Water Decontamination from Cr(VI) by Transparent Silica Xerogel Monolith.

Cr(VI) is highly soluble and mobile in water solution and extremely toxic. In order to obtain a specific material with adsorption properties towards Cr(VI), and that can be used in environmental remediation of water contaminated with Cr(VI), one-step sol-gel technique, at low temperature (50 °C), has been optimized to prepare transparent silica-based xerogel monolith by using tetraethyl orthosilicate as precursor. The obtained xerogel, with disk shape, was fully characterized by Raman, BET, FE-SEM and XRD analysis. The results indicated that the material showed silica amorphous phase and high porosity. The study of the adsorption properties towards different concentrations of Cr(VI), in the form of HCrO4- in acidic condition, showed prominent results. The absorption kinetics were evaluated by studying different models, the final result showing that the absorption of Cr(VI) occurred through intra-particle diffusion process, following two steps, and that the absorption equilibrium is regulated by Freundlich isotherm model. The material can be restored by reducing the hazardous Cr(VI) to Cr(III), a less toxic form of chromium, by 1,5-diphenylcarbazide, and with successive treatment in acidic water.

Microplastics accumulation in gastrointestinal tracts of Mullus barbatus and Merluccius merluccius is associated with increased cytokine production and signaling.

There is clear evidence that different marine species can be impacted by microplastic (MP) ingestion accumulating such MPs mainly in the gastrointestinal tract. However, there is still limited knowledge on the consequences of MPs' accumulation in the gut. The present study aims to assess MPs and their potential immunotoxic effects in the digestive tract of two species showing different ecological traits: the red mullet (Mullus barbatus) and the European hake (Merluccius merluccius). Infrared spectroscopy (FTIR-ATR), micro-Raman and electron scanning microscope (SEM) were used to accurately identify the main plastic polymers detected in gut contents. In addition, we investigated the association between MP uptake and intestinal inflammation by evaluating expression and secretion of proinflammatory cytokines. MP abundance ranged from 1 to 20 items/individual in red mullet and from 2 to 15 items/individual in European hake. The majority of ingested MPs were fibers, while the dominant colors were black and blue in both species. Chemical characterization indicated polyethylene and polypropylene as the most common polymer types. Moreover, it was observed that MP abundance was highly positive correlated to cytokines (i.e. interleukin-1ß, 10, and interferon) and antioxidant enzyme (i.e. catalase and superoxide dismutase) transcript levels suggesting ROS generation and an infiltration of immune cells in the gut. Our findings provide evidence that the induction of cytokine-dependent signaling pathways is one aspect of the complex mechanism by which MPs affect the gut system in fish.

Structural and Interfacial Characterization of a Sustainable Si/Hard Carbon Composite Anode for Lithium-Ion Batteries.

The effects of a biomass-derived hard carbon matrix and a sustainable cross-linked binder are investigated as electrode components for a silicon-based anode in lithium-ion half-cells, in order to reduce the capacity fade due to volume expansion and shrinkage upon cycling. Ex situ Raman spectroscopy and impedance spectroscopy are used to deeply investigate the structural and interfacial properties of the material within a single cycle and upon cycling. An effective buffering of the volume changes of the composite electrode is evidenced, even at a high Si content up to 30% in the formulation, resulting in the retention of structural and interfacial integrity. As a result, a high capacity performance and a very good rate capability are displayed even at high current densities, with a stable cycling behavior and low polarization effects.

Dually Cross-Linked Core-Shell Structure Nanohydrogel with Redox-Responsive Degradability for Intracellular Delivery.

A redox-responsive nanocarrier is a promising strategy for the intracellular drug release because it protects the payload, prevents its undesirable leakage during extracellular transport, and favors site-specific drug delivery. In this study, we developed a novel redox responsive core-shell structure nanohydrogel prepared by a water in oil nanoemulsion method using two biocompatible synthetic polymers: vinyl sulfonated poly(N-(2-hydroxypropyl) methacrylamide mono/dilactate)-polyethylene glycol-poly(N-(2-hydroxypropyl) methacrylamide mono/dilactate) triblock copolymer, and thiolated hyaluronic acid. The influence on the nanohydrogel particle size and distribution of formulation parameters was investigated by a three-level full factorial design to optimize the preparation conditions. The surface and core-shell morphology of the nanohydrogel were observed by scanning electron microscope, transmission electron microscopy, and further confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy from the standpoint of chemical composition. The redox-responsive biodegradability of the nanohydrogel in reducing environments was determined using glutathione as reducing agent. A nanohydrogel with particle size around 250 nm and polydispersity index around 0.1 is characterized by a thermosensitive shell which jellifies at body temperature and crosslinks at the interface of a redox-responsive hyaluronic acid core via the Michael addition reaction. The nanohydrogel showed good encapsulation efficiency for model macromolecules of different molecular weight (93% for cytochrome C, 47% for horseradish peroxidase, and 90% for bovine serum albumin), capacity to retain the peroxidase-like enzymatic activity (around 90%) of cytochrome C and horseradish peroxidase, and specific redox-responsive release behavior. Additionally, the nanohydrogel exhibited excellent cytocompatibility and internalization efficiency into macrophages. Therefore, the developed core-shell structure nanohydrogel can be considered a promising tool for the potential intracellular delivery of different pharmaceutical applications, including for cancer therapy.

Electronic Transport Mechanisms Correlated to Structural Properties of a Reduced Graphene Oxide Sponge.

We report morpho-structural properties and charge conduction mechanisms of a foamy "graphene sponge", having a density as low as ≈0.07 kg/m3 and a carbon to oxygen ratio C:O ≃ 13:1. The spongy texture analysed by scanning electron microscopy is made of irregularly-shaped millimetres-sized small flakes, containing small crystallites with a typical size of ≃16.3 nm. A defect density as high as ≃2.6 × 1011 cm-2 has been estimated by the Raman intensity of D and G peaks, dominating the spectrum from room temperature down to ≃153 K. Despite the high C:O ratio, the graphene sponge exhibits an insulating electrical behavior, with a raise of the resistance value at ≃6 K up to 5 orders of magnitude with respect to the room temperature value. A variable range hopping (VRH) conduction, with a strong 2D character, dominates the charge carriers transport, from 300 K down to 20 K. At T < 20 K, graphene sponge resistance tends to saturate, suggesting a temperature-independent quantum tunnelling. The 2D-VRH conduction originates from structural disorder and is consistent with hopping of charge carriers between sp2 defects in the plane, where sp3 clusters related to oxygen functional groups act as potential barriers.

Silver Nanoparticle-Based Sensor for the Selective Detection of Nickel Ions.

Silver nanoparticles (AgNPs) can be used as a surface plasmon resonance (SPR) colorimetric sensor; the correlation between the SPR phenomenon and the aggregation state of nanoparticle allows the real-time detection of a target molecule. Surface functionalization of NPs with proper molecular baits is often performed to establish the selectivity of the sensor. This work reports on the synthesis of AgNPs under reducing conditions and on the functionalization thereof with mercaptoundecanoic acid (11-MUA). UV-VIS Spectroscopy confirmed the formation of AgNPs, eliciting a surface plasmon absorption band (SPAB) at 393 nm that shifted to 417 nm upon surface coating. Dynamic light scattering was used to investigate the surface coatings; moreover, pelleted AgNPs@11MUA nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analyzers (EDX), and infrared spectroscopy to corroborate the presence of 11MUA on the surface. Most interestingly, the resulting AgNPs@11MUA selectively detected micromolar levels of Ni2+, also in the presence of other cations such as Mn2+, Co2+, Cd2+, Cu2+, Zn2+, Fe2+, Hg2+, Pb2+, and Cr3+.

Development of a New Hyaluronic Acid Based Redox-Responsive Nanohydrogel for the Encapsulation of Oncolytic Viruses for Cancer Immunotherapy.

Oncolytic viruses (OVs) are emerging as promising and potential anti-cancer therapeutic agents, not only able to kill cancer cells directly by selective intracellular viral replication, but also to promote an immune response against tumor. Unfortunately, the bioavailability under systemic administration of OVs is limited because of undesired inactivation caused by host immune system and neutralizing antibodies in the bloodstream. To address this issue, a novel hyaluronic acid based redox responsive nanohydrogel was developed in this study as delivery system for OVs, with the aim to protect the OVs following systemic administration. The nanohydrogel was formulated by water in oil (W/O) nanoemulsion method and cross-linked by disulfide bonds derived from the thiol groups of synthesized thiolated hyaluronic acid. One DNA OV Ad[I/PPT-E1A] and one RNA OV Rigvir® ECHO-7 were encapsulated into the developed nanohydrogel, respectively, in view of their potential of immunovirotherapy to treat cancers. The nanohydrogels showed particle size of approximately 300-400 nm and negative zeta potential of around -13 mV by dynamic light scattering (DLS). A uniform spherical shape of the nanohydrogel was observed under the scanning electron microscope (SEM) and transmission electron microscope (TEM), especially, the successfully loading of OV into nanohydrogel was revealed by TEM. The crosslinking between the hyaluronic acid chains was confirmed by the appearance of new peak assigned to disulfide bond in Raman spectrum. Furthermore, the redox responsive ability of the nanohydrogel was determined by incubating the nanohydrogel into phosphate buffered saline (PBS) pH 7.4 with 10 µM or 10 mM glutathione at 37 °C which stimulate the normal physiological environment (extracellular) or reductive environment (intracellular or tumoral). The relative turbidity of the sample was real time monitored by DLS which indicated that the nanohydrogel could rapidly degrade within 10 h in the reductive environment due to the cleavage of disulfide bonds, while maintaining the stability in the normal physiological environment after 5 days. Additionally, in vitro cytotoxicity assays demonstrated a good oncolytic activity of OVs-loaded nanohydrogel against the specific cancer cell lines. Overall, the results indicated that the developed nanohydrogel is a delivery system appropriate for viral drugs, due to its hydrophilic and porous nature, and also thanks to its capacity to maintain the stability and activity of encapsulated viruses. Thus, nanohydrogel can be considered as a promising candidate carrier for systemic administration of oncolytic immunovirotherapy.

A new internally heated diamond anvil cell system for time-resolved optical and x-ray measurements.

We have developed a new internally heated diamond anvil cell (DAC) system for in situ high-pressure and high-temperature x-ray and optical experiments. We have adopted a self-heating W/Re gasket design allowing for both sample confinement and heating. This solution has been seldom used in the past but proved to be very efficient to reduce the size of the heating spot near the sample region, improving heating and cooling rates as compared to other resistive heating strategies. The system has been widely tested under high-temperature conditions by performing several thermal emission measurements. A robust relationship between electric power and average sample temperature inside the DAC has been established up to about 1500 K by a measurement campaign on different simple substances. A micro-Raman spectrometer was used for various in situ optical measurements and allowed us to map the temperature distribution of the sample. The distribution resulted to be uniform within the typical uncertainty of these measurements (5% at 1000 K). The high-temperature performances of the DAC were also verified in a series of XAS (x-ray absorption spectroscopy) experiments using both nano-polycrystalline and single-crystal diamond anvils. XAS measurements of germanium at 3.5 GPa were obtained in the 300 K-1300 K range, studying the melting transition and nucleation to the crystal phase. The achievable heating and cooling rates of the DAC were studied exploiting a XAS dispersive setup, collecting series of near-edge XAS spectra with sub-second time resolution. An original XAS-based dynamical temperature calibration procedure was developed and used to monitor the sample and diamond temperatures during the application of constant power cycles, indicating that heating and cooling rates in the 100 K/s range can be easily achieved using this device.

Band Gap Implications on Nano-TiO2 Surface Modification with Ascorbic Acid for Visible Light-Active Polypropylene Coated Photocatalyst.

The effect of surface modification using ascorbic acid as a surface modifier of nano-TiO2 heterogeneous photocatalyst was studied. The preparation of supported photocatalyst was made by a specific paste containing ascorbic acid modified TiO2 nanoparticles used to cover Polypropylene as a support material. The obtained heterogeneous photocatalyst was thoroughly characterized (scanning electron microscope (SEM), RAMAN, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and Diffuse Reflectance Spectra (DRS) and successfully applied in the visible light photodegradation of Alizarin Red S in water solutions. In particular, this new supported TiO2 photocatalyst showed a change in the adsorption mechanism of dye with respect to that of only TiO2 due to the surface properties. In addition, an improvement of photocatalytic performances in the visible light photodegration was obtained, showing a strict correlation between efficiency and energy band gap values, evidencing the favorable surface modification of TiO2 nanoparticles.

Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH.

The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV-vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study. In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence; at this low pH, increasing the water amount, the acidic form (THPPH2)2+ resulted more stable due to a polar environment with stronger interaction by hydrogen bonding. In basic pH, reached by NH4OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M2THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.

Structural characterization of electrodeposited copper hexacyanoferrate films by using a spectroscopic multi-technique approach.

A deep structural investigation predominantly by X-ray spectroscopic techniques is conducted on films of copper hexacyanoferrate (CuHCF) deposited under different conditions, aimed at establishing structure-properties relationships. We show that the potentiodynamic electrosynthesis of CuHCF on carbon-based surfaces produces a highly disordered material, with a variable amount of Prussian Blue (PB). The subsequent Cu(2+) intercalation induces the partial conversion of PB into CuHCF, which explains the improved electrocatalytic properties after the intercalation process. Both Cu and Fe K-edge data have been recorded. For the sample with the lower amount of PB, we could perform a multiple edge data analysis to determine the local atomic environment around both metal centres using the same set of structural parameters. The presence of high multiplicity Cu-N-C-Fe linear chains has allowed us to determine accurately the local environment of Fe while fitting the Cu K-edge data only. Using this approach we have retrieved structural information around Fe for those samples in which the concomitant presence of PB would have made impossible the analysis of the Fe K-edge. The Fe-C, C-N and Cu-N bond distances have been found in agreement with those of the bulk structures, but higher values of [Fe(CN)(6)] vacancies for the building blocks have been evidenced, reaching a value of ~45% in one sample. XANES, Raman and SEM data agree with the model proposed for each studied electrode.

Nitroimidazole and glucosamine conjugated heteroscorpionate ligands and related copper(II) complexes. Syntheses, biological activity and XAS studies.

New nitroimidazole and glucosamine conjugated heteroscorpionate ligands, namely 2,2-bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl)acetamide (L(MN)) and 1,3,4,6-tetra-O-acetyl-2-{[bis(3,5-dimethyl-1H-pyrazol-1-yl)acetyl]amino}-2-deoxy-ß-D-glucopyranose (L(DAC)), respectively, were synthesized by direct coupling of preformed side chain acid and amine components. The related copper(II) complexes {[(L(MN))(2)Cu]Cl(2)}, and {[(L(DAC))(2)Cu]Cl(2)} have been prepared from the reaction of CuCl(2)*2H(2)O with L(MN) or L(DAC) ligand in methanol solution. Single crystal structural characterization was undertaken for the L(MN) ligand. In the absence of a coordinated metal core, the overall arrangement of the ligand is determined by some loose intra- and inter-molecular nonbonding contacts. X-Ray Absorption Spectroscopy (XAS) has been used to probe the local structure of the two copper(II) complexes, {[(L(MN))(2)Cu]Cl(2)} and {[(L(DAC))(2)Cu]Cl(2)}. The EXAFS analysis has permitted the identification of the local environment of the copper site. Copper interacts with 2 units of ligand in both complexes, and it is found to be 6-fold coordinated. Its local structure is described by four Cu-N and two Cu-O interactions to form a pseudo-octahedron core, with a 0.14 Å lengthening of the Cu-O bond length in the case of L(DAC) complex with respect to the L(MN) one, likely due to the higher steric hindrance of the glucosamine moiety. The XANES analysis agrees with these results, also confirming the Cu(II) formal copper oxidation state for both complexes. The new copper(II) complexes {[(L(MN))(2)Cu]Cl(2)} and {[(L(DAC))(2)Cu]Cl(2)} as well as the corresponding uncoordinated ligands were evaluated for their cytotoxic activity towards a panel of several human tumour cell lines. The results reported here indicate that both copper(II) complexes show similar spectra of cytotoxicity and very low resistance factors (RF < 2) against C13* ovarian cancer cells which have acquired resistance to cisplatin.

A study on the coordinative versatility of new N,S-donor macrocyclic ligands: XAFS, and Cu2+ complexation thermodynamics in solution.

We investigated, both in the solid state and in aqueous solution, the coordination environment and stability behavior of four macrocyclic ligands (three N(2)S(2) and one N(3)S(2)) and of the corresponding Cu(II) complexes. The structural characterization in the solid state of the copper derivatives was performed by X-Ray Absorption Spectroscopy. Copper is found to be 4-fold coordinated with a CuN(2)S(2) environment with different Cu-S distances depending on the size of the macrocyclic ring. The EXAFS technique has indicated that nitrogen and sulfur atoms are more preferable to oxygen atoms as donor systems, without the evidence of coordination of the carboxylic moieties to copper in the first shell. The joint EXAFS and XANES study of the copper(II) complex with the N(3)S(2) ligand confirms the 4-fold coordination with an additional, long Cu-N interaction. The Cu(2+) complexation constants for one ligand were determined in aqueous solution. The results indicate that the species [CuL], although isolated in the solid state, is not the most abundant at the pH of blood serum. Instead, at pH 7.4 the protonated [Cu(HL)](+) species was found to be the most relevant. The behaviour of the copper complexes in the presence of the strong copper chelating bioagent human serum albumin was also examined in order to gain information on the stability of these compounds in biological fluids.

Correlation of AC-impedance and in situ X-ray spectra of LiCoO2.

In-situ X-ray and AC-impedance spectra have been obtained simultaneously during the deintercalation of lithium from LiCoO2 using a specially designed electrochemical cell. The AC-dispersions have been correlated with the cell parameters obtained from the X-ray spectra. The correlation confirms previous hypothesis on the interpretation of the AC-dispersions in terms of an equivalent circuit comprising an element that relates the change of the intrinsic electronic conductivity, occurring at the early stages of deintercalation, to the semiconductor to metal transition caused by the change of the cell parameters.