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A simple synthesis was applied and tested for the preparation of boron-doped titanium dioxide [TiO2(B)] nanocrystals using titanium tetraisopropoxide (TTIP) together with boric acid (H3BO3) and benzyl alcohol as reaction solvent. Changes in the TTIP/H3BO3 molar ratio allowed a scalable synthetic protocol with a significant B-dopant control. In particular, this approach does not need surfactants or a final calcination step. X-ray diffractometry (XRD), low- and high-resolution transmission electron microscopy (TEM and HRTEM), and micro Raman spectroscopy revealed that the TiO2 nanocrystals produced have diameters up to about 10 nm and are mainly of the anatase phase but that a brookite phase was progressively formed with increased dopant level. The amount of boron was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the presence of boron inside the crystals was determined by 11B cross-polarized magic-angle spinning nuclear magnetic resonance (11B CP-MAS NMR) spectroscopy. X-ray photoelectron spectroscopy (XPS) revealed the presence of boron on the nanocrystal surfaces, confirming the trend in the dopant concentration already observed with ICP-AES elemental analysis. Microphotoluminescence studies indicated the formation of three different typical luminescent defect states in correlation with the amount of added boron in the titania. UV/Vis absorption spectra showed a boron-dependent redshift of the absorption edge.

This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers (MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors. Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work reported in this field, an overview of the most innovative and successful examples will be reviewed.

Novel Donor-pi-Acceptor triphenylamine-based dyes were synthesized and characterized with regard to their photophysical and photoelectrochemical properties by introducing the ethynyl-2-thienyl moiety as spacer (YS-1). The modification of the donor triphenylamine, performed by intodroducing two p-methoxy groups gave the YS-2 dye. Experimental results showed that the UV-Vis absorption spectra changed exhibiting the increasing of the molar extinction coefficient as well as the red-shift in dichloromethane solution. The maximum power conversion efficiency under standard global AM 1.5 illumination for YS-1 was 4.1% rising to 5.3% when the cell was sensitized with YS-2. The interpretation of the improvement and the discussion of the experimental results were corroborated by Time-Dependent Density-Functional Theory calculations, carried out for the photosensitizers in vacuo and in solution. In particular, the effects on the spectroscopic properties of the dyes due to the presence of the solvent and to the common deprotonation of the carboxylic unit in polar solvents have been investigated.

X-Ray Photoelectron Spectroscopy (XPS) was used to extensively investigate the chemical structure of electrosynthesized poly(3-thiophene acetic acid). The observation of the integrity of carboxylic functionalities upon polymerization, along with the strong affinity between monomer and the herbicide atrazine (At) evidenced by Nuclear Magnetic Resonance, prompted the exploitation of the application of the electrosynthesized polymer in the preparation of a Molecularly Imprinted Polymer (MIP) for At. Experimental conditions for film electrosynthesis in the presence of template (At) were selected. XPS spectroscopy was used also for the characterization of the imprinted film, evidencing the entrapment of the template in polymer matrix and the removal of most template upon washing. Moreover, XPS results about the use of a cross-linking agent (3,3-bithiophene) for prospective improvement of MIP structural integrity are illustrated.

Three different metalated tetrapyrrolic macrocycles have been transferred by Langmuir-Blodgett technique directly onto piezoelectric quartz crystal covered with gold electrodes of a commercial quartz crystal microbalance instrument in order to perform a flow injection analysis. All floating films at the air-water interface have been analyzed by registration of Langmuir curves and by UV-vis reflection spectroscopy and brewster angle microscopy. The sensing performances of the modified gold electrodes were investigated by monitoring the frequency variation induced by the presence of several toxic phenols. The explored concentrations ranged around 10-3 M and the corresponding frequency variations ranged between 10 and 200 Hz. All responses observed were fast, reproducible and reversible; moreover, the active layers are stable over long periods of utilization. The observation that interferences from fulvic acid are absolutely negligible is also noteworthy. The responses are not selective for each singular phenol derivative; notwithstanding this, to the best of our knowledge, this contribution represents one of the first examples of sensing layers for the monitoring of the total content of phenols. © 2009 World Scientific Publishing Company.

A molecularly imprinted polymer for recognising selectively 2,3,7,8-tetrachlorodibenzodioxin (TCDD) was made by a new non-covalent method employing a“dummy†template. The proposed way represents a simplification of a synthetic schemeproposed by Lübke et al.[1] for covalent imprinting. Comparison of extraction yields of thenovel polymer, a non imprinted polymer and an imprinting polymer, prepared by theoriginal procedure demonstrates the binding capacity of the proposed polymer, which is inprinciple applicable to solid phase extraction (SPE) of dioxin.

A new zinc phthalocyanine peripherally substituted with methacrylic groups was synthesized to be employed as a functional monomer in the formation of molecularly imprinted polymers as nucleoside receptors. The binding affinity and selectivity of the synthesized phthalocyanine towards nucleosides were evaluated by UV-vis titration experiments in CH 2 Cl 2 at 298 K. The binding constant ( K a) and Gibbs free energy changes (-Δ G 0) were calculated according to the modified Benesi-Hildebrand equation. Binding experiments showed that K a of phthalocyanine with tri-O-acetyladenosine ( TOAA ) is 1.35 × 104, 500 times that of phthalocyanine with tri-O-acetyluridine ( TOAU ), indicating a high selectivity of the synthesized phthalocyanine derivative.

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.

The increasing interest in technologies capable of tracking a biomarker down to the physical limit points toward new opportunities in early diagnostics of progressive diseases. Indeed, single-molecule detection technologies are foreseen to enable clinicians to associate the tiniest increase in a biomarker with the progression of a disease, particularly at its early stage. Bioelectronic organic transistors represent an extremely powerful tool to achieve label-free and single-molecule detection of clinically relevant biomarkers. These electronic devices are millimetric in size and in the future could be mass-produced at low cost. The core of the single molecule with a large transistor (SiMoT) platform, based on an electrolyte-gated field-effect transistor, is a gold gate electrode biofunctionalized with a self-assembled monolayer, a densely packed layer of recognition elements. So far, only the SiMoT detection of proteins, using the corresponding antibodies as recognition elements, has been reported. In this study, the SiMoT sensing response toward genomic biomarkers is proposed. Herein, the gate is functionalized with a genomic biomarker for multiple sclerosis (miR-182). This is relevant, not only because a limit of detection of a single molecule is achieved but also because it proves that the SiMoT label-free, single-molecule detection principle is the only one of its kind that can detect, by means of the same platform, both protein and genomic markers.

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.

Robust electrolyte-gated organic field-effect-transistors (OFETs) are particularly needed for the development of biosensing devices. However, when a FET biosensor operates in aqueous environments or even in real biological fluids, some critical issues may arise due to the possible lack of environmental long-term and/or operational stability. An important source of instability is associated with the degradation of the organic electronic channel materials such as for instance, poly-3-hexylthiophene (P3HT), a benchmark commercially available p-type organic semiconductor. In this work, the investigation of critical parameters, such as the control over spurious electrochemical phenomena as well as the operating conditions that can affect water-gated OFETs lifetime, is reported, together with a proposed modeling of the P3HT stability curve over 1 week in water. The investigation of possible morphological/chemical modifications occurring at the polymer surface after operating in water for 2 weeks was carried out. Moreover, it is proven how the addition of a gel layer can extend the P3HT based water-gated OFET shelf life up to 2 months.

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.

Active investment in research time in the development and study of novel unconventional antimicrobials is trending for several reasons. First, it is one of the ways which might help to fight antimicrobial resistance and bacterial contamination due to uncontrolled biofilm growth. Second, minimizing harmful environmental outcomes due to the overuse of toxic chemicals is one of the highest priorities nowadays. We propose the application of two common natural compounds, chitosan and tannic acid, for the creation of a highly crosslinked polymer blend with not only intrinsic antimicrobial properties but also reducing and stabilizing powers. Thus, the fast and green synthesis of fine spherically shaped Ag nanoparticles and further study of the composition and properties of the colloids took place. A positively charged core-shell nanocomposition, with an average size in terms of the metal core of 17 ± 4 nm, was developed. Nanoantimicrobials were characterized by several spectroscopic (UV-vis and FTIR) and microscopic (transmission and scanning electron microscopies) techniques. The use of AgNPs as a core and an organic polymer blend as a shell potentially enable a synergistic long-lasting antipathogen effect. The antibiofilm potential was studied against the food-borne pathogens Salmonella enterica and Listeria monocytogenes. The antibiofilm protocol efficiency was evaluated by performing crystal violet assay and optical density measurements, direct visualization by confocal laser scanning microscopy and morphological studies by SEM. It was found that the complex nanocomposite has the ability to prevent the growth of biofilm. Further investigation for the potential application of this stable composition in food packaging will be carried out.

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.