MICAELA DEGLI ESPOSTI
DIPENDENTE ALTRA UNIVERSITA presso: Dipartimento di Ingegneria "Enzo Ferrari"
- Development of a redox polymer based on poly(2-hydroxyethyl methacrylate)for disposable amperometric sensors
[Articolo su rivista]
Zanardi, Chiara; Pigani, Laura; Maccaferri, Giulio; DEGLI ESPOSTI, Micaela; Fabbri, Paola; Zannini, Paolo; Seeber, Renato
Membranes based on poly(2-hydroxyethyl methacrylate), chemically modified with ferrocene functionalities, are proposed as novel coatings for the development of disposable amperometric sensors. They are mass-produced on an inert support through an UV photo-induced polymerization, forming self-standing films that can be transferred on an electrode surface. Thanks to the characteristic of the
functionalized methacrylate matrix to rapidly and reversibly swell by incorporation of large amounts of water, the ferrocene moieties are in intimate contact with the electrolytic solution. They can activate effective electrocatalytic processes that can be exploited in the field of amperometric sensing. The performance of the methacrylate coating with respect to the determination of hydroquinone benchmark
analyte has been tested both in a static solution and in a flux cell.
- Multilayer films composed of conductive poly(3-hydroxybutyrate)/carbon nanotubes bionanocomposites and a photoresponsive conducting polymer
[Articolo su rivista]
Luca, Valentini; Fabbri, Paola; Messori, Massimo; DEGLI ESPOSTI, Micaela; Silvia Bittolo, Bon
In order to develop new electronic devices, it is necessary to find innovative solutions to the eco-sustainability problem of materials as substrates for circuits. We realized a photoresponsive device consisting of a semiconducting polymer film deposited onto optically semitransparent and conductive biodegradable poly(3-hydroxybutyrate) (PHB)/carbon nanotube (CNT) substrates. The experiments indicated that the PHB-CNT bionanocomposite substrate behaves as an optical window trapping electric charges produced by the photoexcitation of the semiconducting polymer. Such PHB-CNT functional substrates are expected to be attractive for eco-friendly electronics.
- Chemical and thermomechanical tailoring of the shape memory effect in poly(epsilon-caprolactone)-based systems
[Articolo su rivista]
Messori, Massimo; DEGLI ESPOSTI, Micaela; Paderni, Katia; S., Pandini; S., Passera; T., Riccò; M., Toselli
The thermally activated shape memory response of polymeric materials results from a combination of the material molecular architecture with the thermal/deformational history, or ‘programming’. In this work, we investigate the shape memory response of systems based on poly (epsilon-caprolactone) (PCL) so as to explore the adoption of proper chemical and thermomechanical tailoring routes. Cross-linked semicrystalline PCL-based materials are prepared by different molecular architectures starting from linear, three- and four-arms star PCL functionalized with methacrylate end groups, allowing to tune the melting temperature, Tm, ranging between 36 and 55 °C. The materials’ ability to display the shape memory is investigated by the application of proper thermomechanical cycles on specimens deformed at two different temperatures (23 and 65 °C, i.e. below and above the Tm, respectively). The shape memory response is studied under dynamic thermal conditions in thermally activated recovery tests, to identify the typical transformation temperatures, and under isothermal conditions at given recovery temperatures, to monitor shape recovery as a function of time. All the specimens are capable of full recovery on specific thermal ranges influenced by both melting and deformation temperatures. Specimens deformed above Tm are able to recover the whole deformation in a very narrow temperature region close to Tm, while those deformed at room temperature display broader recovery processes, those onset at about 30 °C. Isothermal tests reveal that when the deformed material is subjected to a constant recovery temperature, the amount of recovered strain and the time required strongly depend on the particular combination of melting temperature, deformation temperature and recovery temperature.
- Designing of antibacterial plastics: Thymol release from photocured thymol-doped acrylic resins
[Articolo su rivista]
Pilati, Francesco; DEGLI ESPOSTI, Micaela; Bondi, Moreno; Iseppi, Ramona; Toselli, M.
Antibacterial thymol-doped plastics can be prepared by photopolymerisation of solutions of thymol in tripropylenglycoldiacrylic monomer. The antibacterial properties of these doped plastics depend on the thymol release rate and this study reports results about the release of thymol from doped resin discs in different media under different conditions. Thymol-doped resin can release thymol in air, even though at a much slower rate than pure thymol in the form of solid powder. In particular. it has been found that the rate of release of thymol in air is mainly dependent on the temperature and on the thymol content in the resin. On the other hand, when a thymol-doped resin is put in contact with liquids, the rate of diffusion of thymol into surrounding liquids depends mainly on the chemical nature of the liquid, other than on the thymol concentration in the resin. In particular, the release is affected by the capability of the liquids to swell the resin and by the plasticizing effect of thymol. The release of thymol can be quantitatively described by a Weibull-type equation up to complete release of thymol.
- Preparation, characterization, and antibacterial activity of photocured thymol-doped acrylic resins
[Articolo su rivista]
DEGLI ESPOSTI, Micaela; Pilati, Francesco; Bondi, Moreno; DE NIEDERHAUSERN, Simona; Iseppi, Ramona; M., Toselli
This article describes the preparation of thymol-doped acrylic resins by photopolymerization of solutions of thymol in tripropylenglycoldiacrylic monomer. This provides an easy, energy-saving, and environmental friendly process to prepare antibacterial plastics (fulfilling most of the "green chemistry" requirements). The results demonstrate that thymol can be included in the resin even at high concentration (up to 28.6%) without affecting the photocuring reaction and losing transparency. The glass transition temperature of the doped resin decreases when the thymol content increases, as it behaves like a plasticizer with respect to the acrylic resin. As indicated by HPLC analysis, thymol can be released in liquid media at a rate that depends on the chemical nature of the liquid. Evaluation by agar diffusion assays showed an antibacterial activity on both Gram-negative and Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli). The antibacterial activity can occur just on the plastic surface when the thymol-doped resins is applied as thin coating, while it is evident also in the surrounding agar medium for doped plastic discs, 1.2 mm thick with a concentration of thymol in the resin higher than 16.7%.
- Tailored One-Way and Two-Way Shape Memory Response of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications
[Relazione in Atti di Convegno]
Pandini, Stefano; Passera, Simone; Riccò, Theonis; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Dassa, Luca; Cambiaghi, Danilo; Paderni, Katia; DEGLI ESPOSTI, Micaela; Toselli, Maurizio; Pilati, Francesco; Messori, Massimo
A series of crosslinked poly(epsilon-caprolactone) (PCL) materials were obtained starting from linear, three- and four-arm star PCL functionalized with methacrylate end-groups, allowing to tune the melting temperature (T-m) on a range between 36 and 55 degrees C. After deforming the specimens at 50% above T-m, the materials are seen to fully restore their original shape by heating them on a narrow region close to T-m; further, when the shape memory effect is triggered under fixed strain conditions, the materials are able to exert stress on a range between 0.2 and 7 MPa. The materials also display two-way shape memory features, reversibly moving between two shapes when cooled and heated under a fixed load. Finally, to investigate the application of the PCL materials as self-expandable stents, one-way shape memory experiments are currently carried out on tubular specimens.
- Attività anti-listeria di Enterococcus casseliflavus 416K1batteriocino-produttore intrappolato in forma vivente incoating applicati a film di PET da impiegarsi nel campodell’active food packaging
[Abstract in Rivista]
Messi, Patrizia; Iseppi, Ramona; DE NIEDERHAUSERN, Simona; Anacarso, Immacolata; Sabia, Carla; DEGLI ESPOSTI, Micaela; Toselli, Moreno; Pilati, Francesco; Bondi, Moreno
OBIETTIVI Il consumo di alimenti “ready-to-eat” e di prodotti refrigerati ha provocato un incremento di listeriosi e, poiché la refrigerazione è uno dei mezzi più efficaci di conservazione, la riconosciuta psicotrofia del patogeno ne rende il controllo estremamente difficoltoso. Una innovativa metodologia di “active food packaging” è stata da noi messa a punto incorporando nel materiale di confezionamento agenti microbici in grado di rallentare o inibire la proliferazione di L. monocytogenes. MATERIALI E METODI E’ stata valutata l’attività antilisteria di film polimerici (coating) contenenti una batteriocina purificata (Enterocina 416K1) e quella di film preparati inglobando lo stesso microrganismo produttore Enterococcus casseliflavus 416K1 in forma vitale. Tale attività è stata determinata qualitativamente “in vitro” e quantitativamente su campioni (formaggio e wurstel) artificialmente contaminati con L. monocytogenes NCTC10888. RISULTATIEntrambe le valutazioni hanno messo in evidenza l’attività antibatterica dei due tipi di coating nei confronti di L. monocytogenes NCTC10888. E’ stato possibile anche osservare nei coating allestiti con batteri vivi, la crescita di minicolonie di E. casseliflavus che in corrispondenza del loro sviluppo evidenziano attività antibatterica. CONCLUSIONI I risultati ottenuti dimostrano una buona attività antilisteria sia della batteriocina che del microrganismo stesso inglobato in forma vitale e che l’intrappolamento nei coating ibridi è sia compatibile col mantenimento della forma attiva della batteriocina che con la vitalità dei microrganismi. Il lavoro presentato è, a nostro avviso, una novità nel campo dell’active food packaging e in prospettiva potrà trovare un’utile applicazione nel campo della bioconservazione.