Asymmetric binary nanocrystals (BNCs) formed by a spherical gamma-Fe(2)O(3) magnetic domain epitaxially grown onto a lateral facet of a rodlike anatase TiO(2) nanorod have been functionalized with PEG-terminated phospholipids, resulting in a micellar system that enables the BNC dispersion in aqueous solution. The further processability of the obtained water-soluble BNC including PEG lipid micelles and their use in bioconjugation experiments has been successfully demonstrated by covalently binding to bovine serum albumin (BSA). The whole process has also been preliminarily performed on spherical iron oxide nanocrystals (NCs) and TiO(2) nanorods (NRs), which form single structural units in the heterostructures. Each step has been thoroughly monitored by using optical, structural, and electrophoretic techniques. In addition, an investigation of the magnetic behavior of the iron oxide NCs and BNCs, before and after incorporation into PEG lipid micelles and subsequently bioconjugation, has been carried out, revealing that the magnetic characteristics are mostly retained. The proposed approach to achieving water-soluble anisotropic BNCs and their bioconjugates has a large potential in catalysis and biomedicine and offers key functional building blocks for biosensor applications.

We report the synthesis of various iron oxide nanocontainers and Pt-iron oxide nanoparticles based on a cast-mold approach, starting from nanoparticles having a metal core (either Au or AuPt) and an iron oxide shell. Upon annealing, the particles evolve to asymmetric core-shells and then to heterodimers. If iodine is used to leach Au out of these structures, asymmetric core-shells evolve into "nanocontainers", that is, iron oxide nanoparticles enclosing a cavity accessible through nanometer-sized pores, while heterodimers evolve into particles with a concave region. When starting from a metal domain made of AuPt, selective leaching of the Au atoms yields the same iron oxide nanoparticle morphologies but now encasing Pt domains (in their concave region or in their cavity). We found that the concave nanoparticles are capable of destabilizing Au nanocrystals of sizes matching that of the concave region. In addition, for the nanocontainers, we propose two different applications: (i) we demonstrate loading of the cavity region of the nanocontainers with the antitumoral drug cis-platin; and (ii) we show that nanocontainers encasing Pt domains can act as recoverable photocatalysts for the reduction of a model dye.

The modification of a UV-vis light curable hybrid methacrylic siloxane resin with organic coated TiO2 nanorods (NRs) has been carried out, in order to fabricate a functional coating for protection of stone artefacts of artistic and cultural relevance. The nanocomposite, formulated without using any harmful and high volatile monomer components, has been deposited onto the surface of stone samples made of a porous carbonate stone, namely Lecce stone. Such a building material, specifically selected as a relevant example of porous and light coloured stone, is widely used in monuments and constructions of cultural and historic interest of the Apulia region (Italy). The protective ability of the nanocomposite against the water vapour capillarity absorption and its self-cleaning properties have been investigated as a function of the TiO2 NR loading, the applied amount of the formulation and the curing conditions. A reliable protocol for the application of the nanocomposite has been implemented, and, remarkably, a single UV-vis light curing step has resulted in a uniform and hydrophobic coating layer, able to preserve the water vapour permeability, the pristine colour and surface morphology of the stone samples. Moreover, the nanocomposite coated stone surface has demonstrated self-cleaning ability when tested for the degradation of an organic molecule, used as a model compound, under both solar light simulated and real sun irradiation. The achieved nanocomposite has ultimately proven to be technologically advantageous as a functional coating, suited to protect surfaces of artistic, archaeological monuments of historical interest, also under outdoor conditions.

Au nanorods (NRs) modified nanostructured TiO2/ITO electrodes have been fabricated and characterized in order to develop a biosensing platform for the photoelectrochemical determination of microRNAs. The proposed method is based on the use of thiolated DNA capture-probes (CPs) immobilized onto Au NR surface. The Au NRs are chemically bound at the surface of TiO2/ITO electrodes by means of the mercaptosuccinic acid linker. Subsequently, the DNA CPs are bound to the Au NR surface through the thiolate group, and reacted with the target RNA sequence. Finally, the obtained biosensing platform is incubated with alkaline phosphatase and I.-ascorbic acid 2-phosphate (AAP) enzymatic substrate, for the in situ generation of ascorbic acid (AA). Such AA molecule, coordinating to surface Ti atoms, generates a charge transfer complex, that results in a shift of the UV absorption threshold toward the visible spectral region of the nanostructured TiO2 forming the electrode and, hence, in the occurrence of an absorption band centered at 450 nm. The photoelectrochemical monitoring of the formation of the AA-TiO2 complex, under the visible light of a commercial LED light source, allows the selective and quantitative detection of the target microRNA strands. (C) 2018 Elsevier Ltd. All rights reserved.

A simple and cost-effective strategy for mercury ion sensing based on an easy and reliable colorimetric approach is investigated through L-cysteine functionalized gold nanorods (Au NRs). Detection tests are performed on several ions, such as Hg2+, Zn2+, Cd2+, Cu2+, Pb2+, and As2+, and monitored by UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), and infrared spectroscopy (ATR-FTIR). L-cysteine functionalized Au NRs demonstrated a remarkable sensitivity for Hg2+ with limit of detection (LOD) at a few ppt level. A red-shift in the maximum of the typical longitudinal plasmon band of Au NRs is observed and recognized related to aggregation phenomena occurring among functionalized Au NRs and triggered only by the presence of Hg2+ ions in solution. Interestingly, a significantly different response is recorded for the other tested ions. The results highlight that the functionalization of Au NRs with L-cysteine is an excellent route to implement a reliable colorimetric sensing device, able to push further down the LOD recorded for similar strategies based on spherical Au NPs.

The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i.e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposome formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA<inf>22</inf>-PDMS<inf>61</inf>-PMOXA<inf>22</inf>. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA<inf>22</inf> region of the polymersome, facing the water bulk solution, rather than in the PDMS<inf>61</inf> transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

A simple and low cost strategy for heavy metal sensing based on an easy and reliable colorimetric detection was investigated by using water soluble gold nanorods (Au NRs), functionalized with L-cysteine. Detection tests have been performed on several heavy metal ions, namely Zn2+, Cd2+, Hg2+, Cu2+, Pb2+ and As3+ ions and monitored by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The system has demonstrated a remarkable sensitivity for Hg2+ with limit of detection (LOD) at ppt level. A red-shift in the maximum of the typical longitudinal plasmon band of Au NRs has been observed and recognized related to aggregation phenomena occurring among Au NRs only in presence of Hg2+ ions. Interestingly, a significantly different response is recorded for the other tested heavy metal ions. The results highlight that the functionalization of Au NRs with L-cysteine is an excellent route to implement a reliable colorimetric sensing device, able to push further down the detection limit recorded for similar strategies based on spherical Au NPs.

Gold nanoparticles exhibit unique electronic, optical, and catalytic properties that are different from those of bulk metal and have several applications in optoelectronics, imaging technology, catalysis, and drug delivery. Currently, there is a growing need to develop eco-friendly nanoparticle synthesis processes using living organisms, such as bacteria, fungi and algae. In particular, microorganisms are well known to protect themselves from metal ion stress either by intracellular-segregation mechanism or by secreting them into the external medium. This defensive behaviour can be exploited to obtain a more efficient fabrication of advanced functional nanomaterials than chemical synthesis routes: biological syntheses do not require hazardous organic solvents and surfactants , and can work at environmental temperature and pressure, preserving high selectivity and reproducibility.Rhodobacter sphaeroides is a facultative phototrophic anoxygenic proteobacterium known for its capacity to grow under a wide range of environmental conditions, with promising applications in bioremediation [1, 2].The response of the photosynthetic bacterium Rhodobacter sphaeroides to gold exposure and its reducing capability of Au(III) to produce stable Au(0) nanoparticles is reported in this study. The properties of prepared nanoparticles were characterized by UV-Visible (UV-Vis) spectroscopy, Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence Spectrometry (XRF) and X-ray Absorption Spectroscopy (XAS) measurements. Gold nanoparticles (AuNPs) were spherical in shape with an average size of 10±3 nm. Based on our experiments, the particles were likely fabricated by the aid of reducing sugars present in the bacterial cell membrane and were capped by a protein/peptide coat. The nanoparticles were hydrophilic and resisted to aggregation for several months. Gold nanoparticles were also positively tested for their catalytic activity in nitroaromatic compounds degradation.

The unique size-and shape-dependent electronic properties of nanocrystals (NCs) make them extremely attractive as novel structural building blocks for constructing a new generation of innovative materials and solid-state devices. Recent advances in material chemistry has allowed the synthesis of colloidal NCs with a wide range of compositions, with a precise control on size, shape and uniformity as well as specific surface chemistry. By incorporating such nanostructures in polymers, mesoscopic materials can be achieved and their properties engineered by choosing NCs differing in size and/or composition, properly tuning the interaction between NCs and surrounding environment. In this contribution, different approaches will be presented as effective opportunities for conveying colloidal NC properties to nanocomposite materials for micro and nanofabrication. Patterning of such nanocomposites either by conventional lithographic techniques and emerging patterning tools, such as ink jet printing and nanoimprint lithography, will be illustrated, pointing out their technological impact on developing new optoelectronic and sensing devices.

Rod-shaped TiO2 nanocrystals (TiO2 NRs), capped by oleic acid molecules (OLEA), were synthesized with controlled size, shape and surface chemistry by using colloidal routes. They were investigated for application as coating materials for preserving architectural stone of monumental and archaeological interest, in consideration of their self-cleaning and protection properties. For this purpose, two different deposition techniques, namely casting and dipping, were tested for the application of a nanocrystal dispersion on a defined stone type, as a relevant example of porous calcarenites, namely the Pietra Leccese, a building stone widely used in monuments and buildings of cultural and historic interest of the Apulia region (Italy). The physical properties of the stone surface were investigated before and after the treatment with the prepared nanostructured materials. In particular, colour, wettability, water transfer properties and stability of the coating were monitored as a function of time and of the application method. The self-cleaning properties of the TiO2 NRs coated surfaces were tested under simulated and real solar irradiation. The obtained results were discussed in the light of the specific surface chemistry and morphology of TiO2 NRs, demonstrating the effectiveness of TiO2 NRs as an active component in formulations for stone protection.

We report a very effective synthetic approach to achieve the in situ growth, directly at the surface of single walled carbon nanotubes, of shape controlled anatase TiO2 nanocrystals, either as nanorods or nanospheres, by simply tuning the ratio between reactants. Remarkably, the obtained SWCNTs/TiO2 heterostructures result dispersible in organic solvents, leading to optically clear dispersions. The photocatalytic activity of the SWCNTs/TiO2 heterostructures, compared with bare TiO2 nanorods or nanospheres demonstrates a significant enhancement. In particular, SWCNTs/TiO2 heterostructures demonstrates an enhancement of reaction rate up to 3 times with respect to the commercially available standard TiO2 powder (TiO2 P25) under UV light and up to 2 times under visible light.

Nanostructured films based on Au nanorods (NRs) have been obtained by layer-by-layer (LbL) assembly driven by electrostatic interaction between metal nanoparticles and polyelectrolytes. Multilayer films have been fabricated by using LbL assembly of poly(sodium styrenesulfonate) (PSS) and positively charged Au NRs on a polyelectrolyte-modified substrate. The effect of fabrication parameters, including the nature of the substrate, the polyelectrolyte initial anchoring layer, and the number of layers has been investigated by means of UV vis absorbance spectroscopy and atomic force microscopy (AFM). The results demonstrated the dependence of morphology and plasmonic features in the multilayered nanostructured architectures from the nature of the anchoring polyelectrolyte on the substrate, the number of layers, and the kind of NR mutual assembly. In addition, a study of the electrochemical activity at the solid/liquid interface has been carried out in order to assess charge transport through the NR multilayer by using two molecular probes in solution, namely, potassium ferricyanide, a common and well-established redox mediator with reversible behavior, and cytochrome C, a robust model redox protein. The presented systematic study of the immobilization of Au NRs opens the venue to several application areas, such as (bio)chemical sensing.

Nanostructured and nano-porous thin films, offering elevated active surface, are of significant importance for a wide variety of technological applications. Here we report on the electrophoretic deposition - on a conductive substrate - of colloidal TiO2 rod-like shaped nanocrystals dispersed in an organic solvent. Colloidal synthesis allowed obtaining a careful control over the morphological properties and the crystallographic phase of nanoparticles, which resulted in rod-shaped anatase nanocrystals. Compared to spherical nanocrystal, the rod-shape offers enhanced surface/volume ratio, which limits the charge recombination. The electrophoretic deposition drives nanorods toward the immobilization on the conductive surface of the substrate, forming homogeneous nanoporous thin-films composed by densely packed nanorods. Indeed, SEM analysis endorsed that the morphology of NRs is preserved in the thinfilm. The approach reported here colloidal synthesis followed by electrophoretic deposition - could be extended to the functionalization of different surfaces with the peculiar properties inferred by the nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.

Inorganic nanocrystals and nanoparticles have aroused increasing attention in the last years due to their original optoelectronic, thermodynamic, mechanical and catalytic properties, which are extremely attractive for fundamental understanding as well as for their huge potential in applications. The ability to strongly exploit the original potential of such nano-objects and access their properties relies on the ability to bridge the gap between the nanoscopic and mesoscopic scale. Indeed, to integrate nanoparticles in structures, materials and finally devices, their incorporation in processable systems, and their organization in morphologically controlled assembly and/or ordered arrays is crucial. The fabrication of 2/3 D patterned micro- and nanostructure is a promising strategy for integrating the nanoparticles in macroscopic entities in order to properly exploit their unprecedented functionality for biomedical, electronic, catalytic materials and devices. In this paper, different and complementary strategies able to engineer inorganic colloidal nanocrystals due to their organization in original functional materials and structures will be described.

The present study aimed to develop and optimize liposome formulation for the colonicdelivery of biologically active compounds. A strategy to facilitate such targeting is to formulateliposomes with a polymer coating sensitive to the pH shifts in the gastrointestinal tract. To this end,liposomes encapsulating curcumin--chosen as the biologically active compound model--and coatedwith the pH-responsive polymer Eudragit S100 were prepared and characterized. Curcumin wasencapsulated into small unilamellar vesicles (SUVs) by the micelle-to-vesicle transition method (MVT)in a simple and organic solvent-free way. Curcumin-loaded liposomes were coated with EudragitS100 by a fast and easily scalable pH-driven method. The prepared liposomes were evaluated for size,surface morphology, entrapment efficiency, stability, in vitro drug release, and curcumin antioxidantactivity. In particular, curcumin-loaded liposomes displayed size lower than 100 nm, encapsulationefficiency of 98%, high stability at both 4 oC and 25 oC, high in vitro antioxidant activity, and acumulative release that was completed within 200 min. A good Eudragit S100 coating which didnot alter the properties of the curcumin-loaded liposomes was obtained. The present work thereforeprovides a fast and solvent-free method to prepare pH-responsive polymer-coated liposomes for thecolonic delivery of biologically active compounds.

An optically transparent and UV-light active anode, characterized by high (photo) conductivity, charge mobility and exciton lifetime, based on graphene, grown by CVD, decorated with colloidal TiO2 nanocrystals (NCs), has been fabricated, by a direct and facile solution-based procedure. TiO2 NCs anchor onto graphene by means of p-p stacking interactions occurring between the pyrene-1-butyric acid (PBA) surface coating ligand and the 2-D platform and assemble in a highly interconnected multilayered layout, by means of interligand pi-pi forces, retaining composition and geometry, along with the graphene structure. Remarkably, the PBA-coated TiO2 NCs on the graphene increase its electrical conductivity, electroactivity, and capacitive behavior, as well as photoelectrical response under UV-light, resulting in a 50% enhanced photoelectroactivity and a long exciton recombination lifetime. The photoanodes can be integrated into solar cells as optically transparent electrodes, in photodetectors, FETs and (bio)sensors.

This paper describes an expeditious and reliable method for determining the thermal effects in a static condition of commercial NOx storage catalysts (NSCs) using scanning electron microscopy with an energy dispersive X-ray analytical system (SEM/EDS). It is worth remarking that possible changes in the morphology and in the elemental composition of the catalyst may be considered as the most important causes of the lower conversion of NOx. The information attained in this work indicates that Pt nanoparticle sintering is strongly increased by the oxygen exposure, and this can be considered a very useful preliminary investigation for the studies already present in the literature on the efficiency of NSCs.

The relaxation dynamics of charge carriers of organic capped TiO2 nanorods dispersed in chloroform was investigated by femtosecond transient absorption in a weak-excitation regime. Anisotropic TiO2 nanocrystals were excited in the UVvis range, using different pump wavelengths, namely above (300 nm), close to (350 nm), and below (430 nm) the direct band gap of anatase TiO2. We show that the ultrafast dynamics strongly depends on excitation wavelength and determine the time constants of all the processes entering the relaxation. Moreover, we demonstrate that two transient absorption bands at 500 and 700 nm, typically attributed to trapped h(+) and e, respectively, are accessible only when TiO2 is photoexcited well above the band gap, while there is no evidence of such bands when TiO2 is photoexcited close to or below its band gap. In such cases the observed dynamics are attributed to trapped excitons.

In this work a genuine combination of a bottom-up approach, which is based on synthesis andfunctionalization of emitting nanocrystals (NCs), with a top-down strategy, which relies on aflexible and versatile cold plasma process, is shown. Luminescent semiconducting colloidalNCs consisting of a CdSe core coated with a ZnS shell (CdSe@ZnS) are directly assembledonto micro-patterned substrates previously functionalized by means of glow dischargesperformed through physical masks. The NC assembly is driven by electrostatic interactionsthat led to their successful organization into spatially resolved domains. Two distinct protocolsare tested, the former using a plasma deposition process combined with an electrostaticlayer-by-layer procedure, the latter based on a two-step plasma deposition/treatment process.The procedures are thoroughly monitored with fluorescence microscopy, atomic forcemicroscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy,transmission electron microscopy and scanning electron microscopy. The two-step plasmaprotocol is demonstrated to be more efficient in directing a uniform and specific assembly ofluminescent NCs with respect to the hybrid procedure. The presented 'mix and match'approach offers great potential for integrating NCs, with their unique size-dependentproperties, into microstructures, providing a universal platform for the fabrication of sensors,biochips, displays and switches.

Semiconductor/metal nanocomposites based on anatase TiO2 nanoparticles and Au nanorods (TiO2/AuNRs) were prepared by means of a co-precipitation method and subsequently calcinated at increasing temperature (from 250° to 650°C) obtaining up to 20 grams of catalysts. The structure and the morphology of the obtained nanocomposite material were comprehensively characterized by means of electron microscopy (SEM and TEM) and X-ray diffraction techniques. The photocatalytic performance of the TiO2/AuNRs nanocomposites was investigated as a function of the calcination temperature in experiment of degradation of water pollutants under both UV and UV-Vis irradiation, Photocatalytic experiments under UV irradiation were performed by monitoring spectrophotometrically the decolouration of a target compound (methylene blue, MB) in aqueous solution. UV-Visible light irradiation was, instead, used for testing the photocatalytic removal of an antibiotic molecule, Nalidixic acid, by monitoring the degradation process by HPLC-MS analysis. Interestingly, TiO2/AuNRs calcined at 450°C was up to 2.5 and 3.2 times faster than TiO2P25 Evonik, that is a commercially available reference material, in the photocatalytic degradation of the Methylene Blue and the Nalidixic Acid, under UV and visible light, respectively. The same nanocomposite material showed a photocatalytic degradation rate for the two target compounds up to 13 times faster than the bare TiO2-based catalysts.The obtained results are explained on the basis of the structure and morphology of the nanocomposites, that could be tuned according to the preparative conditions. The role played by the plasmonic domain in the heterostructured materials, either under UV and UV-Visible illumination, is also highlighted and discussed.The overall results indicate that the high photoactivity of TiO2/AuNRs in the visible range can be profitably exploited in photocatalytic applications, thanks also to the scalability of the proposed synthetic route, thus ultimately envisaging potential innovative solution for environmental remediation.

The replacement of diseased tissues with biological substitutes with suitablebiomechanical properties is one of the most important goal in tissue engineering. Collagenrepresents a satisfactory choice for scaffolds. Unfortunately, the lack of elasticity represents arestriction to a wide use of collagen for several applications. In this work, we studied theeffect of human elastin-like polypeptide (HELP) as hybrid collagen-elastin matrices. Inparticular, we studied the biomechanical properties of collagen/HELP scaffolds ...

Because of the growing potential of nanoparticles in biological and medical applications, tuning and directing their properties toward a high compatibility with the aqueous biological milieu is of remarkable relevance. Moreover, the capability to combine nanocrystals (NCs) with biomolecules, such as proteins, offers great opportunities to design hybrid systems for both nanobiotechnology and biomedical technology. Here we report on the application of the micelle-to-vesicle transition (MVT) method for incorporation of hydrophobic, red-emitting CdSe@ZnS NCs into the bilayer of liposomes. This method enabled the construction of a novel hybrid proteo-NC-liposome containing, as model membrane protein, the photosynthetic reaction center (RC) of Rhodobacter sphaeroides. Electron microscopy confirmed the insertion of NCs within the lipid bilayer without significantly altering the structure of the unilamellar vesicles. The resulting aqueous NC-liposome suspensions showed low turbidity and kept unaltered the wavelengths of absorbance and emission peaks of the native NCs. A relative NC fluorescence quantum yield up to 8% was preserved after their incorporation in liposomes. Interestingly, in proteo-NC-liposomes, RC is not denatured by Cd-based NCs, retaining its structural and functional integrity as shown by absorption spectra and flash-induced charge recombination kinetics. The outlined strategy can be extended in principle to any suitably sized hydrophobic NC with similar surface chemistry and to any integral protein complex. Furthermore, the proposed approach could be used in nanomedicine for the realization of theranostic systems and provides new, interesting perspectives for understanding the interactions between integral membrane proteins and nanoparticles, i.e., in nanotoxicology studies.

The primary aim of the present work was to evaluate the in vitro uptake of 6-Coumarin (6COUM) loaded solid lipid nanoparticles (SLN) by two gilthead seabream (Sparus aurata L.) cell types: an established cell line (SAF-1 cells) and the primary cultures of head-kidney (HK)--the main haemopoietic organ in fish, equivalent to mammalian bone marrow--leucocytes. For this purpose, after the physicochemical characterization of SLN, the uptake by those immunocompetent fish cells was evaluated using flow cytometry and confocal microscopy. Concomitantly, the uptake of 6-COUM loaded {SLN} was compared with that achieved with 6-COUM loaded pectin microparticles (MPs), which were selected as a competitor of the delivery carriers. After {SLN} and {MP} physicochemical characterization, the results demonstrated that SAF-1 cells were able to internalize high percentages of 6-COUM {SLNs} when incubated for 4, 8 and 24&xa0;h, with the highest {SLN} concentration tested (10&xa0;?g/ml). The ability of {HK} leucocytes to internalize {SLN} was also found to vary depending on both incubation time and {SLN} concentration. The highest values of {HK} leucocytes internalizing {SLN} particles (around 16%) were detected at the maximum {SLN} concentration (20&xa0;?g/ml) at incubation times of 4 or 8&xa0;h. Conversely, {HK} leucocytes were unable to internalize {MPs} at any tested concentration and incubation time. A possible mechanism explaining the uptake into cells is proposed. The present work constitutes the first approximation to consider {SLN} as nanocarriers for delivering biologically active substances to fish.

Biological processes using microorganisms for nanoparticle synthesis are appealing as eco-friendly nanofac-tories. The response of the photosynthetic bacterium Rhodobacter sphaeroides to gold exposure and its reducingcapability of Au(III) to produce stable gold nanoparticles (AuNPs), using metabolically active bacteria andquiescent biomass, is reported in this study.In the former case, bacterial cells were grown in presence of gold chloride at physiological pH. Gold exposurewas found to cause a significant increase of the lag-phase duration at concentrations higher than 10 ?M, sug-gesting the involvement of a resistance mechanism activated by Au(III). Transmission Electron Microscopy(TEM) and Scanning Electron Microscopy/Energy Dispersive X-ray Spectrometry (SEM/EDS) analysis of bac-terial cells confirmed the extracellular formation of AuNPs.Further studies were carried out on metabolically quiescent biomass incubated with gold chloride solution.The biosynthesized AuNPs were spherical in shape with an average size of 10 ± 3 nm, as analysed byTransmission Electron Microscopy (TEM). The nanoparticles were hydrophilic and stable against aggregation forseveral months.In order to identify the functional groups responsible for the reduction and stabilization of nanoparticles,AuNPs were analysed by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence Spectrometry (XRF) and X-ray AbsorptionSpectroscopy (XAS) measurements. The obtained results indicate that gold ions bind to functional groups of cellmembrane and are subsequently reduced by reducing sugars to gold nanoparticles and capped by a protein/peptide coat.Gold nanoparticles demonstrated to be efficient homogeneous catalysts in the degradation of nitroaromaticcompounds.

Water-soluble gold nanorods (Au NRs) have been functionalized with an N-alkylaminopyrazole ligand, 1-[2-(octylamino)ethyl]-3,5-diphenylpyrazole (PyL), that has been demonstrated able to coordinate heavy metal ions. The N-alkylaminopyrazole functionalized Au NRs have been characterized by electron microscopy and spectroscopic investigation and tested in optical detection experiments of different ions, namely, Zn2+, Cd2+, Hg2+, Cu2+, Pb2+, and As3+. In particular, the exposure of the functionalized NRs to increasing amounts of Hg2+ ions has resulted in a gradual red-shift and broadening of the longitudinal plasmon band, up to 900 nm. Interestingly, a significantly different response has been recorded for the other tested ions. In fact, no significant shift in the longitudinal plasmon band has been observed for any of them, while a nearly linear reduction in the plasmon band intensity versus ion concentration in solution has been detected. The very high sensitivity for Hg2+ with respect to other investigated ions, with a limit of detection of 3 ppt, demonstrates that the functionalization of Au NRs with PyL is a very effective method to be implemented in a reliable colorimetric sensing device, able to push further down the detection limit achieved by applying similar strategies to spherical Au NPs.

This work demonstrates that lipid-detergent mixed micelles can be employed successfully inorder to achieve and modulate the transfer of bio-active hydrophobic compounds into lipidcarriers by means of a simple and bio-safe procedure. In our specific investigation, liposomepreparations incorporating mixture

Hydrophobic PbS nanocrystals (NCs) emitting in the near infrared spectral region were encapsulated in the core of micelles and in the bilayer of liposomes, respectively, to form polyethylene glycol (PEG)-grafted phospholipids. The phospholipid-based functionalization process of PbS NCs required the replacement of the pristine capping ligand at the NC surface with thiol molecules. The procedures carried out for two systems, micelles and liposomes, using PEG-modified phospholipids were carefully monitored by optical, morphological and structural investigations. The hydrodynamic diameter and the colloidal stability of both micelles and liposomes loaded with PbS NCs were evaluated using Dynamic Light Scattering (DLS) and ?-potential experiments, and both were satisfactorily stable in physiological media. The cytotoxicity of the resulting PbS NC-loaded nanovectors was assessed by the in vitro investigation on Saos-2 cells, indicating that the toxicity of the PbS NC loaded liposomes was lower than that of the micelles with the same NC cargo, which is reasonable due to the different overall composition of the two prepared nanocarriers. Finally, the cellular uptake in the Saos-2 cells of both the NC containing systems was evaluated by means of confocal microscopy studies by exploiting a visible fluorescent phospholipid and demonstrating the ability of both luminescent nanovectors to be internalized. The obtained results show the great potential of the prepared emitting nanoprobes for imaging applications in the second biological window.

The use of fluorescent nanocrystals (NCs) as probes for bioimaging applications has emerged as an advantageous alternative to conventional organic fluorescent dyes. Therefore their toxicological evaluation and intracellular delivery are currently a primary field of research. In this work, hydrophobic and highly fluorescent CdSe@ZnS NCs were encapsulated into the lipid bilayer of liposomes by the micelle-to-vesicle transition (MVT) method. The obtained aqueous NC-liposome suspensions preserved the spectroscopic characteristics of the native NCs. A systematic study of the in vitro toxicological effect on HeLa cells of these red emitting NC-liposomes was then carried out and compared to that of empty liposomes. By using liposomes of different phospholipid composition, we evaluated the effect of the lipid carrier on the cytotoxicity towards HeLa cells. Surprisingly, a cell proliferation and death study along with the MTT test on HeLa cells treated with NC-liposomes have shown that the toxic effects of NCs, at concentrations up to 20 nM, are negligible compared to those of the lipid carrier, especially when this is constituted by the cationic phospholipid DOTAP. In particular, obtained data suggest that DOTAP has a dose- and time-dependent toxic effect on HeLa cells. In contrast, the addition of PEG to the liposomes does not alter significantly the viability of the cells. In addition, the ability of NC-liposomes to penetrate the HeLa cells was assessed by fluorescence and confocal microscopy investigation. Captured images show that NC-liposomes are internalized into cells through the endocytic pathway, enter early endosomes and reach lysosomes in 1 h. Interestingly, red emitting NCs co-localized with endosomes and were positioned at the limiting membrane of the organelles. The overall results suggest that the fluorescent system as a whole, NCs and their carrier, should be considered for the development of fully safe biological applications of CdSe@ZnS NCs, and provide essential indications to define the optimal experimental conditions to use the proposed system as an optical probe for future in vivo experiments.

The photocatalytic degradation of pollutants is a key technological application for nanomaterials. Ourwork aims at developing a multifunctional nanocrystalline heterostructure based on TiO2nanorods,FexOyand Ag nanoparticles (NPs), TiO2NRs/FexOy/Ag, integrating in one nanostructure a visible lightphotoactive moiety (TiO2NRs/Ag) and a magnetic domain (FexOy), in order to address the photoactivityunder visible light and the possibility of recovery and reuse the photocatalyst. The synthesis was carriedby preparing first the TiO2NRs/FexOybased heterostructure and then growing Ag NPs with control on size.The resulting multidomain structures were characterized by FTIR and absorption spectroscopy, TEM andSEM microscopy, EDS and XRD analysis. The influence of the Ag NP domain and of its size on the photoac-tivity of the TiO2NRs/FexOy/Ag nanostructures under visible light were investigated in the photocatalyticdegradation of the Nalidixic Acid, an antibiotic used as a model compound representative of recalci-trant pollutants. In the presence of the Ag domain a significant increase of the photoactivity with respectto TiO2NRs/FexOyheterostructures and to the commercially available TiO2P25 was observed. Such anenhanced photocatalytic efficiency was found dependent on the size of the Ag domain and explainedtaking into account the plasmonic properties and the different possible photoactivation mechanisms.

Photo-oxidation processes assisted by nanosized semiconductors are receiving increasing attention due to their potential application in environmental field. The ability to exploit the strong potential of photoactive nanomaterials and access their properties relies on the ability to integrate them in photo-reactors and to effectively deposit them on large surfaces. Such a strategy can bridge the gap between the nanoscopic and mesoscopic scale and avoiding nanoparticle release in the environment. In order to integrate nanopartides in functional structures and, finally, devices, their incorporation in suitable host matrices is crucial to achieve processable nanocomposite materials. Here, a comprehensive overview on the preparation of photocatalytic nanocomposite materials and their application for pollutants degradation will be provided. In particular, we will focus on modern synthetic approaches to synthetize UV and visible light active nanocatalysts, on their post-synthesis surface functionalization and on their incorporation in suitable host matrices toward nanocomposite preparation. Finally, some examples from recent literature on their application in environmental remediation and as bactericidal and self-cleaning coatings will be reported. (C) 2016 Elsevier B.V. All rights reserved.

Nanocrystalline titania (TiO2) synthesized via sol-gel, by using an alkoxide precursor were deposited ontocommercially available silica and alumina fibers, namely E-Glass and Nextel 650, respectively. Differentprocessing conditions and material preparation parameters, such as amount of TiO2, film composition andannealing temperature were tested in order to obtain nanocrystalline TiO2 with different morphologicaland structural characteristics. The materials were characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD), and the Brunauer, Emmett, and Teller (BET) surface area measurements. Thephotocatalytic activity of the obtained coated fibers was investigated by monitoring the degradationof a model molecule, an azo dye (Methyl Red), under UV irradiation in aqueous solution. The detectedphotocatalytic performance of the sol-gel derived nanocrystalline TiO2 was explained on the basis ofmechanism associated to the photocatalytic decomposition of organic molecules using semiconductoroxides and accounted for the structural and morphological characteristics of the TiO2 based coating. Thematerials with the most suited characteristics for photocatalysis were used to scale up the depositiononto a larger sample of fiber and then tested in a photocatalytic reactor. A commercially available TiO2standard material (TiO2 P25 Degussa) was used as reference, in order to ultimately assess the viability ofthe coating process for real application.

Controlling light interactions with matter on the nanometer scale provides for compelling opportunities for modern technology and stretches our understanding and exploitation of applied physics, electronics, and fabrication science. The smallest size to which light can be confined using standard optical elements such as lenses and mirrors is limited by diffraction. Plasmonic nanostructures have the extraordinary capability to control light beyond the diffraction limit through an unique phenomenon called the localized plasmon resonance. This remarkable capability enables unique prospects for the design, fabrication and characterization of highly integrated photonic signal-processing systems, nanoresolution optical imaging techniques and nanoscale electronic circuits. This paper summarizes the basic principles and the main achievements in the practical utilization of plasmonic effects in nanoparticles. Specifically, the paper aims at highlighting the major contributions of nanoparticles to nanoscale temperature monitoring, modern "drug free" medicine and the application of nanomaterials to a new generation of opto-electronics integrated circuits.

Hypothesis: The interesting properties of Gold Nanoparticles (AuNPs) make them attractive for different application fields such as cosmetology, medicine and clinical nanotechnologies. In this work a fast, easy and eco-friendly method for the AuNPs synthesis is proposed by using the Punica Granatum Juice (PGJ) with potential dermatological and cosmetic applications. The AuNPs antioxidant activity, due to the presence of phenols from the juice, and their use as booster for improving the Sun Protection Factor (SPF) in commercial sunscreen formulations, are thus expounded.

A simple fabrication approach for achieving nanoparticle patterns based on a room temperature chemically driven strategy is reported. Suitably engineered colloidal luminescent nanocrystals (NCs) (4 and 6 nm in diameter), namely organic capped and silica-coated negatively charged CdSe@ZnS NCs, have been selectively assembled onto defined domains in a binary hydrophobic/hydrophilic chemical pattern, purposely fabricated by combining microcontact printing and wet chemistry procedures. The goal of the work has been to investigate the experimental parameters governing the assembly process at molecular level, in order to elucidate factors regulating interactions at the interfaces. For this purpose, specific sets of conditions, namely substrate patterns and NCs with distinct surface functionalization, have been prepared and tested using different NC dispersing solvents. The NC assembly has been demonstrated driven by non-covalent forces, namely Van der Waals or electrostatic interactions occurring at the NC/substrate interface. The overall study has provided a comprehensive understanding of the role of solvent and molecular chemistry at interfaces in NC assembling. The obtained results can be valuable to set up reliable procedures for developing reproducible patterning protocols potentially useful for the fabrication of NC-based devices.

A fundamental and systematic study on the fabrication of a supramolecularly assembled nanostructure of an organic ligand-capped CdS nanocrystal (NC) and multiple heptamine beta-cyclodextrin ((NH2)(7)beta CD) molecules in aqueous solution has been here reported. The functionalization process of presynthesized hydrophobic CdS NCs by means of (NH2)(7)beta CD has been extensively investigated by using different spectroscopic and structural techniques, as a function of different experimental parameters, such as the composition and the concentration of CD, the concentration of CdS NCs, the nature of the NC surface capping ligand (oleic acid and octylamine), and the organic solvent. The formation of a complex based on the direct coordination of the (NH2)(7)beta CD amine groups at the NC surface has been demonstrated and found responsible for the CdS NC phase transfer process. The amine functional group in (NH2)(7)beta CD and the appropriate combination of pristine capping agent coordinating the NC surface and a suitable solvent have been found decisive for the success of the CdS NC phase transfer process. Furthermore, a layer-by-layer assembly experiment has indicated that the obtained (NH2)(7)beta CD functionalized CdS NCs are still able to perform the host guest chemistry. Thus, they offer a model of a nanoparticle-based material with molecular receptors, useful for bio applications.

The enhanced photocatalytic activity for degradation of a wide range of pollutants makes nanostructured TiO2 an ideal candidate for self-cleaning coatings.The deposition of different types of TiO2 nanocrystalline coatings on stone has been investigated in order to test the surface protection and self-cleaning abilities of the nanostructured materials. TiO2 nanocrystals with controlled size, shape and surface chemistry have been prepared by using two distinct synthetic approaches, namely colloidal synthesis by hot injection and hydrothermal nanophase crystallisation. Two different types of stones, possessing different porosity, namely porous calcarenite and a compact limestone have been selected, being both widely used in South Italian monuments and building relevant for cultural heritage.The physical properties of coated and uncoated stone surfaces, respectively, have been investigated, and colour, wettability and stability of the coatings have been checked. The self-cleaning properties of the nanostructured TiO2 coated surfaces under solar irradiation have been tested by monitoring the degradation of a model organic molecule, namely an organic dye. The obtained results have confirmed that the nanocrystalline TiO2 coatings are promising candidate for environmental protection upon appliance on either porous and compact stone. Moreover, the nanostructured TiO2 obtained colloidal synthesis by hot injection has demonstrated to provide hydrophobic treated surfaces.

In this work, the self-cleaning and photocatalytic properties of mesoporousTiO2/AuNRs-SiO2 composites (namely UCA-TiO2Au) prepared by a simple and low-costtechnique were investigated toward application in building materials. Mesoporous photocatalyticnanocomposites coating the surface of stone and other building materials are a very promisingapproach to address relevant questions connected with the increasing atmospheric pollution.We tested three types of preformed TiO2/AuNRs nanostructures in order to evaluate the effectof AuNRs on the photocatalytic activity of resulting coatings deposited on the surface of apopular building limestone. The resulting nanocomposites provide crack-free surface coatingson limestone, effective adhesion, improve the stone mechanical properties and impart hydrophobicand self-cleaning properties. Photocatalytic characterization involved the degradation of a targetcompound (Methylene blue; MB) under direct exposure to simulated solar light using TiO2 P25 Evonik(TiO2 P25) as a reference material. Moreover, these coatings upon irradiation by simulated solarlight were successfully employed for the photocatalytic oxidation of carbon soot. The experimentalresults revealed that UCA-TiO2Au samples are the best performing coating in both MB bleachingand soot degradation.

The photocatalytic properties of anatase TiO2nanorods(NRs) and noble metal
semiconductor nanocomposites (TiO2NRs/Ag)prepared by colloidal chemistry routes and immobilized onto suitablesubstrates were investigated. Photocatalytic experiments were performedunder UV irradiation in order to test the degradation of a target compound(the azo dye, methyl red) in aqueous solution using TiO2P25 Degussa as areference material. Absorbance spectroscopy and liquid chromatography/mass spectrometry (LC/MS) measurements pointed out that, according topH conditions, TiO2NRs and TiO2NRs/Ag presented a photoactivity up to1.3 and 2 times higher than TiO2P25 Degussa, respectively. Notably, theTiO2NRs/Ag-based catalysts demonstrated a photocatalytic activity 2-foldhigher than bare TiO2NRs. Remarkably, only a negligible dependence on pH conditions was detected for the nanocompositecatalyst, whereas both TiO2NRs and TiO2P25 Degussa showed much higher photoactivity at acidic pH. In all the investigated cases,the identified byproducts pointed out the occurrence of the same reaction mechanism, basically relying on the hydroxyl radicalattaching on the benzene ring and on the homolytic rupture of the nitrogen
carbon bond of the dimethyl-amino moiety.

Two different nanosized TiO2-based catalysts supported onto glass with tailored photocatalytic propertiesupon irradiation by UV light were successfully employed for the degradation of nalidixid acid, awidely diffused antibacterial agent of environmental relevance known to be non-biodegradable. Anataserod-like TiO2 nanocrystals (TiO2NRs) and a semiconductor oxide-noble metal nanocomposite TiO2 NRs/Ag nanoparticles (NPs), synthesized by colloidal chemistry routes, were cast onto glass slide andemployed as photocatalysts. A commercially available catalyst (TiO2 P25), also immobilized onto a glassslide, was used as a reference material. It was found that both TiO2 NRs/Ag NPs composite and TiO2 NRsdemonstrated a photocatalytic efficiency significantly higher than the reference TiO2 P25. Specifically,TiO2 NRs/Ag NPs showed a photoactivity in nalidixic acid degradation 14 times higher than TiO2 P25and 4 times higher than bare TiO2 NRs in the first 60 min of reaction. Several by-products were identifiedby HPLC-MS along the nalidixic acid degradation, thus getting useful insight on the degradation pathway.All the identified by-products resulted completely removed after 6 h of reaction

Thermo-sensitive liquid crystals may result, for some aspects, good host materials for plasmonic nanoparticles. In particular they are suitable to study and measure the temperature variations produced by photo-induced plasmonic joule effect in the metallic nanoparticles. Combining the properties of liquid crystals and metallic nanoparticles, allows to measure temperature variations in different ways by exploiting the optical properties of thermotropic liquid crystals: In a first attempt, by combining nematic liquid crystals and spherical metallic nanoparticles, we have predicted and measured temperature changes, under a suitable (resonant) optical illumination, by measuring the photo-thermal induced birefringence variation. In a different experiment, we have combined cholesteric liquid crystals and gold nanorods: Light-induced variations of structural colorations exhibited by cholesteric liquid crystals has been used as a new methodology to measure nanoscale heat variation with a very high sensitivity (0.03 K).

The last few years have seen a growing interest in the ability of metallic nanoparticles (MNPs) to control temperature at the nanoscale. Under a suitable optical radiation, MNPs feature an enhanced light absorption/scattering, thus turning into an ideal nano-source of heat, remotely controllable by means of light. In this framework, we report our recent efforts on modeling and characterizing the photo-thermal effects observed in gold nanoparticles (GNPs) dispersed in thermotropic Liquid Crystals (LCs). Photo-induced temperature variations in GNPs dispersed in Nematic LCs (NLCs) have been studied by implementing an ad hoc theoretical model based on the thermal heating equation applied to an anisotropic medium. Theoretical predictions have been verified by performing photo-heating experiments on a sample containing a small percentage of GNPs dispersed in NLCs. Both theory and experiments represent an important achievement in understanding the physics of heat transfer at the nanoscale, with applications ranging from photonics to nanomedicine.

We report on the thermo-optical properties of gold nanorods (GNRs) dispersed in a thermotropic cholesteric liquid crystal (CLC). We have characterized the CLC reflection band behavior for two different cell thicknesses under the influence of a suitable (resonant) pump beam. It turns out that for the 1.6 mu m thick cell there is a suppression of the CLC reflection band for both pure CLC and CLC/GNRs. For the 10 mu m thick cell, the presence of GNRs desensitizes the shift of the CLC reflection band to temperature. Suitable cell design enables one to 'turn off' the wavelength shift of the peak reflection, thereby turning the system into a pure amplitude measurement tool. This has implications where the probe wavelength is fixed at a common, single wavelength.

Localized plasmon resonance (LPR) of noble Metal Nanoparticles (MNPs) opens up a new horizon for nanoscale materials able to convert light into heat, since the strong electric field generated around the MNPs can transform them into original heat nanosources. Thus, investigation of the heat transport mechanism, from the heated MNPs to their surrounding medium, is fundamental for realizing applications in nanotechnology and thermal-based therapies, and a challenge is definitely represented by the possibility of measuring temperature variations at the surface of the MNPs undergoing optical illumination. In this framework, we show that an ingenious combination of characteristics of short pitch liquid crystalline compounds and MNPs has demonstrated effective to provide an advanced tool to monitor nanoscale temperature variations.

Plasmonic metallic nanoparticles (NPs) represent a relevant class of nanomaterials, which is able to achieve light localization down to nanoscale by exploiting a phenomenon called Localized Plasmon Resonance. In the last few years, NPs have been proposed to trigger DNA release or enhance ablation of diseased tissues, while minimizing damage to healthy tissues. In view of the therapeutic relevance of such plasmonic NPs; a detailed characterization of the electrostatic interaction between positively charged gold nanorods (GNRs) and a negatively charged whole-genome DNA solution is reported. The preparation of the hybrid biosystem has been investigated as a function of DNA concentration by means of zeta-potential; hydrodynamic diameter and gel electrophoresis analysis. The results have pointed out the specific conditions to achieve the most promising GNRs/DNA complex and its photo-thermal properties have been investigated. The overall study allows to envisage the possibility to ingeniously combine plasmonic and biological materials and, thus, enable design and development of an original non invasive all-optical methodology for monitoring photo-induced temperature variation with high sensitivity.

The fabrication of uniform and patterned nanocrystal (NC) assemblies has been investigated by exploiting the possibility of carefully tailoring colloidal NC surface chemistry and the ability of polyelectrolyte (PE) to functionalize substrates through an electrostatic layer-by-layer (LbL) strategy. Appropriate deposition conditions, substrate functionalization, and post-preparative treatments were selected to tailor the substrate surface chemistry to effectively direct the homogeneous electrostatic-induced assembly of NCs. Water-dispersible luminescent NCs, namely, (CdSe)ZnS and CdS, were differently functionalized by (1) ligand-exchange reaction, (2) growth of a hydrophilic silica shell, and (3) formation of a hydrophilic inclusion complex, thus providing functional NCs stable in a defined pH range. The electrostatically charged functional NCs represent a comprehensive selection of examples of surface-functionalized NCs, which enables the systematic investigation of experimental parameters in NC assembly processes carried out by combining LbL procedures with microcontact printing and also exploiting NC emission, relevant for potential applications, as a prompt and effective probe for evaluating assembly quality. Thus, an ample showcase of combinations has been investigated, and the spectroscopic and morphological features of the resulting NC-based structures have been discussed.

The aim of the present investigation was to evaluate the influence of liposome formulation on the ability of vesicles to penetrate a pathological mucus model obtained from COPD affected patients in order to assess the potential of such vesicles for the treatment of chronic respiratory diseases by inhalation. Therefore, Small Unilamellar Liposomes (PLAIN-LIPOSOMEs), Pluronic (R) F127-surface modified liposomes (PF-LIPOSOMEs) and PEG 2000PE-surface modified liposomes (PEG-LIPOSOMEs) were prepared using the micelle-to-vesicle transition (MVT) method and beclomethasone dipropionate (BDP) as model drug. The obtained liposomes showed diameters in the range of 40-65 nm, PDI values between 0.25 and 0.30 and surface electric charge essentially close to zero. The encapsulation efficiency was found to be dependent on the BDP/lipid ratio used and, furthermore, BDP-loaded liposomes were stable in size both at 37 degrees C and at 4 degrees C. All liposomes were not cytotoxic on H441 cell line as assessed by the MTT assay. The liposome uptake was evaluated through a cytofluorimetric assay that showed a non-significant reduction in the internalization of PEG-LIPOSOMEs as compared with PLAIN-LIPOSOMEs. The penetration studies of mucus from COPD patients showed that the PEG-LIPOSOMEs were the most mucus-penetrating vesicles after 27 h. In addition, PEG-and PF-LIPOSOMEs did not cause any effect on bronchoalveolar lavage fluid proteins after aerosol administration in the mouse. The results highlight that PEG-LIPOSOMEs show the most interesting features in terms of penetration through the pathologic sputum, uptake by airway epithelial cells and safety profile.

Two colloidal methods, namely one pot and two steps approaches, have been exploited to synthesize light emitting CdSe/ZnS core-shell nanocrystals, differing in growth process of the inorganic ZnS shell and, therefore in the resulting surface chemistry of the two types of nanocrystals. The synthesized nanocrystals have been incorporated, by using an "ex situ" procedure, in different thermoplastic PMMA-based polymers, including PMMA co-polymer specifically functionalized by means of groups having high chemical affinity to nanocrystal surface, and the resulting nanocomposites have been processed in thin films. Spectroscopic steady state and time-resolved investigations, carried out both on nanocomposite solution and thin film samples, indicate as a change in the optical properties of the two steps nanocrystals is observed upon incorporation in polymers, especially in PMMA homopolymer, where significant aggregation of inorganic nanostructures occurs. On the contrary, the one pot CdSe/ZnS nanocrystals preserve in all investigated samples their long-lived radiative emission. Such nanocrystals result homogeneously dispersed in the polymers, providing high quality films and thus representing ideal candidates for future optical applications.

Nanocomposites based on colloidal CdSe nanocrystals (NCs) and a poly(styrene-co-4-vinylpyridine), able to specifically coordinate the NC surface, have been designed and prepared. For first time, the polymer synthesis has been performed by using 2,2,5-tri-methyl-4-phenyl-3-azahexane-3-nitroxide as a mediator, increasing the percentage of 4-vinylpyridine monomeric unit, thus obtaining a random copolymer. The nanocomposite properties have been investigated as a function of NC surface chemistry and copolymer composition, by means of spectroscopic, morphological and structural characterization techniques. An improved uniformity of NC dispersion in the nanocomposite has been found at increased percentage of 4-vinylpyridine in the copolymer. The improved NC dispersion in the nanocomposite films has been discussed in terms of the ability of the copolymer to act as a multivalent ligand. The reported results offer a valuable contribution toward the design and the fabrication of innovative nanocomposite material, formed of copolymers and colloidal NCs, specifically suited for energy conversion applications.

The amplification of Raman signals of the heteroaromatic cation 1-(N-methylpyrid-4-yl)-2-(N-methylpyrrol-2-yl)ethylene (PEP+)) bound to Au nanorods (NRs) was investigated at different excitation wavelengths to study the effect of the laser resonance with the absorption band of the PEP+ moiety and with the two plasmon oscillation modes of the NR. Two different PEP+ derivatives, differing in the length of the alkyl chain bearing the anchoring group, were used as target molecules. Raman spectra obtained exciting at 514 or at 785 nm (i.e., exciting the transverse or the longitudinal plasmon band) present a higher intensity than that at 488 nm suggesting a higher Raman amplification when the laser excitation wavelength is resonant with one of the two plasmon modes. Moreover, considering results of Discrete Dipole Approximation (DDA) calculations of the local field generated at the NR surface when either the transverse or the longitudinal plasmon modes are excited, we deduced that the resonance condition of the 514-nm laser excitation with the absorption band of the dye strongly contributes to the amplification of the Raman signal.

In the last decades, the enormous interest in 2/3D nanocrystal (NC) architectures boosted the development of many and diverse techniques which allowed to precisely positioning the nanoparticles on substrates. The tremendous importance of such NC organizations is due to the novel collective properties arising from inter-particle interactions that emerge in these artificial materials, with promising application in opto-electronics, photonics and biomedicines.

The surface of gold nanorods (Au NRs) has been appropriately engineered to achieve a suitable interface for bioconjugation with horse heart cytochrome c (HCc). HCc, an extensively studied and well-characterized protein, represents an ideal model for nanoparticle (NP)-protein conjugation studies because of its small size, high stability, and commercial availability. Here, the native state of the protein has been demonstrated for the first time, by means of Raman spectroscopy, to be retained upon conjugation with the anisotropic Au nanostructures, thus validating the proposed protocol as specifically suited to mostly preserve the plasmonic properties of the NRs and to retain the structure of the protein. The successful creation of such bioconjugates with the retention of the protein structure and function along with the preservation of the NP properties represents a challenging but essential task, as it provides the only way to access functional hybrid systems with potential applications in biotechnology, medicine, and catalysis. In this perspective, the organic capping surrounding the Au NRs plays a key role, as it represents the functional interface for the conjugation step. Cetyltrimethylammonium bromide-coated Au NRs, prepared by using a seed-mediated synthetic route, have been wrapped with polyacrylic acid (PAA) by means of electrostatic interactions following a layer-by-layer approach. The resulting water-dispersible negatively charged AuNRs@PAA NPs have then been electrostatically bound to the positively charged HCc. The bioconjugation procedure has been thoroughly monitored by the combined analysis of UV-vis absorption, resonance Raman and Fourier transform infrared spectroscopies, transmission electron microscopy microscopy, and.-potential, which verified the successful conjugation of the protein to the nanorods.

A liquid crystalline, negatively charged, whole-genome DNA is exploited toorganize positively charged gold nanorods (GNRs) by means of electrostatic interaction. Amesoscopic alignment of the composite system along a preferred direction is obtained bycasting a droplet of the DNA-nanorods solution onto an untreated glass substrate. Gelelectrophoresis analysis enables evaluating the effective electric charge of the system, thusminimizing the DNA fragmentation. Polarized optical microscopy, combined with ...

Gold nanorods embedded in cholesteric liquid crystals allow controling the selective reflection of a light beam. Investigation of morphological and optical properties of the obtained material reveals a new efficient tool to detect temperature variations at the nanoscale.

A colloidal route was exploited to synthesize TiO2 anisotropic nanocrystal rods in shape (TiO2 NRs) with a surface chemistry suited for their dispersibility and processability in apolar organic solvents. TiO2 NRs were dispersed in chloroform and n-heptane, respectively, and the two resulting formulations were investigated to identify the optimal conditions to achieve high-quality TiO2 NR-based coatings by the spray-coating application. In particular, the two types of TiO2 NR dispersions were first sprayed on silicon chips as a model substrate in order to preliminarily investigate the effect of the solvent and of the spraying time on the morphology and uniformity of the resulting coatings. The results of the SEM and AFM characterizations of the obtained coatings indicated n-heptane as the most suited solvent for TiO2 NR dispersion. Therefore, an n-heptane dispersion of TiO2 NRs was sprayed on a highly porous limestone-Lecce stone-very commonly used as building material in historic constructions and monuments present in Apulia Region (Italy). A comprehensive physical-chemical investigation of the TiO2 NR based treatment on the surface of the stone specimens, including measurements of colour variation, static contact angle, water transfer properties, and morphological characterization were performed. Finally, the photocatalytic properties of the coatings were assessed under solar irradiation by using Lecce stone specimens and Methyl Red as a model target compound. The obtained results demonstrated that TiO2 NRs based coatings can be successfully applied by spray-coating resulting in an effective photocatalytic and hydrophobic treatment, which holds great promise as a material for the environmental protection of architectural stone in the field of cultural heritage conservation.

Anatase (TiO?) and multiwalled carbon nanotubes bearing polyethylenimine (PEI) anchored on their surface were hybridized in different proportions according to a sol-gel method. The resulting nanocomposites (TiO?@PEI-MWCNTs), characterized by BET, XRD, XPS, SEM, and UV techniques, were found efficient catalysts for CO? photoreduction into formic and acetic acids in water suspension and under visible light irradiation. PEI-grafted nanotubes co-catalysts are believed to act as CO? activators by forming a carbamate intermediate allowing to accomplish the first example in the literature of polyamines/nanotubes/TiO? mediated CO? photoreduction to carboxylic acids

In this work, the manufacturing andcharacterization of an optically transparent and UV-Iightphotoactive anode, formed of monolayer graphene grown bychemical vapor deposition (CVD) and decorated with a closepacked multHayered nanostructured layout of colloidal TiOznanocrystals (NCs), are reported. The hybrid material has beenprepared by a facHe solution-based procedure, which relays onsoaking the CVD graphene in a solution of I-pyrene butyric acid(PBA) surface coated Ti02 NCs, achieved upon implementationof a capping exchange process for displacing the pristine organicligand deriving from the colloidal synthesis. Pyrene undergoes 'It-'It stacking interactions, anchoring the NCs to the platform withretention of the NC geometry and composition. The NCsimmobilize onto the graphene platform with preservation of itsaromatic structure and the resulting hybrid has been foundoptically transparent in the visible spectral range.(Photo)electrochemical investigation shows that the compositematerial has a promising sensitivity for selectively detectingdopamine and norepinephrine and, concomitantly, exhibits a(photo)electric activity higher than that of bare graphene. Thus,the achieved hybrid material results interesting for themanufacturing of photo-active components to integrate in photorenewable sensor elements along with photodetectors and solarcells

In order to improve the dispersion of multi-walled carbon nanotubes (MWCNTs) in aqueous media, their surface functionalization was carried out in O2-fed low-pressure plasmas. Differently from what can be found in the literature of this field, homogeneous functionalization was achieved by generating the plasma inside vials containing the nanotube powders properly stirred. Experimental parameters, such as input power, treatment time and pressure, were varied to investigate their influence on the process efficiency. A detailed characterization of the plasma treated nanotubes, dry and in aqueous suspension, was carried out with a multi-diagnostic analytical approach, to evaluate their surface chemical properties, morphology, structural integrity and stability in the colloidal state. The plasma grafting of polar ionizable (e.g. acid) groups has been proved to successfully limit the agglomeration of MWCNTs and to produce nanotubes suspensions that are stable for one month and more in water.

While the primary reason for nanostructuring lithium-ion active materials is commonly the realization of shorter diffusion pathways for ions and electrons, there are also other, less-expected phenomena occurring when leaving the microscale to enter the nanoscale. Herein, we will present one of these phenomena - the thermally induced fragmentation (i.e., "chopping") of oleic acid-capped anatase TiO<inf>2</inf> nanorods perpendicular to the [001] direction. This fragmentation results in the formation of ultrafine TiO<inf>2</inf> nanoparticles with increased (001) facets. Due to this modified surface facets ratio and the advantageous utilization of carboxymethyl cellulose as binder, these ultrafine nanoparticles present an excellent rate performance and cycling stability - even for cathodic cut-off potentials as low as 0.1 V.

Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red andnear-infrared spectral regions, are of great interest for optoelectronic and bio-imagingapplications. The growth of an inorganic passivation layer on nanocrystal surfaces is a commonstrategy to improve their chemical and optical stability and their photoluminescence quantumyield. In particular, cation exchange is a suitable approach for shell growth at the expense of thenanocrystal core size. Here, the cation exchange process is used to promote the formation of aCdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blueshifting their optical spectra and yielding luminescent and stable nanostructures emitting in therange of 700-850 nm. Structural, morphological and compositional investigation confirms thenanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystallinephase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of apassivation layer with a decrease of the PbS core size, as inferred by the blue-shift of theexcitonic peaks. The surface passivation strongly increases the photoluminescence intensity andthe excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidationover time. Thanks to their absorption and emission spectral range and the slow recombinationdynamics, such highly luminescent nano-objects can find interesting applications in sensitizedphotovoltaic cells and light-emitting devices.

This study shows that the surface modification of TiO2 is an effective route to increase the TiO2 absorption in the visible region up to similar to 600 nm for photocatalytic applications. The In2O3 decorated TiO2 films on polyester obtained by reactive sputtering were shown to accelerate the Escherichia coli inactivation under actinic and simulated solar light. TiO2 sputtered films for 10 min inactivated bacteria within 300 min under actinic light. The inactivation time was reduced when using a TiO2 10 min-In2O3 10 s sample to 150 min when using actinic light and 90 min by simulated sunlight with 50 mW/cm(2) (one half of AM1). Thinner TiO2-In2O3 coatings led to faster bacterial inactivation compared to thicker TiO2-In2O3 layers due to the reverse diffusion of the generated charges. The increase in the optical absorption of the green coloured TiO2-In2O3 film was a function of the In2O3 loading as detected by diffuse reflectance spectroscopy (DRS). Evidence of the lack of TiO2 lattice doping by the sputtered In2O3 was found by X-ray diffraction spectroscopy (XRD). The deconvolution of TiO2 bands detected by X-ray photoelectron spectroscopy (XPS) revealed the existence of Ti4+/Ti3+ signals suggesting redox catalysis at the surface of the TiO2-In2O3. The photo-induced interfacial charge transfer (IFCT) between TiO2 and In2O3 can be accounted for by the band position potentials of both semiconductors. The faster kinetics of TiO2-In2O3 inducing E. coli inactivation with a higher quantum efficiency compared to TiO2 takes place in spite of the low intensity of the IFCT optical absorption bands >400 nm. (C) 2014 Elsevier B.V. All rights reserved.

A novel UV-light-curable nanocomposite material formed of a methacrylic-siloxane resin loaded with 1 wt % oleic acid and 3-(trimethoxysilyl)propyl methacrylate silane (OLEA/MEMO)-coated TiO2 nanorods (NRs) has been manufactured as a potential self-curing Structural coating material for protection of monuments and artworks, optical elements, and dental components. OLEA-coated TiO2 NRs, presynthesized by a colloidal chemistry route, have been surface-modified by a treatment with the methacrylic-based silane coupling agent MEMO. The resulting OLEA/MEMO-capped TiO2 NRs have been dispersed in MEMO; that is a monomer precursor of the organic formulation; used as a "common solvent" for transferring the NRs in prepolymer components of the formulation. Differential scanning calorimetry and Fourier transform infrared spectroscopy have allowed investigation of the effects of the incorporation of the OLEA/MEMO-capped TiO2 NRs on reactivity and photopolymerization kinetics of the nanocomposite, demonstrating that the embedded NRS significantly increase curing reactivity of the neat organic formulation both in air and inert atmosphere. Such a result has-been explained on the basis of the photoactivity of the nanocrystalline TiO2 which behaves as a free-radical donor photocatalyst in the curing reaction, finally turning out more effective than the commonly used commercial photoinitiator. Namely, the NRs have been found to accelerate the cure rate and increase cross-linking density; promoting Multiple covalent bonds between the resin prepolymers and the NR ligand molecules, and, moreover, they limit inhibition effect of oxygen on photopolymerization. The NRs distribute uniformly in the photocurable matrix, as assessed by transmission electron microscopy analysis, and increase glass transition temperature and water contact angle of the nanocomposite with respect to the neat resin.

Photocatalytic nanomaterials such as TiO2 are receiving a great deal of attention owing to their potential applications in environmental remediation. Nonetheless, the low efficiency of this class of materials in the visible range has, so far, hampered their large-scale application. The increasing demand for highly efficient, visible-light-active photocatalysts can be addressed by hybrid nanostructured materials in which two or more units, each characterised by peculiar physical properties, surface chemistry and morphology, are combined together into a single nano-object with unprecedented chemical-physical properties. The present review intends to focus on hybrid nanomaterials, based on TiO2 nanoparticles able to perform visible-light-driven photocatalytic processes for environmental applications. We give a brief overview of the synthetic approaches recently proposed in the literature to synthesise hybrid nanocrystals and discuss the potential applications of such nanostructures in water remediation, abatement of atmospheric pollutants (including NOx and volatile organic compounds (VOCs)) and their use in self-cleaning surfaces

The present invention relates to a method for manufacturing electrode material particularly for lithium and lithium ion batteries comprising the following steps: a) providing nanoparticles of titanium dioxide, lithium titanate, silicon, silicon oxide or a transition metal oxide, coated with a monocarboxylic acid having a chain length of 7 to 26 carbon atoms; b) heat-treatment of the monocarboxylic acid coated nanoparticles of step a) for carbonization of the monocarboxylic acid coating.