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Barbara ZANFROGNINI

Personale tecnico amministrativo
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

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Pubblicazioni

2023 - An electrochemical approach for the prediction of Δ9-tetrahydrocannabinolic acid and total cannabinoid content in Cannabis sativa L [Articolo su rivista]
Monari, A.; Cantalu, S.; Zanfrognini, B.; Brighenti, V.; Verri, P.; Zanardi, C.; Pellati, F.; Pigani, L.
abstract

Two electrochemical sensors are proposed here for the first time for the fast screening of cannabinoids in Cannabis sativa L. plant material (inflorescences). The accurate control of cannabinoid content is important for discriminating between recreational, i.e. illegal, and fibre-type C. sativa samples, which differ mainly according to the amount of Δ9-tetrahydrocannabinol (Δ9-THC) and Δ9-tetrahydrocannabinolic acid (Δ9-THCA). Two screen printed electrodes obtained using different electrode materials were tested for the analysis of extracts from recreational and fibre-type C. sativa and their performance was compared with a consolidated method based on high-performance liquid chromatography (HPLC). The voltammetric responses recorded in the different samples reflected the compositional differences of the recreational and fibre-type extracts in accordance with the results of HPLC analyses. Moreover, the quantification of Δ9-THCA and the total cannabinoid content on the basis of the intensity of the peaks of the voltammograms was possible through a simple and fast electrochemical procedure.

2023 - On the feasibility of a portable electrochemical measuring system for the on-site measurement of cannabinoids [Relazione in Atti di Convegno]
Monari, A.; Zanardi, C.; Bruzzi, L.; Zanfrognini, B.; Cattini, S.; Rovati, L.; Pigani, L.
abstract

Given the neuroprotective, anti-inflammatory, and analgesic properties of cannabidiol (CBD), many countries have recently legalized the use of fiber-type Cannabis products, including those known as 'Cannabis light'. Nonetheless, in freely commercialized products, it is not uncommon to find Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, in concentrations exceeding the legal limit. To determine whether a product is commercially viable, the THC/CBD ratio is typically analyzed using chromatographic techniques. However, chromatographic techniques have costs, complexity, and response times that prevent their in-situ use, making control actions much more expensive and ineffective. In this work, we report our preliminary activities aimed at verifying the possibility of performing in-situ analysis of cannabinoids in cannabis-derived products using an ad-hoc designed measuring system based on screen-printed electrodes modified with carbon black. The results obtained from preliminary tests comparing fiber cannabis (legal THC concentration) and recreational cannabis (illegal THC concentration) suggest that the proposed system can allow the effective and efficient in-situ analysis of cannabis-derived products.

2022 - Fast Analysis of Caffeic Acid-Related Molecules in Instant Coffee by Reusable Sonogel–Carbon Electrodes [Articolo su rivista]
Pigani, Laura; Rioli, Cristina; Zanfrognini, Barbara; García-Guzmán, Juan José; Palacios-Santander, José Maria; Cubillana-Aguilera, Laura María
abstract

2022 - Graphene-Paper-Based Electrodes on Plastic and Textile Supports as New Platforms for Amperometric Biosensing [Articolo su rivista]
Poletti, F.; Scida, A.; Zanfrognini, B.; Kovtun, A.; Parkula, V.; Favaretto, L.; Melucci, M.; Palermo, V.; Treossi, E.; Zanardi, C.
abstract

The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed “graphene paper” (G-paper), conductive as graphite but more flexible and processable. G-paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G-paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon-based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state-of-the-art sensitivity (107.2 μA mm−1 cm−2) and limit of detection (0.6 × 10−6 m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications.

2022 - Preliminary evaluation of the use of a disposable electrochemical sensor for selective identification of Δ9-tetrahydrocannabinol and cannabidiol by multivariate analysis [Articolo su rivista]
Zanfrognini, B.; Monari, A.; Foca, G.; Ulrici, A.; Pigani, L.; Zanardi, C.
abstract

The widespread diffusion of products deriving from Cannabis sativa L. led to the necessity of rapid and reliable methods for the identification of samples containing Δ9-tetrahydrocannabinol (THC), the psychoactive component of the plant, which imparts mental distortions and hallucinations. Although some efficient electrochemical sensors have been already proposed for such a purpose, they do not consider that the plant may also contain huge amounts of cannabidiol (CBD), which possesses an electroactive moiety quite similar to that of THC. The definition of both THC and CBD concentration is at the basis of discrimination between recreational-type and fibretype cannabis samples; detection of these species is not only important in vegetable samples but also in relevant commercial products and in biological fluids. We proposed here a screen-printed electrode coated with a layer of carbon black for the rapid identification of samples containing THC irrespectively of the simultaneous presence of CBD. The most performing carbon black typology used for such a purpose was chosen among various commercial products tested on the basis of preliminary tests performed on 1,3-dihydroxybenzene, constituting the redox active moiety of cannabinoids. The voltammetric responses collected in various solutions containing different amount of THC and CBD were initially elaborated by Principal Component Analysis, assessing the possibility of identifying samples with similar concentrations of THC irrespectively of the CBD concentration values, and vice-versa. Afterwards a preliminary Partial Last Square regression was performed to evaluate the possibility of a quantitative analysis of both THC and CBD. This approach suggests the possibility of using the sensor proposed to screen samples containing THC even in the presence of high amounts of CBD.

2021 - Continuous capillary-flow sensing of glucose and lactate in sweat with an electrochemical sensor based on functionalized graphene oxide [Articolo su rivista]
Poletti, F.; Zanfrognini, B.; Favaretto, L.; Quintano, V.; Sun, J.; Treossi, E.; Melucci, M.; Palermo, V.; Zanardi, C.
abstract

We describe an electrochemical device for the simultaneous monitoring of glucose and lactate in sweat, based on enzymatic sensors exploiting capillary flow to induce continuous, stable sensing. The enzymes, namely glucose oxidase and lactate oxidase, were anchored to a graphene oxide and chitosan composite (GO-Ch) of original synthesis, to achieve stable deposition of the bioreceptors on the electrochemical platform. We tested both biosensors on a realistic device architecture: they were embedded in a nitrocellulose strip, to exploit capillary force to induce a continuous flux of sweat on the sensor platform, ensuring the constant renewal of sample. We could achieve good sensitivity at potentials close to zero by using Prussian Blue as redox mediator, thus avoiding interference from other chemical species present in the complex matrix. The sensing signal was stable and linear over two hours in a concentration range of glucose and lactate between the limit of quantification (32 and 68 nM, respectively) and the upper limit of linearity (3.8 and 50.0 mM, respectively). The device is simple, robust, stable, and can be easily worn without the direct contact of the active part with the skin, making it suitable for simultaneous monitoring of glucose and lactate in human sweat.

2021 - Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts [Articolo su rivista]
Cirrincione, M.; Zanfrognini, B.; Pigani, L.; Protti, M.; Mercolini, L.; Zanardi, C.
abstract

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves. The mechanism of CBD oxidation was studied in relation to simpler phenyl derivatives bearing the same electroactive group, namely resorcinol and 2-methylresorcinol. These molecules also allowed us to determine the best conditions for the electrochemical detection of CBD, as to the pH value and to the best solvent mixture to use. Carbon black was chosen among nanostructured carbon-based materials owing to its outstanding features as an electrode modifier for analyte detection. The performance of the modified electrode was determined by flow injection analyses of standard solutions of CBD, obtaining a linear correlation between the oxidation current and the analyte concentration; the sensor response is characterised by suitable repeatability and reproducibility. The analysis of commercial products by the standard addition method allowed us to ascertain the accuracy of the sensor for the detection of CBD in real samples.

2021 - Simultaneous Detection of Glucose and Fructose in Synthetic Musts by Multivariate Analysis of Silica-Based Amperometric Sensor Signals [Articolo su rivista]
Crespo-Rosa, Joaquin Rafael; Foca, Giorgia; Ulrici, Alessandro; Pigani, Laura; Zanfrognini, Barbara; Cubillana-Aguilera, Laura; Palacios-Santander, José María; Zanardi, Chiara
abstract

Silica-based electrodes which permanently include a graphite/Au nanoparticles composite were tested for non-enzymatic detection of glucose and fructose. The composite material showed an effective electrocatalytic activity, to achieve the oxidation of the two analytes at quite low potential values and with good linearity. Reduced surface passivation was observed even in presence of organic species normally constituting real samples. Electrochemical responses were systematically recorded in cyclic voltammetry and differential pulse voltammetry by analysing 99 solutions containing glucose and fructose at different concentration values. The analysed samples consisted both in glucose and fructose aqueous solutions at pH 12 and in solutions of synthetic musts of red grapes, to test the feasibility of the approach in a real frame. Multivariate exploratory analyses of the electrochemical signals were performed using the Principal Component Analysis (PCA). This gave evidence of the effectiveness of the chemometric approach to study the electrochemical sensor responses. Thanks to PCA, it was possible to highlight the different contributions of glucose and fructose to the voltammetric signal, allowing their selective determination.

2020 - Dopamine-functionalized graphene oxide as a high-performance material for biosensing [Articolo su rivista]
Vulcano, Fabio; Kovtun, Alessandro; Bettini, Cristian; Xia, Zhenyuan; Liscio, Andrea; Terzi, Fabio; Heras, Aranzazu; Colina, Alvaro; Zanfrognini, Barbara; Melucci, Manuela; Palermo, Vincenzo; Zanardi, Chiara
abstract

We describe a nanocomposite material for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH), a coenzyme involved in redox reactions of all living cells and in the detection of many organic species by electrochemical biosensors. The composite is made of nanosheets of electrochemically exfoliated graphene oxide (EGO) covalently functionalized with dopamine (DP) molecules. The EGODP material finally obtained is rich of 1,2-dihydroxyphenyl moieties and is able to detect NADH at a particular low potential value with higher sensitivity with respect to pristine EGO. To study the effectiveness of 1,2-dihydroxyphenyl moieties in inducing electrocatalytic oxidation of NADH, we combined standard voltammetric techniques with UV–Vis absorption spectroelectrochemistry, which allowed us to measure the variations in composition occurring at the electrode|solution interface, i.e. to measure the consumption rate of NADH. Spectroelectrochemical tests performed by polarising the electrode at a fixed potential value were finally used to compare the performance of EGODP with both EGO and EGO-DP blend (MIX) for the detection of NADH. The covalently functionalized EGO (EGODP) shows sensitivity to NADH up to 300 M−1, around 180 % and 140 % better than either pristine EGO or MIX, respectively.

2020 - Preparation and characterization of reusable Sonogel-Carbon electrodes containing carbon black: Application as amperometric sensors for determination of cathecol [Articolo su rivista]
Pigani, L.; Rioli, C.; López-Iglesias, D.; Zanardi, C.; Zanfrognini, B.; Cubillana-Aguilera, L. M.; Palacios-Santander, J. M.
abstract

2020 - Recent advances in the direct electrochemical detection of drugs of abuse [Articolo su rivista]
Zanfrognini, Barbara; Pigani, Laura; Zanardi, Chiara
abstract

2019 - Chemical and electrochemical properties of a hydrophobic deep eutectic solvent [Articolo su rivista]
Ruggeri, S.; Poletti, F.; Zanardi, C.; Pigani, L.; Zanfrognini, B.; Corsi, E.; Dossi, N.; Salomäki, M.; Kivelä, H.; Lukkari, J.; Terzi, F.
abstract

Hydrophobic deep eutectic solvents (DESs) have been recently introduced and acknowledged to offer remarkable advantages over the common organic solvents, thanks to their biodegradability, low toxicity and low cost. In the present paper a first study of the electrochemical properties and extraction capabilities of a prototypical hydrophobic DES, based on tetrabutylammonium chloride-decanoic acid (1:2 M ratio), is carried out. A small water content is shown to be advantageous as it dramatically affects the electrical conductivity and viscosity of the solvent, i.e. the parameters of fundamental importance in electrochemistry. A critical environmental pollutant, namely Cr(VI), has been successfully extracted from aqueous phase and amperometrically detected in the DES phase.

2018 - Synthesis, spectroscopic and electrochemical characterization of Co(II)-terpyridine based metallopolymer [Articolo su rivista]
Zanardi, C.; Zanfrognini, B.; Morandi, S.; Terzi, F.; Pigani, L.; Pasquali, L.; Seeber, R.
abstract

A new oligothienyl-based metallopolymer including Co(terpyridine)2complex units is synthesised by electrochemical oxidation of the relevant monomer. The chemical structure of the polymer chains and the electronic interaction between the organic portions and the metal centres are investigated by spectroscopic (X-rays photoelectron spectroscopy included), electrochemical, and spectroelectrochemical techniques. Thanks to the low potential of the Co(III)/Co(II) redox couple in the Co(terpyridine)2complex and to the presence of oligothienyl spacer, strong electron interaction between the organic backbone and the metal centres have been demonstrated.

2018 - Voltammetric behaviour of Cu alloys toward hydrogen peroxide and organic species [Articolo su rivista]
Ruggeri, Stefano; Miles, Emily; Poletti, Fabrizio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Corsi, Elia; Dossi, Nicolò; Seeber, Renato; Terzi, Fabio
abstract

The communication reports on the electrocatalytic properties exhibited by five Cu alloys (Cu-Zn, Cu-Sn, Cu-Ni, Cu-Zn-Ni, Cu-Al) and of pure Cu, Ni and Al in the reduction or oxidation of a number of representative species. A prototypical strong oxidising agent, namely hydrogen peroxide, and some of the most important oxidisable species, namely methanol, ethanol, and formaldehyde, are tested. Both cathodic and anodic processes are facilitated by using specific alloys in the case of strong oxidants and different organic molecules, respectively.

2017 - Electroanalytical determination of soluble Mn(II) species at high concentration levels [Articolo su rivista]
Ruggeri, Stefano; Terzi, Fabio; Zanfrognini, Barbara; Corsi, E.; Dossi, N.; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Glassy carbon electrodes have been successfully employed for the determination, by differential pulse voltammetry, of Mn(II) ions dissolved in aqueous solutions. In particular, a simple and fast procedure also suitable for on-line or at-line process control has been developed. Statistical analysis of the results obtained reveals that the procedure can be adopted in the range 0.59–57.30 mM Mn(II). The electrochemical responses are repeatable and reproducible. Repeatability is testified by the lack of variation of peak current values calculated from 20 subsequent scans carried out at the maximum explored concentration (relative standard deviation <1%). Reproducibility of the responses is supported by the data from the responses on three different electrodes. The proposed procedure does not require any pre-concentration of Mn species at the electrode surface or de-aeration of the solution. By adopting the developed procedure for the analysis, the GC electrode demonstrates to be suitable also for application in real matrices, namely solutions from spent battery recycling; in particular the results from the present electrochemical method are not significantly different from those obtained through inductively plasma coupled mass spectrometry. Interference from other metal species, such as Zn(II) and Fe(III), is negligible. This result is particularly meaningful, since the experimental conditions chosen, implying particularly high concentrations of heavy metals, are representative of those adopted in recovery and recycle processes of Mn species from batteries.

2015 - Ti metal electrode as an unconventional amperometric sensor for determination of Au(III) species [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Ruggeri, Stefano; Maccaferri, Giulio; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The control of the noble metal concentration is crucial in order to increase the efficiency of hydrometallurgic processes in mining and in the recovery of precious materials from electronic waste. The present study is devoted to the development of an effective procedure for the quantification of Au(III) species dissolved in aqueous solutions, similar real complex matrices included. In particular, a novel electrode system based on Ti has been studied. This electrode material is still poorly investigated in the framework of electroanalysis, despite its lack of sensitivity to common interfering species, such as oxygen; hence, the determination of metal species can be carried out without performing deaeration of the solution. In addition, the interfering effect due to the presence of other heavy metal ions, such as Ag, Fe and Pb, has been minimised by a proper choice of the conditions adopted for the amperometric measurements. Ti electrodes exhibit reproducible electrochemical responses, even in the presence of high concentration of organic fouling species typical of biosorption processes.

2014 - Amperometric Determination of Strong Oxidising Species Through Titanium Electrode Systems [Relazione in Atti di Convegno]
Terzi, Fabio; Zanfrognini, Barbara; Pelliciari, J.; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The amperometric determination of strong oxidising species has been carried out through an unusual electrode material, namely, Ti. In particular the study involves H2O2 and HClO, even at high concentration levels. A complex real matrix, such as an industrial detergent, containing high H 2O2 concentrations, has been taken as a meaningful study case to check the effectiveness of the electrode system and procedure proposed.

2014 - Development of Nanostructured Electrode Coatings for Amperometric Sensors [Relazione in Atti di Convegno]
Terzi, Fabio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Seeber, Renato
abstract

The goal of the communication is to illustrate the main advantages of the use of nanostructured materials as electrode modifiers in the frame of electroanalysis. Particularly meaningful examples extracted from the activity of the research group are discussed. The aim is to evidence the main properties of the single material and the synergic activity deriving from the combination of different materials in hybrids or composites electrode modifiers.

2014 - Novel electrode systems for amperometric sensing: the case of titanium [Relazione in Atti di Convegno]
Terzi, Fabio; Pigani, Laura; Zanardi, Chiara; Zanfrognini, Barbara; Ruggeri, Stefano; Maccaferri, Giulio; Seeber, Renato
abstract

fter working for years on organic materials, e.g., polythiophenes and relevant composites with metal nanoparticles, we shifted our attention to unusual metals, chosen as candidates to effective amperometric sensing on the basis of the atomic structure and crystalline properties. The present contribution aims at proposing an electrode material rarely employed in electroanalysis, namely Ti. We have experimented that the peculiar nature of Ti leads to electrochemical behavior quite different with respect to the conventional electrode materials, including those based on TiO2 (nano) particles. Our work focuses on the determination of strong oxidizing species, namely H2O2 and HClO, and noble metal ions, namely Au(III). Strong oxidizing species are commodity chemicals employed in a number of different industrial processes, in which usually high concentration levels should be monitored. The procedures proposed have been successfully applied also in complex matrices, such as detergent samples. As to Au(III) determination, it also constitutes a crucial tool in order to increase the efficiency of hydrometallurgic processes and of the recovery of precious materials from electronic waste. Ti electrodes allow the determination of dissolved Au species in the presence of other metal ions. In any cases the electrodes exhibit reproducible and repeatable electrochemical responses, even in the presence of high concentration of organic fouling species typical of bio-sorption processes.

2013 - Behaviour of Ti electrode in the amperometric determination of high concentrations of strong oxidising species. [Articolo su rivista]
Terzi, Fabio; Pelliciari, Jonathan; Zanfrognini, Barbara; Pigani, Laura; Zanardi, Chiara; Seeber, Renato
abstract

The study of the capabilities of an unusual electrode material, namely, Ti, is presented: the amperometric determination of species showing responses that, on different materials, cannot be often profitably exploited, is proposed. H2O2 and HClO are successfully analysed, even at high concentrations. In similar conditions, which are quite common in industrial environments, these strong oxidising species are determined by time-consuming, off- or at-line, and multistep procedures. A complex real matrix, such as an industrial detergent, containing high H2O2 concentrations, has been taken as a meaningful study case to check the effectiveness of the electrode system and procedure proposed.

2013 - Development of a Sensor System for the Determination of Sanitary Quality of Grapes. [Articolo su rivista]
Zanardi, Chiara; Ferrari, Luca; Zanfrognini, Barbara; Pigani, Laura; Terzi, Fabio; Cattini, Stefano; Rovati, Luigi; Seeber, Renato
abstract

An instrument for the automatic quantification of glycerol in grapes has been developed. We verify here that this analyte can be taken as a benchmark of a serious disease affecting the grapevines, namely Botrytis cinerea. The core of the instrument is an amperometric biosensor consisting of a disposable screen printed electrode, generating the analytical signal thanks to a bi-enzymatic process involving glycerol dehydrogenase and diaphorase. The full automation of the analysis is realised by three micropumps and a microprocessor under control of a personal computer. The pumps allow the correct and constant dilution of the grape juice with a buffer solution also containing [Fe(CN)6]4- redox mediator and the injection of NAD+ cofactor when the baseline signal reaches a steady state; the instrument leads to automated reading of the analytical signal and the consequent data treatment. Although the analytical method is based on an amperometric technique that, owing to heavy matrix effects, usually requires an internal calibration, the analyses indicate that a unique external calibration is suitable for giving accurate responses for any grapes, both white and black ones.

2012 - Electroreduction of chloramines through novel electrode materials [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Novel electrode materials have been developed and applied to the determination of chloramines by amperometric methods. In particular, a thin layer of a conducting polymer, namely poly(3,4-ethylenedioxythiophene) (PEDOT) has been tested for the first time in the presence of chloramines. Significant improvements in the performance of the modified electrodes are obtained by using composite materials based on differently encapsulated Au nanoparti-cles and PEDOT. The resulting electrode system exhibits repeatability and reproducibility of the voltammetric re-sponses, as well as low limit of detection and high sensitivity in the determination of monochloramine, as testified by the cyclic voltammetric curves and the calibration plots obtained by a rotating disk electrode.

2012 - PEDOT modified microelectrodes. Preparation, characterisation and analytical performances [Articolo su rivista]
Pigani, Laura; Zanfrognini, Barbara; Seeber, Renato
abstract

Poly(3,4-ethylenedioxythiophene) (PEDOT) modified microelectrodes were prepared by electropolymerisation of therelevant monomer from CH3CN and H2O solutions. The electrochemical behaviour of the obtained coatings wasinvestigated by cyclic voltammetry in both organic and aqueous media. The anodic responses obtained for a typicalbenchmark analyte such as ascorbic acid have been chosen in order to test the different coatings; calibration curves havebeen built up in order to evaluate the repeatability of the response and reproducibility of the realised sensing system.Moreover, the ability of the modified microelectrodes to work in low conductivity media has been studied, and exploratorytests in dense food matrix have been performed

2011 - A UV-Visible /Raman spectroelectrochemical study of the stability of poly(3,4-ethylendioxythiophene) films [Articolo su rivista]
Zanfrognini, Barbara; A., Colina; A., Heras; Zanardi, Chiara; Seeber, Renato; J., López Palacios
abstract

Poly(3,4-ethylendioxythiophene) films were electropolymerized in aqueous medium without using any surfactant, on glassy carbon electrodes. UV/Vis and Raman spectroelectrochemical techniques were used to analyze the degradation of the polymer film occurring at different pH values. Spectroelectrochemistry has proven to be a very useful analytical tool for this purpose, thanks to its ability to provide information not only about the extent of degradation, but also about mechanistic aspects of t he process. From our results we extracted important information about the main factors that play a role in the degradation, inparticular about the influence of repetitive doping and de-doping cycles and of photo-induced processes, as a function of the characteristics of the solution, i.e. of pH

2011 - Layer-by-layer deposition of a polythiophene/Au nanoparticles multilayer with effective electrochemical properties [Articolo su rivista]
Zanfrognini, Barbara; Zanardi, Chiara; Terzi, Fabio; T., Aaritalo; A., Viinikanoja; J., Lukkari; Seeber, Renato
abstract

Multilayers consisting of a water soluble polythiophene derivative and Au nanoparticles have been deposited onto different electrode substrates by means of layer-by-layer deposition technique. The assembly of the films has been performed by taking advantage of the electrostatic interactions between the positively charged imidazolic moiety of the polythiophene chain and the negative charges of citrate ions surrounding Au nanoparticles, as well of the affinity of S to Au. The nanoparticles result stably grafted to the organic matrix. The resulting modified electrodes have been characterised through electrochemical, spectroelectrochemical and microscopic techniques. The results evidenced that a high number of individual nanoparticles is present inside the multilayer. The presence of nanoparticles is of chief importance for most effective charge percolation through the multilayer, as suggested by the responses to electroactive probe species in solution. The electrocatalytic performances of the modified electrodes have been tested with respect to the oxidation of ascorbic acid.

2011 - Poly(3,4-ethylenedioxythiophene)/Au-nanoparticles composite as electrode coating suitable for electrocatalytic oxidation [Articolo su rivista]
Terzi, Fabio; Zanfrognini, Barbara; Zanardi, Chiara; Pigani, Laura; Seeber, Renato
abstract

Composite materials consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles, encapsulated by citrate anions, have been firmly deposited on an electrode surface through a simple method, taking advantage of the interaction between Au metal and thiophene polymeric backbone. A series of similar electrode coatings, also including different amounts of nanoparticles inside, has been characterised in terms of thickness and surface morphology, through different microscopic techniques. The electrocatalytic properties have been studied with respect to the oxidation of glucose in alkaline media,which is prevented from occurring on the pure organic material.

2010 - Effective catalytic electrode system based on polyviologen and Au nanoparticles multilayer [Articolo su rivista]
Zanardi, Chiara; Terzi, Fabio; Zanfrognini, Barbara; Pigani, Laura; Seeber, Renato; J., Lukkari; T., Ääritalo
abstract

Au nanoparticles encapsulated by very labile chloride ions are synthesised and characterised. Through layer-by-layer deposition technique they are stably anchored to an electrode surface, using a polyviologen derivative as the polycationic organic component. The structure and morphology of the multilayer is exhaustively studied by UV–vis spectroscopy, X-ray diffraction, scanning and transmission electron microscopy. The nanocomposite material shows very interesting electrocatalytic properties with respect to the reduction of H2O2, which occurs at particularly less negative potentials. Furthermore, the presence of Au nanoparticles inside the electrode coating greatly improves the sensitivity of the electrochemical system. The system results to be a well suitable sensor for H2O2 quantification, with high sensitivity and low detection limit.

2009 - A novel class of tetrairon(III) single-molecule magnets with graphene-binding groups [Articolo su rivista]
Danieli, Chiara; Cornia, Andrea; C., Cecchelli; R., Sessoli; A. L., Barra; Ponterini, Glauco; Zanfrognini, Barbara
abstract

Tripods of general formula R’–O–CH2C(CH2OH)3 are excellent site-specific ligands for the preparation offunctionalized Fe4 single-molecule magnets. Herein, we describe the synthesis and characterization oftwo novel complexes designed to bind graphene surfaces, in which the R group consists of an alkyl spacer–(CH2)n– (n = 6 and 10) and a terminal pyrenyl moiety. The site-specific ligand substitution on [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane) with the new tripods has been studied with 2H NMR on isotopically-enriched samples, revealing that, once formed, these clusters are stable in solution over longtimescales. It was not possible to isolate the new compounds as crystalline solids, nevertheless they werechemically characterized by elemental analysis and 1H NMR. The presence of the pyrenyl ending groupsprompted us to investigate the effect of metal complexation on fluorescence, and a full pyrene-to-ironcluster excitation energy transfer was observed. The analysis of the magnetic behaviour revealed anS = 5 ground spin state with a negative zero-field splitting parameter D = 0.42 cm1.

2009 - Adsorption of 3,4-ethylenedioxythiophene (EDOT) on noble metal surfaces: a photoemission and x-ray absorption study [Articolo su rivista]
Pasquali, Luca; Terzi, Fabio; Montecchi, Monica; B., Doyle; J., Lukkari; Zanfrognini, Barbara; Seeber, Renato; Nannarone, Stefano
abstract

The adsorption of 3,4-ethylenedioxythiophene (EDOT) on Au and Pt surfaces is studied by core level and valence band photoemission using synchrotron radiation and by near edgeX-ray absorption spectroscopy.To closer simulate real applications, the films are grown from aqueous solution at room temperature and are compared to an ‘ideal’ film prepared by dosing the molecules from the vapour phase on a clean Au(1 1 1) single crystal. The S 2p, C 1s and O 1s levels show multiple components which are associatedto molecular fragmentation. NEXAFS confirms that fragmentation takes place at the surface. Thiophene species as well as alkyl chains and Sn species are identified as the most probable fragmentation products.

2009 - Preparation and Characterization of a RedoxMultilayer Film Containing Au Nanoparticles [Articolo su rivista]
Terzi, Fabio; Zanardi, Chiara; Zanfrognini, Barbara; Pigani, Laura; Seeber, Renato; J., Lukkari; T., Aaritalo; J., Kankare
abstract

Gold nanoparticles encapsulated by negatively charged molecules have been stably anchored at a Au substratethrough layer-by-layer deposition technique, employing a redox polyviologen derivative as the cationiccounterpart. UV-vis spectroscopy, quartz crystal microbalance, transmission electron microscopy, scanningelectron microscopy, atomic force microscopy, and voltammetric measurements have been performed in orderto characterize the systems and to give a rationale to the effect of the deposition conditions on the propertiesof the resulting multilayers. The behavior of two benchmark electroactive species ([Fe(CN)6]4- and[Ru(NH3)6]3+) has been studied on nanoparticle-terminated multilayers. The nanoparticles provide chargepercolation through the multilayer and charge transfer with redox species in solution. The results imply thatthe electrochemical behavior of nanoparticle-containing films is partly dependent on the charge compensationmode within polyelectrolyte multilayers.

2009 - Sensori Amperometrici. Nuoivi materiali elettrodici [Articolo su rivista]
Seeber, Renato; Pigani, Laura; Zanardi, Chiara; Terzi, Fabio; Zanfrognini, Barbara
abstract

The article concerns the development of new materials for electrode systems. A complete characterisation of the materials and of the electrochemical systems is obtained by combiningthe results from different spectroscopic and electrochemical techniques. The resulting modified electrodes are tested as amperometric sensors. A particularly attractive applicationof these devices, even using (ultra)microelectrodes, is in the field of “blind analysis”, as elements of electronic tongues for the classification of real matrices.

2008 - Strategies to Reduce Inter-chain Aggregation and Fluorescence Quenching in Alternated Multilayers of a Polythiophene [Articolo su rivista]
Lodi, Andrea; Caselli, Monica; Zanfrognini, Barbara; Cagnoli, Rita; Mucci, Adele; Parenti, Francesca; Schenetti, Luisa; Ponterini, Glauco
abstract

Electrostatically self-assembled multilayers of a fluorescent carboxyalkylsulfanyl polythiophene and poly(diallyldimethylammonium) were prepared using the layer-by-layer deposition approach and were structurally characterized by linear dichroism and atomic-force microscopy. Steady-state measurements revealed that fluorescence was quenched relative to the solution behaviour. The emission quantum yield was found to increase upon decreasing the polymer concentration in the dipping solution as well as by codepositing polythiophene with another polyanion, poly(sodium-4-styrenesulfonate). Fluorescence quenching was therefore attributed to the formation of non-emitting inter-chain aggregate exciton traps.Intercalation of polythiophene layers with non-emitting polymers having larger energy gaps did not result in enhanced fluorescence, thus suggesting negligible polythiophene aggregation and exciton migration across different layers. At best, we could obtain quantum yields around 0.1–0.15, about half the solution value but almost two orders of magnitude larger than found with cast or spin-cast films.