[show abstract][hide abstract] ABSTRACT: In this paper a study of Multi Wall Carbon Nanotube films deposited at low temperature by means of a spray tech-nique on different substrates is presented. Nanodispersion of nanotube powder in a non-polar 1,2-dichloroethane solvent was used as starting solution. Electron Microscopy in Scanning and Transmission modes were used in order to verify the morphological properties of the deposited films. Visible light detectors were prepared spraying Multi Wall Carbon Nanotubes on silicon substrates with different lay-outs. In some detectors the nanotubes were covered by an Indium Tin Oxide (ITO) layer. Electrical measurements, both in dark and under light irradiation, were performed and Current-Voltage characteristics are reported. The Indium Tin Oxide coating effect on the photoconductivity yield is presented and discussed along with device ageing test, resulting in a very good photoconduction and stability over four months.
[show abstract][hide abstract] ABSTRACT: Research on nanomaterials containing one or more transition metals is growing tremendously,
thanks to the large number of preparation processes available, and to the novel applications
that can be envisaged in several fields. This review presents an overview of selected studies in
the field of antimicrobial textiles, employing bioactive nano-phases of elements/compounds
such as silver, copper or zinc oxide. In addition, the history of use of these antimicrobials and
their mechanism of action are shortly reported.. Finally, a short description is provided of
deposition/preparation methods which are being used in the authors labs for the development
of textiles modified by novel nanoantimicrobials.
[show abstract][hide abstract] ABSTRACT: The aim of this study was to evaluate the performance of chitosan (CS) and glycol chitosan (GCS) nanoparticles containing the surfactant Lipoid S100 for the systemic delivery of low molecular weight heparin (LMWH) upon pulmonary administration. These nanoparticles were prepared in acidic and neutral conditions using the ionotropic gelation technique. The size and zeta potential of the NPs were affected by the pH and also the type of polysaccharide (CS or GCS). The size (between 156 and 385nm) was smaller and the zeta potential (from +11mV to +30mV) higher for CS nanoparticles prepared in acidic conditions. The encapsulation efficiency of LMWH varied between 100% and 43% for the nanoparticles obtained in acidic and neutral conditions, respectively. X-ray photoelectron spectroscopy studies indicated that the surfactant Lipoid S100 was localized on the nanoparticle's surface irrespective of the formulation conditions. In vivo studies showed that systems prepared in acidic conditions did not increase coagulation times when administered to mice by the pulmonary route. In contrast, Lipoid S100-LMWH GCS NPs prepared in neutral conditions showed a pharmacological efficacy. Overall, these results illustrate some promising features of CS-based nanocarriers for pulmonary delivery of LMWH.
International journal of pharmaceutics 02/2013; · 2.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a streptavidin protein capturing layer, capable to perform label-free selective electronic detection of biotin at 3 part-per-trillion (mass fraction) or 15 pM, is here proposed. The response shows a logarithmic dependence spanning over five orders of magnitude of analyte concentration. The optimization of the FBI analytical performances is achieved by depositing the capturing layer through a controllable Layer-by-Layer (LbL) assembly, while an easy processable spin-coating deposition is proposed for potential low-cost production of equally highly performing sensors. Furthermore, a Langmuirian adsorption based model allows rationalizing the analyte binding process to the capturing layer. The FBI-OFET device is shown to operate also with an antibody interlayer as well as with an ad hoc designed micro-fluidic system. These occurrences, along with the proven extremely high sensitivity and selectivity, open to FBI-OFETs consideration as disposable electronic strip-tests for assays in biological fluids requiring very low detection limits. Keywords: electronic sensors, bio-electronics, label-free detection, analytical bio-assay, organic field-effect transistors, plastic and paper electronics.
[show abstract][hide abstract] ABSTRACT: One- and two-dimensional carbon nanostructures, i.e. carbon nanotubes (CNTs) and graphene possess exceptional physical properties owing to their distinctive structure and atomic arrangement. High electrical conductivity, highly exposed surface area and stability of these carbon nanostructures institute them as the leading choice of nanomaterials for a number of electrical and industrial applications. Besides these carbon nanostructures are extremely sensitive toward minute changes in the surrounding gas atmosphere, i.e. their conductance (or resistance) varies greatly with the adsorption–desorption of gas molecules such as nitrogen oxides (NOx). This article critically reviews the most recent advances in NOx sensors based on one- and two-dimensional carbon nanostructures and nanohybrids as gas sensitive materials. The advantages and limitations of CNT- and graphene-based devices are briefly discussed in the light of recent literature. The potential and future perspectives of these devices are also outlined in this study.
Sensors and Actuators B Chemical 01/2013; · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: The detailed action mechanism of volatile general anesthetics is still unknown despite their effect has been clinically exploited for more than a century. Long ago it was also assessed that the potency of an anesthetic molecule well correlates with its lipophilicity and phospholipids were eventually identified as mediators. As yet, the direct effect of volatile anesthetics at physiological relevant concentrations on membranes is still under scrutiny. Organic field-effect transistors (OFETs) integrating a phospholipid (PL) functional bio inter-layer (FBI) are here proposed for the electronic detection of archetypal volatile anesthetic molecules such as diethyl ether and halothane. This technology allows to directly interface a PL layer to an electronic transistor channel, and directly probe subtle changes occurring in the bio-layer. Repeatable responses of PL FBI-OFET to anesthetics are produced in a concentration range that reaches few percent, namely the clinically relevant regime. The PL FBI-OFET is also shown to deliver a comparably weaker response to a non-anesthetic volatile molecule such as acetone.
[show abstract][hide abstract] ABSTRACT: Metal nanomaterials have an emerging role in surface-assisted laser desorption ionisation-mass spectrometry (SALDI-MS) providing a useful tool to overcome some limitations intrinsically related to the use of conventional organic matrices in matrix-assisted LDI-MS. In this contribution, the possibility to use a stainless-steel-supported gold nanoparticle (AuNP) film as a versatile platform for SALDI-MS was assessed. A sacrificial anode electrosynthetic route was chosen in order to obtain morphologically controlled core-shell AuNPs; the colloidal AuNPs were, thereafter, drop cast onto a stainless-steel sample plate and the resulting AuNP film was thermally annealed in order to improve its effectiveness as LDI-MS promoter. Spectroscopic characterization of the nanostructured film by X-ray photoelectron spectroscopy was crucial for understanding how annealing induced changes in the surface chemistry and influenced the performance of AuNPs as desorption/ionisation promoter. In particular, it was demonstrated that the post-deposition treatments were essential to enhance the AuNP core/analyte interaction, thus resulting in SALDI-MS spectra of significantly improved quality. The AuNP films were applied to the detection of three different classes of low molecular weight (LMW) analytes, i.e. amino acids, peptides and LMW polymers, in order to demonstrate the versatility of this nanostructured material.
Analytical and Bioanalytical Chemistry 07/2012; 404(6-7):1703-11. · 3.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: In the present, contribution angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was proposed as a useful tool to address the challenge of probing the near-surface region of bio-active sensor surfaces. A model bio-functionalised surface was characterised by parallel AR-XPS and commercially available Thermo Avantage-ARProcess software was used to generate non-destructive concentration depth profiles of protein-functionalised silicon oxide substrates. At each step of the functionalisation procedure, the surface composition, the overlayer thickness, the in-depth organisation and the in-plane homogeneity were evaluated. The critical discussion of the generated profiles highlighted the relevance of the information provided by PAR-XPS technique.
Analytical and Bioanalytical Chemistry 06/2012; · 3.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: Biosystems integration into an organic field-effect transistor (OFET) structure is achieved by spin coating phospholipid or protein layers between the gate dielectric and the organic semiconductor. An architecture directly interfacing supported biological layers to the OFET channel is proposed and, strikingly, both the electronic properties and the biointerlayer functionality are fully retained. The platform bench tests involved OFETs integrating phospholipids and bacteriorhodopsin exposed to 1-5% anesthetic doses that reveal drug-induced changes in the lipid membrane. This result challenges the current anesthetic action model relying on the so far provided evidence that doses much higher than clinically relevant ones (2.4%) do not alter lipid bilayers' structure significantly. Furthermore, a streptavidin embedding OFET shows label-free biotin electronic detection at 10 parts-per-trillion concentration level, reaching state-of-the-art fluorescent assay performances. These examples show how the proposed bioelectronic platform, besides resulting in extremely performing biosensors, can open insights into biologically relevant phenomena involving membrane weak interfacial modifications.
Proceedings of the National Academy of Sciences 04/2012; 109(17):6429-34. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Copper-containing nanomaterials have been developed as antimicrobial additives for
food packaging applications. These nano-antimicrobials are composed of copper nanoparticles
(CuNPs) embedded in poly-lactic acid (PLA), which has been selected as a biodegradable
polymer matrix. Copper nanostructures have been synthesized by laser ablation following two
different protocols: (I) one-pot synthesis in presence of PLA and (II) in absence of polymer
matrix. In the latter route, the as prepared CuNPs suspension has been subsequently mixed to a
PLA solution. The resulting dispersions have been directly drop-cast on several substrates.
Nanoantimicrobials have been characterized by UV-Vis and x-ray photoelectron spectroscopies,
and transmission electron microscopy. The kinetics of copper release in aqueous solution from
antimicrobial nanomaterials have been studied by means of Electro-Thermal Atomic Absorption
Spectroscopy. Finally, preliminary biological tests have been performed on Pseudomonas
species by JIS methods (Japanese Industrial Standard, JIS Z 2801:2000).
[show abstract][hide abstract] ABSTRACT: A new type of nanomaterial has been developed as antibacterial additive for food packaging applications. This nanocomposite is composed of copper nanoparticles embedded in polylactic acid, combining the antibacterial properties of copper nanoparticles with the biodegradability of the polymer matrix. Metal nanoparticles have been synthesised by means of laser ablation, a rising and easy route to prepare nanostructures without any capping agent in a liquid environment. As prepared, nanoparticle suspensions have been easily mixed to a polymer solution. The resulting hybrid solutions have been deposited by drop casting, thus obtaining self-standing antibacterial packages. All samples have been characterized by UV-Vis spectroscopy, X-ray photoelectron spectroscopy and electro-thermal atomic absorption spectroscopy. Ion release data have been matched with bioactivity tests performed by Japanese Industrial Standard (JIS) method (JIS Z 2801:2000) against Pseudomonas spp., a very common Gram-negative microbial group able to proliferate in processed food.
Analytical and Bioanalytical Chemistry 01/2012; 403(4):1179-86. · 3.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: 21st century has already seen huge progress in science and technology of small, highly sensitive gas sensors, which can selectively detect environmental toxins like NOx – the oxides of nitrogen – a byproduct of fossil fuel combustion. Into this bargain, public became more health-aware and environmental bodies grew stricter, stimulating analytical and material scientists to find new strategies from material synthesis to fabrication of NOx sensors in order to produce fast and reliable gas detectors. To the scientists, semiconducting metal oxides, owing to their low cost, easy processing, high gas response, good electrical properties and above all tunable structure at the nanoscale, always presented a first-hand choice for sensor fabrication. This article presents an overview of the most recent developments in semiconducting NOx gas sensors based on these metal oxide nanostructures and their applications in vehicle exhaust and environmental monitoring. A strong emphasis is presented on chemiresistor and field effect transistor devices using semiconducting metal oxides as active layers. The performance levels of these NOx sensors are compared to those of other devices as well as other semiconductor materials. Furthermore, keeping in mind the ultimate user demands, limitations of the current sensor technologies and future strategies are discussed.
Sensors and Actuators B Chemical 01/2012; · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: Pd nanoparticles generated in green reaction media (viz. ionic liquids and water) catalyze the one-pot sequential Heck and Suzuki coupling reactions of bromo-chloroarenes to afford unsymmetrically substituted arenes in good yields.
[show abstract][hide abstract] ABSTRACT: Transistor comprising at least one conductive layer, at least one dielectric layer and
at least one thin organic semiconductor film and characterized by at least one layer of
biological material deposited directly on the surface of the dielectric. Said layer of biological
material is constituted by single or double layers of phospholipids, layers made of proteins
such as receptors, antibodies, ionic channels and enzymes, single or double layers of
phospholipids with inclusion or anchoring of proteins such as: receptors, antibodies, ionic ...
[show abstract][hide abstract] ABSTRACT: Bio-sensing represents one of the most attractive applications of carbon material based electronic devices; nevertheless, the complete integration of bioactive transducing elements still represents a major challenge, particularly in terms of preserving biological function and specificity while maintaining the sensor's electronic performance. This review highlights recent advances in the realization of field-effect transistor (FET) based sensors that comprise a bio-receptor within the FET channel. A birds-eye view will be provided of the most promising classes of active layers as well as different device architectures and methods of fabrication. Finally, strategies for interfacing bio-components with organic or carbon nano-structured electronic active layers are reported.