Origin and Electronic Features of Reactive Oxygen Species at Hybrid Zirconia-Acetylacetonate Interfaces

Indirect daylight oxidative degradation of polyethylene microplastics by a bio-waste modified TiO2-based material

Microplastics are recognized as an emerging critical issue for the environment. Here an innovative chemical approach for the treatment of microplastics is proposed, based on an oxidative process that does not require any direct energy source (irradiation or heat). Linear low-density polyethylene (LLDPE) was selected as target commodity polymer, due to its widespread use, chemical inertness and inefficient recycling. This route is based on a hybrid material coupling titanium oxide with a bio-waste, rosin, mainly constituted by abietic acid, through a simple sol-gel synthesis procedure. The ligand-to-metal charge transfer complexes formed between rosin and Ti4+ allow the generation of reactive oxygen species without UV irradiation for its activation. In agreement with theorical calculations, superoxide radical ions are stabilized at ambient conditions on the surface of the hybrid TiO2. Consequently, an impressive degradation of LLDPE is observed after 1 month exposure in a batch configuration under indirect daylight, as evidenced by the products revealed by gas chromatography-mass spectrometry analysis and by chemical and structural modifications of the polymer surface. In a context of waste exploitation, this innovative and sustainable approach represents a promising cost-effective strategy for the oxidative degradation of microplastics, without producing any toxic by-products.

A Model Eumelanin from 5,6-Dihydroxyindole-2-Carboxybutanamide Combining Remarkable Antioxidant and Photoprotective Properties with a Favourable Solubility Profile for Dermo-Cosmetic Applications

The search for new synthetic melanin-related pigments that maintain the antioxidant and photoprotective properties of naturally occurring dark eumelanins, while overcoming their unfavorable solubility, and molecular heterogeneity is presently a very active issue for dermo-cosmetic purposes. In this work, we explored the potential of a melanin obtained from the carboxybutanamide of a major eumelanin biosynthetic precursor, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), by aerobic oxidation under slightly alkaline conditions. Analysis of the pigment by EPR, ATR-FTIR and MALDI MS indicated a substantial structural similarity to DHICA melanin, while investigation of the early intermediates confirmed unchanged regiochemistry of the oxidative coupling. The pigment exhibited a UVA-visible absorption even more intense than that of DHICA melanin, and a noticeable solubility in polar solvents of dermo-cosmetic relevance. The hydrogen- and/or electron-donor ability, and the iron (III) reducing power as determined by conventional assays provided evidence for marked antioxidant properties not merely ascribable to the more favorable solubility profile, while the inhibitory action of the radical- or photosensitized solar light-induced lipid peroxidation was more marked compared to that of DHICA melanin. Overall, these results hint at this melanin, which remarkable properties are, in part, due to the electronic effects of the carboxyamide functionality as a promising functional ingredient for dermo-cosmetic formulations.

ROS-Generating Hyaluronic Acid-Modified Zirconium Dioxide-Acetylacetonate Nanoparticles as a Theranostic Platform for the Treatment of Osteosarcoma

Materials that are able to produce free radicals have gained increasing attention for environmental and biomedical purposes. Free radicals, such as the superoxide anion (O₂^•-), act as secondary messengers in many physiological pathways, such as cell survival. Therefore, the production of free radicals over physiological levels has been exploited in the treatment of different types of cancer, including osteosarcoma (OS). In most cases, the production of reactive oxygen species (ROS) by materials is light-induced and requires the use of chemical photosensitisers, making it difficult and expensive. Here, for the first time, we propose photoluminescent hybrid ZrO₂-acetylacetonate nanoparticles (ZrO₂-acac NPs) that are capable of generating O₂^•- without light activation as an adjuvant for the treatment of OS. To increase the uptake and ROS generation in cancer cells, we modify the surface of ZrO₂-acac NPs with hyaluronic acid (HA), which recognizes and binds to the surface antigen CD44 overexpressed on OS cells. Since these nanoparticles emit in the visible range, their uptake into cancer cells can be followed by a label-free approach. Overall, we show that the generation of O₂^•- is toxic to OS cells and can be used as an adjuvant treatment to increase the efficacy of conventional drugs.

Azide-functionalized ligand enabling organic–inorganic hybrid dielectric for high-performance solution-processed oxide transistors

We propose a highly efficient crosslinking strategy for organic–inorganic hybrid dielectric layers using azide-functionalized acetylacetonate, which covalently connect inorganic particles to polymers, enabling highly efficient inter- and intra-crosslinking of organic and inorganic inclusions, resulting in a dense and defect-free thin-film morphology. From the optimized processing conditions, we obtained an excellent dielectric strength of over 4.0 MV cm⁻¹, a high dielectric constant of ~14, and a low surface energy of 38 mN m⁻¹. We demonstrated the fabrication of exceptionally high-performance, hysteresis-free n-type solution-processed oxide transistors comprising an In₂O₃/ZnO double layer as an active channel with an electron mobility of over 50 cm² V⁻¹ s⁻¹, on/off ratio of ~10⁷, subthreshold swing of 108 mV dec⁻¹, and high bias-stress stability. From temperature-dependent I–V analyses combined with charge transport mechanism analyses, we demonstrated that the proposed hybrid dielectric layer provides percolation-limited charge transport for the In₂O₃/ZnO double layer under field-effect conditions.

Low cost and low power consumption of transistors are needed for the development of internet of things. Here Chung et al. develop a high performance n-type oxide thin film transistor by introducing a ligand for crosslinking nanoparticles and polymers, obtaining a near-ideal hybrid dielectric layer.

Recovery of Lignins with Potent Antioxidant Properties from Shells of Edible Nuts by a Green Ball Milling/Deep Eutectic Solvent (DES)-Based Protocol

Lignins are phenolic polymers endowed with potent antioxidant properties that are finding increasing applications in a variety of fields. Consequently, there is a growing need for easily available and sustainable sources, as well as for green extraction methodologies of these compounds. Herein, a ball milling/deep eutectic solvent (DES)-based treatment is reported as an efficient strategy for the recovery of antioxidant lignins from the shells of edible nuts, namely chestnuts, hazelnuts, peanuts, pecan nuts, and pistachios. In particular, preliminarily ball-milled shells were treated with 1:2 mol/mol choline chloride:lactic acid at 120 °C for 24 h, and the extracted material was recovered in 19–27% w/w yields after precipitation by the addition of 0.01 M HCl. Extensive spectroscopic and chromatographic analysis allowed for confirmation that the main phenolic constituents present in the shell extracts were lignins, accompanied by small amounts (0.9% w/w) of ellagic acid, in the case of chestnut shells. The recovered samples exhibited very promising antioxidant properties, particularly in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC₅₀ values ranging from 0.03 to 0.19 mg/mL). These results open new perspectives for the valorization of nut shells as green sources of lignins for applications as antioxidants, e.g., in the biomedical, food, and/or cosmetic sector.

Replacement of Cobalt in Lithium-Rich Layered Oxides by n-Doping: A DFT Study

The replacement of cobalt in the lattice of lithium-rich layered oxides (LRLO) is mandatory to improve their environmental benignity and reduce costs. In this study, we analyze the impact of the cobalt removal from the trigonal LRLO lattice on the structural, thermodynamic, and electronic properties of this material through density functional theory calculations. To mimic disorder in the transition metal layers, we exploited the special quasi-random structure approach on selected supercells. The cobalt removal was modeled by the simultaneous substitution with Mn/Ni, thus leading to a p-doping in the lattice. Our results show that cobalt removal induces (a) larger cell volumes, originating from expanded distances among stacked planes; (b) a parallel increase of the layer buckling; (c) an increase of the electronic disorder and of the concentration of Jahn–Teller defects; and (d) an increase of the thermodynamic stability of the phase. Overall p-doping appears as a balanced strategy to remove cobalt from LRLO without massively deteriorating the structural integrity and the electronic properties of LRLO.

Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

Acid Treatment Enhances the Antioxidant Activity of Enzymatically Synthesized Phenolic Polymers

Phenolic polymers produced by enzymatic oxidation under biomimetic and eco-friendly reaction conditions are usually endowed with potent antioxidant properties. These properties, coupled with the higher biocompatibility, stability and processability compared to low-molecular weight phenolic compounds, open important perspectives for various applications. Herein, we report the marked boosting effect of acid treatment on the antioxidant properties of a series of polymers obtained by peroxidase-catalyzed oxidation of natural phenolic compounds. Both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated a remarkable increase in the antioxidant properties for most phenolic polymers further to the acid treatment. In particular, up to a ca. 60% decrease in the EC50 value in the DPPH assay and a 5-fold increase in the Trolox equivalents were observed. Nitric oxide- and superoxide-scavenging assays also indicated highly specific boosting effects of the acid treatment. Spectroscopic evidence suggested, in most cases, that the occurrence of structural modifications induced by the acid treatment led to more extended π-electron-conjugated species endowed with more efficient electron transfer properties. These results open new perspectives toward the design of new bioinspired antioxidants for application in food, biomedicine and material sciences.

Analysis of the Phase Stability of LiMO2 Layered Oxides (M = Co, Mn, Ni)

Transition-metal (TM) layered oxides have been attracting enormous interests in recent decades because of their excellent functional properties as positive electrode materials in lithium-ion batteries. In particular LiCoO2 (LCO), LiNiO2 (LNO) and LiMnO2 (LMO) are the structural prototypes of a large family of complex compounds with similar layered structures incorporating mixtures of transition metals. Here, we present a comparative study on the phase stability of LCO, LMO and LNO by means of first-principles calculations, considering three different lattices for all oxides, i.e., rhombohedral (hR12), monoclinic (mC8) and orthorhombic (oP8). We provide a detailed analysis—at the same level of theory—on geometry, electronic and magnetic structures for all the three systems in their competitive structural arrangements. In particular, we report the thermodynamics of formation for all ground state and metastable phases of the three compounds for the first time. The final Gibbs Energy of Formation values at 298 K from elements are: LCO(hR12) −672 ± 8 kJ mol−1; LCO(mC8) −655 ± 8 kJ mol−1; LCO(oP8) −607 ± 8 kJ mol−1; LNO(hR12) −548 ± 8 kJ mol−1; LNO(mC8) −557 ± 8 kJ mol−1; LNO(oP8) −548 ± 8 kJ mol−1; LMO(hR12) −765 ± 10 kJ mol−1; LMO(mC8) −779 ± 10 kJ mol−1; LMO(oP8) −780 ± 10 kJ mol−1. These values are of fundamental importance for the implementation of reliable multi-phase thermodynamic modelling of complex multi-TM layered oxide systems and for the understanding of thermodynamically driven structural phase degradations in real applications such as lithium-ion batteries.

Antioxidant Properties of Agri-food Byproducts |and Specific Boosting Effects of Hydrolytic Treatments

Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated the superior activity of pomegranate peels and seeds, grape pomace and pecan nut shell. An increase in the antioxidant potency was observed for most of the waste materials following a hydrolytic treatment, with the exception of the condensed tannin-rich pecan nut shell and grape pomace. UV-Vis and HPLC investigation of the soluble fractions coupled with the results from IR analysis and chemical degradation approaches on the whole materials allowed to conclude that the improvement of the antioxidant properties was due not only to removal of non-active components (mainly carbohydrates), but also to structural modifications of the phenolic compounds. Parallel experiments run on natural and bioinspired model phenolic polymers suggested that these structural modifications positively impacted on the antioxidant properties of lignins and hydrolyzable tannins, whereas significant degradation of condensed tannin moieties occurred, likely responsible for the lowering of the reducing power observed for grape pomace and pecan nut shell. These results open new perspectives toward the exploitation and manipulation of agri-food byproducts for application as antioxidant additives in functional materials.

Pecan (Carya illinoinensis (Wagenh.) K. Koch) Nut Shell as an Accessible Polyphenol Source for Active Packaging and Food Colorant Stabilization

Herein, the antioxidant and food stabilizing properties of a pecan nut shell (PNS) hydroalcoholic extract (PNSE) are reported. Chemical degradation of PNSE demonstrated the presence of condensed tannins as the main phenolic components. PNSE showed remarkable antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC₅₀ = 0.004 mg/mL). PNSE was initially tested as an inhibitor of mushroom tyrosinase, exhibiting a quite low IC₅₀ value (0.055 mg/mL) against the enzyme diphenolase activity, suggesting its use in enzymatic browning inhibition. The anthocyanin stabilization properties were evaluated under accelerated aging conditions of both pure pigments and commercial fruit juices, and PNSE was found to be effective at concentrations (0.05 mg/mL) at which well-known stabilizers such as chlorogenic and ferulic acids proved to fail. PNSE also performed well in the stabilization of spray-dried anthocyanins for use as a food colorant, increasing the half-life of blackberry anthocyanins up to 20%. In order to explore the possibility of using PNSE as a functional additive for active packaging, polylactic acid (PLA) films containing PNSE were prepared by solvent casting, and no substantial alteration of the mechanical properties was found on addition of the extract up to 10% w/w. The films showed remarkable antioxidant properties (DDPH reduction >60% with a 3% w/w loading, at a dose of 1 mg/mL in the DPPH solution) and delayed the onset of browning of apple smoothies (ca. 30% inhibition with a 10% w/w loading). These results highlight the exploitation of PNS as a low-cost polyphenol source for food industry applications.

Three-year lifetime and regeneration of superoxide radicals on the surface of hybrid TiO2 materials exposed to air

The generation and stabilization of reactive oxygen species (ROS), including the superoxide radical anion (O₂^-), have a huge potential in environmental remediation and industrial chemical processes, but they still remain a challenge. Here, we elucidate the formation, stability and reactivity of superoxide radicals spontaneously produced on the surface of a hybrid TiO₂-acetylacetonate material exposed to air. EPR spectra reveal an exceptional lifetime (up to three years, in air at room temperature) of the adsorbed O₂^-, which can also be easily regenerated after its decay. The performances of this material in the degradation of organic pollutants in aqueous solution without any light irradiation indicate a heterogeneous catalytic mechanism, mediated by superoxide radicals, with a synergistic homogeneous action of hydroxyl radicals (OH), which are released in solution, as detected by the EPR spin trapping method. The regeneration ability of the adsorbed superoxide radicals by simple exposure to air counteracts the partial instability in aqueous environment of the organic component of the hybrid structure allowing the catalyst reuse. These structural and functional features joined to the simple preparation route open a new perspective in the field of advanced oxidation processes for hybrid TiO₂ materials.

Photosensitive Hybrid Nanostructured Materials: The Big Challenges for Sunlight Capture

Solar radiation is becoming increasingly appreciated because of its influence on living matter and the feasibility of its application for a variety of purposes. It is an available and everlasting natural source of energy, rapidly gaining ground as a supplement and alternative to the nonrenewable energy feedstock. Actually, an increasing interest is involved in the development of efficient materials as the core of photocatalytic and photothermal processes, allowing solar energy harvesting and conversion for many technological applications, including hydrogen production, CO2 reduction, pollutants degradation, as well as organic syntheses. Particularly, photosensitive nanostructured hybrid materials synthesized coupling inorganic semiconductors with organic compounds, and polymers or carbon-based materials are attracting ever-growing research attention since their peculiar properties overcome several limitations of photocatalytic semiconductors through different approaches, including dye or charge transfer complex sensitization and heterostructures formation. The aim of this review was to describe the most promising recent advances in the field of hybrid nanostructured materials for sunlight capture and solar energy exploitation by photocatalytic processes. Beside diverse materials based on metal oxide semiconductors, emerging photoactive systems, such as metal-organic frameworks (MOFs) and hybrid perovskites, were discussed. Finally, future research opportunities and challenges associated with the design and development of highly efficient and cost-effective photosensitive nanomaterials for technological claims were outlined.

Interfacial electronic features in methyl-ammonium lead iodide and p-type oxide heterostructures: new insights for inverted perovskite solar cells

First-principles simulations unveil the interface electronic structures of MAPI/NiO and MAPI/CuGaO₂ heterojunctions in inverted perovskite solar cells.

Titanium based complexes with melanin precursors as a tool for directing melanogenic pathways

Bioinspired melanin based hybrid materials hold huge promise for developing multifunctional systems for a considerable set of applications. Yet, control of melanogenic pathway is a big challenge to allow rational design of nanostructured systems with tuned structures and improved properties. This study proves the ability of titanium ions interactions with melanin precursors in directing melanogenic pathway. To this purpose complementary spectroscopic evidences were collected to reveal that in the presence of a TiO2-sol, amino-acid complex of Ti(IV) ions and DOPA actually inhibits its cyclization, during oxidative process, thus leading to DOPA-based polyphenols, stable even in oxidative environment, rather than eumelanin. This hugely impacts on the biological properties of the final hybrid systems which, discloses relevant and durable antioxidant behavior but poor antimicrobial activity differently from DHICA-based hybrid nanostructures. Overall this study, discloses the high potential of ceramic templated approach in combination with the selection of melanin precursor in achieving a fine tuning of physico-chemical as well as bioactivity of melanin-TiO2 nanostructures, opening new scenarios towards the design of cutting-edge biomaterials with tailored biological properties.

Citric Acid Tunes the Formation of Antimicrobial Melanin-Like Nanostructures

Nature has provided a valuable source of inspiration for developing high performance multifunctional materials. Particularly, catechol-containing amino acid l-3,4-dihydroxyphenylalanine (l-DOPA) has aroused the interest to design hybrid multifunctional materials with superior adhesive ability. DOPA oxidative polymerization mediated by either melanogenic enzymes or an alkaline environment involving catechol intermolecular cross-linking, ultimately leads to melanin oligomers. Recently, relevant studies disclosed the ability of Ti-based nanostructures to tune melanin's supramolecular structure during its formation, starting from melanogenic precursors, thus improving both antioxidant and antimicrobial properties. In this work, we propose a novel biomimetic approach to design hybrid DOPA melanin-like nanostructures through a hydrothermal synthesis opportunely modified by using citric acid to control hydrolysis and condensation reactions of titanium alkoxide precursors. UV-Vis and Electron paramagnetic resonance (EPR) spectroscopic evidences highlighted the key role of citrate-Ti(IV) and DOPA-Ti(IV) complexes in controlling DOPA polymerization, which specifically occurred during the hydrothermal step, mediating and tuning its conversion to melanin-like oligomers. Trasmission electron microscopy (TEM) images proved the efficacy of the proposed synthesis approach in tuning the formation of nanosized globular nanostructures, with high biocide performances. The obtained findings could provide strategic guidelines to set up biomimetic processes, exploiting the catechol-metal complex to obtain hybrid melanin-like nanosystems with optimized multifunctional behavior.

Seasonal and pharmaceutical-induced changes in selenoprotein glutathione peroxidase 4 activity in the reproductive dynamics of the soil biosentinel Podarcis sicula (Chordata: Reptilia)

There is rising concern for the interaction of environmental contaminants with brain transcriptome and the potential effect on reproductive processes. The present study sought to determine selenoprotein glutathione peroxidase 4 (gpx4) transcriptional activity in the brain and testis of the soil biosentinel, Podarcis sicula, through the main phases of the reproductive cycle and whether pharmaceuticals exert an endocrine disruption. Based on gpx4 cloned amminoacids sequence (GenBank AEX09236.1.), we used a bioinformatic approach to assess the structural role. Specifically, we detected seasonally the reactive oxygen species (ROS) level using electron spin resonance spectroscopy and gpx4 transcriptional activity using quantitative real-time polymerase chain reaction. In addition, the impact of pharmaceuticals was assessed after 21-days of treatment with ICI 182,780 and human chorionic gonadotropin administration in mating and winter stasis, respectively. Bioinformatic data shows the gpx4 proteic activity and a phylogenetic profile. ROS contents in lizard brain are significantly less than in testis and display higher levels after treatments. Brain gpx4 expression gives statistically significant seasonal differences, opposite trends in testis and altered expression in both tissues, with evidence of testis morphological and DNA disruption. Taken together, these results provide direct evidence that gpx4 in P. sicula plays a seasonal regulatory role and may be a reliable biomarker for reproductive health toxicity screening.

Effects of Natural Antioxidant Agents on the Bitumen Aging Process: An EPR and Rheological Investigation

Bitumen aging is the major factor contributing to the deterioration of the road pavement. Oxidation and volatilization are generally considered as the most important phenomena affecting aging in asphalt paving mixtures. The present study was carried out to investigate whether various antioxidants provided by natural resources such as phospholipids, ascorbic acid as well as lignin from rice husk, could be used to reduce age hardening in asphalt binders. A selected bituminous material was modified by adding 2% w/w of the anti-aging natural additives and subjected to accelerated oxidative aging regimes according to the Rolling Thin Film Oven Test (RTFOT) method. The effects of aging were evaluated based on changes in sol-gel transition temperature of modified bitumens measured through Dynamic Shear Rheology (DSR). Moreover, changes of Electron Paramagnetic Resonance (EPR) spectra were monitored on the bituminous fractions asphaltene and maltene separated by solvent extraction upon oxidative aging. The phospholipids-treated binder exhibited the highest resistance to oxidation and the lowest age-hardening effect compared to the other tested anti-oxidants. The combination of EPR and DSR techniques represents a promising method for elucidating the changes in associated complex properties of bitumen fractions promoted by addition of free radical scavengers borrowed by green resources.

Electron Spin Resonance (ESR) for the study of Reactive Oxygen Species (ROS) on the isolated frog skin (Pelophylax bergeri): A non-invasive method for environmental monitoring

BACKGROUND

Reactive oxygen species (ROS) in biological tissues of elected biosentinels represent an optimal biomarker for eco-monitoring of polluted areas. Electron spin resonance (ESR) is the most definitive method for detecting, quantifying and possibly identifying radicals in complex systems.

OBJECTIVE

A non-invasive method for monitoring polluted areas by the quantitative determination of ROS in frog skin biopsy is presented.

METHODS

We assessed by ESR spectroscopy the ROS level in adult male of Pelophylax bergeri, specie not a risk of extinction, collected from the polluted Sarno River (SA, Italy) basin. The spin-trap ESR method was validated by immunohistochemical analysis of the well-assessed pollution biomarkers cytochrome P450 aromatase 1A (CYP1A) and glutathione S-transferase (GST), and by determining the poly(ADPribose) polymerase (PARP) and GST enzymatic activity.

RESULTS

ROS concentration in skin samples from frogs collected in the polluted area is significantly higher than that determined for the unpolluted reference area. Immunohistochemical analysis of CYP1A and GST supported the reliability of our approach, even in the absence of evident morphological and ultrastructural differences. PARP activity assay, connected to possible oxidative DNA damage, and the detoxification index by GST enzymatic assay give statistically significant evidence that higher levels of ROS are associated to alterations of the different biomarkers.

CONCLUSIONS

ROS concentration, measured by ESR on isolated frog skin, through the presented non-lethal method, is a reliable biomarker for toxicity screening and represents a useful basic datum for future modelling studies on environmental monitoring and biodiversity loss prevention.

Reactive oxygen species and glutathione antioxidants in the testis of the soil biosentinel Podarcis sicula (Rafinesque 1810)

Important toxicological achievements have been made during the last decades using reptiles. We focus our investigation on gonadal reproductive health of the soil biosentinel Podarcis sicula which is very sensitive to endocrine-disrupting chemicals. The aim of this study is to quantitatively detect, by sensitive microassays, reactive oxygen species and the glutathione antioxidants in the testis and investigate if they are differentially expressed before and after remediation of a site of the "Land of Fires" (Campania, Italy) subject to illicit dumping of unknown material. The oxidative stress level was evaluated by electron spin resonance spectroscopy applying a spin-trapping procedure able to detect products of lipid peroxidation, DNA damage and repair by relative mobility shift, and poly(ADP-ribose) polymerase enzymatic activity, respectively, the expression of glutathione peroxidase 4 transcript by real-time quantitative PCR analysis, the antioxidant glutathione S-transferase, a well-assessed pollution index, by enzymatic assay and the total soluble antioxidant capacity. Experimental evidences from the different techniques qualitatively agree, thus confirming the robustness of the combined experimental approach. Collected data, compared to those from a reference unpolluted site constitute evidence that the reproductive health of this lizard is impacted by pollution exposure. Remediation caused significant reduction of reactive oxygen species and downregulation of glutathione peroxidase 4 mRNAs in correspondence of reduced levels of glutathione S-transferase, increase of antioxidant capacity, and repair of DNA integrity. Taken together, our results indicate directions to define new screening approaches in remediation assessment.

Bioinspired hybrid eumelanin–TiO2 antimicrobial nanostructures: the key role of organo–inorganic frameworks in tuning eumelanin's biocide action mechanism through membrane interaction

Intrinsic biocide efficacy of eumelanins can be markedly enhanced through a templated formation in the presence of a TiO₂-sol, leading to hybrid TiO₂–melanin nanostructures. However, mechanisms and processes behind biocide activity still remain poorly understood. This paper discloses the fundamental mechanism of action of these systems providing mechanistic information on their peculiar interaction with Escherichia coli strains. To this purpose biocide characterization is combined with Electron Paramagnetic Resonance (EPR) spectroscopy to investigate radical species produced by the hybrids as well as their interactions with Gram(−) external bacterial membranes. Experimental results indicate that TiO₂ mediated eumelanin polymerization leads to a peculiar mechanism of action of hybrid nanostructures, whose strong interactions with bacterial membranes enhance the action of reactive oxygen species (ROS) produced by eumelanin degradation itself, also concurring with the final biocide action. These findings provide strategic information for the development of eumelanin-based systems with enhanced activity against drug-resistant strains.

Hybrid TiO₂/eumelanin nanostructures showed a peculiar biocide mechanism against Gram(−) bacteria, based on the ROS action, produced by eumelanin degradation under visible light irradiation, and the interactions with external bacterial membranes.

Structure and dynamics of cetyltrimethylammonium chloride-sodium dodecylsulfate (CTAC-SDS) catanionic vesicles: High-value nano-vehicles from low-cost surfactants

HYPOTHESIS

Catanionic vesicles based on large-scale produced surfactants represent a promising platform for the design of innovative, effective and relatively inexpensive nano-vehicles for a variety of actives. Structural, dynamic and functional behavior of these aggregates is finely tuned by the molecular features of their components and can be opportunely tailored for their applications as drug carriers.

EXPERIMENTS

Here we investigate the aggregates formed by CTAC and SDS, two of the most diffused surfactants, by means of Dynamic Light Scattering, Small Angle Neutron Scattering and Electron Paramagnetic Resonance spectroscopy (EPR). The exploitation of these aggregates as nano-vehicles is explored using the poorly water-soluble antioxidant trans-resveratrol (t-RESV), testing t-RESV solubility and antioxidant activity by means of UV, fluorescence spectroscopy and EPR.

FINDINGS

The presence of a large stability region of catanionic vesicles on the CTAC-rich side of the phase diagram is highlighted and interpreted in terms of the mismatch between the lengths of the surfactant tails and of first reported effects of the chloride counterions. CTAC-SDS vesicles massively solubilize t-RESV, which in catanionic vesicles exerts a potent antioxidant and radical-scavenging activity. This behavior arises from the positioning of the active at the surface of the vesicular aggregates thus being sufficiently exposed to the external medium.

Metal Acetylacetonate Series in Interface Engineering for Full Low-Temperature-Processed, High-Performance, and Stable Planar Perovskite Solar Cells with Conversion Efficiency over 16% on 1 cm2 Scale

A series of metal acetylacetonates produced by a full low-temperature (below 100 °C) process are successfully employed to obtain both "multistable" and high-performance planar-inverted perovskite solar cells. All the three kinds of champion cells in small area exhibit over 18% in conversion-efficiency with negligible hysteresis, along with a conversion efficiency above 16% for planar PSCs in an aperture area of over 1 cm² .

Electronic properties of TiO2-based materials characterized by high Ti3+ self-doping and low recombination rate of electron–hole pairs

Ti³⁺ self-doped black titania is obtained by a simple annealing in air without harsh conditions nor external reducing agents.

Hybrid TiO2–acetylacetonate amorphous gel-derived material with stably adsorbed superoxide radical active in oxidative degradation of organic pollutants

˙O₂⁻superoxide radicals are firmly adsorbed on the surface of the hybrid material giving oxidative degradation without any light irradiation.