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In this work, we unveil the fluorescence features of citric acid and urea-based Carbon Dots (CDs) through a photo-physical characterization of nanoparticles synthesized, under solvent-free and open-air conditions, within silica-ordered mesoporous silica, as a potential host for solid-state emitting hybrids. Compared to CDs synthesized without silica matrices and dispersed in water, silica-CD hybrids display a broader emission in the green range whose contribution can be increased by UV and blue laser irradiation. The analysis of hybrids synthesized within different silica (MCM-48 and SBA-15) calls for an active role of the matrix in directing the synthesis toward the formation of CDs with a larger content of graphitic N and imidic groups at the expense of N-pyridinic molecules. As a result, CDs tuned in size and with a larger green emission are obtained in the hybrids and are retained once extracted from the silica matrix and dispersed in water. The kinetics of the photo-physics under UV and blue irradiation of hybrid samples show a photo-assisted formation process leading to a further increase of the relative contribution of the green emission, not observed in the water-dispersed reference samples, suggesting that the porous matrix is involved also in the photo-activated process. Finally, we carried out DFT and TD-DFT calculations on the interaction of silica with selected models of CD emitting centers, like surface functional groups (OH and COOH), dopants (graphitic N), and citric acid-based molecules. The combined experimental and theoretical results clearly indicate the presence of molecular species and surface centers both emitting in the blue and green spectral range, whose relative contribution is tuned by the interaction with the surrounding media.

Carbon nanodots (CNDs) are the latest and most shining rising stars among photoluminescent (PL) nanomaterials. These carbon-based surface-passivated nanostructures compete with other related PL materials, including traditional semiconductor quantum dots and organic dyes, with a long list of benefits and emerging applications. Advantages of CNDs include tunable inherent optical properties and high photostability, rich possibilities for surface functionalization and doping, dispersibility, low toxicity, and viable synthesis (top-down and bottom-up) from organic materials. CNDs can be applied to biomedicine including imaging and sensing, drug-delivery, photodynamic therapy, photocatalysis but also to energy harvesting in solar cells and as LEDs. More applications are reported continuously, making this already a research field of its own. Understanding of the properties of CNDs requires one to go to the levels of electrons, atoms, molecules, and nanostructures at different scales using modern molecular modeling and to correlate it tightly with experiments. This review highlights different in silico techniques and studies, from quantum chemistry to the mesoscale, with particular reference to carbon nanodots, carbonaceous nanoparticles whose structural and photophysical properties are not fully elucidated. The role of experimental investigation is also presented. Hereby, we hope to encourage the reader to investigate CNDs and to apply virtual chemistry to obtain further insights needed to customize these amazing systems for novel prospective applications.

Magnetic scaffolds have been investigated as promising tools for the interstitial hyperthermia treatment of bone cancers, to control local recurrence by enhancing radio- and chemotherapy effectiveness. The potential of magnetic scaffolds motivates the development of production strategies enabling tunability of the resulting magnetic properties. Within this framework, deposition and drop-casting of magnetic nanoparticles on suitable scaffolds offer advantages such as ease of production and high loading, although these approaches are often associated with a non-uniform final spatial distribution of nanoparticles in the biomaterial. The implications and the influences of nanoparticle distribution on the final therapeutic application have not yet been investigated thoroughly. In this work, poly-caprolactone scaffolds are magnetized by loading them with synthetic magnetic nanoparticles through a drop-casting deposition and tuned to obtain different distributions of magnetic nanoparticles in the biomaterial. The physicochemical properties of the magnetic scaffolds are analyzed. The microstructure and the morphological alterations due to the reworked drop-casting process are evaluated and correlated to static magnetic measurements. THz tomography is used as an investigation technique to derive the spatial distribution of nanoparticles. Finally, in silico multiphysics experiments are used to investigate the influence on the loading patterns on the interstitial bone tumor hyperthermia treatment.

Highly fluorescent blue and green-emitting carbon dots have been designed to be integrated into sol-gel processing of hybrid organic-inorganic materials through surface modification with an organosilane, 3-(aminopropyl)triethoxysilane (APTES). The carbon dots have been synthesised using citric acid and urea as precursors; the intense fluorescence exhibited by the nanoparticles, among the highest reported in the scientific literature, has been stabilised against quenching by APTES. When the modification is carried out in an aqueous solution, it leads to the formation of silica around the C-dots and an increase of luminescence, but also to the formation of large clusters which do not allow the deposition of optically transparent films. On the contrary, when the C-dots are modified in ethanol, the APTES improves the stability in the precursor sol even if any passivating thin silica shell does not form. Hybrid films containing APTES-functionalized C-dots are transparent with no traces of C-dots aggregation and show an intense luminescence in the blue and green range.

The physical and chemical properties shown by nanoporous metals, related to their unique structure, make them very promising for application in several fields. Recently, vapor-phase dealloying has been reported as a method for the preparation of several non-noble nanoporous metals, alternatively to dealloying in aqueous solutions. Using this approach, we have successfully fabricated nanoporous Al starting from an Al20Zn80 nanocomposite obtained by ball milling. The nanocomposite was annealed at 550 °C under high-vacuum conditions, and the difference in the vapor pressures allowed the selective removal of Zn by vapor-phase dealloying. The morphology of the resulting nanoporous material was analyzed by Scanning Electron Microscopy showing pores from few to thousands of nm, moreover, the nanoporous 3D structure was observed through Serial Block Face-Scanning Electron Microscopy. A specific surface area as high as 73 m2 g−1 was estimated by N2 physisorption measurements. In addition, a fractal model able to well reproduce the morphology of nanoporous Al was built. This model has been used for predicting mechanical properties which are in good agreement with experimental data obtained by nanoindentation.

The purpose of this work was the assembly of multicomponent nano-bioconjugates based on mesoporous silica nanoparticles (MSNs), proteins (bovine serum albumin, BSA, or lysozyme, LYZ), and gold nanoparticles (GNPs). These nano-bioconjugates may find applications in nanomedicine as theranostic devices. Indeed, MSNs can act as drug carriers, proteins stabilize MSNs within the bloodstream, or may have therapeutic or targeting functions. Finally, GNPs can either be used as contrast agents for imaging or for photothermal therapy. Here, amino-functionalized MSNs (MSN–NH2) were synthesized and characterized through various techniques (small angle X-rays scattering TEM, N2 adsorption/desorption isotherms, and thermogravimetric analysis (TGA)). BSA or lysozyme were then grafted on the external surface of MSN–NH2 to obtain MSN–BSA and MSN–LYZ bioconjugates, respectively. Protein immobilization on MSNs surface was confirmed by Fourier transform infrared spectroscopy, ζ-potential measurements, and TGA, which also allowed the estimation of protein loading. The MSN–protein samples were then dispersed in a GNP solution to obtain MSN–protein–GNPs nano-bioconjugates. Transmission electron microscopy (TEM) analysis showed the occurrence of GNPs on the MSN–protein surface, whereas almost no GNPs occurred in the protein-free control samples. Fluorescence and Raman spectroscopies suggested that proteins–GNP interactions involve tryptophan residues.

The structures and properties, including second-order non-linear optical properties in solution and in polymethylmethacrylate (PMMA) films, of new nickel heteroleptic donor-acceptor dithiolene complexes are reported here ([Ni(Bn(2)pipdt)L1-4], 1-4). The acceptor dithione system (Bn(2)pipdt = 1,4-dibenzylpiperazine-2,3-dithione) is invariant, whereas the donor dithiolate moiety varies in 1 to 4 (i-mnt = 2,2-dicyanoethylene-1,1-dithiolate) (L1), sqdt = 1,2-dithiosquarate (L2), ddmedt = 1,2-dicarbomethoxyethylene dithiolate (L3), and dddmedt = 5,6-bis(methoxycarbonyl)-1,4-dithiine-2,3-bis(thiolate) (L4). Molecular structural characterization of 1, 3 and 4 points out that the metal center exhibits a square-planar geometry bound by the dithione ligand Bz(2)pipdt, and by three different dithiolate-type ligands. Complexes 1-4 are characterized in the visible region by a peak of moderately strong intensity, which undergoes negative solvatochromism. The molecular quadratic optical nonlinearities were determined in DMF solution by the electric field induced second harmonic generation technique, working with a 1907 nm incident wavelength. The mu beta(1907) values (-680 (1), -855 (2), -1080 (3); and -1180 (4)) (10(-48) esu) were measured, showing that 1-4 exhibit negative second-order polarizabilities whose values depend on the donor ligand. While 1-4 exhibit similar thermolytic behavior, when embedded in a PMMA poled matrix, only 3 maintains second-order NLO properties in the solid state. A good NLO response with a value of the three nonzero coefficients of the second-order susceptibility tensor chi(2)33, chi(2)31, and chi(2)15 = 2.20 +/- 0.44 pm V-1, 0.56 +/- 0.12 pm V-1 and 0.42 +/- 0.08 pm V-1, respectively, was found. According to computational studies, the mu beta(1907) sequence is mainly related to the donor capability of the dithiolate ligands, which affects the HOMO-LUMO energy gap (2.05 (1), 1.80 (2), 1.56 (3), and 1.36 (4) eV), and it can thus modulate the position of the low-energy absorption and related properties in the series.

Carbonized polymer dots (CPDs), a peculiar type of carbon dots, show extremely high quantum yields, making them very attractive nanostructures for application in optics and biophotonics. The origin of the strong photoluminescence of CPDs resides in a complicated interplay of several radiative mechanisms. To understand the correlation between CPD processing and properties, the early stage formation of carbonized polymer dots has been studied. In the synthesis, citric acid monohydrate and 2-amino-2-(hydroxymethyl)propane-1,3-diol have been thermally degraded at 180 °C. The use of an oil bath instead of a more traditional hydrothermal reactor has allowed the CPD properties to be monitored at different reactions times. Transmission electron microscopy, time-resolved photoluminescence, nuclear magnetic resonance, infrared, and Raman spectroscopy have revealed the formation of polymeric species with amide and ester bonds. Quantum chemistry calculations have been employed to investigate the origin of CPD electronic transitions. At short reaction times, amorphous C-dots with 80 % quantum yield, have been obtained.

Surfactant-mediated chemical routes allow one to synthesize highly engineered shape- and size-controlled nanocrystals. However, the occurrence of capping agents on the surface of the nanocrystals is undesirable for selected applications. Here, a novel approach to the production of shape-controlled nanocrystals which exhibit high thermal stability is demonstrated. Ceria nanocubes obtained by surfactant-mediated synthesis are embedded inside a highly porous silica aerogel and thermally treated to remove the capping agent. Powder X-ray Diffraction and Scanning Transmission Electron Microscopy show the homogeneous dispersion of the nanocubes within the aerogel matrix. Remarkably, both the size and the shape of the ceria nanocubes are retained not only throughout the aerogel syntheses but also upon thermal treatments up to 900 °C, while avoiding their agglomeration. The reactivity of ceria is measured by in situ High-Energy Resolution Fluorescence Detected - X-ray Absorption Near Edge Spectroscopy at the Ce L3 edge, and shows the reversibility of redox cycles of ceria nanocubes when they are embedded in the aerogel. This demonstrates that the enhanced reactivity due to their prominent {1 0 0} crystal facets is preserved. In contrast, unsupported ceria nanocubes begin to agglomerate as soon as the capping agent decomposes, leading to a degradation of their reactivity already at 275 °C.

In this study, new CeO\(_2\)-SiO\(_2\) aerogel nanocomposites obtained by controlled growth of CeO\(_2\) nanoparticles within the highly porous matrix of a SiO\(_2\) aerogel are presented. The nanocomposites have been synthesized via a sol-gel route, employing cerium (III) nitrate as the CeO\(_2\) precursor and selected capping agents to control the growth of the CeO\(_2\) nanoparticles, which occurs during the supercritical drying of the aerogels. Samples with different loading of the CeO\(_2\) dispersed phase, ranging from 5 to 15%, were obtained. The nanocomposites showed the morphological features typical of the SiO\(_2\) aerogels such as open mesoporosity with surface area values up to 430 m\(^2\)·g\(^{-1}\). TEM and XRD characterizations show that nanocrystals of the dispersed CeO\(_2\) nanophase grow within the aerogel already during the supercritical drying process, with particle sizes in the range of 3 to 5 nm. TEM in particular shows that the CeO\(_2\) nanoparticles are well distributed within the aerogel matrix. We also demonstrate the stability of the nanocomposites under high temperature conditions, performing thermal treatments in air at 450 and 900°C. Interestingly, the CeO\(_2\) nanoparticles undergo a very limited crystal growth, with sizes up to only 7 nm in the case of the sample subjected to a 900°C treatment.

Ensuring high quality of water is an urgent challenge for today's research. In spite of the enormous progress achieved in the area, the quest for all-in-one systems able to adsorb, detect and degrade pollutants has not been sufficiently accomplished. Here, we present multi-functional plasmonic hydrogels composed of β-cyclodextrin-functionalized silver nanoparticles (Ag NPs) embedded within bubbles made of alginate. The synergistic combination of individual building blocks enables multi-purpose systems to be obtained: the alginate matrix ensures good adsorption properties, β-cyclodextrins (βCD) act as molecular receptors and Ag NPs enable the pollutant detection through surface enhanced Raman spectroscopy (SERS) and its plasmon-assisted photo-degradation. Their activity has been tested during the capture, detection and photodegradation of methylene blue and sulfamethoxazole, but the general affinity of βCD receptors towards benzene and heterocyclic rings makes these nanocomposite hydrogels extremely versatile scavengers for most of the common organic pollutants, including biphenyls, other dyes and pharmaceutical compounds. In addition, their stability, ease of manipulation, dispersion and recovery make these systems ideal for both in situ and ex situ applications, enabling water-treatment under real conditions.

International audience; Carbon Nitride and its polymorphs have recently gained large interests for their huge properties and applications in different fields, from lighting to photocatalysis. Further, several attempts were recently devoted to tune and control its optical and electrical properties. In this report we analyze phenyl modified Carbon Nitride structures obtained by simple thermal polymerization at different temperatures (250-400°C) of the starting precursor: 2,4-diamino-6-phenyl-1,3,5-triazine. A multi-technique experimental data (XRD patterns, Raman, TGA and DTG, steady-time and time resolved Luminescence, Photoluminescence Excitation spectra, Reflectivity spectra) was applied to analyze the relationship between structural and optical properties and to give more insight on the effect of synthesis procedure on the final polymer. The optical properties evidenced an interesting shift towards the visible region of the absorption spectrum of the phenyl modified g-C 3 N 4 polymer that, associated with the high optical quantum yield (about 60%) and to a broad emission in the green-red spectral region, makes the samples very suitable for lighting applications. Indeed, we report a first prototype of white LED emission by assembly of a commercial blue LED and the Phenyl modified g-C 3 N 4 powders as phosphor, verifying the structural and optical stability over about 10,000 working hours.

Eco-sustainable solutions for the neutralization of air and water pollutants have increasingly gravitated toward the use of heterogeneous photocatalysts. This approach, which transforms pollutants into harmless substances through a light-driven chemical reaction on a catalytic surface, must comply with eco-sustainability requirements and be easily applicable. Semiconductor-based photocatalysis is a promising pathway for the degradation of environmental pollutants and, among all the various semiconductors used, titanium dioxide has proved itself to be the foremost material for environmental remediation due to its highly desirable photocatalytic properties. Titanium dioxide, however, poorly exploits the visible part of the electromagnetic spectrum due to the relatively large band-gap of its anatase phase, and as such, the UV portion of the solar spectrum is largely responsible for its photocatalytic activity. Herein, we demonstrate a highly efficient visible light hybrid catalyst based on titanium dioxide and phenyl carbon nitride (PhCN). With the organic component providing a broad absorption up to 600 nm and fast charge exchange to the conduction band of TiO2, the combination allows for the highly efficient photocatalytic degradation of Rhodamine B under visible excitation.

The optical properties of microwave-synthesized carbon dots dispersed in water and in mesoporous ordered silica are reported. The fluorescence characteristics of bare carbon dots are compared to th...

Contrast agents with a strong R-1 dispersion have been shown to be effective in generating target-specific contrast in MRI. The utilization of this R-1 field dependence requires the adaptation of an MRI scanner for fast field-cycling (FFC). Here, we present the first implementation and validation of FFC-MRI at a clinical field strength of 3 T. A field-cycling range of +/- 100 mT around the nominal Bo field was realized by inserting an additional insert coil into an otherwise conventional MRI system. System validation was successfully performed with selected iron oxide magnetic nanoparticles and comparison to FFC-NMR relaxometry measurements. Furthermore, we show proof-of-principle R-1 dispersion imaging and demonstrate the capability of generating R-1 dispersion contrast at high field with suppressed background signal. With the presented ready-to-use hardware setup it is possible to investigate MRI contrast agents with a strong R-1 dispersion at a field strength of 3 T. (C) 2018 Elsevier Inc. All rights reserved.

Hybrid organic–inorganic luminescent lanthanide-based nanomaterials are currently attracting great interest for a variety of applications from bioimaging/sensing to optics and photonics. Herein, we present a concept model system based on purely silica-based core–shell nanoparticles (NPs), where luminescent Eu3+ ions are confined to a thin silica layer and are efficiently remotely photosensitized through an antenna unit covalently grafted on the surface of the outer shell. The obtained core–shell NPs, synthesized through mild sol–gel methods, are of rare quality in terms of size distribution, homogeneity and smoothness of the coating shell, the absence of core-free silica, and dispersion of the dopant phase. Convenient indirect optical pumping through the remote photosensitizer allows a remarkable intensity enhancement of the Eu3+-based NP luminescence by 190-fold with respect to that achievable upon direct metal excitation, yielding the highest intrinsic (ΦEu = 49%) and overall (Φ = 19%) quantum yields and ligand-to-metal sensitization efficiency (ηsens ∼ 40%) reported so far for Eu3+-based remotely sensitized organic–inorganic nanosystems. These performances are achieved thanks to the suppression of unexpected nonradiative decay channels pertaining to the silica matrix as revealed by an in-depth analysis of the temporal dynamics of Eu3+ emission upon direct and indirect excitation. These results show that silica matrices are a suitable highly performing host alternative to commonly investigated nanocrystals such as fluorides for the development of lanthanide-based luminescent materials with the additional potentiality of high processing versatility through well-established sol–gel chemistry methods.

CuFe2O4 is an example of ferrites whose physico-chemical properties can vary greatly at the nanoscale. Here, sol-gel techniques are used to produce CuFe2O4-SiO2 nanocomposites where copper ferrite nanocrystals are grown within a porous dielectric silica matrix. Nanocomposites in the form of both xerogels and aerogels with variable loadings of copper ferrite (5 wt%, 10 wt% and 15 wt%) were synthesized. Transmission electron microscopy and X-ray diffraction investigations showed the occurrence of CuFe2O4 nanoparticles with average crystal size ranging from a few nanometers up to around 9 nm, homogeneously distributed within the porous silica matrix, after thermal treatment of the samples at 900 °C. Evidence of some impurities of CuO and α-Fe2O3 was found in the aerogel samples with 10 wt% and 15 wt% loading. DC magnetometry was used to investigate the magnetic properties of these nanocomposites, as a function of the loading of copper ferrite and of the porosity characteristics. All the nanocomposites show a blocking temperature lower than RT and soft magnetic features at low temperature. The observed magnetic parameters are interpreted taking into account the occurrence of size and interaction effects in an ensemble of superparamagnetic nanoparticles distributed in a matrix. These results highlight how aerogel and xerogel matrices give rise to nanocomposites with different magnetic features and how the spatial distribution of the nanophase in the matrices modifies the final magnetic properties with respect to the case of conventional unsupported nanoparticles.

A facile and efficient protocol for the α-benzoyloxylation of β-keto sulfides is presented. This methodology provides a step-economical, mild and practical access to highly functionalized α-O-benzoyloxy substituted β-keto sulfides, including those with quaternary carbons, which are not easily obtained through currently available methods.

In this work, a dealloying technique is proposed as a synthesis method to obtain highly porous Nickel electrodes starting from Ni-Cu co-deposit: pulsed corrosion is applied adopting different corrosion and relaxation times. Different morphologies, pore size distribution and residual copper amount were obtained depending on the corrosion conditions. For the developed electrodes, the surface roughness factor, Rf, was evaluated by electrochemical impedance spectroscopy (EIS). The hydrogen evolution reaction (HER) on these electrodes was evaluated by means of steady-state polarization curves, and the related parameters were derived by Tafel analysis. Finally, a thin layer of NiO on the porous structures was obtained to exploit the semiconductor characteristic of the oxide, so that an extra-photopotential was obtained by the simulated solar light action. Results demonstrate greater apparent activity of the developed electrodes towards HER in comparison with commercial smooth Ni electrode, which can be mainly attributed to the large Rf obtained with the proposed technique.

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

Highly porous MFe2O4-SiO2 (M = Co, Mn, Ni) nanocomposite aerogels were tested for the first time as catalysts for multi walled carbon nanotubes production by Catalytic Chemical Vapour Deposition. Structural and textural characterization points out that the catalysts are made out of nanocomposites where nanocrystalline ferrite phases with controlled composition and size in the range 9-13 nm are finely dispersed into the highly porous silica support. Remarkably, CoFe2O4-SiO2 and MnFe2O4-SiO2 catalysts have shown poor catalytic activity, whereas NiFe2O4-SiO2 catalyst has given rise to good quality nanotubes with high yields at deposition temperatures in the range 500-650 °C. The different catalytic behaviour of the mixed ferrite-silica aerogels as a function of the bivalent metal (M = Co, Mn, Ni) can been ascribed to how easily the nanophase can be reduced. In particular, it was demonstrated that the most active NiFe2O4 nanoparticles undergo an in-situ reduction process during the Catalytic Chemical Vapour Deposition reaction, forming a NiFe alloy phase that is responsible for promoting the multi walled carbon nanotubes growth.

A new promising inert matrix as host of luminescent ions is proposed. Al2SiO5 samples, doped with rare earths (Ce, Tb single doped and co-doped) are proposed as good prospect for the development of new UV–vis converter with reduced content of rare earths elements. Structural characterization by Raman, XRD spectroscopy and TEM imaging reveals the sillimanite phase and nano sized dimension of the investigated powders. Optical characterization by steady time and time resolved emission spectroscopy for the single doped and co-doped samples allows to identify an efficient energy transfer from Ce to Tb ions under near UV excitation wavelength. The intense green emission observed in the Ce:Tb co-doped Al2SiO5 system suggests its potential application as efficient blue pumped green emitter phosphor to be exploited for white LED: to this purpose we tested the compound in combination with a red emitting doping ion recording for Ce:Tb:Cr:ASO system a correlated color temperature of 6720 K.

Cu-based nanoparticles, supported on either a silica aerogel or cubic mesostructured silicas obtained using two different synthetic protocols, were used as catalysts for the Water Gas Shift reaction. The obtained nanocomposites were thoroughly characterized before and after catalysis using N2 adsorption-desorption measurements at -196 °C, transmission electron microscopy, wide-angle and low-angle X-ray diffraction. It was found that the samples before catalysis contain nanoparticles of copper oxides – either CuO or Cu2O – while the formation of metallic copper nanoparticles, constituting the active catalytic phase, is observed either using a pretreatment in reducing atmosphere or directly during the catalytic reaction due to the presence of CO. A key role in determining the catalytic performances of the samples is played by the ability of the different matrices in promoting a high dispersion of Cu metal nanoparticles. The best catalytic performances are obtained with the aerogel sample, which also exhibits constant CO conversion values at constant temperature and quite a reproducible behaviour after subsequent catalytic runs. On the other hand, in the catalysts based on cubic mesostructured silica the detrimental effects related to sintering of Cu nanoparticles are avoided only on the silica support which is able to produce a reasonable dispersion of the copper nanophase.

In the present study, the use of surfactant-free mesoporous TiO2 combined with an antioxidant and photo-protecting agent, such as ferulic acid (FA), as a sunscreen was investigated for the first time. Ferulic acid is a natural antioxidant characterized by UV absorption capacity and radical scavenging activities and, due to these properties, it has been approved as an active ingredient in several skin lotions and sunscreens. However, despite the double function exerted by FA, the use of this molecule in the cosmetic field is limited by its poor stability. Aiming to overcome this drawback, mesoporous TiO2, prepared by using a sol–gel route assisted by a polyoxyethylene–polyoxypropylene block copolymer template followed by solvothermal treatment, was used as a matrix for the encapsulation of ferulic acid. The stability studies performed confirmed the ability of the prepared material to preserve the active molecule from degradation induced by light and, therefore, its properties. Antioxidant and anti-inflammatory activities of FA-loaded titania (TiO2@FA) and titania matrix (TiO2) were evaluated and high scavenging activity towards DPPH, ABTS and NO radicals were recorded. The in vitro assessment of the spectrophotometric Sun Protection Factor (SPF) was also performed and a value of 14.7 was observed for TiO2@FA while mesoporous TiO2 showed a lower SPF value equal to 2.6. These results suggested the potential application of the titania-doped FA as a “booster of SPF” that is able to enhance the SPF of a sunscreen. Furthermore, in vitro safety studies confirmed the biocompatibility of the prepared material and the absence of skin irritation.

Graphene/silica nanocomposites in the form of highly porous aerogels are obtained for the first time by integrating a novel approach for the production of low defectivity graphene with a two-step route for the synthesis of a silica-based monolith. Different from the other synthetic methods, the use of co-gelation of a dispersed phase and matrix followed by high temperature supercritical drying leads to well dispersed bilayered graphene inside a high surface area silica matrix with an open texture porosity. Physico-chemical characterization provides evidence that the developed graphene/SiO2 bulk aerogel nanocomposites combine the distinct features of both the dispersed graphene sheets and the porous silica aerogel matrix. It was found that incorporation of graphene in the aerogel, even at low loading, increases significantly the hydrophobic behaviour of the materials. This, combined with the high surface/volume ratio of the aerogel, makes the resulting nanocomposite a suitable candidate as a novel oil sorbent for water remediation. In particular, the developed graphene/silica aerogels selectively and quickly uptake oil, up to more than 7 times the aerogel sorbent mass, from oil–water mixtures, and keeps floating on water after absorbing the oil phase. The suitability of the developed composites as a class of novel sorbents for environmental remediation in the occurrence of flammable liquid spills, where burning represents a major threat, is supported by the specific features of silica aerogels such as a relative fire-resistance, in addition to the high porosity and hydrophobic nature.

Blue-emitting nitrogen-doped carbon dots (CDN) produced by a solvent-free method have been successfully incorporated into silica (SiO2) through a sol-gel procedure. By exploiting the co-gelation of the dispersed carbon dots and of the silica matrix, homogeneous distribution of the carbon dots was obtained throughout the matrix. The CDN-SiO2 composites in the form of xero-, cryo-, and aerogels featuring different porous textures were produced by exploiting different gel drying strategies. The most critical parameters and the material features associated to the different synthesis were investigated by transmission electron microscopy, thermal analysis, Mid-infrared spectroscopy, N2 physisorption isotherms and time-resolved spectrofluorimetry. The emissive properties of CDN-SiO2 composites in the form of aero-, cryo- and xerogel were studied. The spectral properties and the efficiency of the emission change in the CDN-SiO2 composites pointed at the effect of CD loading and porous texture of xerogels. Our investigation expands the exploitation of functional carbon dots through the production of fluorescent solid-state composites with tunable porosities.

Clean-up of crude-oil spills ranks among the major environmental remediation issues and demands for sorbents with high and stable oleophilic and hydrophobic features. Here, aerogels with durable hydrophobicity are produced by incorporating reduced graphene oxide (rGO) in highly porous silica matrices. By a sol-gel protocol, high rGO loadings are achieved by exploiting highly dispersible hydrophilic graphene oxide as rGO precursor. Homogeneous rGO-silica composite monoliths are obtained with tunable loading up to 10 wt%, enabling a detailed analysis of the sorption behaviour towards oil spills. Composite aerogels demonstrate an excellent performance towards oil sorption with oil uptake from ∼7 to ∼10 times the aerogel mass. Although the sorption ability is lower than for plain hydrophobic silica, composites with a minimum loading of 5 wt% exhibit very high oil selectivity and show a durable and reliable behaviour over time, providing longer shelf-life than plain SiO2 aerogels. The synergetic effect of rGO towards long-term hydrophobicity and oil selectivity on silica composite aerogels allows for the implementation of such composite materials in real water remediation processes.

Poly(3,4-ethylenedioxythiophene) (PEDOT) polymerization has been carried out both in a template-free environment and inside the nanopores of SBA-15 mesoporous silica. Comparing the two methods and the secondary doping of commercial PEDOT:PSS, we were able to study the structural effect of the templated polymerization via a multi-technique approach. We found that the confined polymerization favours a more linear configuration of the polymer chains, in a similar way to the well-known secondary doping with organic solvents. Moreover, comparison of computational and experimental results suggests that the PEDOT mean chain length is greater when the polymerization occurs in the nanoporous template, promoting the formation of a polymer with larger molecular weight and crystallinity.

Contrast agents with a strong R

Biomedical application of nanoparticles is largely associated to their fate in biological media which, in turn, is related to their surface properties. Surface functionalization plays a key role in determining biodegradation, cytotoxicity and biodistribution through interactions which may be mediated by the macromolecules occurring in biological media. A typical example is given by several proteins which lead to the formation of coated nanoparticles referred as protein corona. In this work we focus on mesoporous silica nanoparticles which, due to their intrinsic textural features, show potential as carriers for sustained drug release. Mesoporous silica nanoparticles functionalized by different biopolymers such as hyaluronic acid and chitosan were synthesized and characterized through small angle X-rays scattering, thermal analysis, and infrared spectroscopy. Biopolymer-coated mesoporous silica nanoparticles were used to investigate the interaction with bovine serum albumin, and to point out the role of different biopolymer coating. Gold-conjugated-bovine serum albumin was used to gain evidence on the occurrence of surface bound proteins enabling direct observation by transmission electron microscopy. Our findings provide insights on how different biopolymers affect the formation of a protein corona around functionalized mesoporous silica nanoparticles.

Complex [Pt(iPr(2)pipdt)(Quinoxdt)] (iPr(2)pipdt=1,4-diisopropyl-piperazine-2,3-dithione; Quinoxdt=[1,4]dithiino[2,3-b]quinoxaline-2,3-dithiolate) exhibits a remarkable green emission at 570nm (room temperature), which is above the lowest excited state. The complex is characterized by negative solvatochromism as well as a high second-order polarizability. Addition of Ag-I ions induces 1)hypsochromic shift of the lowest frequencies and 2)reversible quenching of luminescence. The corresponding Ni and Pd complexes have also been prepared and investigated to assist interpretation of optical properties within the triad. Computational studies based on DFT and time-dependent DFT highlight the electronic properties of [Pt(iPr(2)pipdt)(Quinoxdt)]. The preferential site of interaction between the Pt complex and incoming Ag-I is evidenced by the shape of the Fukui functions, pointing to the thiolic sulfur and platinum atoms as the most reactive sites towards a soft cation. Calculated optical properties are in agreement with experimental findings. This study sheds light on the structure-property relationship for this class of compounds.

We investigated the theranostic properties of magnetosomes (MNs) extracted from magnetotactic bacteria, promising for nanomedicine applications. Besides a physico-chemical characterization, their potentiality as mediators for magnetic fluid hyperthermia and contrast agents for magnetic resonance imaging, both in vitro and in vivo, are here singled out. The MNs, constituted by magnetite nanocrystals arranged in chains, show a superparamagnetic behaviour and a clear evidence of Verwey transition, as signature of magnetite presence. The phospholipid membrane provides a good protection against oxidation and the MNs oxidation state is stable over months. Using an alternate magnetic field, the specific absorption rate was measured, resulting among the highest reported in literature. The MRI contrast efficiency was evaluated by means of the acquisition of complete NMRD profiles. The transverse relaxivity resulted as high as the one of a former commercial contrast agent. The MNs were inoculated into an animal model of tumour and their presence was detected by magnetic resonance images two weeks after the injection in the tumour mass.

Graphene sheets increase the Raman signal through a chemical enhancement mechanism that gives rise to graphene-mediated enhanced Raman scattering (GERS). The low enhancement factor and the surface available for analysis are, however, a limitation on the application of GERS. We have, therefore, developed a new GERS platform, which is based on mesoporous ordered films made of titania anatase containing dispersed sheets of exfoliated graphene. The analytical enhancement factor has revealed that the combination of titania and graphene produces a significant increase in GERS response using Rhodamine 6G as molecular probe. This is a new effect, which we have defined as Ti-GERS (titania-induced graphene-mediated ERS), and is attributed to synergic interfacial interactions between graphene sheets and titania at the nanocrystal edges within the nanocomposite. In the future, the Ti-GERS effect is expected to foster a development of better performing Raman-based analytical devices avoiding the use of expensive noble...

CdSe@CdS dot@rods with diameter around 6 nm and length of either\ud 20, 27, or 30 nm and dot@octapods with pod diameters of ?15 nm and lengths of ?50\ud nm were investigated by X-ray absorption spectroscopy. These heterostructures are\ud prepared by seed-mediated routes, where the structure, composition, and morphology of\ud the CdSe nanocrystals used as a seed play key roles in directing the growth of the second\ud semiconducting domain. The local structural environment of all the elements in the\ud CdSe@CdS heterostructures was investigated at the Cd, S, and Se K-edges by taking\ud advantage of the selectivity of X-ray absorption spectroscopy, and was compared to pure\ud reference compounds. We found that the structural features of dot@rods are\ud independent of the size of the rods. These structures can be described as made of a\ud CdSe dot and a CdS rod, both in the wurtzite phase with a high crystallinity of both the\ud core and the rod. This result supports the effectiveness of high temperature colloidal\ud synthesis in promoting the formation of core@shell nanocrystals with very low\ud defectivity. On the other hand, data on the CdSe@CdS with octapod morphology suggest the occurrence of a core composed of\ud a CdSe cubic sphalerite phase with eight pods made of CdS wurtzite phase. Our findings are compared to current models\ud proposed for the design of functional heterostructures with controlled nanoarchitecture.

The structure of the iron oxyhydroxide called feroxyhyte (δ-FeOOH), which shows an elusive X-ray powder diffraction pattern, has been represented so far using models describing a mean structure based on the crystalline network of the iron(III) oxide hematite (α-Fe 2 O 3 ). In this paper, a novel description of the mean structure of feroxyhyte is presented, which is based on the structure of the thermodynamically stable iron oxyhydroxide goethite. Starting from different local arrangements present in the goethite network, a mean structural model is determined which shows an X-ray powder diffraction pattern almost coincident with previous studies. This outcome enables to integrate the structure of feroxyhyte among those of other well characterized iron oxyhydroxides.

A one-pot approach making use of a zinc oxide sol precursor and carbon quantum dots, together with a partially fluorinated block copolymer as templating agent, has been used to synthesize a porous matrix characterized by interesting energy transfer properties. The choice of the fluorinated surfactant for inducing the porosity into the inorganic matrix has allowed an easy removal of the templating agent at low temperature, preserving at the same time the functional properties of the carbon quantum dots. The resulting nanocomposite films have been characterized by steady-state 3D mapping that has evidenced a complex behavior as a function of the carbon quantum dots concentration. In particular, the luminescence bands of the zinc oxide matrix appear to be modulated by the broad emission of the carbon quantum dots, which depends on their aggregation state. These results can be thus considered as a step further toward the fine-tuning of the luminescence properties provided by zinc oxide-based nanocomposites as a result of a doping effect due to the presence of carbon quantum dots.

Samples of nickel cobaltite, a mixed oxide occurring in the spinel structure which is currently extensively investigated because of its prospective application as ferromagnetic, electrocatalytic, and cost-effective energy storage material were prepared in the form of nanocrystals stabilized in a highly porous silica aerogel and as unsupported nanoparticles. Nickel cobaltite nanocrystals with average size 4 nm are successfully grown for the first time into the silica aerogel provided that a controlled oxidation of the metal precursor phases is carried out, consisting in a reduction under H

The application of titania materials to gas sensing devices based on thin films are of limited utility because they only operate at a high working temperature and exhibit in general a low sensitivity. To overcome these constraints, a new type of oxygen sensor based on mesoporous titania thin films working at room temperature under UV irradiation has been developed. The increased density of charge carriers induced by the photoconductive effect, has been used to enhance the sensitivity of the thin oxide layers. Mesostructured titania films have been prepared via self-assembly and thermal processing to remove the organic template obtaining anatase nanocrystals. The mesoporous films show a striking decrease of the current in the presence of oxygen that acts as an electron scavenger. Mesoporous samples exhibit a much higher response with respect to dense titania, due to the higher surface area and the larger number of surface defects., RAS is acknowledged for funding this project through CRP 30 L.R. 7/2007 ‘‘Bando Capitale Umano ad Alta Qualificazione annualita` 2015’’. This work was partially supported by the project ‘‘Mi ADATTI E L’ABBATTI’’- INSTM-Regione Lombardia project INSTMRL6.

Highly porous nanocomposite aerogels based on bimetallic Fe and Mo nanoparticles with a variable Fe:Mo weight ratio ranging from 5:1; 3:1; and 0.7:1 dispersed on amorphous silica were obtained. N2 physisorption, X-ray diffraction, and transmission electron microscopy indicate that the Fe/Mo–SiO2 nanocomposite aerogels as obtained by a co-gelation sol–gel route followed by supercritical drying and reduction treatment under H2 exhibit Fe and Mo nanocrystals with size in the range 4–10 and 15 nm, respectively, supported on highly porous silica. The catalytic performance of the Fe/Mo–SiO2 aerogels for the synthesis of multi wall carbon nanotubes (MWCNT) by catalytic chemical vapour deposition (CCVD) was evaluated in terms of amount and quality of the produced CNTs as assessed by gravimetric results, thermal analysis, and TEM. The effect of catalyst composition and CCVD temperature was investigated, pointing out that high reaction temperatures (800 °C) favor the formation of MWCNTs with high quality in elevated yield, the highest C uptake value being >400 %. Catalyst composition and CCVD temperature were also found to affect the homogeneity of CNT morphology, the best MWCNT quality (with outer diameter 23–25 nm) being achieved at 800 °C with the catalyst having the largest Mo content.

Silica-based ordered mesoporous materials are very attractive matrices to prepare smart depot systems for several kinds of therapeutic agents. This work focuses on the well-known SBA-15 mesoporous silica and lysozyme, an antimicrobial protein. In order to improve the bioadhesion properties of SBA-15 particles, the effect of hyaluronic acid (HA) functionalization on lysozyme adsorption was investigated. SBA-15 samples having high (H-SBA) and low (L-SBA) levels of functionalization were analyzed during the three steps of the preparations: (1) introduction of the -NH2 groups to obtain the SBA-NH2 samples; (2) functionalization with HA to obtain the SBA-HA matrices; (3) adsorption of lysozyme. All silica matrices were characterized through N2-adsorption/desorption isotherms, small-angle X-ray scattering, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The whole of the experimental data suggests that a high level of functionalization of the silica surface allows for a negligible lysozyme adsorption mainly due to unfavorable electrostatic interactions (H-SBA-NH2) or steric hindrance (H-SBA-HA). A low degree of functionalization of the silica surface brings about a very good performance toward lysozyme adsorption, being 71% (L-SBA-NH2) and 63% (L-SBA-HA) respectively, compared to that observed for original SBA-15. Finally, two different kinetic models--a "pseudo-second order" and a "intraparticle diffusion"--were compared to fit lysozyme adsorption data, the latter being more reliable than the former.

A series of catalysts containing iron and cobalt nanoparticles supported on a highly ordered mesoporous cubic Im3m silica (SBA-16) were prepared by wet impregnation and used for the production of multi-walled carbon nanotubes (MWCNTs) by catalytic chemical vapor deposition (CCVD) of acetylene. The catalysts were characterized by low- and wide-angle X-ray diffraction, N2 physisorption analysis at 77 K and transmission electron microscopy to study the influence of different metal loading and impregnation time on the CCVD process. Quality and morphology of the MWCNTs was assessed by transmission and scanning electron microscopy, whereas thermal analysis was used to estimate the amount of CNTs produced. It was found that the nanocomposites are catalytically active with particular reference to samples with relatively high metal loading, and are stable under the conditions adopted for the CNT production by the CCVD process.

Porous monoliths of nanocomposites containing Ni (5 wt.%) and FeNi (5 wt.%) nanoparticles dispersed on an SBA-16 type matrix were prepared following a templated-gelation method based on the sol–gel process. The nanocomposites were characterized by energy dispersive X-ray spectroscopy, N2 physisorption at 77 K, X-ray diffraction and transmission and scanning electron microscopy. In particular, N2 physisorption and transmission electron microscopy analysis show that the ordered mesoporous structure and the high surface area of all the samples are preserved after calcination in air at 500 °C and also after reduction in H2 flux at 800 °C, indicating a very high thermal stability of the samples. As a result of the effective dispersion of the nanophase within the porous texture, nanocomposites containing Ni nanocrystals with an average size of 6 nm homogeneously dispersed within the pores of the amorphous silica matrix were obtained.