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Chitosan-cyclodextrin hybrid nanoparticles (NPs) were obtained by the ionic gelation process in the presence of glutathione (GSH), chosen as a model drug. NPs were characterized by means of transmission electron microscopy and zeta-potential measurements. Furthermore, a detailed X-ray photoelectron spectroscopy study was carried out in both conventional and depth-profile modes. The combination of controlled ion-erosion experiments and a scrupulous curve-fitting approach allowed for the first time the quantitative study of the GSH in-depth distribution in the NPs. NPs were proven to efficiently encapsulate GSH in their inner cores, thus showing promising perspectives as drug carriers.

Plasma-enhanced chemical vapour deposition has been applied to the fabrication of high-quality SiO2/Si interfaces and to the functionalization of the silicon dioxide surfaces for organic thin film transistor applications. The advantage of the method herein reported resides in the possibility of activating the substrate, depositing and functionalizing high-quality SiO2 films in a single-run process, at low temperature. The structural properties of silicon dioxide samples have been studied by infrared spectroscopy, angle resolved and depth profiling X-ray photoelectron spectroscopy. The electronic properties have been retrieved from the leakage current values and the Fowler-Nordheim current plots. (c) 2007 Elsevier B.V. All rights reserved.

Copper–fluoropolymer (Cu-CFx) nano-composite films are deposited by dual ion-beam sputtering. The extensive analytical characterization of these layers reveals that inorganic nanoparticles composed of Cu(II) species are evenly dispersed in a branched fluoropolymer matrix. In particular, X-ray photoelectron spectroscopy has been employed to study the surface chemical composition of the material and to assess how it changes on increasing the copper loading in the composite. Transmission electron microscopy reveals that the copper nanoclusters have a mean diameter of 2–3 nm and are homogeneously in-plane distributed in the composite films. Electrothermal atomic absorption spectroscopy has been used to study the kinetics of copper release in the solutions employed for the biological tests. The Cu-CFx layers are employed as bioactive coatings capable of inhibiting the growth of target microorganisms such as Saccharomyces cerevisiae, Escherichia coli, Staphylococcus aureus, and Lysteria. The results of the analytical characterization enable a strict correlation to be established among the chemical composition of the material surface, the concentration of copper dissolved in the microorganisms broths, and the bioactivity of the nano-structured layer.

The electrosynthesis of copper and silver core-shell nanoparticles (NPs) by the sacrificial anode technique, employing tetraoctylammonium (TOA) salts as base electrolyte for the first time, is described. These surfactants were selected because they combine high NP stabilizing power with useful disinfecting properties. The resulting colloids were mixed with a solution of an inert dispersing polymer and used to prepare nanostructured composite thin films. The morphologies and chemical compositions of the nanomaterials were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The TEM reveals that the average core diameter of the metal NPs ranges between 1.7 and 6.3 nm, as a function of the nature of the metal and of the electrosynthesis conditions, and does not change significantly upon inclusion in the polymer matrix. An appreciable concentration of the metal is detected on the nanoparticle surface by XPS. High-resolution XP spectra indicate that both copper and silver are present at zero oxidation state in all of the materials (colloids and composite films). This demonstrates the high efficiency of the surfactant at controlling the morphology and the chemical composition of the nanodispersed metal in both the as-synthesized colloid and in the polymeric dispersion. The nanocoatings are shown to exert a marked inhibitory effect on the growth of eukaryote and prokaryote target microrganisms, and experimental evidence of a synergic disinfecting effect due to the surfactant and the nanodispersed metal is provided. On the basis of these stability and bioactivity results, it is clear that Cu-NPs and Ag-NPs are suitable for application in disinfecting or antifouling paint and coating formulations.

Biocompatible methods capable of rapid purification and fractionation of analytes from complex natural matrices are increasingly in demand, particularly at the forefront of biotechnological applications. Field-flow fractionation is a separation technique suitable for nano-sized and micro-sized analytes among which bioanalytes are an important family. The objective of this preliminary study is to start a more general approach to field-flow fractionation for bio-samples by investigation of the correlation between channel surface composition and biosample adhesion. For the first time we report on the use of X-ray photoelectron spectroscopy (XPS) to study the surface properties of channels of known performance. By XPS, a polar hydrophobic environment was found on PVC material commonly used as accumulation wall in gravitational field-flow fractionation (GrFFF), which explains the low recovery obtained when GrFFF was used to fractionate a biological sample such as Staphylococcus aureus. An increase in separation performance was obtained first by conditioning the accumulation wall with bovine serum albumin and then by using the ion-beam sputtering technique to cover the GrFFF channel surface with a controlled inert film. XPS analysis was also employed to determine the composition of membranes used in hollow-fiber flow field-flow fractionation (HF FlFFF). The results obtained revealed homogeneous composition along the HF FlFFF channel both before and after its use for fractionation of an intact protein such as ferritin.

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Immunoglobulin M (IgM) single-molecule and label-free detection is demonstrated, for the first time, by means of an electrolyte-gated thin-film transistor. The sensor integrates a millimeter-wide self-assembled monolayer (SAM) that includes trillions of anti-IgM capturing proteins. This adds generality to the already introduced single molecule with a transistor (SiMoT) platform. Besides the extremely high sensitivity, the SAM confers to the SiMoT bioelectronic sensor a high selectivity that is here assessed by measuring the differential responses of the IgM or the immunoglobulin G (IgG) cognate biomarkers mutually interacting with anti-IgM or anti-IgG capturing SAMs. At the same time, no response to IgG or IgM is measured with the anti-IgM or anti-IgG SAM, respectively. The SiMoT technology is known to exploit the hydrogen bonding network present in the SAM. In this paper, further elements supporting the model of this network enabling single-molecule sensitivity are provided by demonstrating that, once this electrostatic connecting element is removed, the sensing is suppressed. It also provides a plausible explanation of the wide-field single-molecule sensing mechanism in terms of the amplified field-effect response and propagation of electrostatic domains associated with the electrostatic hydrogen bonding network. Future possible applications to low-cost early detection of infection diseases can be envisaged.

In this study a conservation treatment of stone monuments meant for consolidation, protection, and inhibition of biofilm formation is proposed. The method is developed as a part of a systematic investigation aimed at producing nanocomposite coatings able to exert a marked biological activity over a long period of time thanks to their peculiar structure. Zinc oxide nanoparticles, synthesised by means of simple and reproducible electrochemical procedures, are embedded in commercially available and commonly used consolidant/water repellent matrices to obtain nanostructured materials. Products based on tetraethoxysilane and/or polysiloxanes were tested. In a first step the nanomaterials were applied on stone samples and studied with scanning electron microscopy and spectrophotocolorimetry. Then, in situ experimentation was undertaken by applying nanocomposite coatings on the exterior of a 12th-century church in the south of Italy. The performances of the ZnO-nanoparticles based composite coating were compared with a previously investigated copper nanoparticles based material, successfully tested and monitored in situ for more than two years. Finally, preliminary tests on the inhibitory effect on the growth of the fungus Aspergillus niger were also carried out. The results showed that in case of zinc oxide a tenfold higher concentration of nanoparticles as compared with Cu-NPs can be utilized in the matrices without affecting the colour of the stone substrate, which means that the new material should be able to exert a long-lasting biocide activity. Laboratory and in situ tests of the developed innovative nanomaterials yielded very promising, though preliminary, results in terms of chromatic changes, morphological characteristics and bioactivity. Constant monitoring of the coatings will be continued in order to obtain all necessary information on their long term behaviour and inhibition of biological colonisation.

Since 2004, we have been developing nanomaterials with antimicrobial properties, the so-called nanoantimicrobials. When the coronavirus disease 2019 (COVID-19) emerged, we started investigating new and challenging routes to nanoantivirals. The two fields have some important points of contact. We would like to share with the readership our vision of the role a (nano)materials scientist can play in the fight against the COVID-19 pandemic. As researchers specifically working on surfaces and nanomaterials, in this letter we underline the importance of nanomaterial-based technological solutions in several aspects of the fight against the virus. While great resources are understandably being dedicated to treatment and diagnosis, more efforts could be dedicated to limit the virus spread. Increasing the efficacy of personal protection equipment, developing synergistic antiviral coatings, are only two of the cases discussed. This is not the first nor the last pandemic: our nanomaterials community may offer several technological solutions to challenge the ongoing and future global health emergencies. Readers’ feedback and suggestions are warmly encouraged.

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag2O, Cu, Cu2O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.