: Volume: Vs. area
[Articolo su rivista]
Bianchi, M.; Carli, S.; Di Lauro, M.; Prato, M.; Murgia, M.; Fadiga, L.; Biscarini, F.
abstract
Poly(3,4-ethylentedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most studied materials for organic bioelectronics, supercapacitors and organic photovoltaics. Its low impedance is ascribed to the so-called volumetric capacitance, a property that phenomenologically correlates the capacitive coupling/charge storage in devices to the PEDOT:PSS volume/thickness. Here we investigate the correlation between the capacitance and the electroactive surface area (ESA) for large-volume spin-cast PEDOT:PSS electrodes. We measure the capacitance with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and characterize the surface morphology by atomic force microscopy and X-ray photoelectron spectroscopy. Capacitance of PEDOT:PSS films scales with volume up to ∼5 × 106 μm3 but is saturated at larger volumes. This scaling behavior is paralleled by the scaling of the ESA, hence the ratio between the effective capacitance and ESA remains constant across the whole data set, thus showing that the specific areal capacitance is indeed the relevant material property of PEDOT:PSS. EIS data fit supports the experimental evidence obtained by CV, further revealing that the diffusion time constant is also saturated at high volumes. This supports the scenario where the effective capacitance relates to the ion accessible ESA, and shows that the saturation of the capacitance arises from a change of ion penetration from a diffusive (at small volumes) to a non-diffusive regime at large volumes.
2020
- The pulsed electron deposition technique for biomedical applications: A review
[Articolo su rivista]
Liguori, A.; Gualandi, C.; Focarete, M. L.; Biscarini, F.; Bianchi, M.
abstract
The "pulsed electron deposition" (PED) technique, in which a solid target material is ablated by a fast, high-energy electron beam, was initially developed two decades ago for the deposition of thin films of metal oxides for photovoltaics, spintronics, memories, and superconductivity, and dielectric polymer layers. Recently, PED has been proposed for use in the biomedical field for the fabrication of hard and soft coatings. The first biomedical application was the deposition of low wear zirconium oxide coatings on the bearing components in total joint replacement. Since then, several works have reported the manufacturing and characterization of coatings of hydroxyapatite, calcium phosphate substituted (CaP), biogenic CaP, bioglass, and antibacterial coatings on both hard (metallic or ceramic) and soft (plastic or elastomeric) substrates. Due to the growing interest in PED, the current maturity of the technology and the low cost compared to other commonly used physical vapor deposition techniques, the purpose of this work was to review the principles of operation, the main applications, and the future perspectives of PED technology in medicine.
2020
- Tribological response of laser-textured steel pins with low-dimensional micrometric patterns
[Articolo su rivista]
Fiaschi, G.; Di Lauro, M.; Ballestrazzi, A.; Rota, A.; Biscarini, F.; Valeri, S.
abstract
Our purpose was to study the tribological eects of surface texturing at the mesoscale, generally disregarded. We realized hemispherical dimples on 100Cr6 steel pins using a ns-pulsed Nd:YAG laser. Both radius and depth of the patterns fall in the very-low part of the micrometric scale, ranging respectively from 10 to 13 m and from 4 to 6.5 m. To map Stribeck curves, we used a pin-on-disk apparatus and a commercial motor oil as lubricant. The results conrm that the post-texturing lapping process is crucial to achieve a reduction in the coecient of friction. These patterns show a tribological eect mainly in mixed lubrication regime, and partially in hydrodynamic regime. Even very small dierences in radius and depth may induce very dierent response, evidencing the need of very ne tuning of the geometrical characteristics of the patterns. The lower friction was recorded for larger and deeper dimples. Friction reduction for increasing dimples density has been found as well. Endurance tests in boundary lubrication regime show a more stable coecient of friction and a larger mean lifetime of patterned surfaces with respect to polished one. Furthermore, water-contact-angle tests show a weak hydrophobic eect for high aspect ratio patterns. However, no correlation was observed between wettability and tribological response.
2020
- Tunable Short-Term Plasticity Response in Three-Terminal Organic Neuromorphic Devices
[Articolo su rivista]
Di Lauro, M.; De Salvo, A.; Sebastianella, G. C.; Bianchi, M.; Carli, S.; Murgia, M.; Fadiga, L.; Biscarini, F.
abstract
Reversibly tunable short-term plasticity (STP) of the channel current in organic neuromorphic devices is demonstrated with a three-terminal architecture. Electrolyte-gated organic transistors - EGOTs - are driven with square voltage pulses at the drain electrodes, while the gate bias enables the modulation of the amplitude and characteristic time scale of the depressive STP spiking response up to 1 order of magnitude. The gate potential sets the baseline and the steady-state current, preluding multilevel memory writing. The fine-tuning of the STP response, which is not possible with two-electrode organic neuromorphic devices, is reversible and does not imply chemical modifications of the active layer.
2020
- Ultra-low noise PEDOT:PSS electrodes on bacterial cellulose: A sensor to access bioelectrical signals in non-electrogenic cells
[Articolo su rivista]
Inacio, P. M. C.; Medeiros, M. C. R.; Carvalho, T.; Felix, R. C.; Mestre, A.; Hubbard, P. C.; Ferreira, Q.; Morgado, J.; Charas, A.; Freire, C. S. R.; Biscarini, F.; Power, D. M.; Gomes, H. L.
abstract
This study is focused on the particular advantages of organic-based devices to measure cells that do not generate action potentials, also known as non-electrogenic cells. While there is a vast literature about the application of organic conductors to measure neurons, cardiomyocytes and brain tissues, electrical measurements of non-electrogenic cells are rare. This is because non-electrogenic cells generate weak signals with frequencies below 1 Hz. Designing low noise devices in a millihertz frequency range is extremely challenging due to the intrinsic thermal and 1/f type noise generated by the sensing electrode. Here, we demonstrate that the coating of cellulose nanofibers with conducting PEDOT:PSS ink allows the fabrication of a nanostructured surface that establishes a low electrical double-layer resistance with liquid solutions. The low interfacial resistance combined with the large effective sensing area of PEDOT:PSS electrodes minimizes the thermal noise and lowers the amplitude detection limit of the sensor. The electrode noise decreases with frequency from 548 nV r.m.s at 0.1 Hz to a minimum of 6 nV r.m.s for frequencies higher than 100 Hz. This low noise makes it possible to measure low frequency bioelectrical communication signals, typical of non-electrogenic cells, that have until now been difficult to explore using metallic-based microelectrode arrays. The performance of the PEDOT:PSS-based electrodes is demonstrated by recording signals generated by populations of glioma cells with a signal-to-noise ratio as high as 140.
2020
- Water-Based PEDOT:Nafion Dispersion for Organic Bioelectronics
[Articolo su rivista]
Carli, S.; Di Lauro, M.; Bianchi, M.; Murgia, M.; De Salvo, A.; Prato, M.; Fadiga, L.; Biscarini, F.
abstract
The water dispersion of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is one of the most used material precursors in organic electronics also thanks to its industrial production. There is a growing interest for conductive polymers that could be alternative surrogates or replace PEDOT:PSS in some applications. A recent study by our group compared electrodeposited PEDOT:Nafion vs PEDOT:PSS in the use for neural recordings. Here, we introduce an easy and reproducible synthetic protocol to prepare a water dispersion of PEDOT:Nafion. The conductivity of the pristine material is on the order of 2 S cm-1 and was improved up to ≈6 S cm-1 upon treatment with ethylene glycol. Faster ion transfer was assessed by electrochemical impedance spectroscopy (EIS), and, interestingly, an improved adhesion was observed for coatings of the new PEDOT:Nafion dispersion on glass substrates, even without the addition of the silane cross-linker needed for PEDOT:PSS. As proof of concept, we demonstrate the use of this novel water dispersion of PEDOT:Nafion in three different organic electronic device architectures, namely, an organic electrochemical transistor (OECT), a memristor, and an artificial synapse.
2019
- Biosensing with Electrolyte Gated Organic Field Effect Transistors
[Capitolo/Saggio]
Bortolotti, Carlo Augusto; Berto, Marcello; Sensi, Matteo; DI LAURO, Michele; Biscarini, Fabio
abstract
Electrolyte Gated Organic Field Effect Transistors (EGOFETs) are rapidly emerging as novel players in the field of biosensing: they allow ultra-sensitive, label-free and fast response, and can be employed to sense very diverse analytes, from small molecules to large multimeric proteins. Here, we present the current level of understanding of the working mechanism of EGOFETs, and review some of the most recent and relevant applications as sensors for healthcare and life sciences, discussing advantages and limitations of this technology. EGOFETs appear as a powerful sensing platform that can be readily adapted to the detection of a wide range of biologically relevant species.
2019
- EGOFET Gated by a Molecular Electronic Switch: A Single-Device Memory Cell
[Articolo su rivista]
Parkula, V.; Maglione, M. S.; Casalini, S.; Zhang, Q.; Greco, P.; Bortolotti, C. A.; Rovira, C.; Mas-Torrent, M.; Biscarini, F.
abstract
Electrolyte-gated organic field-effect transistors (EGOFETs) exploit the transduction of interfacial phenomena, such as biorecognition or redox processes, into detectable changes of electrical response. Here, it is shown that, beyond sensing applications, EGOFETs may act effectively as memory devices, through the functionalization of the gate electrode with a self-assembly monolayer comprising a switching molecule undergoing a large and persistent change of dipole moment, upon application of a small (0.6 V) programming potential. This first example of a switchable EGOFET device with memory retention is based on a tetrathiafulvalene derivative self-assembled on gold and an aqueous buffer as electrolyte in a microfluidic assembly. Changes of the self-assembled monolayer redox state lead to variations of the gate electrochemical potential and, as a consequence, the EGOFET's threshold voltage undergoes reversible shifts larger than 100 mV. The distinctive electrical readout upon different redox states opens the possibility of writing and erasing information, thus making the transistor behave as a single memory cell.
2019
- Electrodeposited PEDOT:Nafion Composite for Neural Recording and Stimulation
[Articolo su rivista]
Carli, S.; Bianchi, M.; Zucchini, E.; Di Lauro, M.; Prato, M.; Murgia, M.; Fadiga, L.; Biscarini, F.
abstract
Microelectrode arrays are used for recording and stimulation in neurosciences both in vitro and in vivo. The electrodeposition of conductive polymers, such as poly(3,4-ethylene dioxythiophene) (PEDOT), is widely adopted to improve both the in vivo recording and the charge injection limit of metallic microelectrodes. The workhorse of conductive polymers in the neurosciences is PEDOT:PSS, where PSS represents polystyrene-sulfonate. In this paper, the counterion is the fluorinated polymer Nafion, so the composite PEDOT:Nafion is deposited onto a flexible neural microelectrode array. PEDOT:Nafion coated electrodes exhibit comparable in vivo recording capability to the reference PEDOT:PSS, providing a large signal-to-noise ratio in a murine animal model. Importantly, PEDOT:Nafion exhibits a minimized polarization during electrical stimulation, thereby resulting in an improved charge injection limit equal to 4.4 mC cm−2, almost 80% larger than the 2.5 mC cm−2 that is observed for PEDOT:PSS.
2019
- Interface Engineering in Organic Devices
[Articolo su rivista]
Samori, P.; Biscarini, F.
abstract
2019
- Label free detection of plant viruses with organic transistor biosensors
[Articolo su rivista]
Berto, Marcello; Vecchi, Eugenia; Baiamonte, Luca; Condò, Carla; Sensi, Matteo; Di Lauro, Michele; Sola, Marco; De Stradis, Angelo; Biscarini, Fabio; Minafra, Angelantonio; Bortolotti, Carlo Augusto
abstract
Plum Pox Virus (PPV) is the pathogen responsible for Sharka, a highly infectious disease affecting stone fruit trees and causing severe economic damages, which can be only contained through early-detection and frequent monitoring. We propose a bioelectronic PPV biosensor, based on a electrolyte-gated organic field-effect transistor (EGOFET), for the specific detection of PPV in plant extracts with a sub ng/ml detection limit. The sensing unit of the biosensor is based on anti-PPV antibodies, uniformly oriented on the gold gate electrode by using a sub-monolayer of Protein G. The sensitivity and dynamic range of the EGOFET-based biosensor are comparable to those of commercially available platforms for detection of plant pathogens. This novel electronic immunosensor is compatible with low-cost fabrication procedures and can be easily reconfigured into a fully portable device to be operated in greenhouse and in the field orchards.
2019
- Modulating the Faradic Operation of All-Printed Organic Electrochemical Transistors by Facile in Situ Modification of the Gate Electrode
[Articolo su rivista]
Sensi, Matteo; Berto, Marcello; Candini, Andrea; Liscio, Andrea; Cossarizza, Andrea; Beni, Valerio; Biscarini, Fabio; Bortolotti, Carlo Augusto
abstract
Organic electrochemical transistors (OECTs) operated in the faradic regime were shown as outperforming transducers of bioelectric signals in vitro and in vivo. Fabrication by additive manufacturing techniques fosters OECTs as ideal candidates for point-of-care applications, as well as imposes limitations on the choice of materials and their processing conditions. Here, we address the question of how the response of fully printed OECTs depends on gate electrode material. Toward this end, we investigate the redox processes underlying the operation of OECTs under faradic regime, to show OECTs with carbon gate (C-gate) that exhibit no current modulation gate voltages <1.2 V. This is a hallmark that no interference with the faradic operation of the device enabled by redox processes occurs when operating C-gate OECTs in the low-voltage range as label-free biosensors for the detection of electroactive (bio)molecules. To tune the faradic response of the device, we electrodeposited Au on the carbon gate (Au-C-gate), obtaining a device that operates at lower gate voltage values than C-gate OECT. The presence of gold on the gate allowed further modification of the electrical performances by functionalization of the Au-C-gate with different self-assembled monolayers by fast potential-pulse-assisted method. Moreover, we show that the presence in the electrolyte solution of an external redox probe can be used to drive the faradic response of both C- and Au-C-gate OECTs, impacting on the gate potential window that yields effective drain current modulation. The results presented here suggest possible new strategies for controlling the faradic operation regime of OECTs sensors by chemical modification of the gate surface.
2019
- Retinoic acid/calcite micro-carriers inserted in fibrin scaffolds modulate neuronal cell differentiation
[Articolo su rivista]
Barbalinardo, M.; Di Giosia, M.; Polishchuk, I.; Magnabosco, G.; Fermani, S.; Biscarini, F.; Calvaresi, M.; Zerbetto, F.; Pellegrini, G.; Falini, G.; Pokroy, B.; Valle, F.
abstract
The controlled release of cell differentiating agents is crucial in many aspects of regenerative medicine. Here we propose the use of hybrid calcite single crystals as micro-carriers for the controlled and localized release of retinoic acid, which is entrapped within the crystalline lattice. The release of retinoic acid occurs only in the proximity of stem cells, upon dissolution of the calcite hybrid crystals that are dispersed in the fibrin scaffold. These hybrid crystals provide a sustained dosage of the entrapped agent. The environment provided by this composite scaffold enables differentiation towards neuronal cells that form a three-dimensional neuronal network.
2018
- EGOFET Peptide Aptasensor for Label-Free Detection of Inflammatory Cytokines in Complex Fluids
[Articolo su rivista]
Berto, Marcello; Diacci, Chiara; D'Agata, Roberta; Pinti, Marcello; Bianchini, Elena; Lauro, Michele Di; Casalini, Stefano; Cossarizza, Andrea; Berggren, Magnus; Simon, Daniel; Spoto, Giuseppe; Biscarini, Fabio; Bortolotti, Carlo A.
abstract
Organic electronic transistors are rapidly emerging as ultrahigh sensitive
label-free biosensors suited for point-of-care or in-field deployed applications.
Most organic biosensors reported to date are based on immunorecognition
between the relevant biomarkers and the immobilized antibodies, whose use
is hindered by large dimensions, poor control of sequence, and relative instability.
Here, an electrolyte-gated organic field effect transistor (EGOFET) biosensor
where the recognition units are surface immobilized peptide aptamers
(Affimer proteins) instead of antibodies is reported. Peptide aptasensor for
the detection of the pro-inflammatory cytokine tumor necrosis factor alpha
(TNFα) with a 1 × 10−12 M limit of detection is demonstrated. Ultralow sensitivity
is met even in complex solutions such as cell culture media containing
10% serum, demonstrating the remarkable ligand specificity of the device.
The device performances, together with the simple one-step immobilization
strategy of the recognition moieties and the low operational voltages, all
prompt EGOFET peptide aptasensors as candidates for early diagnostics and
monitoring at the point-of-care.
2018
- Exploiting interfacial phenomena in organic bioelectronics: Conformable devices for bidirectional communication with living systems
[Articolo su rivista]
Di Lauro, Michele; Benaglia, Simone; Berto, Marcello; Bortolotti, Carlo A.; Zoli, Michele; Biscarini, Fabio
abstract
A novel fully organic bioelectronic device is presented and validated as electronic transducer and current stimulator for brain implants. The device integrates polymeric electrodes made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) on paper thin foils, resulting in a high surface-to-volume ratio architecture that exhibits high sensitivity to interfacial ionic transport phenomena. The prototyping technique herein presented yields devices for the bidirectional communication with biological systems whose dimensionality can be controlled according to the desired application. Transduction of ultra-low local-field potentials and delivery of voltage pulse-trains alike those used in deep-brain stimulation are herein assessed, paving the way towards novel theranostic strategies for the treatment of Parkinson's Disease and other severe neurodegenerative and/or traumatic pathologies of the central nervous system.
2018
- Insulin amyloid structures and their influence on neural cells
[Articolo su rivista]
Bystrenova, Eva; Bednarikova, Zuzana; Barbalinardo, Marianna; Valle, Francesco; Gazova, Zuzana; Biscarini, Fabio
abstract
Peptide aggregation into oligomers and fibrillar architectures is a hallmark of severe neurodegenerative pathologies, diabetes mellitus or systemic amyloidoses. The polymorphism of amyloid forms and their distribution are both effectors that potentially modulate the disease, thus it is important to understand the molecular basis of protein amyloid disorders through the interaction of the different amyloid forms with neural cells and tissues. Here we explore the effect of amyloid fibrils on the human neuroblastoma (SH-SY5Y) cell line in vitro. We control the kinetic of fibrillization of insulin at low pH and higher temperature. We use a multiscale characterization via fluorescence microscopy and multimodal scanning probe microscopy to correlate the number of cells and their morphology, with the finer details of the insulin deposits. Our results show that insulin aggregates deposited on neuroblastoma cell cultures lead to a progressive modification and decreased number of cells that correlates with the degree of fibrillization. SPM unravels that the aggregates strongly interact with the cell membrane, forming a stiff encase that possibly leads to an increased cell membrane stiffness and deficit in the metabolic exchanges between the cells and their environment. The presence of fibrils does not affect the number of cells at 24 h whereas drop down to 60% is observed after 48 h of incubation.
2018
- Label free urea biosensor based on organic electrochemical transistors
[Articolo su rivista]
Berto, Marcello; Diacci, Chiara; Theuer, Lorenz; Di Lauro, Michele; Simon, Daniel T.; Berggren, Magnus; Biscarini, Fabio; Beni, Valerio; Bortolotti, Carlo A.
abstract
The quantification of urea is of the utmost importance not only in medical diagnosis, where it serves as a potential indicator of kidney and liver disfunction, but also in food safety and environmental control. Here, we describe a urea biosensor based on urease entrapped in a crosslinked gelatin hydrogel, deposited onto a fully printed PEDOT:PSS-based organic electrochemical transistor (OECT). The device response is based on the modulation of the channel conductivity by the ionic species produced upon urea hydrolysis catalyzed by the entrapped urease. The biosensor shows excellent reproducibility, a limit of detection as low as 1 μM and a response time of a few minutes. The fabrication of the OECTs by screen-printing on flexible substrates ensures a significant reduction in manufacturing time and costs. The low dimensionality and operational voltages (0.5 V or below) of these devices contribute to make these enzymatic OECT-based biosensors as appealing candidates for high-throughput monitoring of urea levels at the point-of-care or in the field.
2018
- Nanomaterials properties tuned by their environment: Integrating supramolecular concepts into sensing devices
[Articolo su rivista]
Samori, P.; Biscarini, F.
abstract
2017
- Asymmetric Injection in Organic Transistors via Direct SAM Functionalization of Source and Drain Electrodes
[Articolo su rivista]
Mosciatti, Thomas; Greco, Pierpaolo; Leydecker, Tim; Eredia, Matilde; Biscarini, Fabio; Samorì, Paolo
abstract
The fabrication of organic optoelectronic devices integrating asymmetric electrodes enables optimal charge injection/extraction at each individual metal/semiconductor interface. This is key for applications in devices such as solar cells, light-emitting transistors, photodetectors, inverters, and sensors. Here, we describe a new method for the asymmetric functionalization of gold electrodes with different thiolated molecules as a viable route to obtain two electrodes with drastically different work function values. The process involves an ad hoc design of electrode geometry and the use of a polymeric mask to protect one electrode during the first functionalization step. Photoelectron yield ambient spectroscopy and X-ray photoelectron spectrometry were used to characterize the energetic properties and the composition of the asymmetrically functionalized electrodes. Finally, we used poly(3-hexylthiophene)-based organic thin-film transistors to show that the asymmetric electronic response stems from the different electronic structures of the functionalized electrodes.
2017
- Bioelectrical signal detection using conducting polymer electrodes and the displacement current method
[Articolo su rivista]
Inacio, Pedro; Mestre, Ana; de Medeiros, Maria; Asgarifar, Sanaz; Canudo, Joana; Elamine, Youssef; Santos, Joao; Morgado, Jorge; Braganca, Jose; Biscarini, Fabio; Gomes, Henrique
abstract
Conducting polymer electrodes based on poly(3,4- ethylenedioxythiophene):polystyrene sulfonate were used to record electrophysiological signals from autonomous cardiac contractile cells present in embryoid bodies. Signal detection was carried-out by measuring the displacement current across the polymer/electrolyte double-layer capacitance, and compared with voltage detection. While for relatively low capacitance electrodes the voltage amplification provides higher signal quality, for high capacitive electrodes the displacement current method exhibits a higher signal-to-noise ratio. It is proposed that the displacement current method combined with high capacitive polymer-based electrodes is adequate to measure clusters of cells and whole organs. Our approach has a great potential in fundamental studies of drug discovery and safety pharmacology.
2017
- Interfacing Polymers and Tissues: Quantitative Local Assessment of the Foreign Body Reaction of Mononuclear Phagocytes to Polymeric Materials
[Articolo su rivista]
Giusto, Elena; Donegà, Matteo; Dumitru, Andra C.; Foschi, Giulia; Casalini, Stefano; Bianchi, Michele; Leonardi, Tommaso; Russo, Alessandro; Occhipinti, Luigi G.; Biscarini, Fabio; Garcia, Ricardo; Pluchino, Stefano
abstract
A quantitative method to assess the in vitro foreign body reaction (FBR) of mononuclear phagocytes (MP) to polymers relevant in implants for prosthetics, advanced therapies, and regenerative medicine is presented. It integrates single-cell force spectroscopy (SCFS) with immunogenic profiles of the MPs. In cell force spectroscopy experiments a single phagocyte, linked at the end of an atomic force microscopy cantilever, probes the adhesion forces between the cell and the polymer surface. SCFS measures adhesion forces in a range from 10 pN to 100 nN and with spatial resolution from cell size down to nanometers, accessing the early adhesion events established at contact times between milliseconds and minutes. The time evolution within the first 60 s of the adhesion force between the phagocyte and the polymer surface before and after the treatment with an immunosuppressive drug, viz. Minocycline, a Federal Drug Administration (FDA)-approved third generation tetracycline with anti-inflammatory effects, is then studied. The adhesion force values measured at the single cell level is shown to correlate to the immunogenic profiles obtained by analysis of biomarkers and morphology of the MPs in culture. Also, Minocycline causes a decrease of both proinflammatory gene expression profiles and adhesive forces of single cells.
2017
- Label-free detection of interleukin-6 using electrolyte gated organic field effect transistors
[Articolo su rivista]
Diacci, Chiara; Berto, Marcello; Di Lauro, Michele; Bianchini, Elena; Pinti, Marcello; Simon, Daniel T.; Biscarini, Fabio; Bortolotti, Carlo A.
abstract
Cytokines are small proteins that play fundamental roles in inflammatory processes in the human body. In particular, interleukin (IL)-6 is a multifunctional cytokine, whose increased levels are associated with infection, cancer, and inflammation. The quantification of IL-6 is therefore of primary importance in early stages of inflammation and in chronic diseases, but standard techniques are expensive, time-consuming, and usually rely on fluorescent or radioactive labels. Organic electronic devices and, in particular, organic field-effect transistors (OFETs) have been proposed in the recent years as novel platforms for label-free protein detection, exploiting as sensing unit surface-immobilized antibodies or aptamers. Here, the authors report two electrolyte-gated OFETs biosensors for IL-6 detection, featuring monoclonal antibodies and peptide aptamers adsorbed at the gate. Both strategies yield biosensors that can work on a wide range of IL-6 concentrations and exhibit a remarkable limit of detection of 1 pM. Eventually, electrolyte gated OFETs responses have been used to extract and compare the binding thermodynamics between the sensing moiety, immobilized at the gate electrode, and IL-6.
2017
- Liquid-Gated Organic Electronic Devices Based on High-Performance Solution-Processed Molecular Semiconductor
[Articolo su rivista]
DI LAURO, Michele; Berto, Marcello; Giordani, Martina; Benaglia, Simone; Schweicher, Guillaume; Vuillaume, Dominique; Bortolotti, Carlo Augusto; Geerts, Yves H.; Biscarini, Fabio
abstract
High-mobility organic semiconductors such as [1]benzothieno[3,2-b]benzothiophene (BTBT) derivatives are potential candidates for ultrasensitive biosensors. Here 2,7-dioctyl BTBT (C8-BTBT-C8)-based liquid-gated organic electronic devices are demonstrated with two device architectures, viz. electrolyte-gated organic field-effect transistor (EGOFET) and electrolyte-gated organic synapstor (EGOS), and different electrode materials, viz. gold and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). EGOFETs exhibit a mean transconductance of about 45 µS, on a par with literature, and a max value up to 256 µS at the state-of-the-art in aqueous electrolyte, with a mean product of charge mobility and effective capacitance of about 0.112 and 0.044 µS V−1 for gold and PEDOT:PSS electrodes, respectively. EGOSs exhibit a dynamic response with 15 ms characteristic timescale with Au electrodes and about twice with PEDOT:PSS electrodes. These results demonstrate a promising route for sensing applications in physiological environment based on fully solution-processed whole-organic electronic devices featuring ultrahigh sensitivity and fast response.
2017
- Self-assembled monolayers in organic electronics
[Articolo su rivista]
Casalini, Stefano; Bortolotti, Carlo Augusto; Leonardi, Francesca; Biscarini, Fabio
abstract
Self-assembly is possibly the most effective and versatile strategy for surface functionalization. Self-assembled monolayers (SAMs) can be formed on (semi-)conductor and dielectric surfaces, and have been used in a variety of technological applications. This work aims to review the strategy behind the design and use of self-assembled monolayers in organic electronics, discuss the mechanism of interaction of SAMs in a microscopic device, and highlight the applications emerging from the integration of SAMs in an organic device. The possibility of performing surface chemistry tailoring with SAMs constitutes a versatile approach towards the tuning of the electronic and morphological properties of the interfaces relevant to the response of an organic electronic device. Functionalisation with SAMs is important not only for imparting stability to the device or enhancing its performance, as sought at the early stages of development of this field. SAM-functionalised organic devices give rise to completely new types of behavior that open unprecedented applications, such as ultra-sensitive label-free biosensors and SAM/organic transistors that can be used as robust experimental gauges for studying charge tunneling across SAMs.
2017
- Specific Dopamine Sensing Based on Short-Term Plasticity Behavior of a Whole Organic Artificial Synapse
[Articolo su rivista]
Giordani, Martina; Berto, Marcello; Di Lauro, Michele; Bortolotti, Carlo A.; Zoli, Michele; Biscarini, Fabio
abstract
In this work, we demonstrate the ultrasensitive and selective detection of dopamine by means of a neuro-inspired device platform without the need of a specific recognition moiety. The sensor is a whole organic device featuring two electrodes made of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate - PEDOT:PSS - patterned on a polydymethylsiloxane - PDMS - flexible substrate. One electrode is pulsed with a train of voltage square waves, to mimic the presynaptic neuron behavior, while the other is used to record the displacement current, mimicking the postsynaptic neuron. The current response exhibits the features of synaptic Short-Term Plasticity (STP) with facilitating or depressing response according to the stimulus frequency. We found that the response characteristic time USTPdepends on dopamine (DA) concentration in solution. The dose curve exhibits superexponential sensitivity at the lowest concentrations below 1 nM. The sensor detects [DA] down to 1 pM range. We assess the sensor also in the presence of ascorbic acid (AA) and uric acid (UA). Our sensor does not respond to UA, but responds to AA only at concentration above 100 μM. However, it is still able to detect DA down to 1 pM range in the presence of [AA] = 100 μM and 100 pM in the presence of [UA] = 3 μM, these values for AA and UA being the physiological levels in the cerebrospinal fluid and the striatum, respectively.
2016
- An electrical method to measure low-frequency collective and synchronized cell activity using extracellular electrodes
[Articolo su rivista]
Medeiros, Maria C. R.; Mestre, Ana; Inácio, Pedro; Asgarif, Sanaz; Araújo, Inês M.; Hubbard, Peter C.; Velez, Zélia; Cancela, M. Leonor; Rocha, Paulo R. F.; de Leeuw, Dago M.; Biscarini, Fabio; Gomes, Henrique L.
abstract
An electrical method to measure extracellular bioelectrical activity in vitro is presented. This method exploits the Helmholtz capacitive double-layer established at the electrode surface. Small extracellular voltage variations in the order of μVs induce through the double-layer capacitor a displacement current that is measured. This current is then enhanced by a gain factor proportional to the electrode capacitance. In addition, when measurements are carried out at low frequencies in current mode the electrode contribution to the noise can be minimized. The performance of the electrodes and the method is demonstrated using zebrafish hearts and glioma cell cultures. We propose that this electrical method is an ideal tool to measure in vitro slow and temporally synchronized events that are often involved in long range intracellular signaling.
2016
- Biorecognition in Organic Field Effect Transistors Biosensors: The Role of the Density of States of the Organic Semiconductor
[Articolo su rivista]
Berto, Marcello; Casalini, Stefano; Di Lauro, Michele; Marasso, Simone L; Cocuzza, Matteo; Perrone, Denis; Pinti, Marcello; Cossarizza, Andrea; Pirri, Candido F; Simon, Daniel T; Berggren, Magnus; Zerbetto, Francesco; Bortolotti, Carlo Augusto; Biscarini, Fabio
abstract
Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNFα at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNFα concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNFα concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNFα in human-plasma derived samples as an example for point-of-care application.
2016
- Electric Field Promotes Pentacene Dimerization in Thin Film Transistors
[Articolo su rivista]
Matta, Micaela; Biscarini, Fabio; Zerbetto, Francesco
abstract
Density functional theory (DFT) calculations were used to assess the effect of electric fields of varying magnitudes and directions on the molecular structure of pentacene and other acenes. The aim is to understand the response of acenes in organic field effect transistors, specifically the structure of the first monolayer(s) deposited on the gate dielectric, where the transversal electric field and the charge carrier density are largest and charge transport occurs. Pentacene cycloaddition can be enhanced by the application of electric fields oriented along the direction of the forming bonds. Dimerization is likely to occur in low-density, disordered domains, such as grain boundaries or terrace edges. Together with other factors, dimerization could affect device performance leading to an irreversible decrease of mobility due to the creation of new trap states.
2016
- Electrochemical noise and impedance of Au electrode/electrolyte interfaces enabling extracellular detection of glioma cell populations
[Articolo su rivista]
Rocha, Paulo R. F; Schlett, Paul; Kintzel, Ulrike; Mailänder, Volker; Vandamme, Lode K. J.; Zeck, Gunther; Gomes, Henrique L.; Biscarini, Fabio; De Leeuw, Dago M.
abstract
Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 μVpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 μVpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations.
2016
- Electrolyte-gated organic synapse transistor interfaced with neurons
[Articolo su rivista]
Desbief, Simon; DI LAURO, Michele; Casalini, Stefano; Guerin, David; Tortorella, Silvia; Barbalinardo, Marianna; Kyndiah, Adrica; Murgia, Mauro; Cramer, Tobias; Biscarini, Fabio; Vuillaume, Dominique
abstract
We demonstrate an electrolyte-gated hybrid nanoparticle/organic synapstor (synapse-transistor, termed EGOS) that exhibits short-term plasticity as biological synapses. The response of EGOS makes it suitable to be interfaced with neurons: short-term plasticity is observed at spike voltage as low as 50 mV (in a par with the amplitude of action potential in neurons) and with a typical response time in the range of tens milliseconds. Human neuroblastoma stem cells are adhered and differentiated into neurons on top of EGOS. We observe that the presence of the cells does not alter short-term plasticity of the device.
2016
- Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations
[Articolo su rivista]
Rocha, Paulo R. F; Medeiros, Maria C. R; Kintzel, Ulrike; Vogt, Johannes; Araújo, Inês M; Mestre, Ana L. G; Mailänder, Volker; Schlett, Paul; Dröge, Melanie; Schneider, Leonid; Biscarini, Fabio; de Leeuw, Dago M; Gomes, Henrique L.
abstract
Glioma patients often suffer from epileptic seizures because of the tumor's impact on the brain physiology. Using the rat glioma cell line C6 as a model system, we performed long-term live recordings of the electrical activity of glioma populations in an ultrasensitive detection method. The transducer exploits large-area electrodes that maximize double-layer capacitance, thus increasing the sensitivity. This strategy allowed us to record glioma electrical activity. We show that although glioma cells are nonelectrogenic, they display a remarkable electrical burst activity in time. The low-frequency current noise after cell adhesion is dominated by the flow of Na+ ions through voltage-gated ion channels. However, after an incubation period of many hours, the current noise markedly increased. This electric bursting phenomenon was not associated with apoptosis because the cells were viable and proliferative during the period of increased electric activity. We detected a rapid cell culture medium acidification accompanying this event. By using specific inhibitors, we showed that the electrical bursting activity was prompted by extracellular pH changes, which enhanced Na+ ion flux through the psalmotoxin 1-sensitive acid-sensing ion channels. Our model of pH-triggered bursting was unambiguously supported by deliberate, external acidification of the cell culture medium. This unexpected, acidosis-driven electrical activity is likely to directly perturb, in vivo, the functionality of the healthy neuronal network in the vicinity of the tumor bulk and may contribute to seizures in glioma patients.
2016
- Performance assessment of polymer based electrodes for in vitro electrophysiological sensing: The role of the electrode impedance
[Relazione in Atti di Convegno]
Medeiros, M. C. R.; Mestre, A. L. G.; Inacio, P. M. C.; Santos, J. M. L.; Araujo, I. M.; Braganca, J.; Biscarini, F.; Gomes, H. L.
abstract
Conducting polymer electrodes based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are used to record extracellular signals from autonomous cardiac contractile cells and glioma cell cultures. The performance of these conducting polymer electrodes is compared with Au electrodes. A small-signal impedance analysis shows that in the presence of an electrolyte, both Au and polymer electrodes establish high capacitive double-layers. However, the polymer/electrolyte interfacial resistance is 3 orders of magnitude lower than the resistance of the metal/electrolyte interface. The polymer low interfacial resistance minimizes the intrinsic thermal noise and increases the system sensitivity. However, when measurements are carried out in current mode a low interfacial resistance partially acts as a short circuit of the interfacial capacitance, this affects the signal shape.
2016
- The substrate is a pH-controlled second gate of electrolyte-gated organic field-effect transistor
[Articolo su rivista]
Di Lauro, Michele; Casalini, Stefano; Berto, Marcello; Campana, Alessandra; Cramer, Tobias; Murgia, Mauro; Geoghegan, Mark Anthony; Bortolotti, Carlo Augusto; Biscarini, Fabio
abstract
Electrolyte-gated organic field-effect transistors (EGOFETs), based on ultrathin pentacene films on quartz, were operated with electrolyte solutions whose pH was systematically changed. Transistor parameters exhibit nonmonotonic variation versus pH, which cannot be accounted for by capacitive coupling through the Debye-Helmholtz layer. The data were fitted with an analytical model of the accumulated charge in the EGOFET, where Langmuir adsorption was introduced to describe the pH-dependent charge buildup at the quartz surface. The model provides an excellent fit to the threshold voltage and transfer characteristics as a function of the pH, which demonstrates that quartz acts as a second gate controlled by pH and is mostly effective from neutral to alkaline pH. The effective capacitance of the device is always greater than the capacitance of the electrolyte, thus highlighting the role of the substrate as an important active element for amplification of the transistor response.
2016
- Water-gated organic transistors on polyethylene naphthalate films
[Articolo su rivista]
de Oliveira, Rafael Furlan; Casalini, Stefano; Cramer, Tobias; Leonardi, Francesca; Ferreira, Marystela; Vinciguerra, Vincenzo; Casuscelli, Valeria; Alves, Neri; Murgia, Mauro; Occhipinti, Luigi; Biscarini, Fabio
abstract
Water-gated organic transistors have been successfully exploited as potentiometric transducers in a variety of sensing applications. The device response does not depend exclusively on the intrinsic properties of the active materials, as the substrate and the device interfaces play a central role. It is therefore important to fine-tune the choice of materials and layout in order to optimize the final device performance. Here, polyethylene naphthalate (PEN) has been chosen as the reference substrate to fabricate and test flexible transistors as bioelectronic transducers in liquid. PEN is a biocompatible substrate that fulfills the requirements for both bio-applications and micro-fabrication technology. Three different semiconducting or conducting polymer thin films employing pentacene, poly(3-hexylthiophene) or poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) were compared in terms of transconductance, potentiometric sensitivity and response time. The different results allow us to identify material properties crucial for the optimization of organic transistor-based transducers operating in water.
2016
- Whole organic electronic synapses for dopamine detection
[Relazione in Atti di Convegno]
Giordani, Martina; DI LAURO, Michele; Berto, Marcello; Bortolotti, Carlo Augusto; Vuillaume, Dominique; Gomes, Henrique L.; Zoli, Michele; Biscarini, Fabio
abstract
A whole organic artificial synapse has been fabricated by patterning PEDOT:PSS electrodes on PDMS that are biased in frequency to yield a STP response. The timescale of the STP response is shown to be sensitive to the concentration of dopamine, DA, a neurotransmitter relevant for monitoring the development of Parkinson's disease and potential locoregional therapies. The sensitivity of the sensor towards DA has been validated comparing signal variation in the presence of DA and its principal interfering agent, ascorbic acid, AA. The whole organic synapse is biocompatible, soft and flexible, and is attractive for implantable devices aimed to real-time monitoring of DA concentration in bodily fluids. This may open applications in chronic neurodegenerative diseases such as Parkinson's disease.
2015
- Amorphous Aggregation of Amyloid Beta 1-40 Peptide in Confined Space
[Articolo su rivista]
Foschi, Giulia; Albonetti, Cristiano; Liscio, Fabiola; Milita, Silvia; Greco, Pierpaolo; Biscarini, Fabio
abstract
The amorphous aggregation of Aβ1-40 peptide is addressed by using micromolding in capillaries. Both the morphology and the size of the aggregates are modulated by changing the contact angle of the sub-micrometric channel walls. Upon decreasing the hydrophilicity of the channels, the aggregates change their morphology from small aligned drops to discontinuous lines, thereby keeping their amorphous structure. Aβ1-40 fibrils are observed at high contact angles.
2015
- Changes of the Molecular Structure in Organic Thin Film Transistors during Operation
[Articolo su rivista]
Liscio, Fabiola; Ferlauto, Laura; Matta, Micaela; Pfattner, Raphael; Murgia, Mauro; Rovira, Concepció; Mas Torrent, Marta; Zerbetto, Francesco; Milita, Silvia; Biscarini, Fabio
abstract
Thin films of organic semiconductors have been widely studied at different length scales for improving the electrical response of devices based on them. Hitherto, a lot of knowledge has been gained about how molecular packing, morphology, grain boundaries, and defects affect the charge transport in organic thin film transistors. However, little is known about the impact of an electric field on the organic semiconductor microstructure and the consequent effect on the device performances. To fill this gap, we investigated the evolution of the structure of pentacene thin film transistors during device operation by in situ real time X-ray diffraction measurements and theoretical calculations. We observed for the first time the occurrence of a reversible structural strain taking place during the bias application mainly due to reorientation at the terrace edges of monolayer islands under the effect of electrical field. Strain exhibits the same trend of the threshold voltage hinting to the existence of a direct correlation between the phenomenon of bias stress and the structural modification.
2015
- Charge Transfer and Percolation in C60/Pentacene Field-Effect Transistors
[Articolo su rivista]
Kyndiah, Adrica; Cramer, Tobias; Albonetti, Cristiano; Liscio, Fabiola; Chiodini, Stefano; Murgia, Mauro; Biscarini, Fabio
abstract
Charge transfer at organic-organic heterojunctions is fundamental to several organic electronics devices, including light-emitting diodes, photovoltaic cells, light-emitting transistors, and ambipolar field-effect transistors. Here, probe charge transfer (CT) processes during the formation of an organic-organic heterojunction are probed by performing in situ real-time electrical characterization during the growth of pentacene/C60 ambipolar transistors. N-type C60 channel formation follows two different percolation pathways, one being associated to linear C60 structures growing along pentacene grain boundaries and the other to C60 island percolation. Upon n-channel formation a shift of pentacene p-type transfer characteristics is observed, which is attributed to CT across the heterojunction interface as a result of Fermi level alignment. The findings allow estimation of the energy of thermally accessible CT-states and their mobility along the interface. Finally, a model is proposed that relates the amount of transferred charge to details in the bilayer morphology and layer thicknesses. The model relies on the capacitive coupling between C60 and pentacene in the accumulation layer, which is consistent with a single hole transport channel.
2015
- Charge density increase in submonolayer organic field-effect transistors
[Articolo su rivista]
Cramer, T.; Kyndiah, A.; Kloes, A.; Murgia, Mauro; Fraboni, B.; Biscarini, Fabio
abstract
Interface confinement plays a central role in charge carrier accumulation and transport along the channel of organic field-effect transistors. Understanding the relevant interfacial interactions that affect the energy landscape experienced by carriers in the channel is of fundamental interest. Here we investigate charge transport in the submonolayer regime of pentacene transistors in which confinement arises due to the finite size of the interconnected semiconducting islands. In situ real-time electrical characterization is used to monitor the formation and evolution of the accumulation layer at the very early stages of growth. The morphology of the confining interfaces is controlled by growth conditions and pentacene coverage. Charge transport occurs when percolation pathways connecting source and drain electrodes are formed at a critical coverage. The displacement current across the oxide/semiconductor interface is observed starting from the onset of percolation (0.69 monolayer coverage). The analysis of the characteristics shows that already the submonolayer film fully screens the gate field and accumulates higher charge carrier density as compared to the monolayer film. We propose an electrostatic model to correlate the charge density to the characteristic length scale of the submonolayer film and the thickness of the dielectric layer. This explains charge mobility and threshold voltage of thin-film transistors in the submonolayer regime.
2015
- Charge-Injection Organic Gauges to Detect Dopamine Down to the Nanomolar Scale
[Articolo su rivista]
Leonardi, Francesca; Casalini, Stefano; Albonetti, Cristiano; Kovtun, Alessandro; Liscio, Andrea; Biscarini, Fabio
abstract
A multilayer self-assembled monolayer (MuL-SAM) composed by i) cysteamine, ii) 4-formilphenyl boronic acid and iii) dopamine has been used to functionalize polycrystalline Au. Its electrochemical characterization shows how this surface engineering makes Au reactive toward dopamine. Kelvin probe measurements have shown how MuL-SAM tunes the surface potential of the bare Au. Such measurements are correlated with the electrical performances of organic field-effect transistors (OFETs), whose source/drain electrodes have been functionalized by MuL-SAM. Such devices, operated as charge-injection organic gauges (CIOGs), have shown sensitivity to the concentration of dopamine in the range of [1, 50] nM.
2015
- Electrical release of dopamine and levodopa mediated by amphiphilic β-cyclodextrins immobilized on polycrystalline gold
[Articolo su rivista]
Foschi, Giulia; Leonardi, Francesca; Scala, Angela; Biscarini, Fabio; Kovtun, Alessandro; Liscio, Andrea; Mazzaglia, Antonino; Casalini, Stefano
abstract
Vesicles of cationic amphiphilic β-cyclodextrins have been immobilized on polycrystalline gold by exploiting the chemical affinity between their amino groups and Au atoms. The presence of cyclodextrins has been widely investigated by means of AFM, XPS, kelvin probe and electrochemical measurements. This multi-functional coating confers distinct electrochemical features such as pH-dependent behavior and partial/total blocking properties towards electro-active species. The host-guest properties of β-cyclodextrins have been successfully exploited in order to trap drugs, like dopamine and levodopa. The further release of these drugs was successfully achieved by providing specific electrical stimuli. This proof-of-concept led us to fabricate an electronic device (i.e. an organic transistor) capable of dispensing both dopamine and levodopa in aqueous solution.
2015
- Elettronica organica
[Voce in Dizionario o Enciclopedia]
Biscarini, Fabio; Berto, Marcello; Campana, Alessandra; DI LAURO, Michele
abstract
Lemma "Elettronica Organica" definisce il settore tecnologico e scientifico, ne descrive i fondamenti e le applicazioni sul mercato e in via di sviluppo.
2015
- Flattening mountains: Micro-fabrication of planar replicas for bullet lateral striae analysis
[Articolo su rivista]
Cominato, Laura; Valle, Francesco; Pierini, Giovanni; Bonini, Paolo; Biscarini, Fabio; D'Elia, Marcello
abstract
The application of replica molding has proven to be a valuable tool in the analysis of different forensic evidences in particular for its ability to extract the toolmarks from complex sample surfaces. A well known problem in the analysis of ballistic evidences is the accurate characterization of the lateral striae of real bullets seized on crime scenes after shots, due primarily to impact deformations and to unpredictable issues related to laboratory illumination setup. To overcome these problems a possible way is to confine over a flat surface all the features still preserving their three dimensionality. This can be achieved by a novel application of replica molding performed onto the relevant lateral portion of the bullet surface. A quasi-two-dimensional negative copy of the original tridimensional indented surface has been thus fabricated. It combines the real tridimensional topography of class characteristics (land and groove impressions) and of individual caracteristics (striae) impressed by rifled barrels on projectiles, moreover with the possibility of quantitative characterization of these features in a planar configuration, that will allow one-shot comparison of the "whole striae landscape" without the typical artifacts arising from the bullet shape and the illumination issue. A detailed analysis has been carried on at the morphological level by standard optical and scanning electron microscopy, while the 3D topography has been characterized by white light optical profilometry. A quantitative characterization of toolmarks of bullets derived from ammunitions shot by guns of large diffusion, as the Beretta 98 FS cal. 9×21mm, has been performed and will be presented ranging between the whole landscape and the sub-μm resolution. To investigate the real potentiality of this technique, the experiment has been extended to highly impact-deformed projectiles.
2015
- Human Neuronal SHSY5Y Cells on PVDF:PTrFE Copolymer Thin Films
[Articolo su rivista]
Tonazzini, Ilaria; Bystrenova, Eva; Chelli, Beatrice; Greco, Pierpaolo; De Leeuw, Dago; Biscarini, Fabio
abstract
Here, we investigate the in vitro biocompatibility of polyvinylidenefluoride (PVDF)–polytrifluoroethylene (PTrFE) copolymer thin films using neuronal cells. The aim is to obtain an optimal capping layer material for hybrid bio-organic electronic transducers based on organic electronic devices, which can be applied for bidirectional communication with the central nervous system. PVDF:PTrFE thin films were grown by spin coating and characterized by AFM. Human neuroblastoma SHSY5Y cells were used as neuronal model and their interaction with PVDF:PTrFE films was investigated in term of cell adhesion, proliferation, differentiation, and cytoskeleton organization. We show that PVDF:PTrFE thin films allowed standard SHSY5Y proliferation and neuronal differentiation, even if with reduced short-term cell adhesion and spreading.
2015
- In situ nanomechanical characterization of the early stages of swelling and degradation of a biodegradable polymer
[Articolo su rivista]
Dumitru, A. C; Espinosa, F. M.; Garcia, R.; Foschi, Giulia; Tortorella, S.; Valle, F.; Dallavalle, M.; Zerbetto, F.; Biscarini, Fabio
abstract
The interactions of a biodegradable scaffold with cells or living tissues depend on the time-evolution of the nanoscale properties of the scaffold. We present an in situ quantitative study on the early-stage swelling and degradation of poly(lactic-co-glycolic acid) (PLGA). A novel metrology scheme based on force microscopy measurements of the patterns of PLGA nanostructures is developed to characterize the evolution of topography, volume and nanomechanical properties. The volume and nanoscale roughness show an oscillating behaviour during the first eight days of immersion; at a later stage, we observe a continuous decrease of the volume. The effective Young's modulus exhibits a monotonic decrease from an initial value of about 2.4 GPa down to 9 MPa at day 14. The oscillating behaviour of the volume before the onset of full degradation is explained by a coupled diffusion-swelling mechanism. The appearance of a second maximum in the volume evolution results from the competition between swelling and degradation.
2015
- Low voltage and time constant organic synapse-transistor
[Articolo su rivista]
Desbief, Simon; Kyndiah, Adrica; Guérin, David; Gentili, Denis; Murgia, Mauro; Lenfant, Stéphane; Alibart, Fabien; Cramer, Tobias; Biscarini, Fabio; Vuillaume, Dominique
abstract
We report on an artificial synapse, an organic synapse-transistor (synapstor) working at 1 V and with a typical response time in the range 100–200 ms. This device (also called NOMFET, Nanoparticle Organic Memory Field Effect Transistor) combines a memory and a transistor effect in a single device. We demonstrate that short-term plasticity (STP), a typical synaptic behavior, is observed when stimulating the device with input spikes of 1 V. Both significant facilitating and depressing behaviors of this artificial synapse are observed with a relative amplitude of about 50% and a dynamic response <200 ms. From a series of in-situ experiments, i.e. measuring the current–voltage characteristic curves in-situ and in real time, during the growth of the pentacene over a network of gold nanoparticles, we elucidate these results by analyzing the relationship between the organic film morphology and the transport properties. This synapstor works at a low energy of about 2 nJ/spike. We discuss the implications of these results for the development of neuro-inspired computing architectures and interfacing with biological neurons.
2015
- Multiscale sensing of antibody-antigen interactions by organic transistors and single-molecule force spectroscopy
[Articolo su rivista]
Casalini, Stefano; Dumitru, Andra C.; Leonardi, Francesca; Bortolotti, Carlo Augusto; Herruzo, Elena T.; Campana, Alessandra; De Oliveira, Rafael F.; Cramer, Tobias; Garcia, Ricardo; Biscarini, Fabio
abstract
Antibody-antigen (Ab-Ag) recognition is the primary event at the basis of many biosensing platforms. In label-free biosensors, these events occurring at solid-liquid interfaces are complex and often difficult to control technologically across the smallest length scales down to the molecular scale. Here a molecular-scale technique, such as single-molecule force spectroscopy, is performed across areas of a real electrode functionalized for the immunodetection of an inflammatory cytokine, viz. interleukin-4 (IL4). The statistical analysis of force-distance curves allows us to quantify the probability, the characteristic length scales, the adhesion energy, and the time scales of specific recognition. These results enable us to rationalize the response of an electrolyte-gated organic field-effect transistor (EGOFET) operated as an IL4 immunosensor. Two different strategies for the immobilization of IL4 antibodies on the Au gate electrode have been compared: antibodies are bound to (i) a smooth film of His-tagged protein G (PG)/Au; (ii) a 6-aminohexanethiol (HSC6NH2) self-assembled monolayer on Au through glutaraldehyde. The most sensitive EGOFET (concentration minimum detection level down to 5 nM of IL4) is obtained with the first functionalization strategy. This result is correlated to the highest probability (30%) of specific binding events detected by force spectroscopy on Ab/PG/Au electrodes, compared to 10% probability on electrodes with the second functionalization. Specifically, this demonstrates that Ab/PG/Au yields the largest areal density of oriented antibodies available for recognition. More in general, this work shows that specific recognition events in multiscale biosensors can be assessed, quantified, and optimized by means of a nanoscale technique.
2014
- Comparative STM studies of mixed ligand monolayers on gold nanoparticles in air and in 1-phenyloctane
[Articolo su rivista]
Ong, Quy Khac; Zhao, Shun; Reguera, Javier; Biscarini, Fabio; Stellacci, Francesco
abstract
Scanning tunnelling microscopy (STM) studies have found stripe-like domains on gold nanoparticles (NPs) coated with certain binary mixtures of ligand molecules. The majority of these NPs' properties have been investigated for particles in solvents. Yet, most STM studies are for NPs in a dry state. Images of the same particles in air and liquid have not been obtained yet. In this work, a judicious choice of ligand molecules led to NPs with close-to-ideal STM imaging conditions in air and in 1-phenyloctane (PO). Large datasets under both conditions were acquired and rapidly evaluated through power spectral density (PSD) analysis. The result is a quantitative comparison of stripe-like domains in air and PO on the same NPs. PSD analysis determines a characteristic length-scale for these domains of ~1.0 nm in air and in PO showing persistence of striped domains in these two media. A length scale of ~0.7 nm for homoligand NPs was found.
2014
- Customizing Properties of β-Chitin in Squid Pen (Gladius) by Chemical Treatments
[Articolo su rivista]
Ianiro, Alessandro; Di Giosia, Matteo; Fermani, Simona; Samorì, Chiara; Barbalinardo, Marianna; Valle, Francesco; Pellegrini, Graziella; Biscarini, Fabio; Zerbetto, Francesco; Calvaresi, Matteo; Falini, Giuseppe
abstract
The squid pen (gladius) from the Loligo vulgaris was used for preparation of β-chitin materials characterized by different chemical, micro- and nano-structural properties that preserved, almost completely the macrostructural and the mechanical ones. The β-chitin materials obtained by alkaline treatment showed porosity, wettability and swelling that are a function of the duration of the treatment. Microscopic, spectroscopic and synchrotron X-ray diffraction techniques showed that the chemical environment of the N-acetyl groups of the β-chitin chains changes after the thermal alkaline treatment. As a consequence, the crystalline packing of the β-chitin is modified, due to the intercalation of water molecules between β-chitin sheets. Potential applications of these β-chitin materials range from the nanotechnology to the regenerative medicine. The use of gladii, which are waste products of the fishing industry, has also important environmental implications. - See more at: http://www.mdpi.com/1660-3397/12/12/5979/htm#sthash.7aVdC53H.dpuf
2014
- Electrocardiographic recording with conformable organic electrochemical transistor fabricated on resorbable bioscaffold
[Articolo su rivista]
Campana, Alessandra; Cramer, Tobias; Simon, Daniel T; Berggren, Magnus; Biscarini, Fabio
abstract
Organic electrochemical transistors are fabricated on a poly(L-lactide-co-glycolide) substrate. Fast and sensitive performance of the transistors allows recording of the electrocardiogram. The result paves the way for new types of bioelectronic interfaces with reduced invasiveness due to bioresorption and soft mechanical properties.
2014
- Enhancing the Charge Transport in Solution-Processed Perylene Di-imide Transistors via Thermal Annealing of Metastable Disordered Films
[Articolo su rivista]
Ferlauto, Laura; Liscio, Fabiola; Orgiu, Emanuele; Masciocchi, Norberto; Guagliardi, Antonietta; Biscarini, Fabio; Samorì, Paolo; Milita, Silvia
abstract
The application of replica molding has proven to be a valuable tool in the analysis of different forensic evidences in particular for its ability to extract the toolmarks from complex sample surfaces. A well known problem in the analysis of ballistic evidences is the accurate characterization of the lateral striae of real bullets seized on crime scenes after shots, due primarily to impact deformations and to unpredictable issues related to laboratory illumination setup. To overcome these problems a possible way is to confine over a flat surface all the features still preserving their three dimensionality. This can be achieved by a novel application of replica molding performed onto the relevant lateral portion of the bullet surface.
A quasi-two-dimensional negative copy of the original tridimensional indented surface has been thus fabricated. It combines the real tridimensional topography of class characteristics (land and groove impressions) and of individual caracteristics (striae) impressed by rifled barrels on projectiles, moreover with the possibility of quantitative characterization of these features in a planar configuration, that will allow one-shot comparison of the “whole striae landscape” without the typical artifacts arising from the bullet shape and the illumination issue.
A detailed analysis has been carried on at the morphological level by standard optical and scanning electron microscopy, while the 3D topography has been characterized by white light optical profilometry.
A quantitative characterization of toolmarks of bullets derived from ammunitions shot by guns of large diffusion, as the Beretta 98 FS cal. 9 × 21 mm, has been performed and will be presented ranging between the whole landscape and the sub-μm resolution. To investigate the real potentiality of this technique, the experiment has been extended to highly impact-deformed projectiles.
2014
- Influence of metal-support interaction on the surface structure of gold nanoclusters deposited on native SiO(x)/Si substrates
[Articolo su rivista]
Portale, Giuseppe; Sciortino, Luisa; Albonetti, Cristiano; Giannici, Francesco; Martorana, Antonino; Bras, Wim; Biscarini, Fabio; Longo, Alessandro
abstract
The structure of small gold nanoclusters (around 2.5 nm) deposited on different silica-on-silicon (SiOx/Si) substrates is investigated using several characterization techniques (AFM, XRD, EXAFS and GISAXS). The grain morphology and the surface roughness of the deposited gold cluster layers are determined by AFM. The in-plane GISAXS intensity is modelled in order to obtain information about the cluster size and the characteristic length scale of the surface roughness. The surface morphology of the deposited clusters depends on whether the native defect-rich (n-SiOx/Si) or the defect-poor substrate obtained by thermal treatment (t-SiO2/Si) is used. Gold clusters show a stronger tendency to aggregate when deposited on n-SiOx/Si, resulting in films characterized by a larger grain dimension (around 20 nm) and by a higher surface roughness (up to 5 nm). The more noticeable cluster aggregation on n-SiOx/Si substrates is explained in terms of metal-support interaction mediated by the defects located on the surface of the native silica substrate. Evidence of metal-support interaction is provided by EXAFS, demonstrating the existence of an Au-O distance for clusters deposited on n-SiOx/Si that is not found on t-SiO2/Si.
2014
- Neural cell alignment by patterning gradients of the extracellular matrix protein laminin
[Articolo su rivista]
Chelli, Beatrice; Barbalinardo, Marianna; Valle, Francesco; Greco, Pierpaolo; Bystrenova, Eva; Bianchi, Michele; Biscarini, Fabio
abstract
Anisotropic orientation and accurate positioning of neural cells is achieved by patterning stripes of the extracellular matrix protein laminin on the surface of polystyrene tissue culture dishes by micromoulding in capillaries (MIMICs). Laminin concentration decreases from the entrance of the channels in contact with the reservoir towards the end. Immunofluorescence analysis of laminin shows a decreasing gradient of concentration along the longitudinal direction of the stripes. The explanation is the superposition of diffusion and convection of the solute, the former dominating at length scales near the entrance (characteristic length around 50 μm), the latter further away (length scale in excess of 900 μm). These length scales are independent of the channel width explored from about 15 to 45 μm. Neural cells are randomly seeded and selectively adhere to the pattern, leaving the unpatterned areas depleted even upon 6 days of incubation. Cell alignment was assessed by the orientation of the long axis of the 4',6-diamidino-2-phenylindole-stained nuclei. Samples on patterned the laminin area exhibit a large orientational order parameter. As control, cells on the unpatterned laminin film exhibit no preferential orientation. This implies that the anisotropy of laminin stripes is an effective chemical stimulus for cell recruiting and alignment.
2014
- Organic Bioelectronics for Regenerative Medicine
[Abstract in Rivista]
Biscarini, Fabio
abstract
Electronic transducers of neuronal cellular activity are important devices in neuroscience and neurology. Organic field-effect transistors (OFETs) offer tailored surface chemistry, mechanical flexibility, and high sensitivity to electrostatic potential changes at device interfaces. These properties make them attractive for interfacing electronics to neural cells and performing extracellular recordings and stimulation of neuronal network activity.
Here I want to present an emerging area of interest where the OFET is used as a gauge to supply a variety of electrical, chemical and electrochemical stimuli to neuronal cells, in an effort to stimulate their plasticity else to differentiate neuronal stem cells into neurons. I will overview the progresses of an ongoing EU project, “Implantable Organic Nanoelectronics” (I-ONE-FP7) which is aimed to the use of organic electronics in implantable devices for the treatment of the spinal cord injury (SCI). The project is presently at midterm, and I will highlight the advances to date and discuss the direction of further development towards in-vivo experiments on animal model of the SCI.
This work involves collaboration of several partners, that I would like to acknowledge through the principal investigators: S. Pluchino (Univ. of Cambridge), M. Berggren and D. Simon (Univ. Linkoeping), F. Zerbetto and S. Rapino (Univ. of Bologna), P. Greco (Scriba Nanotecnologie Srl Bologna), L. Occhipinti (ST Microelectronics Catania), D. Vuillaume (CNRS, Lille), R. Garcia (CSIC Madrid), H. Gomes (Univ. do Algarve), R. Frycek (Amires Sarl, Neuchatel), E. Cerna and V. Velebny (Contipro Dolni Dobrouc), T. Cramer, S. Casalini, F. Valle (CNR-ISMN Bologna), G. Foschi, C. A. Bortolotti, N. Dorigo (UNIMORE).
This work is supported by EU NMP Project I-ONE Grant Agreement n. 280772.
2014
- Organic Electrochemical Transistors: Electrocardiographic Recording with Conformable Organic Electrochemical Transistor Fabricated on Resorbable Bioscaffold (Adv. Mater. 23/2014)
[Articolo su rivista]
Campana, Alessandra; Cramer, Tobias; Simon, Daniel T.; Berggren, Magnus; Biscarini, Fabio
abstract
Conformable organic electrochemical transistors are fabricated on a resorbable bioscaffold, as discussed by F. Biscarini, T. Cramer, and co-workers on page 3874. The devices show a fast and sensitive transistorcurrent response to electrophysiological potential changes and allow the recording of the human electrocardiogram. The result paves the way for new types of bioelectronic interfaces with reduced invasiveness due to bioresorption and soft mechanical properties.
2014
- Surface nanostructures in manganite films
[Articolo su rivista]
Gambardella, A; Graziosi, P; Bergenti, I; Prezioso, M; Pullini, D; Milita, S; Biscarini, Fabio; Dediu, V. A.
abstract
Ultrathin manganite films are widely used as active electrodes in organic spintronic devices. In this study, a scanning tunnelling microscopy (STM) investigation with atomic resolution revealed previously unknown surface features consisting of small non-stoichiometric islands. Based upon this evidence, a new mechanism for the growth of these complex materials is proposed. It is suggested that the non-stoichiometric islands result from nucleation centres that are below the critical threshold size required for stoichiometric crystalline growth. These islands represent a kinetic intermediate of single-layer growth regardless of the film thickness, and should be considered and possibly controlled in manganite thin-film applications.
2014
- Trap densities and transport properties of pentacene metal-oxide-semiconductor transistors. I. Analytical modeling of time-dependent characteristics
[Articolo su rivista]
Basile, A. F.; Cramer, T.; Kyndiah, A.; Biscarini, Fabio; Fraboni, B.
abstract
Metal-oxide-semiconductor (MOS) transistors fabricated with pentacene thin films were characterized by temperature-dependent current-voltage (I-V) characteristics, time-dependent current measurements, and admittance spectroscopy. The channel mobility shows almost linear variation with temperature, suggesting that only shallow traps are present in the semiconductor and at the oxide/semiconductor interface. The admittance spectra feature a broad peak, which can be modeled as the sum of a continuous distribution of relaxation times. The activation energy of this peak is comparable to the polaron binding energy in pentacene. The absence of trap signals in the admittance spectra confirmed that both the semiconductor and the oxide/semiconductor interface have negligible density of deep traps, likely owing to the passivation of SiO2 before pentacene growth. Nevertheless, current instabilities were observed in time-dependent current measurements following the application of gate-voltage pulses. The corresponding activation energy matches the energy of a hole trap in SiO2. We show that hole trapping in the oxide can explain both the temperature and the time dependences of the current instabilities observed in pentacene MOS transistors. The combination of these experimental techniques allows us to derive a comprehensive model for charge transport in hybrid architectures where trapping processes occur at various time and length scales.
2014
- Trap densities and transport properties of pentacene metal–oxide–semiconductor transistors: II—Numerical modeling of dc characteristics
[Articolo su rivista]
Basile, A. F.; Kyndiah, A.; Biscarini, Fabio; Fraboni, B.
abstract
A numerical procedure to calculate the drain-current (ID) vs. gate-voltage (VG) characteristics from numerical solutions of the Poisson equation for organic Thin-Film Transistors (TFTs) is presented. Polaron transport is modeled as two-dimensional charge transport in a semiconductor having free-carrier density of states proportional to the density of molecules and traps with energy equal to the polaron-hopping barrier. The simulated ID-VG curves are proportional to the product of the density of free carriers, calculated as a function of VG, and the intrinsic mobility, assumed to be a constant independent of temperature. The presence of traps in the oxide was also taken into account in the model, which was applied to a TFT made with six monolayers of pentacene grown on an oxide substrate. The polaron-hopping barrier determines the temperature dependence of the simulated ID-VG curves, trapping in the oxide is responsible for current reduction at high bias and the slope of the characteristics near threshold is related to the metal-semiconductor work-function difference. The values of the model parameters yielding the best match between calculations and experiments are consistent with previous experimental results and theoretical predictions. Therefore, this model enables to extract both physical and technological properties of thin-film devices from the temperature-dependent dc characteristics.
2013
- Facile maskless fabrication of organic field effect transistors on biodegradable substrates
[Articolo su rivista]
Campana, Alessandra; Cramer, Tobias; Greco, Pierpaolo; Foschi, Giulia; Murgia, Mauro; Biscarini, Fabio
abstract
Fabrication of a test pattern with interdigitated gold electrodes (channel length 12 μm) on a biodegradable substrate is achieved by direct laser ablation of a Au film using a high-precision multifunction infrared-laser scan marker. The whole process involves two solvent-free steps: Au film deposition by sublimation followed by maskless ablation. The approach is suited for fast prototyping of a variety of materials. We demonstrate the fabrication of a water-gated organic field effect transistor on the biodegradable poly(lactic-co-glycolic acid) scaffold and its operations in water.
2013
- Hydrophilic self-assembly monolayers for pentacene-based thin-film transistors
[Articolo su rivista]
S., Casalini; A., Shehu; F., Leonardi; C., Albonetti; F., Borgatti; Biscarini, Fabio
abstract
A series of hydrophilic alkanethiols, HS(CH2)nOH with n = 3, 4, 6, 8, 9 and 11, have been self-assembled on gold electrodes of pentacene-based thin-film transistors. The multi-parametric and ultra-sensitive response of these devices allows us to characterize both charge–injection and electrical stability moving from vacuum to air. The decay exponent β of charge injection is found to be 0.7–1.1 Å−1 in agreement with earlier measurements of charge tunneling done by electrochemistry and large-area molecular junctions. We find that the intermediate chain lengths (n = 4 and 6) yield an optimum response as they represent the best compromise in terms of decrease of the contact-resistance and bias stress.
2013
- Low-Dimensionality Effects in Organic Field Effect Transistors
[Capitolo/Saggio]
Casalini, Stefano; Cramer, Tobias; Leonardi, Francesca; Cavallini, Massimiliano; Biscarini, Fabio
abstract
The organic field effect transistor (OFET) is a device where a thin film of an organic semiconductor (OS) bridges a channel between source and drain electrodes. This chapter looks into the OFET as a low-dimensional device and how this distinctive feature can be exploited for a rational design of sensing devices. The chapter provides a brief description of OFET working principles. It reviews different approaches to unconventional fabrication and growth of OFETs. The chapter focuses on the charge injection response, when the OFET acts as a charge tunneling device. It talks about low-dimensional charge transport in OFETs and reviews sensing principles and applications of OFETs. Problems of stability and repeatability have to be addressed for the future, as well as for standardization of the OFET response, but this appears as dominant in the near future, especially in view of implantable devices.
2013
- Molecular Reorganization in Organic Field-Effect Transistors and Its Effect on Two-Dimensional Charge Transport Pathways
[Articolo su rivista]
Liscio, F; Albonetti, C; Broch, K; Shehu, A; Quiroga S., D; Ferlauto, L; Frank, C; Kowarik, S; Nervo, R; Gerlach, A; Milita, S; Schreiber, F; Biscarini, Fabio
abstract
Charge transport in organic thin film transistors takes place in the first few molecular layers in contact with the gate dielectric. Here we demonstrate that the charge transport pathways in these devices are extremely sensitive to the orientational defects of the first monolayers, which arise from specific growth conditions. Although these defects partially heal during the growth, they cause depletion of charge carriers in the first monolayer, and drive the current to flow in the monolayers above the first one. Moreover, the residual defects induce lower crystalline order and charge mobility. These results, which are not intuitively explained by electrostatics arguments, have been obtained by combining in situ real time structural and electrical characterization together with ex situ AFM measurements, on thin films of a relevant n-type organic semiconductor, N,N′-bis(n-octyl)-dicyanoperylene-3,4:9,10-bis dicarboximide grown by sublimation in a quasi-layer-by-layer mode at different substrate temperatures.
2013
- Organic Ultra-Thin Film Transistor with Liquid Gate for Extracellular Stimulation and Recording of Electric Activity of Stem Cell-Derived Neuronal Networks
[Articolo su rivista]
Cramer, T; Chelli, B; Murgia, M; Barbalinardo, M; Bystrenova, E; de Leeuw, D; Biscarini, Fabio
abstract
Electronic transducers of neuronal cellular activity are important devices in neuroscience and neurology. Organic field-effect transistors (OFETs) offer tailored surface chemistry, mechanical flexibility, and high sensitivity to electrostatic potential changes at device interfaces. These properties make them attractive for interfacing electronics with neural cells and performing extracellular recordings and stimulation of neuronal network activity. In this work we operate pentacene ultra-thin film (9 nm thick) transistors with a liquid gate both as transducers and electrical stimulators of neuronal network activity. These devices are highly sensitive to small potential changes in cell medium and exhibit sufficient stability under standard cell culture conditions for nine days. We show that murine neural stem cells can be adhered on top of functional devices without the need for an additional layer of cell-adhesive molecules, and then differentiated into neuronal networks. OFET response is monitored during the different phases of the neuronal differentiation process up to nine days. Only when stem cells are differentiated into neurons, it is possible to measure electrical signals in the OFET current following the stimulation. Due to the large sensing area of our device, which accommodates from hundreds to thousands of interconnected neurons, the OFET electrical signals arise from the collective electrophysiological response of the neuronal population. The maximum extracellular potential change in the cleft region adjacent to the transistor surface amounts to 350 mu V. This demonstrates that pentacene ultra-thin film OFETs enable good cellular adhesion and efficient coupling of the ionic currents at the biological-organic semiconductor interface with the OFET current.
2013
- Organic field-effect transistor for label-free dopamine sensing
[Articolo su rivista]
Casalini, S; Leonardi, F; Cramer, T; Biscarini, Fabio
abstract
We describe a potentiometric sensor based on Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) for “in vitro” detection of dopamine. The sensing element of this device resides at the Au gate–aqueous solution interface by means of a self-assembled monolayer (SAM) composed by cysteamine and 4-formylphenyl boronic acid. The covalent and selective adsorption of dopamine induces a surface dipole potential which shifts the electrode work function and modulates the double layer capacitance. As a result, our device is capable to detect dopamine up to pico-molar concentration showing higher sensitivity with respect to other approaches. For this reason the interface engineering of our EGOFET gate is a promising route for diagnostic applications.
2013
- Quantitative analysis of scanning tunneling microscopy images of mixed-ligand-functionalized nanoparticles
[Articolo su rivista]
Biscarini, Fabio; Ong, Quy Khac; Albonetti, Cristiano; Liscio, Fabiola; Longobardi, Maria; Mali, Kunal S; Ciesielski, Artur; Reguera, Javier; Renner, Christoph; De Feyter, Steven; Samorì, Paolo; Stellacci, Francesco
abstract
Ligand-protected gold nanoparticles exhibit large local curvatures, features rapidly varying over small scales, and chemical heterogeneity. Their imaging by scanning tunneling microscopy (STM) can, in principle, provide direct information on the architecture of their ligand shell, yet STM images require laborious analysis and are challenging to interpret. Here, we report a straightforward, robust, and rigorous method for the quantitative analysis of the multiscale features contained in STM images of samples consisting of functionalized Au nanoparticles deposited onto Au/mica. The method relies on the analysis of the topographical power spectral density (PSD) and allows us to extract the characteristic length scales of the features exhibited by nanoparticles in STM images. For the mixed-ligand-protected Au nanoparticles analyzed here, the characteristic length scale is 1.2 ± 0.1 nm, whereas for the homoligand Au NPs this scale is 0.75 ± 0.05 nm. These length scales represent spatial correlations independent of scanning parameters, and hence the features in the PSD can be ascribed to a fingerprint of the STM contrast of ligand-protected nanoparticles. PSD spectra from images recorded at different laboratories using different microscopes and operators can be overlapped across most of the frequency range, proving that the features in the STM images of nanoparticles can be compared and reproduced.
2013
- Self-Assembly of Mono- And Bidentate Oligoarylene Thiols onto Polycrystalline Au
[Articolo su rivista]
Casalini, S.; Berto, M.; Leonardi, F.; Operamolla, A.; Bortolotti, Carlo Augusto; Borsari, Marco; Sun, W.; DI FELICE, Rosa; Corni, Stefano; Albonetti, C.; Hassan Omar, O.; Farinola, G. M.; Biscarini, Fabio
abstract
Four thiolated oligoarylene molecules (i) 4-methoxy-terphenyl-4″-methanethiol (MTM), (ii) 4-methoxy-terphenyl-3″,5″-dimethanethiol (MTD), (iii) 4-nitro-terphenyl-4″-methanethiol (NTM), and (iv) 4-nitro-terphenyl-3″,5″-dimethanethiol (NTD) were synthesized and self-assembled as monolayers (SAMs) on polycrystalline Au electrodes of organic field-effect transistors (OFETs). SAMs were characterized by contact angle and AC/DC electrochemical measurements, whereas atomic force microscopy was used for imaging the pentacene films grown on the coated electrodes. The electrical properties of functionalized OFETs, the electrochemical SAMs features and the morphology of pentacene films were correlated to the molecular organization of the thiolated oligoarylenes on Au, as calculated by means of the density functional theory. This multi-methodological approach allows us to associate the systematic replacement of the SAM anchoring head group (viz. methanethiol and dimethanethiol) and/or terminal tail group (viz. nitro-, -NO2, and methoxy, -OCH3) with the change of the electrical features. The dimethanethiol head group endows SAMs with higher resistive features along with higher surface tensions compared with methanethiol. Furthermore, the different number of thiolated heads affects the kinetics of Au passivation as well as the pentacene morphology. On the other hand, the nitro group confers further distinctive properties, such as the positive shift of both threshold and critical voltages of OFETs with respect to the methoxy one. The latter experimental evidence arise from its electron-withdrawing capability, which has been verified by both DFT calculations and DC electrochemical measurements.
2013
- Self-organisation of molecular nanostructures triggered by atomic force microscopy
[Articolo su rivista]
Cavallini, Massimiliano; Biscarini, Fabio
abstract
Scanning probe microscopy are an extraordinary tools for surfaces characterization at nano and atomic scale and also for nanofabrication whose major limitation depends on the serial nature of the related techniques. Here we propose an interesting approach applied to a supramolecular system (rotaxane) that contributes to overcome this limitation. When a local mechanical perturbation is applied to the surface of a thin film of a rotaxane, the molecules self-organize into periodic arrays of discrete dots or lines. The dimensionality of the nanostructures depends on whether the mechanical stimulus acts along a 1D line or over a 2D area. The size and periodicity of the patterns are controlled solely by the film thickness. The phenomenon can be exploited as a new bottom-up nanofabrication method.
2013
- Technological Applications of Dewetting
[Capitolo/Saggio]
Biscarini, Fabio; Gentili, Denis; Margapoti, Manuela; Cavallini, Massimiliano
abstract
N/A
2013
- Water-gated organic field effect transistors – opportunities for biochemical sensing and extracellular signal transduction
[Articolo su rivista]
Cramer, T.; Campana, A.; Leonardi, F.; Casalini, Stefano; Kyndiah, A.; Murgia, M.; Biscarini, Fabio
abstract
There is a quest for electronic biosensors operated in water for biomedical applications and environmental monitoring. Water is an aggressive medium for standard electronics materials and devices due to its strong polarizability and electrochemical activity. Thick dielectric encapsulation provides necessary stability while it damps the sensitivity of the device to sensing events occurring in the aqueous environment. Organic electronics provides materials that exhibit stable electronic conduction in direct contact with water combined with other desirable properties like mechanical softness, biocompatibility and processability onto flexible substrates. In this review, we introduce an emerging class of organic transistors, in which the current across the organic film is gated by the electric field of the Debye–Helmholtz layer. We discuss the device physics, the sensing mechanism and the relevant electrochemical processes. Applications of water-gated transistors range from the sensing of biologically relevant molecules like DNA, proteins or hormones to non-invasive recording and stimulation of electrical activity of neurons. Materials chemistry is crucial to control properties of electrically active films and to allow the introduction of specific chemical functionalities and receptors at sensing interfaces of the device.
2012
- Anti-amyloidogenic activity of glutathione-covered gold nanoparticles
[Articolo su rivista]
A., Antosova; Z., Gazova; D., Fedunova; E., Valusova; E., Bystrenova; F., Valle; Z., Daxnerova; Biscarini, Fabio; M., Antalik
abstract
This study is an investigation of the effect of biocompatible glutathione-covered gold nanoparticles (AuSG_7) with an average size of 3 nm on the amyloid fibrils of hen egg-white lysozyme. The anti-amyloid activity of AuSG_7 nanoparticles on this protein was monitored with thioflavin T assay, atomic force microscopy and transmission electron microscopy. The study found that AuSG_7 nanoparticles in vitro depolymerize the amyloid aggregates and inhibit lysozyme aggregate formation. The ability to inhibit amyloid formation and promote amyloid disassembly has concentration-dependent characteristics: the concentration of nanoparticles at which inhibition is half maximal (IC50) was found to be 6.19 mu g/mL, and the concentration at which depolymerization is half maximal (DC50) was found to be 826 mu g/ml. (C) 2012 Elsevier B.V. All rights reserved.
2012
- Applications of dewetting in micro and nanotechnology
[Articolo su rivista]
D., Gentili; G. Foschi F., Valle; M., Cavallini; BISCARINI, FABIO
abstract
Dewetting is a spontaneous phenomenon where a thin film on a surface ruptures into an ensemble of separated objects, like droplets, stripes, and pillars. Spatial correlations with characteristic distance and object size emerge spontaneously across the whole dewetted area, leading to regular motifs with long-range order. Characteristic length scales depend on film thickness, which is a convenient and robust technological parameter. Dewetting is therefore an attractive paradigm for organizing a material into structures of well-defined micro-or nanometre-size, precisely positioned on a surface, thus avoiding lithographical processes. This tutorial review introduces the reader to the physical-chemical basis of dewetting, shows how the dewetting process can be applied to different functional materials with relevance in technological applications, and highlights the possible strategies to control the length scales of the dewetting process.
2012
- Cell-fluidics: producing cellular streams on micropatterned synthetic surfaces
[Articolo su rivista]
M., Ventre; F., Valle; M., Bianchi; Biscarini, Fabio; P., Netti
abstract
Patterning cell-adhesive molecules on material surfaces provides a powerful tool for controlling and guiding cell locomotion and migration. Here we report fast, reliable, easy to implement methods to fabricate large patterns of proteins on synthetic substrates to control the direction and speed of cells. Two common materials exhibiting very different protein adsorption capacities, namely, polystyrene and Teflon, were functionalized with micrometric stripes of laminin. The protein was noncovalently immobilized onto the surface by following either lithographically controlled wetting (LCW) or micromolding in capillaries (MIMIC). These techniques proved to be sufficiently mild so as not to interfere with the protein adhesion capability. Cells adhered onto the functionalized stripes and remained viable for more than 20 h. During this time frame, cells migrated along the lanes and the dynamics of motion was strongly affected by the substrate surface chemistry and culturing conditions. In particular, enhanced mismatches of cell adhesive properties obtained by the juxtaposition of bare and laminin-functionalized Teflon caused cells to move slowly and their movement to be highly confined. The patterning procedure was also effective at guiding migration on conventional cell culture dishes that were functionalized with laminin patterns, even in the presence of serum proteins, although to a lesser extent compared to that for Teflon. This work demonstrates the possibility of creating well-defined, long-range cellular streams on synthetic substrates by pursuing straightforward functionalizing techniques that can be implemented for a broad class of materials under conventional, long-time cell-culturing conditions. The procedure effectively confines cells to migrate along predefined patterns and can be implemented in different biomedical and biotechnological applications.
2012
- Double layer capacitance measured by organic field effect transistor operated in water
[Articolo su rivista]
T., Cramer; A., Kyndiah; M., Murgia; F., Leonardi; S., Casalini; Biscarini, Fabio
abstract
Pentacene ultra thin film transistors were exposed to water and operated with a conventional silicon/silicon oxide bottom gate and an electrolyte top gate controlled by a working electrode. The transistors are highly sensible (mu V) to the electrochemical potential of the aqueous electrolyte. We show that dual gate operation permits the measurement of the double layer capacitance, C-DL = 14.6 mu F/cm(2). The device exhibits a fast (4.6 ms) and stable response, without bias stress as opposed to conventional bottom gate operations, when controlled with the electrolyte gate. These features make the device a promising candidate for potentiometric transducers required for non-invasive electrophysiology.
2012
- Ethanol disinfection affects physical properties and cell response of electrospun poly(l-lactic acid) scaffolds
[Articolo su rivista]
Gualandi, C; Govoni, M; Foroni, L; Valente, S; Bianchi, M; Giordano, E; Pasquinelli, F; Biscarini, Fabio; Focarete, Ml
abstract
Disinfection of electrospun materials is commonly carried out by ethanol (EtOH) soaking. However, in the literature no systematic investigation on the effect of EtOH disinfection on scaffold properties is available. In this study electrospun poly(L-lactic acid) (PLLA) scaffolds were differently treated in EtOH and changes of fiber morphology, fiber surface topography and scaffold thermo-mechanical properties were evaluated. It was found that EtOH induced the formation of an amount of crystal phase, in the initially amorphous fibers, which depends on EtOH grade, soaking time and temperature. Completely amorphous PLLA (a-PLLA) and semicrystalline PLIA (sc-PLLA) scaffolds were produced by applying different EtOH treatments to as-spun PLLA scaffold. Compared to a-PLLA, sc-PLLA was stiffer and composed of fibers with rougher surface. Cell culture performed by using permanent cell line H9c2 demonstrated that changes of scaffold properties determined a different cell response, in particular in the expression of proteins correlated to cell motility and cell adhesion.
2012
- In-situ Dynamic SPM Studies of Organic Semiconductor Thin Film Growth on Test Patterns
[Abstract in Rivista]
Biscarini, Fabio; Andreas, Straub; Stefano, Donati; Stefano, Chiodini; Cristiano, Albonetti; Francesco, Borgatti
abstract
The physics of organic field effect transistors is strongly correlated with the organization of the organic semiconductor at multiple length scales. In the case of molecular semiconductors, which are deposited on device test patterns by high- or ultra-high vacuum sublimation, this organization arises from the nucleation anf growth phenomena occurring at timescales which are often not easily accessed by standard ex-situ characterization. We use in-situ dynamic scanning force microscopy to study the early stages of growth of a conjugated oligomer semiconductor, viz. sexithienyl (T6), on a technologically-relevant substrate, silicon oxide/silicon wafer and on test patterns with Au electrodes. In an ultra-high vacuum chamber a Knudsen cell produces a thermal beam of T6 molecules directly under the tip of a variable temperature SPM. Non-contact AFM images of the same sample area is acquired at different times to be mounted into a movie depicting the growth of the ultra-thin film. The coexistence of quasi-layer-by-layer and 3D growth modes, the latter promoted by heteronucleation on surface defects, is observed. By performing the experiment at different temperatures, we extract the relevant molecular energy barriers of T6 thin film growth: desorption energy (0.53 eV), layer-dependent diffusional barriers (0.15-0.20 eV), Erlich-Schwoebel barrier (0.070 eV). The latter is cause of the transition from layer-by-layer to island growth, which appears to be universal occurrence in organic semiconductor growth with important implications in the charge transport in organic field effect transistors.
2012
- Micro-and nanopatterning by lithographically controlled wetting
[Articolo su rivista]
M., Cavallini; D., Gentili; P., Greco; F., Valle; Biscarini, Fabio
abstract
This protocol describes how to perform lithographically controlled wetting (LCW). LCW enables large-area patterning of microstructures and nanostructures of soluble materials, either organic or inorganic, including biological compounds in buffer solutions or compounds for cell guidance. LCW exploits the capillary forces of menisci established under the protrusions of a stamp placed in contact with a liquid film. In the space confined by each meniscus, the self-organization of the deposited solute yields highly ordered structures that replicate the motif of the stamp protrusions. The method does not require any particular infrastructure and can be accomplished by using simple tools such as compact discs or microscopy grids. Compared with other printing methods, LCW is universal for soluble materials, as it does not require chemical binding or other specific interactions between the solute and the surface. A process cycle takes from 2 to 36 h to be completed, depending on the choice of materials.
2012
- Mono/bidentate thiol oligoarylene-based self-assembled monolayers (SAMs) for interface engineering
[Articolo su rivista]
S., Casalini; F., Leonardi; Bortolotti, Carlo Augusto; A., Operamolla; O. H., Omar; Paltrinieri, Licia; C., Albonetti; G. M., Farinola; Biscarini, Fabio
abstract
A new set of linear oligoarylene thiol molecules, namely (4′-(Thiophen-2-yl)Biphenyl-3,5-diyl)Dimethanethiol (TBD), (4′-(Thiophen-2-yl)Biphenyl-4-yl)Methanethiol (TBM) and ([1,1′;4′,1′′]Terphenyl-3,5-diyl)Dimethanethiol (TD), were synthesized and used for functionalizing the polycrystalline gold electrodes. Such molecules differ for the number of anchoring groups (TBM vs. TBD) and the terminal rings (TD vs. TBD). As shown by electrochemical measurements, they form homogeneous and pinholes-free self-assembly monolayers (SAMs) when deposited on the gold electrode. Moreover, the wettability of the functionalized surface and the morphological changes of pentacene films grown on SAMs were investigated by contact angle and atomic force microscopy, respectively. OTFT has been used as organic gauge for investigating the metal–SAM–organic semiconductor structure. Charge carriers mobility, threshold voltage, contact resistance were measured in both air and vacuum to assess the influence of the anchoring groups and the terminal rings to the transistor performance. Although these SAMs do not show an improvement of mobility due to an increase of contact resistance, they allow a better modulation of the current flowing across the electrode–organic semiconductor (OS) interface, pointing out the structural differences between the three SAMs in terms of resistance drop combined with the critical voltage.
2012
- Nanotechnology for forensic sciences: Analysis of PDMS replica of the case head of spent cartridges by optical microscopy, SEM and AFM for the ballistic identification of individual characteristic features of firearms
[Articolo su rivista]
F., Valle; M., Bianchi; S., Tortorella; G., Pierini; BISCARINI, FABIO; M., D’Elia
abstract
A novel application of replica molding to a forensic problem, viz. the accurate reproduction of the case head of gun and rifle cartridges, prior and after been shot, is presented. The fabrication of an arbitrary number of identical copies of the region hit by the firing pin and by the breech face is described. The replicas can be (i) handled without damaging the original evidence, (ii) distributed to different law enforcement agencies for comparison against other evidences found on crime scenes or ballistic tests of seized firearms, (iii) maintained on a file by the laboratories. A detailed analysis of the morphological features of the replicas has been carried out by standard microscopy techniques as well as by advanced microscopy such as scanning probe and scanning electron leading to a quantitative morphological characterization of the case heads down to the nanometer scale. The assignment of the cartridge replicas to the shooting weapon is demonstrated to hold below the micron scale, while it is hindered at the nanometer level both by the manufacturing differences and by eventual modifications occurring on the firing pin.
2012
- Organic field-effect transistors as a test-bed for molecular electronics: A combined study with large-aera molecular junctions
[Articolo su rivista]
Asadi, Kamal; Katsouras, Ilias; Harkema, Jan; Gholamrezaie, Fatemeh; Smits, Edsger C. P.; Biscarini, Fabio; Blom, Paul W. M.; de Leeuw, Dago M.
abstract
The contact resistance of a transistor using self-assembled monolayer (SAM)-modified source and drain electrodes depends on the SAM tunnel resistance, the height of the injection barrier and the morphology at the contact. To disentangle the different contributions, we have combined here the transmission line measurements in transistors with transport measurements of SAMs in large-area molecular junctions. The tunnel resistance of the SAM has been independently extracted in two-terminal large-area molecular junctions. We show that the tunneling resistance of the SAM can be added linearly to the contact resistance of the transistor with bare Au electrodes, to account for the increased contact resistance in the SAM-modified transistor. The observed agreement is discussed. The manifestation of the SAM in the contact resistance shows that transistors can potentially be used as an experimental test-bed for molecular electronics.
2012
- Organic field-effect transistors as new paradigm for large-area molecular junctions
[Articolo su rivista]
S., Casalini; A., Shehu; S., Destri; W., Porzio; M. C., Pasini; F., Vignali; F., Borgatti; C., Albonetti; F., Leonardi; Biscarini, Fabio
abstract
Self-Assembly Monolayers (SAMs) are considered a promising route for solving technological hindrances (such as bias-stress, contact resistance, charge trapping) affecting the electrical performances of the Organic Field-Effect Transistors (OFETs). Here we use an OFET based on pentacene thin film to investigate the charge transport across conjugated SAMs at the Au/pentacene interface. We synthesized a homolog series of pi-conjugated molecules, termed Tn-C8-SH, consisting of a n-unit oligothienyl Tn (n = 1...4) bound to an octane-1-thiol (C8-SH) chain that self-assembles on the Au electrodes. The multi-parametric response of such devices yields an exponential behavior of the field-effect mobility (mu), current density (J), and total resistivity (R), due to the SAM at the charge injection interface (i.e. Au-SAM-pentacene). The surface treatment of the OFETs induces a clear stabilization of different parameters, like sub-threshold slope and threshold voltage, thanks to standardized steps in the fabrication process.
2012
- Processing and Low Voltage Switching of Organic Ferroelectric Phase-Separated Bistable Diodes
[Articolo su rivista]
M., Li; N., Stingelin; J. J., Michels4; M. J., Spijkman; K. l., Asadi; R., Beerends; Biscarini, Fabio; P. W. M., Blom; D. M., de Leeuw
abstract
2012
- Structure and Morphology of PDI8-CN2 for n-Type Thin-Film Transistors
[Articolo su rivista]
F., Liscio; S., Milita; C., Albonetti; P., D'Angelo; A. Guagliardi N., Masciocchi; R. G., Della Valle; E., Venuti; A., Brillante; Biscarini, Fabio
abstract
2012
- Structure and dynamics of pentacene on SiO2: From monolayer to bulk structure
[Articolo su rivista]
A., Brillante; I., Bilotti; R. G., Della Valle; E., Venuti; A., Girlando; M., Masino; F., Liscio; S., Milita; C., Albonetti; P., D'Angelo; A., Shehu; Biscarini, Fabio
abstract
We have used confocal micro Raman spectroscopy, atomic force microscopy (AFM), and x-ray diffraction (XRD) to investigate pentacene films obtained by vacuum deposition on SiO2 substrates. These methods allow us to follow the evolution of lattice structure, vibrational dynamics, and crystal morphology during the growth from monolayer, to TF, and, finally, to bulk crystal. The Raman measurements, supported by the AFM and XRD data, indicate that the film morphology depends on the deposition rate. High deposition rates yield two-dimensional nucleation and quasi-layer-by-layer growth of the T-F form only. Low rates yield three-dimensional nucleation and growth, with phase mixing occurring in sufficiently thick films, where the T-F form is accompanied by the "high-temperature" bulk phase. Our general findings are consistent with those of previous work. However, the Raman measurements, supported by lattice dynamics calculations, provide additional insight into the nature of the TFs, showing that their characteristic spectra originate from a loss of dynamical correlation between adjacent layers.
2012
- Thermal collapse of snowflake fractals
[Articolo su rivista]
T., Gallo; A., Jurjiu; Biscarini, Fabio; A., Volta; F., Zerbetto
abstract
Snowflakes are thermodynamically unstable structures that would ultimately become ice balls. To investigate their dynamics, we mapped atomistic molecular dynamics simulations of small ice crystals – built as filled von Koch fractals – onto a discrete-time random walk model. Then the walkers explored the thermal evolution of high fractal generations. The in silico experiments showed that the evolution is not entirely random. The flakes step down one fractal generation before forfeiting their architecture. The effect may be used to trace the thermal history of snow.
2012
- Two-Dimensional Charge Transport in Disordered Organic Semiconductors
[Articolo su rivista]
J. J., Brondijk; W. S. C., Roelofs; S. G. J., Mathijssen; A., Shehu; T., Cramer; Biscarini, Fabio; P. W. M., Blom; D. M., de Leeuw
abstract
We analyze the effect of carrier confinement on the charge-transport properties of organic field-effect transistors. Confinement is achieved experimentally by the use of semiconductors of which the active layer is only one molecule thick. The two-dimensional confinement of charge carriers provides access to a previously unexplored charge-transport regime and is reflected by a reduced temperature dependence of the transfer curves of organic monolayer transistors.
2012
- Unconventional Multi-Scale Patterning of Titanium Dioxide: A New Tool for the Investigation of Cell–Topography Interactions
[Articolo su rivista]
Biscarini, Fabio; M., Bianchi; B., Chelli; F., Valle; C., Dionigi; E., Bystrenova; P., Greco
abstract
Titanium dioxide (TiO2) is a biocompatible material with important applications in the field of regenerative medicine. Here we show that a multi-scale hierarchical architecture of TiO2, realized with sub-micrometer polystyrene beads as templating agent patterned by micromolding in capillaries (MIMICs), is a viable functional tool for the systematic investigation of cell behavior with respect to a complex topographic texture of the substrate. TiO2 stripes of different width and interconnected porosity whose size ranges from a few hundred to a few tens nanometer, are obtained after thermal treatment of the precursors with concurrent removal of the templating agent. The adhesion and proliferation of two human secondary neural cell lines, i.e., 1321N1 astrocytoma and SH-SY5Y neuroblastoma, on the patterns is statistically assessed with respect to the TiO2 stripe width and porosity. Our results show that cells have a strong preference for TiO2 patterns with respect to glass, the proliferation rate is not affected by cell porosity whereas adhesion is although ligthly, whereas the response of cell density to stripe width is very different in astocytoma cells with respect to neuroblastoma cells.
2011
- A high-vacuum deposition system for in situ and real-time electrical characterization of organic thin-film transistors
[Articolo su rivista]
S. D., Quiroga; A., Shehu; C., Albonetti; M., Murgia; P., Stoliar; F., Borgatti; Biscarini, Fabio
abstract
We present a home-built high-vacuum system for performing organic semiconductor thin-film growth and its electrical characterization during deposition (real-time) or after deposition (in situ). Since the environment conditions remain unchanged during the deposition and electrical characterization process, a direct correlation between growth mode and electrical properties of thin film can be obtained. Deposition rate and substrate temperature can be systematically set in the range 0.1-10 ML/min and RT-150 degrees C, respectively. The sample-holder configuration allows the simultaneous electrical monitoring of up to five organic thin-film transistors (OTFTs). The OTFTs parameters such as charge carrier mobility mu, threshold voltage V(TH), and the on-off ratio I(on)/I(off) are studied as a function of the semiconductor thickness, with a submonolayer accuracy. Design, operation, and performance of the setup are detailed. As an example, the in situ and real-time electrical characterization of pentacene TFTs is reported.
2011
- Ambipolar Multi-Stripe Organic Field-Effect Transistors
[Articolo su rivista]
M., Cavallini; P., D'Angelo; V., Vendrell Criado; D., Gentili; A., Shehu; F., Leonardi; S., Milita; F., Liscio; Biscarini, Fabio
abstract
Organic field-effect transistors (OFETs) based on molecular multiwires are obtained by driving the self-organization of two types of molecular semiconductors inside an electronic device structure by means of a stamp-assisted deposition, followed by vacuum sublimation of a second OS, to yield an ambipolar OFET.
2011
- Atomic Force Microscope nanolithography on chromosomes to genrate single-cell genetic probes
[Articolo su rivista]
S., Di Bucchianico; A. M., Poma; M. F., Giardi; L., Di Leandro; F., Valle; Biscarini, Fabio; D., Botti
abstract
2011
- Beyond the Nernst-limit with dual-gate ZnO ion-sensitive field-effecttransistors
[Articolo su rivista]
M., Spijkman; E. C. P., Smits; J. F. M., Cillessen; Biscarini, Fabio; P. W. M., Blom; D. M., de Leeuw
abstract
The sensitivity of conventional ion-sensitive field-effect transistors (ISFETs) is limited to 59 mV/pH, which is the maximum detectable change in electrochemical potential according to the Nernst equation. Here we demonstrate a transducer based on a ZnO dual-gate field-effect transistor that breaches this boundary. To enhance the response to the pH of the electrolyte, a self-assembled monolayer has been used as a top gate dielectric. The sensitivity scales linearly with the ratio between the top and bottom gate capacitances. The sensitivity of our ZnO ISFET of 22 mV/pH is enhanced by more than two orders of magnitude up to 2.25 V/pH.
2011
- Doping and photo-induced current in discotic liquid crystals thin films: Long-time and temperature effects
[Articolo su rivista]
A., Calò; P., Stoliar; M. Cavallini Y. H., Geerts; Biscarini, Fabio
abstract
Here we address the problem of time and temperature instability of the electrical current related to parasitic doping effects in discotic liquid crystals (DLCs). We investigated the electrical transport in thin films of a phthalocyanine-based DLC in-dark and upon laser irradiation during long thermal cycles. Measuring the electrical transport between two electrodes we observed that in-dark the current is mostly due to doping levels while, upon laser irradiation, the photocurrent reflects the diffusion length of the photogenerated charge carriers and it is limited by the coherence length of a column. We prove here that the two contributions are completely independent. Our result experimentally supports the theoretical studies performed at the molecular level on discotic liquid crystals.
2011
- Kinetic characterization of amyloid-beta 1-42 aggregation with a multimethodological approach
[Articolo su rivista]
M., Bartolini; M., Naldi; J., Fiori; F., Valle; Biscarini, Fabio; D. V., Nicolau; V., Andrisano
abstract
Extensive evidence suggests that the self-assembly of amyloid-beta peptide (A beta) is a nucleation-dependent process that involves the formation of several oligomeric intermediates. Despite neuronal toxicity being recently related to A beta soluble oligomers, results from aggregation studies are often controversial, mainly because of the low reproducibility of several experimental protocols. Here a multimethodological study that included atomic force microscopy (AFM), transmission electron microscopy (TEM), fluorescence microscopy (FLM), mass spectrometry techniques (matrix-assisted laser desorption/ionization time-of-flight [MALDI-TOF] and electrospray ionization quadrupole time-of-flight [ESI-QTOF]), and direct thioflavin T (ThT) fluorescence spectroscopy were enabled to set up a reliable and highly reproducible experimental protocol for the characterization of the morphology and dimension of A beta 1-42 (A beta 42) aggregates along the self-assembly pathway. This multimethodological approach allowed elucidating the diverse assembly species formed during the A beta aggregation process and was applied to the detailed investigation of the mechanism of A beta 42 inhibition by myricetin. In particular, a very striking result was the molecular weight determination of the initial oligomeric nuclei by MALDI-TOF, composed of up to 10 monomers, and their morphology by AFM.
2011
- Label-free Sensing of Biomolecules and Neural Networks with Ultra-thin Film Organic Field Effect Transistors
[Abstract in Rivista]
Biscarini, Fabio; Eva, Bystrenova; Beatrice, Chelli; Arian, Shehu; Casalini, Stefano; Santiago, Quiroga; Mauro, Murgia
abstract
N/A
2011
- METHOD FOR THE CREATION OF COMPLEX STRUCTURES ON A MICROMETRIC 0R NANOMETRIC SCALE AND THE COMPLEX STRUCTURE THUS OBTAINED
[Brevetto]
Bianchi, Mlchele; Cavallini, Massimiliano; Biscarini, Fabio; Valle, Francesco
abstract
A method for the creation of complex structures (5) comprising the substrate (S) deposit steps with at least one surface or substrate (1) that can be corroded by a material (2) to be dispersed in a corrosive solution (3); the aforementioned deposits steps are simultaneously created in a single step through the step in which distribution of said solution (3) and said material (2) is spatially guided onto the substrate (S) by applying a mould (4).
2011
- Mastering Self-Organization of Functional Materials at Different Length Scale
[Articolo su rivista]
P., Samorì; A., Helman; Biscarini, Fabio; F., Cacialli
abstract
-
2011
- Morphological and mechanical properties of alkanethiol self-assembled monolayers investigated via bimodal atomic force microscopy
[Articolo su rivista]
C., Albonetti; S., Casalini; F., Borgatti; L., Floreano; BISCARINI, FABIO
abstract
Alkanethiol Self-Assembly Monolayers (SAMs) were investigated by means of BiModal Atomic Force Microscopy. Morphological and mechanical properties show a parabolic trend vs. the chain length n, which is ascribed to the disorder at the SAMs/Au interface. This explains the trend of charge injection across SAMs in organic field effect transistors.
2011
- Observation and Analysis of Flat-Lying Molecular Layer via Scanning Probe Microscopy
[Articolo su rivista]
C., Albonetti; Biscarini, Fabio
abstract
2011
- One-step substrate nanofabrication and patterning of nanoparticles by lithographically controlled etching
[Articolo su rivista]
M., Bianchi; D. L., Herrero; F., Valle; P., Greco P; G. M., Ingo; S., Kalicius; Biscarini, Fabio; M., Cavallini
abstract
We propose an integrated top-down and bottom-up approach to single-step nanofabrication of complex nanostructures made of different materials. The process, termed lithographically controlled etching (LCE), starts with a drop of an etching solution cast on the surface to be patterned. By placing a polymeric mold on the substrate, the stamp protrusions come into contact with the surface, thus protecting it, whereas the surface beneath the mold recesses is exposed to a thin layer of etching solution, allowing the surface to be etched. By dispersing nanoparticles into the etching solution, these can be deposited and self-organize in the recesses on the substrate as these are excavated. We demonstrate here the fabrication of complex structures and nanowires 30 nm wide. Moreover, by exploiting capillary forces, it is possible to deposit nanoparticles at precise positions with respect to optically addressable microstructures, thus realizing a multiscale functional pattern.
2011
- Selective Growth of α-Sexithiophene by Using Silicon Oxides Patterns
[Articolo su rivista]
C., Albonetti; M., Barbalinardo; S., Milita; M., Cavallini; F., Liscio; J. F., Moulin; Biscarini, Fabio
abstract
A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiOx substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiOx substrates with the selective arrangement of molecular ultra-thin film. The former is used to fabricate silicon oxide arrays of parallel lines of 400 nm in width over an area of 1 cm(2). Selective growth arises from the interplay between kinetic growth parameters and preferential interactions with the patterned surface. The result is an ultra-thin film of organic molecules that is conformal to the features of the fabricated motives.
2011
- Structure-activity relationship of acridine derivatives to amyloid aggregation of lysozyme
[Articolo su rivista]
A., Antosova; B., Chelli; E., Bystrenova; K., Siposova; F., Valle; J., Imrich; M., Vilkova; P., Kristian; Biscarini, Fabio; Z., Gazova
abstract
Background: Amyloid-related diseases (such as Alzheimer's disease or diabetes type II) are associated with self-assembly of protein into amyloid aggregates.
Methods: Spectroscopic and atomic force microscopy were used to determine the ability of acridines to affect amyloid aggregation of lysozyme.
Results: We have studied the effect of acridine derivatives on the amyloid aggregation of lysozyme to investigate the acridine structure-activity relationship. The activity of the effective planar acridines was characterized by the half-maximum depolymerization concentration DC(50) and half-maximal inhibition concentration IC(50). For the most effective acridine derivatives we examined their interaction with DNA and their effect on cell viability in order to investigate their eventual influence on cells. We thus identified planar acridine derivatives with intensive anti-amyloid activity (IC(50) and DC(50) values in micromolar range), low cytotoxicity and weak ability to interfere with the processes in the cell.
Conclusions: Our findings indicate that both the planarity and the tautomerism of the 9-aminoacridine core together with the reactive nucleophilic thiosemicarbazide substitution play an important role in the anti-amyloid activities of studied derivatives.
General significance: The present findings favor the application of the selected active planar acridines in the treatment of amyloid-related diseases.
2010
- Control of neuronal cell adhesion on single-walled carbon nanotubes 3D patterns
[Articolo su rivista]
C., Dionigi; M., Bianchi; O., D’Angelo; A., Shehu; B., Chelli; P., Greco; A., Shehu; I., Tonazzini; A. N., Lazar; Biscarini, Fabio
abstract
2010
- Dual-Gate Organic Field-Effect Transistors as Potentiometric Sensors in Aqueous Solution
[Articolo su rivista]
M. J., Spijkman; J. J., Brondijk; T. C. T., Geuns; E. C. P., Smits; T., Cramer; F., Zerbetto; P., Stoliar; Biscarini, Fabio; P. W. M., Blom; D. M., de Leeuw; Dago, M.
abstract
2010
- Effect of Fe3O4 magnetic nanoparticles on lysozyme amyloid aggregation
[Articolo su rivista]
A., Bellova; E., Bystrenova; M., Koneracka; P., Kopcansky; F., Valle; N., Tomasovicova; M., Timko; J., Bagelova; Biscarini, Fabio; Z., Gazova
abstract
2010
- Electric Field Effects on Short Fibrils of A beta Amyloid Peptides
[Articolo su rivista]
F., Lugli; F., Toschi; Biscarini, Fabio; F., Zerbetto
abstract
Amyloid fibrils are highly ordered protein aggregates, which are associated with many neurodegenerative diseases. The assembling dynamics of monomeric beta-amyloid peptides, A beta, into small aggregates (and then into long fibrils) is still debated and has become a hot topic. In this study, we conducted molecular dynamics simulations in explicit water of small A beta protofibrils (from monomer to pentamer) under the perturbation of an externally applied electric field with the aim of investigating the fundamental molecular interactions involved in the aggregation mechanism. Dynamics of small adducts of A beta(16-42) in the presence of an electric field, which was shown before to accelerate the conformational change of a single molecule, indicate that the structural resilience increases with the number of molecules in the aggregate. In particular, for 50 ns, the pentamer shows an enhanced stability in secondary structure, number of hydrogen bonds, and number of salt bridges, even in the presence of the field perturbation. The resilience to the field perturbation is linked to the variation of the induced dipole moment of the aggregates that tends to level off very rapidly with the growing number of molecules, thereby reducing the energy available per molecule to produce structural changes. The results also show that in the presence of the field the stability of the hydrophobic second beta-sheet (32, residues 31-42) is higher than that of the first one (beta 1, residues 18-26). In particular, we identify Gly33, Gly37, and Met35 as the most important residues that stabilize the intermolecular packing and may act as nucleation sites for fibrillization. Furthermore, dynamics of the full-length A beta(1-42) pentameric aggregate, which include the highly charged random coil residues 1-15, confirmed the key role of the second hydrophobic core in the protofibril structure.
2010
- Fabrication of Fractal Surfaces by Electron Beam Lithography
[Articolo su rivista]
P., Stoliar; A., Calò; F., Valle; Biscarini, Fabio
abstract
2010
- Fabrication of ordered carbon nanotube structures by unconventional lithography
[Articolo su rivista]
P., Greco; M., Facchini; M., Cavallini; G., Ruani; C., Dionigi; Biscarini, Fabio
abstract
2010
- Flexible, digital enhanced reading device
[Brevetto]
Biscarini, Fabio; Cavallini, Massimiliano; Matacotta, Francesco Cino; Greco, Pierpaolo; Lanza, Serena; Mattiazzi, Pietro; Natalini, Davide
abstract
A flexible, digital enhanced reading device (P) comprises at least one label containing encoded information, a spatially structured element placed over the label itself, defined by a material indicating predetermined temperature level and exposure time range, and comprising a material with morphological and/or structural and/or chemical and/or physical state changing properties detectable following a predetermined heat absorption; the mentioned spatially structural element is adapted to at least partially cover determined zones of said label with dimensions between 0.01% and 100% of the surface of the label itself, and comprises molecular materials and/or polymer materials and/or liquid crystals and/or mixtures of said materials in any proportion.
2010
- High performance single crystal OFETs based on two dithiophene-tetrathiafulvalene (DT-TTF) polymorphs
[Articolo su rivista]
R., Pfattner; M., MAS TORRENT; I., Bilotti; A., Brillante; S., Milita; F., Liscio; Biscarini, Fabio; T., Marszalek; J., Ulański; A., Nosal; M., GAZICKI LIPMAN; M., Leufgen; G., Schmidt; L. W., Molenkamp; V., Laukhin; J., Veciana; C., Rovira
abstract
2010
- Layered Distribution of Charge Carriers in Organic Thin Film Transistors
[Articolo su rivista]
A., Shehu; S. D., Quiroga; P., D'Angelo; C., Albonetti; F., Borgatti; M., Murgia; A., Scorzoni; P., Stoliar; Biscarini, Fabio
abstract
2010
- Monitoring the crystallization process of nano-confined organic molecules by synchrotron X-ray diffraction
[Articolo su rivista]
S., Milita; C., Dionigi; F., Borgatti; W., Porzio; Biscarini, Fabio
abstract
2010
- Multiscale Morphology of Organic Semiconductor Thin Films Controls the Adhesion and Viability of Human Neural Cells
[Articolo su rivista]
I., Tonazzini; E., Bystrenova; B., Chelli; P., Greco; P., Stoliar; A., Calò; A., Lazar; F., Borgatti; P., D'Angelo; C., Martini; Biscarini, Fabio
abstract
2010
- Patterning pentacene surfaces by local oxidation nanolithography
[Articolo su rivista]
N. S., Losilla; J., Martinez; E., Bystrenova; P., Greco; Biscarini, Fabio; R., Garcia
abstract
2010
- Real-time Structural and Electrical Investigation of PDI8-CN2 based OFET
[Abstract in Rivista]
Fabiola, Liscio; Santiago David, Quiroga; Arian, Shehu; Biscarini, Fabio; C., Frank; F., Schreiber; S., Kowarik
abstract
Semiconductor thin-film devices based on organic molecules are of great interest for the development of high performance organic field effect transistors (OFETs) and organic light emitting diodes (OLEDs), as well as to underscore fundamental charge transport effects in molecular solids. Among the n-type organic molecules, perylene derivatives are very promising. In particular PDI-8CN2, N,N’-bis(n-octyl)-dicyanoperylene-3,4:9,10-bis (dicarb-oximide), has been reported to allow the fabrication of OFETs with excellent electrical performance (high-mobility: 0.16-0.6 cm2 V-1s-1) and remarkably high stability in air. In these systems, the charge mobility depends on the overlap between π-π orbitals of vicinal molecules, which is mainly influenced by the structure and morphology of the first layers of organic film at the interface with the dielectric. Since the structure of these first layers may significantly differ from that of the bulk, the determination of the molecular orientation and packing of organic molecules at the substrate interface is a crucial input for modelling the electronic band structure and the associated charge-transport properties. For this reason we have performed Grazing Incidence X-ray Diffraction (GIXD) and X-Ray Reflectivity (XRR) measurements, in situ and real time during the UHV deposition of PDI-8CN2. Moreover, in situ and real time electrical measurements were performed on FET structures during the semiconductor deposition. Thanks to these time resolved measurements we could describe i) the thin-film growth dynamics, ii) the molecular packing and microstructure of the organic thin film, iii) the influence of the substrate temperature and the deposition flux, and iv) the relation between the charge transport properties and the growth mechanism of the thin film.
2010
- Stable Non-Covalent Large Area Patterning of Inert Teflon-AF Surface: A New Approach to Multiscale Cell Guidance
[Articolo su rivista]
F., Valle; B., Chelli; M., Bianchi; P., Greco; E., Bystrenova; I., Tonazzini; Biscarini, Fabio
abstract
2010
- Synchronized optical and electrical characterization of discotic liquid crystals thin films
[Articolo su rivista]
A., Calò; P., Stoliar; M., Cavallini; Y. H., Geerts; Biscarini, Fabio
abstract
2010
- Time-Temperature Integrator Based on the Dewetting of Polyisobutylene Thin Films
[Articolo su rivista]
A., Calò; P., Stoliar; F. C., Matacotta; M., Cavallini; Biscarini, Fabio
abstract
2009
- DNA adsorption measured with ultra-thin film organic field effect transistors
[Articolo su rivista]
P., Stoliar; E., Bystrenova; M., Facchini; P., Annibale; M. J., Spijkman; S., Setayesh; D., de Leeuw; Biscarini, Fabio
abstract
Organic ultra-thin film field effect transistors (FET) are operated as label-free sensors of deoxyribonucleic acid (DNA) adsorption. Linearized plasmid DNA molecules (4361 base pairs) are deposited from a solution on two monolayers thick pentacene FEE The amount of adsorbed DNA is measured by AFM and correlated to the concentration of the solution. Electrical characteristics on the dried DNA/pentacene FETs were studied as a function of DNA concentration in the solution. Shift of the pinch-off voltage across a wide range of DNA concentration, from very diluted to highly concentrated, is observed. It can be ascribed to additional positive charges in the semiconductor induced by DNA at a rate of one charge for every 200 base pairs. The sensitivity 74ng/cm(2), corresponding to 650 ng/ml, is limited by the distribution of FET parameters upon repeated cycles, and is subjected to substantial improvement upon standardization. Our work demonstrates the possibility to develop label-free transducers suitable to operate in regimes of high molecular entanglement. (C) 2009 Elsevier B.V. All rights reserved.
2009
- Effects of Electric Field Stress on a beta-Amyloid Peptide
[Articolo su rivista]
Toschi, TOSCHI F.; Francesca, ; Lugli, LUGLI F.; Francesca, ; Biscarini, Fabio; Fabio, ; Zerbetto, ZERBETTO F.; Francesco,
abstract
2009
- Imaging and Detection of Single Molecule Recognition Events on Organic Semiconductor Surfaces
[Articolo su rivista]
J., Preiner; N. S., Losilla; A., Ebner; P., Annibale; Biscarini, Fabio; R., Garcia; P., Hinterdorfer
abstract
The combination of organic thin film transistors and biological molecules could open new approaches for the detection and measurement of properties of biological entities. To generate specific addressable binding sites on such substrates, it is necessary to determine how single biological molecules, capable of serving as such binding sites behave upon attachment to semiconductor surfaces. Here, we use a combination of high-resolution atomic force microscopy topographical imaging and single molecule force spectroscopy (TREC), to study the functionality of antibiotin antibodies upon adsorption on pentacene islands, using biotin-functionalized, magnetically coated AFM tips. The antibodies could be stably adsorbed on the pentacene, preserving their functionality of recognizing biotin over the whole observation time of more than one hour. We have resolved individual antigen binding sites on single antibodies for the first time. This highlights the resolution capacity of the technique.
2009
- Influence of the substrate hydrophilicity on the grid assisted deposition of tris-(8-hydroxyquinolinato) aluminum(III) thin films
[Articolo su rivista]
M., Massi; M., Cavallini; Biscarini, Fabio
abstract
The influence of the substrate wetting properties on the grid assisted deposition of tris-(8-hydroxyquinolinato)aluminum(Ill) (Alq(3)) Onto Si/SiOx Surfaces was investigated. Different degrees of hydrophilicity/hydrophobicity on the Si/SiOx were obtained by changing the surface chemical functionalities with wet treatments. We observed that the deposited Alq(3) films can be spatially controlled and assembled either into continuous grid-like stripes or ordered dots depending upon the wetting properties of the substrate
2009
- Lithographic Alignment of Discotic Liquid Crystals: A New Time-Temperature Integrating Framework
[Articolo su rivista]
M., Cavallini; A., Calo; P., Stoliar; J. C., Kengne; S., Martins; F. C., Matacotta; F., Quist; G., Gabode; N., Dumont; Y. H., Geerts; Biscarini, Fabio
abstract
Liquid crystals are a successful example of how the control of self-assembly via chemical design leads to novel applications. Direct patterning of a continuous metal-free mesogenic phthalocyanine film (discotick liquid crystals) is shown by the spatial control of columns orientation by unconventional lithography. These patterned films work as time-temperature integrators at a columnar rectangular-hexagonal transition temperature.
2009
- Measurement of DNA Morphological Parameters at Highly Entangled Regime on Surfaces
[Articolo su rivista]
A., Calò; P., Stoliar; E., Bystrenova; F., Valle; Biscarini, Fabio
abstract
The morphology of circular DNA deposited from a solution on the mica surface is analyzed from the power spectrum density (PSD) of the atomic force microscopy (AFM) images. Sample morphology is modulated in a broad range of concentration C from isolated molecules to highly entangled networks. DNA exhibits a multiaffine behavior with two correlation length scales: the persistence length P which remains constant (approximate to 50 nm) within the C range and the intermolecular distance which exhibits a decay with increasing C. Applying a diffusion based model in which xi scales as xi approximate to D(-0.25)center dot C(-0.5), we extracted the DNA diffusion coefficient D approximate to 2 x 10(-7) cm(2)/S. This value is consistent with a high-molecular-weight plasmid DNA supercoiled in the solution.
2009
- Molecular scale energy dissipation in oligothiophene monolayers measured by dynamic force microscopy
[Articolo su rivista]
N. F., Martinez; W., Kaminski; C. J., Gomez; C., Albonetti; Biscarini, Fabio; R., Perez; R., Garcia
abstract
We perform a combined experimental and theoretical approach to establish the atomistic origin of energy dissipation occurring while imaging a molecular surface with an amplitude modulation atomic force microscope. We show that the energy transferred by a single nano-asperity to a sexithiophene monolayer is about 0.15 eV/cycle. The configuration space sampled by the tip depends on whether it approaches or withdraws from the surface. The asymmetry arises because of the presence of energy barriers among different deformations of the molecular geometry. This is the source of the material contrast provided by the phase-shift images.
2009
- Nanopatterning Soluble Multifunctional Materials by Unconventional Wet Lithography
[Articolo su rivista]
M., Cavallini; C., Albonetti; Biscarini, Fabio
abstract
Molecular multifMolecular multifunctional materials have potential applications in many fields of technology, such as electronics, optics and optoelectronics, information storage, sensing, and energy conversion and storage. These materials are designed exhibit enhanced properties, and at the same time are endowed with functional groups that control their interactions, and hence self-organization, into a variety of supramolecular architectures. Since most of the multifunctional materials are soluble, lithographic methods suitable for solutions are attracting increasing interest for the manufacturing of the new materials and their applications. The aim of this paper is to highlight some of the recent advances of solution-based fabrication of multifunctional materials. We explain and examine the principles, processes, materials, and limitations of this class of patterning techniques, which we term unconventional wet lithographies (UWLs). We describe their ability to yield patterns and structures whose feature sizes range from nanometers to micrometers. In the following sections, we focus our attention on micromolding in capillaries, lithographically controlled wetting, and grid-assisted deposition, the most used methods demonstrated to lead to fully operating devices.
2009
- On the Feasibility of Frequency Doubling Microwave RFIDs Exploiting Paper-Based Antennas and Pentacene Diodes
[Relazione in Atti di Convegno]
F., Alimenti; P., Mezzanotte; V., Palazzari; L., Roselli; A., Shehu; S. D., Quiroga; P., Placidi; Biscarini, Fabio; A., Scorzoni
abstract
N/A
2009
- Quantitative analysis of charge-carrier trapping in organic thin-film transistors from transfer characteristics
[Articolo su rivista]
P., D'Angelo; P., Stoliar; T., Cramer; A., Cassinese; F., Zerbetto; Biscarini, Fabio
abstract
A dynamic method for quantifying the amount and mechanism of trapping in organic field effect transistors (OFETs) is proposed. It exploits transfer characteristics acquired upon application of a triangular waveform gate sweep V (G). The analysis of the transfer characteristics at the turning point V (G)=-V (max) between forward and backward gate sweeps, viz. around the maximum gate voltage V (max) applied, provides a differential slope Delta m which depends exclusively on trapping. Upon a systematic change of V (max) it is possible to extract the initial threshold voltage, equivalent to one of the observables of conventional stress measurements, and assess the mechanism of trapping via the functional dependence on the current. The analysis of the differential logarithmic derivative at the turning point yields the parameters of trapping, as the exponent beta and the time scale of trapping tau. In the case of an ultra-thin pentacene OFET we extract beta=1 and tau=10(2)-10(3) s, in agreement with an exponential distribution of traps. The analysis of the hysteresis parameter Delta m is completely general and explores time scales much shorter than those involved in bias stress measurements, thus avoiding irreversible damage to the device.
2009
- Towards All-Organic Field-Effect Transistors by Additive Soft Lithography
[Articolo su rivista]
D. A., Serban; P., Greco; S., Melinte; A., Vlad; C. A., Dutu; S., Zacchini; M. C., Iapalucci; Biscarini, Fabio; M., Cavallini
abstract
N/A
2009
- Water-induced polaron formation at the pentacene surface: Quantum mechanical molecular mechanics simulations
[Articolo su rivista]
T., Cramer; Steinbrecher, T. h.; Koslowski, T. h.; D. A., Case; Biscarini, Fabio; F., Zerbetto
abstract
Water is an omnipresent polar impurity that is expected to be the origin of many electric degradation phenomena observed in organic semiconductors. Here, we describe a microscopic model for polaron formation in the outermost layer of a pentacene crystal due to the polarization of a nearby water layer. The efficient coupling of a classical force field that describes the liquid with a tight-binding model that represents the pi system of the organic layer permits the calculation of nanosecond length trajectories. The model predicts that the reorientation of water dipoles stabilizes positive charge carriers on average by 0.6 eV and thus leads to a polaron trap state at the liquid interface. Thermal fluctuations of the water molecules provoke two-dimensional diffusive hopping of the charge carrier parallel to the interface with mobilities of up to 0.6 cm(2) s(-1) V-1 and lead to an amorphous broadening of the valence-band tail. As a consequence, water-filled nanocavities act as trapping sites in pentacene transistors. Instead, a complete wetting of the organic film is expected to result in fast thermally activated hopping transport. Polaron trapping is thus not expected to be a limiting factor for transistor-based sensors that operate under water.
2008
- 3D Hierarchical Porous TiO2 Films from Colloidal Composite Fluidic Deposition
[Articolo su rivista]
Dionigi, C; Greco, P; Ruani, G; Cavallini, M; Borgatti, F; Biscarini, Fabio
abstract
2008
- Conductive sub-micrometric wires of platinum-carbonyl clusters fabricated by soft-lithography
[Articolo su rivista]
Greco, P; Cavallini, M; Stoliar, P; Quiroga, Sd; Dutta, S; Zacchini, S; Iapalucci, Mc; Morandi, V; Milita, S; Merli, Pg; Biscarini, Fabio
abstract
2008
- Crystallization of organic semiconductor molecules in nanosized cavities: Mechanism of polymorphs formation studied by in situ XRD
[Articolo su rivista]
Milita, S; Dionigi, C; Borgatti, F; Lazar, An; Porzio, W; Destri, S; Wermeille, D; Felici, R; Andreasen, Jw; Nielsen, Mm; Biscarini, Fabio
abstract
2008
- Driving Force for the Adsorption of Sexithiophene on Gold
[Articolo su rivista]
Sandig, N; Biscarini, Fabio; Zerbetto, F.
abstract
2008
- Monolayer control of discotic liquid crystal by electromigration of dewetted layers in thin film devices
[Articolo su rivista]
Calo, A; Stoliar, P; Cavallini, M; Sergeyev, S; Geerts, Yh; Biscarini, Fabio
abstract
2008
- Neural networks grown on organic semiconductors
[Articolo su rivista]
Bystrenova, E; Jelitai, M; Tonazzini, I; Lazar, An; Huth, M; STOLIAR P., DIONIGI C; Cacace, Mg; Nickel, B; Madarasz, E; Biscarini, Fabio
abstract
2008
- Parallel-local anodic oxidation of silicon surfaces by soft stamps
[Articolo su rivista]
Albonetti, C; Martinez, J; Losilla, Ns; Greco, P; Cavallini, M; Borgatti, F; Montecchi, Monica; Pasquali, Luca; Garcia, R; Biscarini, Fabio
abstract
We investigate the fabrication of nanometric patterns on silicon surfaces by using the parallel-local anodic oxidation technique with soft stamps. This method yields silicon oxide nanostructures 15 nm high, namely at least five times higher than the nanostructures made with local anodic oxidation using atomic force microscopy, and thanks to the size of the stamp enables one to pattern the surface across a centimetre length scale. To implement this technique, we built a machine to bring the metallized polydimethylsiloxane stamp in contact with the silicon surface, subsequently inserted in a sealed chamber with controlled relative humidity. The oxide nanostructures are fabricated when a bias voltage of 36 V is applied between the stamp and the silicon for 2 min, with a relative humidity of 90%. The flexibility of the stamp enables a homogeneous conformal contact with the silicon surface, resulting in an excellent reproducibility of the process. Moreover, by means of two subsequent oxidations with the same stamp and just rotating the sample, we are able to fabricate complex nanostructures. Finally, a detailed study of the oxidation mechanism, also using a finite element analysis, has been performed to understand the underlying mechanism.
2008
- Single molecule magnets: from thin films to nano-patterns
[Articolo su rivista]
Cavallini, M; Facchini, M; Albonetti, C; Biscarini, Fabio
abstract
2008
- Structure, morphology, and growth dynamics of perfluoro-pentacene thin films
[Articolo su rivista]
Kowarik, S; Gerlach, A; Hinderhofer, A; Milita, S; Borgatti, F; Zontone, F; Suzuki, T; Biscarini, Fabio; Schreiber, F.
abstract
2008
- The four polymorphic modifications of the semiconductor dibenzo-tetrathiafulvalene
[Articolo su rivista]
A., Brillante; I., Bilotti; R. G., DELLA VALLE; E., Venuti; S., Milita; C., Dionigi; F., Borgatti; A. N., Lazar; Biscarini, Fabio; M., MAS TORRENT; N., Oxtoby; N., Crivillers; J., Veciana; C., Rovira; M., Leufgen; G., Schmidt; L. W., Molenkamp
abstract
2007
- Carbon nanotube networks patterned from aqueous solutions of latex bead carriers
[Articolo su rivista]
Chiara, Dionigi; Pablo, Stoliar; Giampiero, Ruani; SANTIAGO DAVID, Quiroga; Massimo, Facchini; Biscarini, Fabio
abstract
2007
- Charge Injection across Self-Assembly Monolayers in Organic Field Effect Transistors: Odd-Even Effects
[Articolo su rivista]
PABLO, STOLIAR; RAJENDRA, KSHIRSAGAR; MASSIMILIANO, MASSI; PAOLO, ANNIBALE; CRISTIANO, ALBONETTI; DAGO M., DE LEEUW; BISCARINI, FABIO
abstract
We investigate the role of self-assembly monolayers in modulating the response of organic field-effect transistors. Alkanethiol monolayers of chain length n are self-assembled on the source and drain electrodes of pentacene field-effect transistors. The charge carrier mobility mu exhibits large fluctuations correlated with odd-even n. For n < 8, mu increases by 1 order of magnitude owing to the decrease of the hole injection barrier and the improved molecular order at the organic-metallic interface. For n >= 8, mu decays exponentially with an inverse decay length beta = 0.6 A(-1). Our results show that (i) charge injection across the interface occurs by through-bond tunneling of holes mediated by the alkanethiol layer; (ii) in the long-chain regime, the charge injection across the alkanethiol monolayer completely governs the transistor response; (iii) the transistor is a sensitive gauge for probing charge transport across single monolayers. The odd-even effect is ascribed to the anisotropic coupling between the alkanethiol terminal sigma bond and the HOMO level of ordered pentacene molecules.
2007
- Charge Injection across Self-Assembly Monolayers in Organic Field Effect Transistors: Odd-Even Effects
[Abstract in Rivista]
Biscarini, Fabio; Pablo, Stoliar; Rajendra, Kshirsagar; Massimiliano, Massi; Dago M., de Leeuw
abstract
Alkanethiol monolayers self-assembled on the Au source and drain electrodes have been used to improve the response of organic field effect transistors by different groups in the past. Here, we investigate the role of self-assembly monolayers of chain length n, where n ranges between 3 and 18, in modulating the charge injection in pentacene field effect transistors. The charge carrier mobility μ exhibits large fluctuations correlated with odd-even n. For n < 8, μ increases by one order of magnitude due to the decrease of the hole injection barrier and the improved molecular order at the organic-metallic interface. For n > 8, μ decays exponentially with an inverse decay length β=0.6 Å-1. As the morphology in the channel is invariant, we account for both the electron structure and the molecular disorder at the interface by introducing a length scale of injection as a function of the chain length. Charge injection across the interface occurs by through-bond tunneling of holes mediated by the alkanethiol layer. At short chain length, decrease of both interfacial morphological disorder and pentacene-surface interactions dominates over the increasing thickness of the alkanethiol monolayer. At long chain length, the charge injection across the alkanethiol monolayer completely governs the transistor response. The odd-even effect is ascribed to the anisotropic coupling between the alkanethiol terminal sigma bond and the HOMO level of ordered pentacene molecules. Our results show that the pentacene transistor is a sensitive gauge for probing charge transport across single monolayers, and that its response is sensitive to sub-molecular details of the interface. This work was supported by the EU-Integrated Project NAIMO (No NMP4-CT-2004-500355).
2007
- Confocal Raman spectroscopy of alpha-sexithiophene: From bulk crystals to field-effect transistors
[Articolo su rivista]
Brillante, A; Bilotti, I; Albonetti, C; Moulin, Jf; Stoliar, P; Biscarini, Fabio; DE LEEUW, Dm
abstract
2007
- DEVICE AND METHOD FOR PROTECTION AND ACTIVATION OF SENSORS
[Brevetto]
Cavallini, Massimiliano; Biscarini, Fabio; Matacotta, Francesco Cino; Massaccesi, Gianluca
abstract
A device and a corresponding method which allows to protect, preserve and activate (making it sensitive to external agents) a sensitive element, which changes its morphology and/or produces phase segregations following exposure to external agents.
2007
- Field Effect Transistors based on Self-Organised Molecular Nanostructures
[Abstract in Rivista]
Biscarini, Fabio; Chiara, Dionigi; Pablo, Stoliar; Cristiano, Albonetti; Jean Francois, Moulin; Silvia, Milita; Massimiliano, Cavallini
abstract
N/A
2007
- Field-effect transistors with organic semiconductor layers assembled from aqueous colloidal nano composites
[Articolo su rivista]
C., Dionigi; P., Stoliar; W., Porzio; S., Destri; M., Cavallini; I., Bilotti; A., Brillante; Biscarini, Fabio
abstract
2007
- High-resolution mapping of the electrostatic potential in organic thin-film transistors by phase electrostatic force microscopy
[Articolo su rivista]
ANNIBALE, P; ALBONETTI, C; STOLIAR, P; BISCARINI, FABIO
abstract
2007
- Microscopie a scansione di forza di nanostrutture molecolari: morfologia, proprietà, nanofabbricazione
[Capitolo/Saggio]
Cristiano, Albonetti; Massimiliano, Cavallini; Rajendra, Kshirsagar; Biscarini, Fabio
abstract
Le microscopie a scansione di sonda (scanning probe microscopies (SPM)) sono basate sull’interazione locale tra una punta (probe) e la superficie del campione di interesse (Wiesendanger R., 1994). La rapida variazione spaziale dell’interazione con la distanza punta-campione conferisce alle SPM la sensibilità alla topografia locale e ne determina l’elevata risoluzione laterale e verticale. La topografia della superficie è l’osservabile principale di ogni esperimento di imaging SPM. Viene acquisita ai nodi di una griglia di scansione registrando lo spostamento verticale punta-campione che serve a mantenere costante l’interazione rispetto ad un valore di riferimento (setpoint).
Un attuatore piezoelettrico (scanner) mantiene la punta in prossimità della superficie e permette di effettuare la scansione con la richiesta stabilità, accuratezza e linearità. La scansione nello spazio xyz è generata da un’elettronica di potenza e un circuito di retroazione (feedback) controlla il movimento lungo la direzione z in funzione del valore di setpoint dell’interazione. L’architettura di controllo di un SPM è oggi basata su un’interfaccia digitale/analogico che permette all’utilizzatore di variare i parametri di controllo e visualizzare gli osservabili in tempo reale. Questi fattori rendono gli SPM strumenti utili sia per imaging sia per applicazioni metrologiche.
Cambiando la sonda, cambiano l’interazione e il campione può essere mappato in funzione della struttura elettronica, della composizione, della risposta elettrostatica e magnetica, del comportamento viscoelastico e tribologico. Inoltre, il controllo accurato della forza dell’interazione permette di modificare intenzionalmente la superficie su scale confrontabili con quelle caratteristiche dell’interazione in gioco. Ripristinando le condizioni di imaging si può verificare il risultato della modificazione. Il microscopio a scansione di sonda è quindi uno strumento versatile non solo per l’imaging e per effettuare esperimenti locali, ma anche per la manipolazione e la fabbricazione delle superfici e dei materiali.
In questo capitolo vogliamo mostrare, con alcuni esempi, come le microscopie a scansione di sonda siano uno strumento indispensabile per la scienza e la tecnologia sulla scala nanometrica. Abbiamo scelto di discutere gli aspetti della microscopia a scansione di forza (SFM) nello studio di film sottili e nanostrutture, con particolare attenzione ai fenomeni di crescita, auto-assemblamento ed auto-organizzazione, passando per la fabbricazione di dispositivi, lo stoccaggio dell’informazione e la nanotribologia. Molti esempi riguardano la materia soffice, in quanto SFM è una delle tecniche più diffuse per studiare la sua organizzazione su scale spaziali diverse, per l’ elevata risoluzione spaziale, e per il fatto che il campione può essere visualizzato nello stato nativo evitandone il danneggiamento.
2007
- Scaling of mobility in pentacene transistors and stabilization using alkanethiol treated gold electrodes
[Relazione in Atti di Convegno]
Dutta, S.; Stoliar, P.; Biscarini, F.
abstract
We investigate the scaling of field-effect mobility as a function of channel length in case of pentacene-based transistors with coplanar geometry. The apparent variation of mobility is mainly attributed to the effect of disorder at the metal-semiconductor interface and injection limited charge transport in case of smaller channel length. The scaling is modified using drain-source electrodes, treated with self-assembly monolayer of alkanethiol with varying carbon atoms. Copyright © 2007 Materials Research Society.
2007
- Solid-state assemblies and optical properties of conjugated oligomers combining fluorene and thiophene units
[Articolo su rivista]
Biscarini, Fabio
abstract
Two conjugated oligomers, representing elementary segments of fluorene–thiophene copolymers, are compared in terms of the microscopic morphology and the optical properties of thin deposits. The atomic force microscopy morphological data and the solid-state absorption and emission spectra are interpreted in terms of the assembly of the conjugated molecules. The compound with a terthiophene central unit and fluorene end-groups shows well-defined monolayer-by-monolayer assembly into micrometer-long stripe-like structures, with a crystalline herringbone-type organization within the monolayers. Polarized confocal microscopy indicates a strong orientation of the crystalline domains within the stripes. In contrast, the compound with a terfluorene central unit and thiophene end groups forms no textured aggregates and the optical spectra in the solid-state are very similar to those recorded in solution, suggesting that the molecules interact only weakly in the solid. The difference in behaviour between the two compounds most probably originates from their different capability to form densely-packed assemblies of interacting π-systems.
2007
- Spin polarized La0.7Sr0.3MnO3 thin films on silicon
[Articolo su rivista]
Bergenti, I; Dediu, V; Arisi, E; Cavallini, M; Biscarini, Fabio; Taliani, C; DE JONG, Mp; Dennis, Cl; Gregg, Jf; Solzi, M; Natali, M.
abstract
2007
- Two-dimensional self-organization of CdS ultra thin films by confined electrochemical atomic layer epitaxy growth
[Articolo su rivista]
Biscarini, Fabio
abstract
2006
- Biscarini "Ordered Patterning of Nanometric Rings of Single Molecule Magnets on Polymers by Lithographic Control of Demixing"
[Articolo su rivista]
M. CAVALLINI J., GOMEZ SEGURA; C., Albonetti; D., Ruiz; J., Veciana; Biscarini, Fabio
abstract
2006
- Development of a parallel local oxidation nanolithography instrument
[Articolo su rivista]
J., Martinez; N. S., Losilla; Biscarini, Fabio; G., Schmidt; T., Borzenko; L. W., Molenkamp; R., Garcia
abstract
2006
- Effects of surface chemical composition on the early growth stages of α-sexithienyl films on silicon oxide substrates
[Articolo su rivista]
F., Dinelli; J. F., Moulin; M. A., Loi; E., DA COMO; M., Massi; M., Murgia; M., Muccini; Biscarini, Fabio; J., Wie; P., Kingshott
abstract
2006
- Electrical instabilities in organic semiconductors caused by trapped supercooled water
[Articolo su rivista]
H. L., Gomes; P., Stallinga; M., Coelle; Biscarini, Fabio; D. M., DE LEEUW
abstract
2006
- In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth
[Articolo su rivista]
J. F., Moulin; F., Dinelli; M., Massi; C., Albonetti; R., Kshirsagar; Biscarini, Fabio
abstract
2006
- Multiple length-scale patterning of DNA by stamp-assisted deposition
[Articolo su rivista]
E., Bystrenova; M., Facchini; M., Cavallini; M. G., Cacace; Biscarini, Fabio
abstract
2006
- Nanostructured assemblies
[Articolo su rivista]
W., Huck; Biscarini, Fabio; J., Preece
abstract
2006
- Patterning Organic Nanostructures by Scanning Probe Nanolithography
[Capitolo/Saggio]
Albonetti, Cristiano; Kshirsagar, Rajendra; Cavallini, Massimiliano; Biscarini, Fabio
abstract
N/A
2006
- Polymorphs of alpha-sexithiophene probed by lattice phonon Raman microscopy
[Articolo su rivista]
A., Brillante; I., Bilotti; Biscarini, Fabio; R. G., DELLA VALLE; E., Venuti
abstract
2006
- Self-organization of rotaxane thin films into spatially correlated nanostructures: Morphological and structural aspects
[Articolo su rivista]
J. F., Moulin; J. C., Kengne; R., Kshirsagar; M., Cavallini; Biscarini, Fabio; S., Leon; F., Zerbetto; G. BOTTARI AND D. A., Leigh
abstract
2006
- Supramolecular assembly of conjugated polymers: From molecular engineering to solid-state properties
[Articolo su rivista]
Leclere, P. H.; M., Surin; P., Brocorens; M., Cavallini; Biscarini, Fabio; R., Lazzaroni
abstract
2006
- Synthesis, multiphase characterization, and helicity control in chiral DACH-linked oligothiophenes
[Articolo su rivista]
M., Melucci; G., Barbarella; M., Gazzano; M., Cavallini; Biscarini, Fabio; A., Bongini; F., Piccinelli; M., Monari; M., Bandini; A., UMANI RONCHI; AND P., Biscarini
abstract
2006
- The effect of water related traps on the reliability of organic based transistors
[Articolo su rivista]
Gomes, H. L.; Stallinga, P.; Colle, M.; Biscarini, F.; de Leeuw, D. M.
abstract
The electrical stability of metal-insulator-semiconductor (MIS) capacitors and field-effect transistor structures based in organic semiconductors were investigated. The device characteristics were studied using steady state measurements AC admittance measurements as well as techniques for addressing trap states. Temperature-dependent measurements show clear evidence that an electrical instability occurs above 200 K and is caused by an electronic trapping process. Experimental results show that water is responsible for the trapping mechanism. © 2006 Elsevier B.V. All rights reserved.
2006
- Toward amorphous conductors: Enhanced conductivity of doped polyaniline via interchain crosslinking promoted by acid-functionalized aluminum quinolines
[Articolo su rivista]
M., Massi; M., Facchini; C., Albonetti; M., Cavallini; Biscarini, Fabio
abstract
2006
- “Self-Organization of Rotaxane Nano-lines and Dots Triggered by a Local Mechanical Stimulus”
[Articolo su rivista]
Biscarini, Fabio; M., Cavallini; R. B., Kshirsagar; S., Leon; F., Zerbetto; D. A., Leigh
abstract
2005
- Correlation between morphology and charge mobility in tetracene-based light emitting transistors
[Articolo su rivista]
F., Cicoira; C., Santato; F., Dinelli; M., Murgia; M. A., Loi; Biscarini, Fabio; R., Zamboni; P., Heremans; M., Muccini
abstract
2005
- Electrical characterization of organic based transistors: stability issues
[Articolo su rivista]
Gomes, Hl; Stallinga, P; Dinelli, F; Murgia, M; Biscarini, Fabio; DE LEEUW, Dm; Muccini, M; Mullen, K.
abstract
2005
- Electrochemical Fabrication of Cobalt and Nickel Tips for Scanning Tunneling Microscopy
[Articolo su rivista]
C., Albonetti; M., Cavallini; M., Massi; J. F., Moulin; Biscarini, Fabio
abstract
2005
- Electronic Structure and Energy Transfer in Solid α-Sexithienyl
[Capitolo/Saggio]
Taliani, Carlo; Biscarini, Fabio; Muccini, Michele
abstract
N/A
2005
- Field Effect Transistors based on Self-Organized Molecular Nano-stripes
[Articolo su rivista]
M., Cavallini; P., Stoliar; J. F., Moulin; M., Surin; Leclere, P. H.; R., Lazzaroni; D. W., Breiby; J. W., Andreasen; M. M., Nielsen; P., Sonar; A. C., Grimsdale; K., Muellen; Biscarini, Fabio
abstract
2005
- Magnetic Information Storage on Polymers using Patterned Mn12 Molecules
[Articolo su rivista]
M., Cavallini; JORDI GOMEZ, Segura; DANIEL RUIZ, Molina; Massimiliano, Massi; Cristiano, Albonetti; Concepcio, Rovira; Jaume, Veciana; Biscarini, Fabio
abstract
2005
- Meta-stability effects in organic based transistors
[Relazione in Atti di Convegno]
Gomes, H. L.; Stallinga, P.; Murgia, M.; Biscarini, F.; Muck, T.; Wagner, V.; Smits, E.; De Leeuw, D. M.
abstract
The electrical stability of metal insulator semiconductor (MIS) capacitors and field effect transistor structures based in organic semiconductors were investigated. The device characteristics were studied using steady state measurements AC admittance measurements as well as techniques for addressing trap states. Temperature-dependent measurements show clear evidence that an electrical instability occurs above 200 K. and is caused by an electronic trapping process. It is suggested that the trapping sites are created by a change in the organic conjugated chain, a process similar to a phase transition.
2005
- Molecular orientation in ultrathin films of α-sexithiophene on silicon dioxide revealed by spatially resolved confocal spectroscopy
[Articolo su rivista]
Da Como, E.; Loi, M. A.; Dinelli, F.; Murgia, M.; Biscarini, F.; Zamboni, R.; Muccini, M.
abstract
In organic semiconductors devices like thin film transistors (TFTs), the supra-molecular organization on the substrate is one of the most important parameters to control the charge transport. Unprecedented insights into the molecular orientation of vacuum sublimed ultrathin films of α- sexithiophene (T6) on silicon dioxide are revealed by confocal laser scanning microscopy (CLSM) and spectroscopy. By the cross correlation of confocal microscopy and atomic force microscopy measurements, we demonstrated that in films thinner than 2 nm, regions where molecules are oriented perpendicular to the substrate and regions where molecules are parallel to the substrate co-exist. By spatially resolved spectroscopy, we gain information about the supra-molecular organization in ultrathin films. Implications for charge transport in thin film transistors are considered and discussed. © 2005 Elsevier B.V. All rights reserved.
2005
- Structural and magnetic properties of thin manganite films grown on silicon substrates
[Articolo su rivista]
Bergenti, I.; Dediu, V.; Arisi, E.; Cavallini, M.; Moulin, J. F.; Biscarini, F.; De Jong, M.; Dennis, C.; Gregg, J.
abstract
Polycrystalline La0.7Sr0.3MnO3 manganite thin films were grown on silicon substrates covered by SiOx amorphous native oxide. Unusual splitting of the manganite layer was found: on the top of an intermediate layer characterised by lower crystalline order, a magnetic robust layer is formed. Curie temperatures of about 325 K were achieved for 70 nm thick films. A strong room temperature XMCD signal was detected indicating high spin polarisation near the surface. © 2005 Elsevier Ltd. All rights reserved.
2005
- Supramolecular organization in ultra-thin films of α-sexithiophene on silicon dioxide
[Articolo su rivista]
Loi, M. A.; Como, E. D. A.; Dinelli, F.; Murgia, M.; Zamboni, R.; Biscarini, F.; Muccini, M.
abstract
The study of the supramolecular organization of organic semiconductors on the dielectric layer of thin-film field effect transistors was presented. It was demonstrated that AFM cannot reveal ultra-thin domains of T6 molecules lying flat on the substrate. The film was found to be composed of two complete layers of T6 molecules for a total height profile of ∼nm as per the AFM measurement. It was observed that in submonolayer films of T6 on silicon dioxide, there is coexistence of two phases composed, respectively by molecules perpendicular and parallel to the substrate.
2004
- Bias-induced threshold voltages shifts in thin-film organic transistors
[Articolo su rivista]
H. L., Gomes; P., Stallinga; F., Dinelli; M., Murgia; Biscarini, Fabio; D. M., DE LEEUW; T., Muck; J., Geurts; L. W., Molenkamp; V., Wagner
abstract
2004
- Bottom-up nanofabrication of materials for organic electronics
[Articolo su rivista]
M., Cavallini; M., Facchini; M., Massi; Biscarini, Fabio
abstract
2004
- Conjugated Material Self-assembly: Towards Supramolecular Electronics
[Articolo su rivista]
Leclere, P. H.; M., Surin; M., Cavallini; P., Jonkheijm; O., Henze; A. P. H. J., Schenning; Biscarini, Fabio; A. C., Grimsdale; W. J., Feast; E. W., Meijer; K., Muellen; J. L., Bredas; AND R., Lazzaroni
abstract
2004
- Electronic Transport in Field Effect Transistors of Sexithiophene
[Articolo su rivista]
P., Stallinga; H. L., Gomes; Biscarini, Fabio; M., Murgia; D., DE LEEUW
abstract
2004
- Experimental Investigation of the Contat Mechanics of Rough Fractal Surfaces
[Articolo su rivista]
R., Buzio; K., Malyska; Z., Rymuza; Biscarini, Fabio; F., BUATIER DE MONGEOT; U., Valbusa
abstract
2004
- FET device performance, morphology and X-ray thin film structure of unsubstituted and modified quinquethiophenes
[Articolo su rivista]
P., Ostoja; P., Maccagnani; M., Gazzano; M., Cavallini; J. C., Kengne; Biscarini, Fabio; M., Melucci; M., Zambianchi; G., Barbarella
abstract
2004
- Microwave assisted synthesis of manganese mixed oxide nanostructures using plastic templates
[Articolo su rivista]
Leyva, A. G.; Stoliar, P.; Rosenbusch, M.; Lorenzo, V.; Levy, P.; Albonetti, C.; Cavallini, M.; Biscarini, F.; Troiani, H. E.; Curiale, J.; Sanchez, R. D.
abstract
The synthesis method for obtaining sub-micrometric structures of rare earth manganese-based mixed oxide compounds is described. Pore wetting of porous polycarbonate templates with the liquid precursor was followed by a two-stage thermal treatment to obtain single phase La 0.325Pr 0.300Ca 0.375MnO 3 hollow and solid structures, with external diameter determined by the sacrificial template pore size. The first thermal stage, a microwave assisted denitration process, determines the shape of the structures. The second treatment, performed at 1073 K, allows to obtain the crystallographic structure of the compound. A variety of techniques (scanning and transmission electron microscopy, scanning probe microscopy) allowed to fully characterize the microstructure and morphology of these self-standing manganite nanostructures. For 1 μm pore size templates we obtained tubes, with external diameter around 800 nm and wall thickness around 150 nm; densely packed nanoparticles sized 20-50 nm are the building blocks of the walls. For pore size below 0.1 μm, solid nanowires were obtained, the size of constituent crystallites being around 10 nm. Overall obtained material exhibits ferromagnetic ordering below 200 K. Micrograph of tubular structures of La 0.325Pr 0.300Ca 0.375MnO 3 grown in a 1 micron pore size policarbonate template. © 2004 Elsevier Inc. All rights reserved.
2004
- Oligothiophene Self-Assembly: from Aggregation in Solution to Solid-State Nanostructures
[Articolo su rivista]
Leclere, P. H.; M., Surin; P., Viville; R., Lazzaroni; A. F. M., Kilbinger; O., Henze; W. J., Feast; M., Cavallini; Biscarini, Fabio; A. P. H. J., Schenning; AND E. W., Meijer
abstract
2004
- Organic Semi-Conducting Architectures for Supramolecular Electronics
[Articolo su rivista]
Leclere, P. H.; M., Surin; P., Jonkheijm; O., Henze; A. P. H. J., Schenning; Biscarini, Fabio; A. C., Grimsdale; W. J., Feast; E. W., Meijer; K., Muellen; J. L., Bredas; Lazzaroni, A. N. D. R.
abstract
2004
- Poly(α-vinyl-ω-alkyloligothiophene) side-chain polymers, synthesis, fluorescence, and morphology
[Articolo su rivista]
M., Melucci; G., Barbarella; M., Zambianchi; M., Benzi; Biscarini, Fabio; M., Cavallini; A., Bongini; S., Frabboni; M., Mazzeo; M., Anni; G., Gigli
abstract
2004
- Size and Shape Controlled Growth of Molecular Nanostructures on Silicon Oxide Templates
[Articolo su rivista]
R., Garcia; M., Tello; J. F., Moulin; Biscarini, Fabio
abstract
2004
- Spatially Correlated Charge Transport in Organic Thin Film Transistors
[Articolo su rivista]
F., Dinelli; M., Murgia; J. F., Moulin; M., Cavallini; P., Levy; Biscarini, Fabio; D., DE LEEUW
abstract
2004
- Surface-controlled self-assembly of chiral sexithiophenes
[Articolo su rivista]
Leclere, P. H.; R., Lazzaroni; J. L., Bredas; M., Cavallini; Biscarini, Fabio; C., Taliani; P., Jonkheim; A. P. H. J., Schenning; E. W., Meijer; A. F. M., Kilbinger; W. J., Feast
abstract
2004
- Thermal Annealing Effects on Morphology and Electrical Response in Ultrathin Film Organic Transistors
[Articolo su rivista]
F., Dinelli; M., Murgia; Biscarini, Fabio; D., DE LEEUW
abstract
2003
- A nanoporous molecular magnet with reversible solvent-induced mechanical and magnetic properties
[Articolo su rivista]
D., Maspoch; D., RUIZ MOLINA; N., Dominguez; K., Wurst; M., Cavallini; Biscarini, Fabio; J., Tejada; C. ROVIRA AND J., Veciana
abstract
2003
- Fabrication of material patterns by grid-assisted deposition
[Articolo su rivista]
Massi, M.; Cavallini, M.; Stagni, S.; Palazzi, A.; Biscarini, F.
abstract
We developed a simple patterning approach where a grid with micrometer rule is used in order to control the deposition of a solute. Ordered patterns were obtained, over large areas, in a few seconds. The patterning process we propose here is fast and low cost. It can also be applied to diverse soluble molecular and supramolecular species. We also investigated what parameters have to be changed in order to have total control on the final tridimensional architecture of the material. © 2003 Elsevier B.V. All rights reserved.
2003
- Growth morphology and electronic structure of 2D ordered pentacene on the Au(1 1 0)-(1 × 2) surface
[Relazione in Atti di Convegno]
Corradini, V.; Menozzi, C.; Cavallini, M.; Biscarini, F.; Betti, M. G.; Mariani, C.
abstract
High-quality ordered growth and characterization of organic systems is an important requirement to understand the physical properties underlying the new organic-molecule based electronic devices. In this work, pentacene (C22H14) is ultra-high-vacuum deposited in situ on the (1 × 2)-reconstructed surface of Au(110), at different substrate temperatures. Low-energy electron diffraction reveals a two-dimensional (2D) ordered phase, showing the presence of a (1×3) pentacene-induced long-range periodicity, for room-temperature deposition. High-resolution UV photoelectron spectroscopy investigations for pentacene adsorption at room- and low- (80 K) temperature, bring to light the new interface electronic levels and the molecular orbital evolution. Higher substrate temperature (370 K) during adsorption induces higher pentacene mobility, thus improving long-range ordering. Atomic force microscopy images at higher coverage show the presence of pentacene stripes, grown on top of the first 2D ordered layer, with a preferred orientation perpendicular to the substrate [1-10] direction. © 2003 Elsevier Science B.V. All rights reserved.
2003
- Half Metallic Response of Manganite Films at Room Temperature from Spin-Polarized Scanning Tunneling Microscopy
[Working paper]
Cavallini, M.; Biscarini, Fabio; Dediu, V.; Nozar, P.; Taliani, C.; Zamboni, R.
abstract
The ferromagnetic phase in La0.7Sr0.3MnO3 manganite is completely spin
polarized (100%) at room temperature. This is demonstrated on high quality
epitaxial films by Spin-Polarized Scanning Tunneling Microscopy. The films
consist of a highly homogeneous ferromagnetic (FM) phase in which minority
paramagnetic (PM) defects are embedded (less than 1% for best films). PM
defects exhibit featureless tunneling spectroscopic characteristics and an
insulating-like conductance. FM phase exhibit metallic behavior and strongly
nonlinear characteristics. Deconvolution of the spectroscopic curves for the FM
phase reveals the totally spin-splitted egt2g manganite bands whose shape and
width are in an excellent agreement with optical and photoemission spectroscopy
data. These results promote the manganites as efficient spin polarized
injectors at ambient conditions.
2003
- Information storage using supramolecular surface patterns
[Articolo su rivista]
M., CAVALLINI; BISCARINI, FABIO; S., LEON; F., ZERBETTO; G., BOTTARI; D. A., LEIGH
abstract
2003
- Multiple Length scale patterning of single molecule magnets
[Articolo su rivista]
M., Cavallini; Biscarini, Fabio; J., GOMEZ SEGURA; D., Ruiz; J., Veciana
abstract
2003
- Multiscale self-organization of the organic semiconductor α-quinquethiophene
[Articolo su rivista]
M., Melucci; M., Cavallini; M., Gazzano; G., Barbarella; Biscarini, Fabio; P., Maccagnani; P., Ostoja
abstract
2003
- Nanostructuring conjugated materials by lithographically controlled wetting
[Articolo su rivista]
M., Cavallini; Biscarini, Fabio
abstract
2003
- ONE- AND TWO-DIMENSIONAL SEMICONDUCTING NANOSTRUCTURES OBTAINED BY SELF-ASSEMBLING PROCESSES
[Abstract in Rivista]
Leclere, Philippe; Surin, M.; Henze, O; Feast, W. J.; Biscarini, Fabio; Meijer, E. W.; Grimsdale, A. C.; Muellen, K.; Braédas, J. L.; Lazzaroni, R.
abstract
N/A
2003
- One and Two-Dimensional Semiconducting Nanostructures Self-Assembly of Conjugated Oligomers
[Relazione in Atti di Convegno]
Leclèrea, P. h.; M., Surin; P., Jonkheijm; O., Henze; A. P. H. J., Schenning; Biscarini, Fabio; A. C., Grimsdale; W. J., Feast; E. W., Meijer; K., Müllen; J. L., Brédas; R., Lazzaroni
abstract
The properties of organic electronic materials in the solid-state are determined not only by those of individual molecules but also by those of ensembles of molecules. The ability to control the architectures of these ensembles is thus essential for optimising the properties of conjugated materials for use in electronic devices (light emitting diodes, field effect transistors, solar cells,…) and is primordial for potential technological applications in nanoelectronics.
Here, we report on the observation by atomic force microscopy (AFM) of 1D and 2D nanoscale architectures obtained in the solid-state from solutions of molecularly-dissolved conjugated block copolymers or oligomers, and demonstrate that the conjugated molecules can organize onto a surface over lengthscales from nanometers to several microns, forming semiconducting fibrils by π-stacking processes.
2003
- Parallel Writing by Local Oxidation Nanolithography with sub-Micrometer Resolution
[Articolo su rivista]
M., Cavallini; P., Mei; Biscarini, Fabio; R., Garca
abstract
2003
- Pentacene self-aggregation at the Au(110)-(1x2) surface: growth morphology and interface electronic states
[Relazione in Atti di Convegno]
C., Menozzi; C., Corradini; V., Cavallini; Biscarini, Fabio; M. G., Betti; C., Mariani
abstract
We present an investigation of the growth morphology and electronic properties of pentacene (C22H14) deposited in situ on the (1×2)-reconstructed Au(110) surface, in ultra-high-vacuum conditions, at different substrate temperatures. Atomic force microscopy (AFM) investigates evidence of the growth of pentacene in linear stripes preferentially oriented along the [001] direction, on a first thin film phase. Low Energy Electron Diffraction (LEED) data reveal a clear (1×3) periodicity induced by the thin film phase, which is stable up to 500 K. The long range periodicity of this 2D ordered phase is improved at higher substrate temperature, due to higher diffusion of the pentacene oligomers, while stripes become more disordered. The electronic properties of the interface are studied by means of high-resolution UV photoelectron spectroscopy, bringing to light the Au–Pentacene interaction electronic levels leading to the formation of the ordered phase.
2003
- The contact mechanics of fractal surfaces
[Articolo su rivista]
R., Buzio; C., Boragno; F., BUATIER DE MONGEOT; Biscarini, Fabio; U., Valbusa
abstract
2002
- Direct patterning of tris-(8-hdroxyquinoline)-aluminum (III) thin film at submicron scale by modified micro-transfer molding
[Articolo su rivista]
M., Cavallini; Biscarini, Fabio
abstract
2002
- Electrochemical preparation of cobalt tips for scanning tunneling microscopy
[Articolo su rivista]
Albonetti, C.; Bergenti, I.; Cavallini, M.; Dediu, V.; Massi, M.; Moulin, J. -F.; Biscarini, F.
abstract
An electrochemical method for fabricating sharp cobalt tips was presented. THe tips were prepared from 0.25 mm cobalt wire by electrochemical etching. The tips were useful for the scanning tunneling microscopy (STM) experiments where the focus was on magnetic properties of the surface.
2002
- I pionieri dell’optoelettronica plastica” Articolo Speciale su Premio Italgas per la Ricerca e l’Innovazione Tecnologica 2001
[Articolo su rivista]
Biscarini, Fabio
abstract
l Premio Italgas 2001, assegnato ex-aequo a Richard
Friend e a Jean-Luc Brédas, è il riconoscimento
dell’importanza dell’optoelettronica plastica. Una
tecnologia innovativa basata su film sottili di materiali
semiconduttori coniugati, che ha aperto la strada ad
una nuova elettronica integrata, dove i componenti
sono interamente realizzati con materiali organici.
2002
- Investigation of the mesoscopic contact mechanics of sexithienyl thin films
[Relazione in Atti di Convegno]
Buzio, R.; Boragno, C.; Buatier De Mongeot, F.; Biscarini, F.; Valbusa, U.
abstract
We demonstrate that the mechanical properties of self-affine fractal thin films can be investigated on mesoscopic scale with an atomic force microscope. Sexithienyl films have been studied by acquiring load-displacement curves with flat micrometric tips. It is shown that the mechanical response of these samples strongly depends on their surface morphology, the contact stiffness varying an order of magnitude upon small but significative changes of fractal parameters. This indicates a general route to tailor films properties at the stage of their deposition and growth.
2002
- Mechanism of nonrandom pattern formation of polar-conjugated molecules in a partial wetting regime
[Articolo su rivista]
Brinkmann, M.; Graff, S.; Biscarini, F.
abstract
An original nucleation and growth process has been investigated for vacuum-deposited films of a polarconjugated molecule, tris-(8-hydroxyquinoline) aluminum (III) (Alq3), onto the apolar H-terminated Si(100). Homogeneous nucleation of amorphous Alq3 clusters is restricted to the early stage of deposition and is characterized by a large critical nucleus size i = 5, as determined from the dependence of the density of stable nuclei N on deposition rate κ. Alq3 clusters grow in a partial wetting regime to form correlated droplet patterns. For moderate deposition rates around 1 nm/min, patterns exhibit both (i) a typical scale invariance of the droplet size distribution with coverage and substrate temperature and (ii) strong correlations between the size and position of the droplets. Both these characteristics result from the absence of coarsening - e.g., Ostwald ripening, secondary nucleation, and coalescence during growth. Spatial correlations are analyzed by using Voronoi tesselation, which demonstrates the validity of a phenomenological capture zone model for correlated growth. Correlations emerge in the early stage of growth via direct ripening and further develop during growth by diffusive interactions between domains. Direct ripening manifests itself by the introduction of a minimum cutoff distance between droplets, which causes a significant narrowing of the droplet size distribution. During growth, diffusive interactions between droplets cause their centers of mass to move towards empty depleated areas, which results in enhanced spatial correlations. This peculiar nucleation and growth mechanism allows one to obtain droplet patterns where the interdroplet distance and droplet size can be tuned independently via deposition temperature and time.
2002
- Method for manufacturing and controlling structures and patterns of soluble and colloidal substances by printing on the micrometer and nanometer scale and with reduction of the dimensions of the stamp's features
[Brevetto]
Biscarini, Fabio; Cavallini, Massimiliano
abstract
A printing process for obtaining patterns of nanometer and micrometer dimensions on a substrate, comprising i) the application of a solution or suspension of an imprinting material to the substrate, ii) the positioning, without applying pressure, of a stamp provided with relief patterns at a distance of 0 nm to 500 μm from the substrate, and iii) the evaporation of the solution or suspension.
2002
- Morphology and trap luminescence in thin oligothiophene films on HOPG
[Articolo su rivista]
M., Schneider; M., Brinkmann; M., Muccini; Biscarini, Fabio; C., Taliani; W., Gebauer; M., Sokolowski; E., Umbach
abstract
2002
- Nanoimprint Lithography For Organic Electronics
[Articolo su rivista]
C., CLAVIJO CEDENO; J., Seekamp; A. P., Kam; T., Hoffmann; S., Zankovych; C. M., SOTOMAYOR TORRES; C., Menozzi; M., Cavallini; M., Murgia; G., Ruani; Biscarini, Fabio; M., Behl; R. ZENTEL AND J., Ahopelto
abstract
2002
- Nanomanufacturing and Processing—Research, Education, Infrastructure, Security, Resource
[Articolo su rivista]
Biscarini, Fabio; Taliani, Carlo; Chen, Julie; Komanduri, Ranga
abstract
N/A
2002
- Nanotecnologie per il transistor “verde”
[Articolo su rivista]
Biscarini, Fabio
abstract
N/A
2002
- Organic-inorganic hybrid spin-valve: A novel approach to Spintronics
[Articolo su rivista]
Biscarini, Fabio; C., Dediu; V., Biscarini; F., Cavallini; M., Murgia; M, Ruani; G., Nozar
abstract
2002
- Progettazione e Realizzazione di un sistema STM in ultra alto vuoto a controllo digitale
[Working paper]
Albonetti, C.; Moulin, J. F.; Mei, P.; Bonfiglioli, T.; Biscarini, Fabio
abstract
Si descrive una nuova configurazione di microscopio a scansione a effetto tunnel con controller digitale.
2002
- Spontaneous Fabrication of Microscopic Arrays of Molecular Structures with Submicron Length Scales
[Articolo su rivista]
M., Cavallini; Biscarini, Fabio; Massi, ; A. F., Morales; D. A., Leigh; F., Zerbetto
abstract
We show the spontaneous fabrication of organized structures with multiple lengthscales from a solution of rotaxanes cast onto a holey mesh in contact with a substrate. The mesh controls the spatial distribution of deposited material on a micrometer scale. The borders around a hole in the mesh pin the solution, and dewetting within the hole generates droplets of rotaxane with nanometer length scale. The droplet size is controlled by the radial concentration profile.
2002
- Spontaneous dissociation of a conjugated molecule on the Si(100) surface
[Articolo su rivista]
R., Lin; M., Galili; U. J., Quaade; M., Brandbyge; Bjoernholm, T. H.; A., DEGLI ESPOSTI; Biscarini, Fabio; AND K., Stokbro
abstract
2002
- Supramolecular organization of α,α′-disubstituted sexithiophenes
[Articolo su rivista]
A. P. H. J., Schenning; A. F. M., Kilbinger; Biscarini, Fabio; M., Cavallini; H. J., Cooper; P. J., Derrick; W. J., Feast; R., Lazzaroni; Leclere, P. H.; L. A., Mcdonell; E. W., Meijer; AND S. C. J., Meskers
abstract
2002
- The Effect of Mechanical Interlocking on Crystal Packing: Predictions and Testing
[Articolo su rivista]
Biscarini, Fabio; M., Cavallini; D. A., Leigh; S., Leon; S. J., Teat; J. K. Y., Wong; AND F., Zerbetto
abstract
2002
- “The mechanism of non-random pattern formation of polar conjugated molecules in a partial wetting regime”
[Articolo su rivista]
Brinkmann, M; S., Graaf; Biscarini, Fabio
abstract
2001
- Energy Transfer Tailoring in Conjugated Molecular Thin Films
[Articolo su rivista]
M., Muccini; M., Murgia; Biscarini, F; Taliani, C
abstract
In α-sexithienyl (T6) molecular thin films the spectral features of photoluminescence can be correlated to precise structural topologies and the nature of photoluminescence can be controlled. AFM images show that the topological features of T6 films evolve progressively from 2D to 3D structures with film thickness. It is shown that coalescence between different domains results in photoluminescence spectra that are dominated by the aggregate emission. The Figure shows the photoluminescence spectra of submonolayer and lamellae architectures.
2001
- Excimer-like Electroluminescence from Thin Films of Switchable Supermolecular Anthracene-based Rotaxanes
[Articolo su rivista]
G., Giro; M., Cocchi; V., Fattori; G., Gadret; G., Ruani; M., Murgia; M., Cavallini; Biscarini, Fabio; R., Zamboni; T., Loontjens; J., Thies; D. A., Leigh; A. F., Morales
abstract
2001
- Fabrication method at micrometer- and nanometer- scales for generation and control of anisotropy of structural, electrical, optical and optoelectronic properties of thin films of conjugated materials
[Brevetto]
Murgia, Mauro; Mei, Paolo; Biscarini, Fabio; Taliani, Carlo
abstract
A non-conventional lithographic process for modifying, improving and fabricating structural anisotropy, organization and order, and anisotropy of the mechanical, electrical, optical, optoelectronics, charge-carrying and energy-carrying properties in thin films constituted by organic materials with double conjugated bonds. The method consists in molding, performed directly on the conjugated thin film by virtue of intimate contact with the surface of a mold. The parts of the film in direct contact with the mold undergo a transformation that is local in character and whose dimensions depend on the dimensions of the structures provided on the mold. Molding can be performed both in static conditions and in dynamic conditions.
2001
- Intedigitated p-n junction: A route to improve the efficiency in organic photovoltaic cells
[Articolo su rivista]
M., Murgia; Biscarini, Fabio; M., Cavallini; C., Taliani; AND G., Ruani
abstract
2001
- Nanostructured organic thin films: Electronic energetics and devices
[Relazione in Atti di Convegno]
Taliani, C.; Biscarini, F.; Lunedei, E.; Mei, P.; Muccini, M.; Murgia, M.; Schneider, M.; Lanzani, G.
abstract
We report on the optoelectronic properties of vacuum sublimed organic thin films of the oligothienyls (Tn model systems. The Davydov splitting (DS) of the lowest exciton is about 0.3 eV and decreases with the conjugation length when going from T4 to T6. The lowest DS component is partially forbidden due to the crystal packing and the spectral activity occurs via Herzberg-Teller (HT) vibronic coupling. We show the real time dynamics of the HT coupling by coherent vibrational spectroscopy and the role of aggregates in the energy transfer processes within the films.
2001
- Patterning a Conjugated Molecular thin film at submicron scale by modified micro-transfer molding
[Articolo su rivista]
M., Cavallini; M., Murgia; Biscarini, Fabio
abstract
2001
- Photophysical properties of Thin Films and Solid Phase of Switchable Supermolecular Anthracene- based Rotaxanes
[Articolo su rivista]
Giro, ; M., Cocchi; V., Fattori; G., Gadret; G., Ruani; M., Cavallini; Biscarini, Fabio; R., Zamboni; T., Loontjens; J., Thies; D. A., Leigh; A. F., Morales; R. F., Mahrt
abstract
2001
- Scaling Aspects of the Kinetics of Thermally-Induced Phase Separation in Bis-Phenol-A Polycarbonate/Poly(methyl methacrylate) Blends
[Articolo su rivista]
P., Viville; Biscarini, Fabio; J. L., Bredas; AND R., Lazzaroni
abstract
2001
- “Conformational Self-Recognition as the Origin of Dewetting in Bistable Molecular Surfaces”
[Articolo su rivista]
M., Cavallini; R., Lazzaroni; R., Zamboni; Biscarini, Fabio; D., Timpel; F., Zerbetto; G. J., Clarkson; D. A., Leigh
abstract
2001
- “Optical and electroemission properties of thin films of anthracene- based rotaxanes”
[Articolo su rivista]
G., Gadret; G., Ruani; M., Cavallini; Biscarini, Fabio; M., Murgia; R., Zamboni; G., Giro; M., Cocchi; V., Fattori; T., Loontjens; J., Thies; D. A., Leigh; A. F., Morales; R. F., Mahrt
abstract
2000
- "Growth of Mesoscopic Correlated Droplet Patterns by High-Vacuum Sublimation"
[Articolo su rivista]
M., Brinkmann; Biscarini, Fabio; C., Taliani; I., Aiello; AND M., Ghedini
abstract
A novel growth mode, characterized by absence of grain coarsening, Ostwald ripening, and secondary nucleation, is observed for a polar conjugated molecule, viz. tris-(8-hydroxyquinoline) aluminum (III) (Alq(3)), grown onto an apolar silicon substrate by high-vacuum sublimation. It results in correlated droplet patterns on a mesoscopic length scale with narrow size distribution, which can be tuned by means of the deposition time t and substrate temperature T-s. A comprehensive analysis of the results is obtained on the basis of a capture zone model.
2000
- Electrochemically Etched Nickel Tips for Spin-Polarised Scanning Tunneling Microscopy
[Articolo su rivista]
Biscarini, Fabio
abstract
1999
- "Morphology dependent fluorescence in (-sexithienyl thin films at 4.2 K"
[Articolo su rivista]
E., Lunedei; P., Moretti; M., Murgia; M., Muccini; Biscarini, Fabio; AND C., Taliani
abstract
We investigated by fluorescence spectroscopy at 4.2K high vacuum sublimated thin films of alpha-sexithienyl grown on mica upon a systematic variation of the growth parameters. We studied how the film morphology, induced by different conditions of growth (thickness and substrate temperature), acts on the emission properties at the early stages of growth. We show how the increased molecular order corresponds to a less efficient excitation energy transfer to low energy levels (due to the presence of defects and aggregates) and to an enhanced excitonic character of the fluorescence.
1999
- "Quantum Coherence Effects in the Scanning Tunneling Microscope: a Simple Interpretation of the Contact Resistance Experiments"
[Articolo su rivista]
Biscarini, Fabio
abstract
1999
- "STM Investigation of Flexible Supramolecules: Benzylic Amide [2] Catenanes"
[Articolo su rivista]
Biscarini, Fabio; W., Gebauer; D., DI DOMENICO; R., Zamboni; J. I., Pascual; D. A., Leigh; A., Murphy; AND D., Tetard
abstract
1999
- Anisotropic ordered Planar Growth of alpha- Sexithienyl Thin Films
[Articolo su rivista]
Stefano, Prato; Luca, Floreano; Dean, Cvetko; DE RENZI, Valentina; Alberto, Morgante; Silvio, Modesti; Biscarini, Fabio; Roberto, Zamboni; C., Taliani
abstract
We show how the anisotropy of the (1 × 2) reconstructed Au(110) surface can be effectively used to achieve spontaneous ordered planar growth of rodlike conjugated oligomers uniaxially oriented on the substrate. The growth of the first few monolayers of α-sexithienyl (T6) films on the (1 × 2) reconstructed Au(110) surface in ultrahigh vacuum has been investigated by He atom scattering (HAS), scanning tunneling microscopy (STM), and low-energy electron diffraction (LEED). T6 molecules lie flat on the substrate forming long chains along the [110] direction of the Au rows. The interchain spacing is coverage dependent and uniaxially commensurate with the substrate along [001]. Three ordered structures with 12, 16, and 20 A periods are formed during the deposition of the first two T6 monolayers. This T6 overlayer acts as a template for the growth of at least five monolayers which are still planar and orientationally ordered.
1999
- Intermolecular Interactions and Energy Transfer in Solid α-sexithienyl
[Capitolo/Saggio]
Taliani, Carlo; Biscarini, Fabio; Muccini, Michele
abstract
Chapter 8 on Intermolecular Interactions and Energy Transfer in Solid α-sexithienyl
1999
- Raman and far infrared characterization of the simplest Benzylic Amide [2] Cantenane
[Articolo su rivista]
Zamboni, R.; Muccini, M.; Gebauer, W.; Biscarini, F.; Murgia, M.; Ruani, G.; Leigh David, A.; Murphy, A.; Tetard, D.
abstract
The Benzylic Amide [2] Catenane (CAT1) is the simplest member of a family of supramolecules prepared by self-assembly synthesis and discovered at UMIST. The molecular system consists of 136 atoms forming two identical macrocycles mechanically interlocked. This unique structural property allows novel mechanical and electronic interactions that modify the properties of the Catenane with respect to the macrocycle monomer. In particular, a circumrotational motion of the two interlocked rings has been found in solution of CAT1 by NMR spectroscopy. In this work we report on Raman and Far Infrared experiments on polycrystalline CAT1 with the aim of contributing to the understanding of the basic mechanism of the intra-ring rotation of Catenanes.
1999
- “Determination of deep and shallow levels in conjugated polymers by electrical methods”
[Articolo su rivista]
P., Stallinga; H. L., Gomes; H., Rost; A. B., Holmes; M. G., Harrison; R. H., Friend; Biscarini, Fabio; C., Taliani; G. W., Jones; D. M., Taylor
abstract
1999
- “Influence of the Metal Center on the Morphology of Coordination Compounds Thin Films"
[Articolo su rivista]
F., Toffolo; M., Brinkmann; O., Greco; Biscarini, Fabio; C., Taliani; H. L., Gomes; I., Aiello; M., Ghedini
abstract
1998
- "Influence of Thermal Annealing on the Morphology of Sexithienyl Thin Films"
[Articolo su rivista]
Biscarini, Fabio; R., Lazzaroni; J. L., Brdas; P., Moretti; P., Samor; AND F., Biscarini
abstract
1998
- Abrupt Orientational Changes for Liquid Crystals Adsorbed on a Graphite Surface"
[Articolo su rivista]
V., Palermo; Biscarini, Fabio; AND C., Zannoni
abstract
1998
- Scanning Force Microscopy of Conjugated Anisotropic Thin Films Grown in High-Vacuum
[Relazione in Atti di Convegno]
Biscarini, Fabio
abstract
Scanning force microscopy has been used to investigate the quantitative aspects of the morphology transition from isotropic grains to anisotropic lamellae in sexithienyl thin films. 2-D islands made of few molecular layers grow up to a critical thickness which depends on the deposition temperature, then the film grows as a rough 3-D surface. A statistical analysis of SFM data yields domain size and shape distributions, diffusional barriers, roughness scaling parameters, and orientational ordering. This framework provides an explanation for the mechanism of growth in terms of competition between diffusion and capture.
1997
- "Fabrication of Step-Edge Structures on R-plane Sapphire Using a Selective Wet Etch Process"
[Articolo su rivista]
P., Levy; S., Nicoletti; L., Correra; M., Cervera; M., Bianconi; Biscarini, Fabio; F., Corticelli; AND E., Gabilli
abstract
1997
- "Nanoscale Caliper for the Direct Measurement of Scanning Force Microscopy Probes"
[Articolo su rivista]
Biscarini, Fabio
abstract
1997
- "Roughness Increase and Dimensional Transitions during the Growth of GdBa2Cu3O7-x Films on NdGaO3"
[Articolo su rivista]
Biscarini, Fabio; V., Dediu; O., Greco; F. C., Matacotta; AND A., Migliori
abstract
1997
- "Scaling Behavior of Anisotropic Organic Thin Films Grown in High-Vacuum"
[Articolo su rivista]
Biscarini, Fabio; P., Samori; O., Greco; R., Zamboni
abstract
1997
- "The Growth and Characterization of a-sexithienyl-based light-emitting diodes"
[Articolo su rivista]
R. N., Marks; Biscarini, Fabio; T., Virgili; M., Muccini; R., Zamboni; AND C., Taliani
abstract
1996
- "Observation of the Stranski-Krastanov Growth Transition in GdBa2Cu3O7-x Films"
[Articolo su rivista]
V., Dediu; A., Kursumovic; O., Greco; Biscarini, Fabio; AND F. C., Matacotta
abstract
1996
- "Orientational ordering of domains in vacuum-grown oligomer thin films: a scanning force microscopy study"
[Articolo su rivista]
Biscarini, Fabio; O., Greco; A., Lauria; R. ZAMBONI AND C., Taliani
abstract
1996
- "Temperature Effects on the Morphology of Conjugated Oligomer Thin Films"
[Articolo su rivista]
Biscarini, Fabio; P., Samori; A., Lauria; P., Ostoja; R., Zamboni; C., Taliani; P., Viville; R., Lazzaroni; AND J. L., Bredas
abstract
1996
- Growth of high-vacuum sublimed oligomer thin films
[Articolo su rivista]
Biscarini, F.; Greco, O.; Lauria, A.; Samorì, P.; Taliani, C.; Zamboni, R.
abstract
N/A
1995
- "Growth of Conjugated Oligomer Thin Films Studied by Atomic-Force Microscopy"
[Articolo su rivista]
Biscarini, Fabio; R., Zamboni; P., Samori; P. OSTOJA AND C., Taliani
abstract
1995
- "Observation of interface excitons and energy transfer processes in an oligo-thiophene multilayer structure"
[Articolo su rivista]
M., Muccini; R. F., Mahrt; U., Lemmer; R., Hennig; H., Bssler; Biscarini, Fabio; R., Zamboni; AND C., Taliani
abstract
1995
- "Phase Diagram and Orientational Order in a Biaxial Lattice Model. A Montecarlo Study."
[Articolo su rivista]
Biscarini, Fabio; C., Chiccoli; P., Pasini; F. SEMERIA AND C., Zannoni
abstract
1995
- "Polarised Electroluminescence from Vacuum-Grown Organic Light-Emitting Diodes"
[Articolo su rivista]
R. N., Marks; Biscarini, Fabio; R., Zamboni; AND C., Taliani
abstract
1995
- "Studies of Scanning Tunneling Microscopy of Adsorbates I: Theoretical Framework and Coherence Effects"
[Articolo su rivista]
V. M., Kenkre; Biscarini, Fabio
abstract
1995
- "Studies of Scanning Tunneling Microscopy of Adsorbates II: Calculation of Images of Atomic and Molecular Adsorbates"
[Articolo su rivista]
Biscarini, Fabio; C., Bustamante; AND V. M., Kenkre
abstract
1995
- Atomic Force Microscopy on Molecular Thin Films: Rubbing of Teflon Oligomers
[Relazione in Atti di Convegno]
Lauria, A.; Biscarini, F.; Taliani, C.
abstract
N/A
1995
- Effect of Ion Milling on the Topography Multilayer Hetrostructure Cross Sections
[Relazione in Atti di Convegno]
Biscarini, Fabio; Greco, Ornella; Garulli, Alberto; Merli, Piergiorgio
abstract
N/A
1993
- Cluster Models for the Simulation of STM Images of Adsorbates: Origin of Non-Topographical Features
[Abstract in Rivista]
Biscarini, Fabio; Bustamante, C; Kenkre, V. M.
abstract
N/A
1992
- "A theoretical framework for the interpretation of STM images of adsorbates"
[Articolo su rivista]
V. M., Kenkre; Biscarini, F
abstract
A theoretical formalism for the interpretation of STM images of adsorbates is developed by approaching the calculation of the observed current as a transport problem in quantum statistical mechanics. The STM configuration is treated as a system of three groups of states - the substrate, the adsorbate and the tip - in contact with a thermal reservoir, with which it exchanges energy. A new definition of current is introduced, and shown to be related to that given in the traditional transfer Hamiltonian approach. The transport instrument used for the description is the stochastic Liouville equation, known to have the advantage of allowing the incorporation of thermal effects as well as arbitrary degree of coherence in the quantum transport. Some preliminary calculations of STM images of simple adsorbate models are presented.
1992
- Scanning tunneling microscopy of adsorbed molecules: theoretical considerations
[Relazione in Atti di Convegno]
Biscarini, Fabio; Bustamante, C.; Kenkre, V. M.
abstract
The interpretation of scanning tunneling microscopy (STM) images of adsorbed molecules requires a redefinition of the current, that goes beyond the limitations imposed by the Transfer Hamiltonian formalism. Here we discuss two expressions for the tunneling current we derived, both suitable for situations in which an adsorbate is placed between tip and substrate. The former is still based on a perturbative approach, but emphasizes the contributions to the STM current due to the adsorbate. The latter is an exact expression obtained by treating the STM current like an electron transport process. This allows the inclusion of both the quantum aspects of the transport and thermal effects, and it can be used in widely different situations.
1991
- "Head-tail asymmetry and ferroelectricity in uniaxial liquid crystals. Model Calculations"
[Articolo su rivista]
Biscarini, F; Zannoni, C.; Chiccoli, C.; Pasini, P.
abstract
Abstract
1991
- A Theory of Electron Tunneling Through Adsorbed Molecules in STM
[Abstract in Rivista]
Kenkre, V. M.; Biscarini, Fabio; Bustamante, C.; García, R.
abstract
Theory of STM
1990
- "On a simple model of ferroelectricity in liquid crystals"
[Articolo su rivista]
Biscarini, Fabio; C., Chiccoli; P. PASINI AND C., Zannoni
abstract
1988
- "The P4 model and its orientational phase transition"
[Articolo su rivista]
C., Chiccoli; P., Pasini; Biscarini, Fabio
abstract