Nicola Cioffi

Electrosynthesis and characterisation of nanostructured palladium–polypyrrole composites

Abstract Palladium–polypyrrole composite thin films have been synthesised using three different bottom-up procedures all comprising the electrochemical synthesis of palladium nanoparticles that are subsequently potentiostatically deposited or embedded into an electrochemically produced polypyrrole thin film. Transmission electron micrographs of the resulting composites show that the metallic inclusions have a mean diameter of about 5 nm with a homogeneous size distribution. Experimental evidence is also provided that both the nanoparticles and the composite thin films are electroactive. Preliminary results on the extendibility of this approach to the electrosynthesis of other metal–polypyrrole materials (namely Ag–PPy composites) are also presented.

A comparative study of chitosan and chitosan/cyclodextrin nanoparticles as potential carriers for the oral delivery of small peptides ☆

The aim of this study was to characterize new nanoparticles (NPs) containing chitosan (CS), or CS/cyclodextrin (CDs), and evaluate their potential for the oral delivery of the peptide glutathione (GSH). More precisely, NP formulations composed of CS, CS/alpha-CD and CS/sulphobutyl ether-beta-cyclodextrin (SBE(7m)-beta-CD) were investigated for this application. CS/CD NPs showed particle sizes ranging from 200 to 500nm. GSH was loaded more efficiently in CS/SBE(7m)-beta-CD NPs by forming a complex between the tripeptide and the CD. X-ray Photoelectron Spectroscopy (XPS) analysis suggested that GSH is located in the core of CS/SBE(7m)-beta-CD NPs and that it is almost absent from the NP surface. Release studies performed in vitro at pH 1.2 and pH 6.8 showed that NP release properties can be modulated by selecting an appropriate CD. Transport studies performed in the frog intestine model confirmed that both CS and CS/CD nanoparticles could induce permeabilization of the intestinal epithelia. However, CS/SBE(7m)-beta-CD NPs provided absorption-enhancing properties in all segments of the duodenum, whereas CS NPs effect was restricted to the first segment of the duodenum. From the data obtained, we believe that CS/CD nanoparticles might represent an interesting technological platform for the oral administration of small peptides.

Antifungal activity of polymer-based copper nanocomposite coatings

Eukaryotes, such as fungi, can be harmful pathogen agents, and the control of their bioactivity is critical as humans are eukaryote organisms, too. Here, copper∕polymer nanocomposites are proposed as antifungal spinnable coatings with controlled copper-releasing properties. The tests of the bioactivity show that fungal growth is inhibited on the nanocomposite-coated plates, and the antifungal activity can be modulated by controlling the Cu nanoparticle loading.

Carbon based materials for electronic bio-sensing

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 sensors 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.

Interfacial electronic effects in functional biolayers integrated into organic field-effect transistors

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.

Analytical characterization of laser-generated copper nanoparticles for antibacterial composite food packaging

AbstractA 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. Online abstract figureAnalytical characterization of copper nanoparticles: an XPS spectrum and a TEM image

Nanostructured palladium–polypyrrole composites electrosynthesised from organic solvents

Abstract Palladium–polypyrrole nanostructured composite films can be easily synthesised using a two-step procedure comprising the electrochemical synthesis of palladium nanoparticles (Pd-NPs) that are subsequently potentiostatically deposited onto a polypyrrole thin film electrosynthesised from an acetonitrile solution. The composite thin films have good conductivity and their transmission electron micrographs show that the metallic inclusions have a mean diameter of about 5 nm with a homogeneous size distribution. X-ray photoelectron spectroscopy (XPS) analysis reveals the presence of two surface oxidation states for the as-synthesised Pd-NPs as well as for those deposited on the films. On the basis of experimental findings, a structural model for the Pd-NPs is proposed.

NTCDA organic thin-film-transistor as humidity sensor: weaknesses and strengths

Abstract 1,4,5,8-Naphthalene-tetracarboxylic-dianhydride (NTCDA) organic thin-film-transistors employed as humidity sensors exhibit higher performance level compared to NTCDA chemiresitors. In particular, the transistor on-current exhibits higher values and a larger dynamic range as well as a better reversibility, compared to the response of an NTCDA resistor. On the basis of the FT-IR spectra of NTCDA humid and anhydrous thin-films, a model for the NTCDA/H 2 O system is proposed which eventually explains the variation of NTCDA thin-film-transistor parameters, while the device is exposed to changing water vapor atmosphere.

Glucose as a Clean and Renewable Reductant in the Pd-Nanoparticle-Catalyzed Reductive Homocoupling of Bromo- and Chloroarenes in Water

An efficient and highly sustainable Ullmann-type homocoupling of bromo- and chloroarenes, including the more challenging electron-rich chloroarenes (e.g., 4-chloroanisole), catalyzed by in situ generated Pd colloids, is carried out in aqueous medium under relatively mild conditions (temperatures ranging from 40 to 90 degrees C). Glucose is used as a clean and renewable reductant, while tetrabutylammonium hydroxide (TBAOH) acts as base, surfactant, and phase-transfer agent, creating a favorable environment for the catalyst. Pd nanoparticle sizes, morphology, and chemical composition are ascertained by TEM and XPS analyses.

Regioregular polythiophene field-effect transistors employed as chemical sensors

Abstract Soluble alkyl- and alkoxyl-substituted regiochemically defined polyterthiophenes are used as active layers in sensing organic thin films transistors (OTFTs). Such active layers have a polycrystalline morphology and the substituent chains bear different associated dipole moments. Volatile organic compounds carrying moieties that are chemically homologous to the selected polymers’ side chains are used as analytes. Both electrical and quartz crystal microbalance sensor responses are evaluated and a rationale for the sensing mechanisms involving weak polar/polar-type interactions is proposed.