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The importance of 3D printable hydrogels is constantly increasing in the field of tissue engineering, due to their characteristic structure and similarity with the human body extracellular matrix (ECM). Herein, Quinizarin-based bioderived photoactive dyes were employed for the 3D printing of methacrylated chitosan by vat photopolymerization (VPP). Dyes are commonly needed in VPP to obtain good resolution avoiding the light scattering in the vat, here the bioderived molecules had further utility granting the printability with good resolution while acting both as photosensitizers and fillers/crosslinkers. Defined and detailed architectures in the range of millimetres were obtained with low printing times showing for the first time the possibility to obtain all-chitosan 3D structures with suspended features by Digital Light Processing (DLP), which is a form of vat photopolymerization; such a result is not achievable without the quinizarin-derived dyes. The same structures were achieved with an optimized concentration of poly(ethylene glycol) diacrylate, as a comparison, enhancing the resolution. For all the formulations, the important feature to obtain the gel printability (considering reactiveness, viscosity, shear thinning behaviour, mechanical properties and stability) were evaluated. The hydrogels mechanical characterization and swelling properties were also tested and reported. Lastly, the possible application in tissue engineering was also evaluated through cell proliferation analysis over samples, including metabolic activity and DNA contempt assays. The use of such bioderived photoactive molecules that simultaneously act as photosensitizer enhancing the ink reactivity, as dye improving the definition of the final structures and as filler/crosslinker increasing the mechanical stability, could represent a valuable route for the DLP printing of soft hydrogels., Dr. Davy-Louis Versace would like to thank UPEC, CNRS and French National Agency for their financial support. He would also thank Prof. Vlasta Brezova for EPR investigations. Paula Bosch, Enrique MartinezCampos and Raquel Cue-Lopez thank European Union (Nextgeneration EU), and CSIC Interdisciplinary Thematic Platform Salud Global+ (PTISALUDGLOBAL+) for financial suppor

Nowadays, Li–S batteries are considered as one of the most promising alternatives to Li-ion technology in the near future, thanks to their high specific capacity and their significantly lower environmental impact and production costs. Consequently, many efforts have been directed to tackle with the inherent issues that affect Li–S batteries. One of the main problems is the so-called shuttle effect, which basically entails the unwanted migration of lithium polysulfides (LiPSs) from the cathode to the anode side, causing the degradation of the cell. Here, we report an effective strategy to restrain the shuttle effect and increase the kinetics at the cathode of the lithium–sulfur (Li–S) battery. A functional layer including high entropy oxides (HEO) coated onto the sulfur cathode allows to exploit the HEOs capability as promoter catalysts for the conversion of LiPSs. Pure HEO powders are synthesized by fast, highly efficient microwave irradiation, followed by heat treatment at 930 °C. The formation of highly crystalline HEO is confirmed by X-ray diffraction analysis. The LiPSs adsorption capability of HEO is evaluated by UV–vis and X-ray photoelectron spectroscopy analyses. The effect of the HEO-coated sulfur cathode on the electrochemical performance of the Li–S battery is studied by cyclic voltammetry and galvanostatic charge/discharge. The cell with double-coated cathode delivers an initial discharge capacity of 1173 mAh/g at C/10 with 45% capacity retention over 500 cycles at C/5, approaching ~ 99% coulombic efficiency. Graphical abstract

Light processable natural polymers are highly attractive for 3D printing of biomedical hydrogels with defined geometries and sizes. However, functionalization with photo-curable groups, such as methacrylate or acrylate groups, is required. Here, we investigated a microwave-assisted process for methacrylation of chitosan to replace conventional methacrylation processes that can be time consuming and tedious. The microwave-assisted methacrylation reaction was optimized by varying the synthesis parameters such as the molar ratio of chitosan to the methacrylic agent, the launch and reaction times and process temperature. The optimized process was fast and efficient and allowed tuning of the degree of substitution and thereby the final hydrogel properties. The successful methacrylation and degree of substitution were verified by 1H NMR and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The influence of the degree of methacrylation on photo-rheology, mechanical stiffness, swelling degree and gel content was evaluated. Furthermore, favourable 3D printability, enzymatic degradability, biocompatibility, cell migration and proliferation were demonstrated giving promise for further applications in tissue engineering.

Zinc oxide nanoparticles (ZnO NPs) are currently among the most promising nanomaterials for theranostics. However, they suffer from some drawbacks that could prevent their application in nanomedicine as theranostic agents. The doping of ZnO NPs can be effectively exploited to enhance the already-existing ZnO properties and introduce completely new functionalities in the doped material. Herein, we propose a novel synthetic approach for iron-doped ZnO (Fe:ZnO) NPs as a multifunctional theranostic nanoplatform aimed at cancer cell treatment. Pure ZnO and Fe:ZnO NPs, with two different levels of iron doping, were synthesized by a rapid wet-chemical method and analyzed in terms of morphology, crystal structure and chemical composition. Interestingly, Fe:ZnO NPs featured bioimaging potentialities thanks to superior optical properties and novel magnetic responsiveness. Moreover, iron doping provides a way to enhance the electromechanical behavior of the NPs, which are then expected to show enhanced therapeutic functionalities. Finally, the intrinsic therapeutic potentialities of the NPs were tested in terms of cytotoxicity and cellular uptake with both healthy B lymphocytes and cancerous Burkitt’s lymphoma cells. Furthermore, their biocompatibility was tested with a pancreatic ductal adenocarcinoma cell line (BxPC-3), where the novel properties of the proposed iron-doped ZnO NPs can be potentially exploited for theranostics.

In this work, it is proposed an environmental friendly sonophotocatalytic approach to efficiently treat polluted waters from industrial dyes exploiting ZnO micro- and nano-materials. For the first time, we deeply investigated the generation of reactive oxygen species (ROS) under ultrasound stimulation of different ZnO structures by Electron Paramagnetic Resonance Spectroscopy (EPR). Indeed, five zinc oxide (ZnO) micro- and nano-structures, i.e. Desert Roses (DRs), Multipods (MPs), Microwires (MWs), Nanoparticles (NPs) and Nanowires (NWs), were studied for the Rhodamine B (RhB) sonodegradation under ultrasonic irradiation. The DRs microparticles demonstrated the best sonocatalytic performance (100% degradation of RhB in 180 min) and the highest OH· radicals generation under ultrasonic irradiation. Strikingly, the coupling of ultrasound and sun-light irradiation in a sonophotodegradation approach led to 100% degradation efficiency, i.e. color reduction, of RhB in just 10 min, revealing a great positive synergy between the photocatalytic and sonocatalytic mechanisms. The RhB sonophotocatalytic degradation was also evaluated at different initial dye concentrations and with the presence of anions in solution. It was demonstrated a good stability over repeated cycles of dye treatment, which probe the applicability of this technique with industrial effluents. In conclusion, sonophotocatalytic degradation synergizing sunlight and ultrasound in the presence of DRs microparticles shows a great potential and a starting point to investigate further the efficient treatment of organic dyes in wastewater.

The need to reduce the costs of renewable energy sources such as (bio)electrochemical systems, has pushed the research towards alternative materials, especially for cathodes performing the oxygen reduction reaction, trying to maintain a catalytic efficiency close to that of platinum or platinum-based catalysts. In this work, at first, we present a manganese oxide-based catalyst in the form of xerogel, providing a complete description of the material. Later on, we present the comparison of two nanostructured manganese oxide-based catalysts, prepared from the same precursor, manganese acetate, but with different templating agents and with two different nanostructures: the xerogel previously discussed, and the nanofibers. With these two nanostructures, we prepared carbon-based electrodes, obtaining cathodes to be tested in microbial fuel cells. One of these cathodes performed very well and its performance was comparable to that of the reference which used Pt/C as catalyst.

In this study, we report on the facile synthesis of a novel electrocatalysts for the oxygen reduction reaction (ORR), based on reduced graphene oxide (RGO), functionalized with metallic and non-metallic elements. In particular, thanks to a fast one-pot microwave-assisted procedure, we induced, in the RGO graphene lattice, a combined doping with nitrogen and sulphur, and the simultaneous decoration with antimony oxide nanocrystals. The multi-doped–decorated material shows enhanced catalytic performance towards ORR, with respect to common nitrogen- or sulphur-doped carbon-based materials. The presence of co-doping is confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy analysis. The detailed electrochemical characterization shows the simultaneous effects of dopant atoms on the catalytic behavior. In particular, the importance of nitrogen and sulphur atoms in driving the oxygen absorption, together with the role of antimony in enhancing the electrochemical performance toward the ORR, are discussed.

The discovery of novel catalytic materials showing unprecedented properties and improved functionalities represents a major challenge to design advanced oxidation processes for wastewater purification. In this work, antimony (Sb) doping is proposed as a powerful approach for enhancing the photo- and piezocatalytic performances of piezoelectric zinc oxide (ZnO) thin films. To investigate the role played by the dopant, the degradation of Rhodamine-β (Rh-β), a dye pollutant widely present in natural water sources, is studied when the catalyst is irradiated by ultraviolet (UV) light or ultrasound (US) waves. Depending on the doping level, the structural, optical, and ferroelectric properties of the catalyst can be properly set to maximize the dye degradation efficiency. Independently of the irradiation source, the fastest and complete dye degradation is observed in the presence of the doped catalyst and for an optimal amount of the inserted dopant. Among ZnO:Sb samples, the most doped one (5 at. %) shows improved UV light absorption and photocatalytic properties. Conversely, the piezocatalytic efficiency is maximized using the lowest Sb amount (1 at. %). The superior ferroelectric polarization observed in this case highly favors the adsorption of electrically charged species, in particular of the dye in the protonated form (Rh-β+) and of OH-, to the catalyst surface and the production of hydroxyl radicals responsible for dye degradation.

Oxidative stress represents a common issue in most neurological diseases, causing severe impairments of neuronal cell physiological activity that ultimately lead to neuron loss of function and cellular death. In this work, lipid-coated polydopamine nanoparticles (L-PDNPs) are proposed both as antioxidant and neuroprotective agents, and as a photothermal conversion platform able to stimulate neuronal activity. L-PDNPs showed the ability to counteract reactive oxygen species (ROS) accumulation in differentiated SH-SY5Y, prevented mitochondrial ROS-induced dysfunctions and stimulated neurite outgrowth. Moreover, for the first time in the literature, the photothermal conversion capacity of L-PDNPs was used to increase the intracellular temperature of neuron-like cells through near-infrared (NIR) laser stimulation, and this phenomenon was thoroughly investigated using a fluorescent temperature-sensitive dye and modeled from a mathematical point of view. It was also demonstrated that the increment in temperature caused by the NIR stimulation of L-PDNPs was able to produce a Ca2+ influx in differentiated SH-SY5Y, being, to the best of our knowledge, the first example of organic nanostructures used in such an approach. This work could pave the way to new and exciting applications of polydopamine-based and of other NIR-responsive antioxidant nanomaterials in neuronal research.

In this work we present a green approach to the synthesis of nitrogen-doped carbon-based aerogels with good conductivity and catalytic properties. With the aim to design an easily sustainable process, the starting precursors were selected among abundant waste-related organic materials. The naturally-derived polysaccharide agar worked as the carbon source in a water solution, while an amino acid, glycine or lysine has been used as the nitrogen source. By this synthesis approach, nitrogen defects were created into a 3D porous aerogel: they successfully acted as active catalytic sites for the reaction of oxygen reduction to water as demonstrated by electrochemical measurements. The best performing materials have been tested as cathodes in microbial fuel cells for 50 days, in conditions close to those the device could face in a real environment. The glycine derived carbon aerogels with the higher content of pyridinic nitrogen, as confirmed by several morphological characterizations, showed the best performance.

In this work we investigated the behavior of TiO2 nanotube (NT) arrays, grown by anodic oxidation of Ti foil, as catalysts for the oxygen reduction reaction (ORR) in alkaline water solution. In particular, as-grown amorphous NTs were compared to crystalline anatase nanostructures, obtained following two different procedures, namely thermal and vapor-induced crystallizations. The catalytic activity of these materials toward the ORR was evaluated by cyclic voltammetry measurements. ORR polarization curves, combined with the rotating disk technique, indicated a predominant four-electrons reduction path, especially for crystalline samples. The effect of the structural characteristics of the investigated materials on the catalytic activity was analyzed in details by electrochemical impedance spectroscopy. The catalytic performance of the crystalline NTs is only slightly lower with respect to the reference material for fuel cell applications, namely platinum, but is in line with other cost-effective catalysts recently proposed in the literature. However, if compared to the larger part of these low-cost catalysts, anodically-grown TiO2 NTs are characterized by a synthesis route which is highly reproducible and easily up-scalable.

Nitrogen-doped reduced graphene oxide is successfully synthesized and functionalized with hydroxylated copper ions via one-pot microwave-assisted route. The presence of cationic Cu coordinated to the graphene layer is fully elucidated through a set of experimental characterizations and theoretical calculations. Thanks to the presence of these hydroxyl-coordinated Cu2+ active sites, the proposed material shows good electrocatalytic performance for the oxygen reduction reaction, as evidenced by an electron transfer number of almost 4 and by high onset and half-wave potentials of 0.91 V and 0.78 V vs. the reversible hydrogen electrode, respectively. In addition, the N-doped Cu-functionalized graphene displays a superior current retention with respect to a commercial Pt/C catalyst during the stability test, implying its potential implementation in high-performance fuel cells and metal-air batteries.

Manganese oxides (MnxOy) are considered as a promising catalyst alternative to platinum in fuel cell applications. In fact, a proper catalyst is needed in order to facilitate the oxygen reduction reaction (ORR) at the cathode, and platinum is considered the best material due to its low overpotential for this reaction. Contrary to platinum, MnxOy is inexpensive, environmentally friendly and can be shaped into several nanostructures; furthermore, most of them show significant electro-catalytic performance. Several strategies have been carried out in order to increase their efficiency, by preparing light and high-surface area materials. In this framework, nanofibres are among the most promising nanostructures that can be used for this purpose. In this work, a study of the thermal, morphological and catalytic behavior of MnxOy nanofibres obtained through the electrospinning technique is proposed. Emphasis is given to the thermal evolution of the precursors, proposing a possible crystallization mechanism of the different manganese oxides obtained. It turns out that manganese oxide nanofibres exhibit good catalytic performance for the ORR, comparable to those obtained by using Pt-based catalysts.

Self-standing and flexible membranes based on reduced graphene oxide (rGO)/SnO2 nanocomposite and cellulose fibers are here presented. The flexible membranes are prepared through an easy and eco-friendly protocol: the rGO/SnO2 nanocomposite is synthetized via a microwave-assisted procedure and then assembled with microfibrillated cellulose (MFC) through a water-based process. This process leads to the formation of a nanocomposite in which cellulose nanofibers are integrated with the graphene matrix. Beyond the good flexibility, the nanocomposite membranes present interesting properties in terms of capacitive behavior and catalytic activity: the electrochemical characterizations revealed that such material is an extremely competitive candidate for the oxygen reduction reaction, even comparable to the commonly used Pt-based catalysts. Furthermore, the possible application as electrodes for flexible supercapacitors and piezoresistive sensors is also investigated showing the great potential of such composite material.

The use of nanomaterials in the field of bone tissue engineering implants is continuously dealing with the development of innovative solutions to common problems, as infection by colonization with common microbial agents, antibiotic bacterial resistance, and the formation of new bone tissue. Among them, ZnO nanostructures are promising candidates thanks to their intrinsic antimicrobial activity and high biocompatibility. In this paper we aim to analyse the behaviour of ZnO nanocrystals (ZnO NCs), prepared with a new synthetic approach and not embedded in any composite matrix, for bone implants applications in-vitro. In particular, we have developed a novel, fast and reproducible microwave-assisted synthesis, obtaining highly-crystalline, round-shaped ZnO NCs of 20 nm in diameter as an extremely-stable colloidal solution in ethanol. Part of them were also chemically functionalized by anchoring amino-propyl groups to the ZnO surface (ZnO-NH2 NCs). Thus, the role of both ZnO NCs concentration and surface chemistry are tested in terms of biocompatibility towards pre-osteoblasts cells, promotion of cell proliferation and differentiation, and also in terms of antimicrobial activity against Gram positive and negative bacteria, such as Escherichia coli and Staphylococcus aureus, respectively. The results propose the ZnO-NH2 NCs as the most promising candidate to solve infections disease in bone implants and promote bone tissue proliferation at the same time, even at high concentrations. Whereas further investigations are needed for example to clarify the mechanism inhibiting biofilm formation and to investigate their role in in-vivo assays, we demonstrated that a fine and reproducible control over the chemical and structural parameters in ZnO nanomaterials can open new horizons in the use of functionalized ZnO NCs as a highly biocompatible and osteoinductive nanoantibiotic agent for bone tissue engineering.

The lack of low-cost, durable and highly efficient electrocatalysts to perform oxygen reduction reaction (ORR) still represents a significant challenge for the development of fuel cells cathodes. Recently, Pt-free metalloporphyrins supported on N-doped reduced graphene oxide (N-rGO) have been proposed as innovative ORR catalysts characterized by notable stability and superior performance. In this paper, we propose a fast and green microwave-assisted method to synthetize manganese-nitrogen co-doped rGO, characterized by catalytic activity comparable to Pt-containing materials and improved long-term stability. Theoretical calculations and experimental results showed that our synthetic method produces N-rGO matrices which coordinate Mn2+ ions in porphyrin-like structures. These Mn/N-rGO complexes are responsible for the outstanding performance of the proposed catalyst, being able to weaken O–O molecular bond, thus effectively reducing the activation energy towards oxygen catalytic reaction. Our findings open the path to a green co-doping process of graphene for the production of low-cost and efficient alternatives to noble metals-based ORR catalysts.

Aim The effective application of nanoparticles in cancer theranostics is jeopardized by their aggregation in biological media, rapid degradation and clearance. The design of biomimetic nanoconstructs with enhanced colloidal stability and non-immunogenicity is therefore essential. We propose naturally stable cell-derived extracellular vesicles to encapsulate zinc oxide (ZnO) nanocrystals as efficacious nanodrugs, to obtain highly biomimetic and stable Trojan nano-horses (TNHs). Materials & methods Coupling efficiency, biostability, cellular cytotoxicity and internalization were tested. Results In vitro studies showed a high internalization of TNHs into cancer cells and efficient cytotoxic activity thanks to ZnO intracellular release. Conclusion TNHs represent an efficient biomimetic platform for future nanotheranostic applications, with biomimetic extracellular vesicle-lipid envelope, facilitated ZnO cellular uptake and potential therapeutic implications., Graphic abstract

Neurodegenerative diseases comprise a large group of disorders characterized by a dramatic synaptic connections loss, occurring as a result of neurodegeneration, which is closely related to the overproduction of reactive oxygen and nitrogen species. Currently, the treatment of neurodegenerative diseases has been limited mainly because of the inability of the synthesized delivery systems to cross the blood-brain barrier and to successfully deliver their therapeutic cargo to the diseased tissue. Taking into consideration the aforementioned limitations, we designed a lipid-based nanotherapeutic vector composed of biomimetic lipids and CeO2nanoparticles (nanoceria, NC). NC have shown to be a promising tool for the treatment of several pathological conditions ranging from cancer to neurological diseases, mainly because of their antioxidant properties, while lipid-based structures have been shown to have an inherent ability to cross the blood-brain barrier. The lipid-based nanotherapeutics were successfully fabricated using a combination of ultrasonication and high-pressure homogenization techniques, and they were fully characterized morphologically and physicochemically. Their antioxidant ability was demonstrated using electron paramagnetic resonance spectroscopy and antioxidant assays. These innovative nanotherapeutics demonstrated a higher colloidal stability with respect to free NC, preserving at the same time their antioxidant properties. Finally, the ability of the lipid carriers to cross a model of the blood-brain barrier and to be internalized by neurons, acting both as neuroprotective and pro-neurogenic agents, was demonstrated using single- and triple-culture systems.

Nanoparticles able to promote inertial cavitation when exposed to focused ultrasound have recently gained much attention due to their vast range of possible applications in the biomedical field, such as enhancing drug penetration in tumor or supporting ultrasound contrast imaging. Due to their nanometric size, these contrast agents could penetrate through the endothelial cells of the vasculature to target tissues, thus enabling higher imaging resolutions than commercial gas-filled microbubbles. Herein, Zinc Oxide NanoCrystals (ZnO NCs), opportunely functionalized with amino-propyl groups, are developed as novel nanoscale contrast agents that are able, for the first time, to induce a repeatedly and over-time sustained inertial cavitation as well as ultrasound contrast imaging. The mechanism behind this phenomenon is investigated, revealing that re-adsorption of air gas nanobubbles on the nanocrystal surface is the key factor for this re-chargeable cavitation. Moreover, inertial cavitation and significant echographic signals are obtained at physiologically relevant ultrasound conditions (MI 1.9), showing great potential for low side-effects in in-vivo applications of the novel nanoscale agent from diagnostic imaging to gas-generating theranostic nanoplatforms and to drug delivery.

Plastic smart windows are becoming one of the key elements in view of the fabrication of inexpensive, lightweight electrochromic (EC) devices to be integrated in the new generation of high-energy-efficiency buildings and automotive applications. However, fabricating electrochromic devices on polymer substrates requires a reduction of process temperature, so in this work we focus on the development of a completely room-temperature deposition process aimed at the preparation of ITO-coated polycarbonate (PC) structures acting as transparent and conductive plastic supports. Without providing any substrate heating or surface activation pretreatments of the polymer, different deposition conditions are used for growing indium tin oxide (ITO) thin films by the radiofrequency magnetron sputtering technique. According to the characterization results, the set of optimal deposition parameters is selected to deposit ITO electrodes having high optical transmittance in the visible range (∼90%) together with low sheet resistance (∼8 ohm/sq). The as-prepared ITO/PC structures are then successfully tested as conductive supports for the fabrication of plastic smart windows. To this purpose, tungsten trioxide thin films are deposited by the reactive sputtering technique on the ITO/PC structures, and the resulting single electrode EC devices are characterized by chronoamperometric experiments and cyclic voltammetry. The fast switching response between colored and bleached states, together with the stability and reversibility of their electrochromic behavior after several cycling tests, are considered to be representative of the high quality of the EC film but especially of the ITO electrode. Indeed, even if no adhesion promoters, additional surface activation pretreatments, or substrate heating were used to promote the mechanical adhesion among the electrode and the PC surface, the observed EC response confirmed that the developed materials can be successfully employed for the fabrication of lightweight and inexpensive plastic EC devices.

Nanostructured LiFePO4/C composites having ordered olivine structure are prepared by a newly elaborated low temperature microwave-assisted solvothermal synthesis in the presence of a cationic surfactant. The microwave-assisted approach is simple and cost effective: it significantly decreases reaction times compared to the conventional hydrothermal/solvothermal processes. A study on the influence of the synthesis parameters on both the morphology and the electrochemical behavior of the samples is performed by means of X-ray powder diffraction, N2 physisorption at 77 K, scanning electron microscopy, cyclic voltammetry and constant current charge/discharge cycling. Moreover, a chemometric approach through design of experiments (DoE) is here successfully demonstrated for the first time for the optimization and fine tuning of the experimental conditions, including synthetic procedure and electrochemical characteristics of the materials. As a result, we show a nanostructured LiFePO4/C with high rate capability and delivering a very stable cycling behavior for more than thousand cycles with excellent Coulombic efficiency and exceptional capacity retention at 1C.

ZnO nanostructures are grown by a simple chemical vapour deposition method directly on a stainless steel disc current collector and successfully tested in lithium cells. The structural/morphological characterization points out the presence of well-defined polycrystalline nanostructures having different shapes and a preferential orientation along the c -axis direction. In addition, the high active surface of the ZnO nanostructures, which accounts for a large electrode/electrolyte contact area, and the complete wetting with the electrolyte solution are considered to be responsible for the good electrical transport properties and the adequate electrochemical behaviour, as confirmed by cyclic voltammetry and galvanostatic charge/discharge cycling. Indeed, despite no binder or conducting additives are used, when galvanostatically tested in lithium cells, after an initial decay, the ZnO nanostructures can provide a rather stable specific capacity approaching 70 μA h cm −2 (i.e., around 400 mA h g −1 ) after prolonged cycling at 1 C, with very high Coulombic efficiency and an overall capacity retention exceeding 62%.

In recent years transdermal drug delivery has aroused significant interest as a sustained and non-invasive way of administering active substances. The advancements of nanotechnology allowed the development of novel pharmaceutical formulations overcoming skin barrier. Furthermore, such nano-system can be combined with conventional fabrics to pave the way to a new generation of wearable drug delivery devices: bio-functional garments. First the NP were produced by flash nanoprecipitation technique (FNP), the production process was optimized to produce particles with suitable size for transdermal applications. The nanoparticles were characterized in terms of drug content by UV-visible spectroscopy and in term of antioxidant activity by Electron Paramagnetic Resonance spectroscopy (EPR) coupled with spin trapping technique. The NPs were used to functionalize cotton and viscose-micromodal fabrics and the transdermal release properties were tested in vitro by Franz's Cell experiment. FNP was proven to be an effective technique to produce tunable size particles. Moreover, the nanoencapsulated drug exhibited antioxidant activity. The Franz's Cell test evidenced a controlled release behavior, providing evidence that the bio-functional textile is suitable for applications where sustained release and antioxidant properties are required.

Vertically oriented arrays of high surface area TiO2 nanotubes (NTs) are fabricated by the fast and facile anodic oxidation of a titanium foil. The formation of well-defined one-dimensional nanotubular carpets is assessed by means of morphological Field Emission Scanning Electron Microscopy characterisation, while X-ray diffraction analysis and Transmission Electron Microscopy imaging confirm the amorphous nature of the samples. The electrochemical response evaluated in lab-scale lithium cells is highly satisfying with near-theoretical initial specific capacity and remarkable rate capability, noteworthy in the absence of binders and conductive agents, which would affect the overall energy density. A specific capacity exceeding 200 mAh g−1 is observed at very high 24 C and approx. 80 mAh g−1 are retained even at very high 96 C rate, thus accounting for the promising prospects in storage devices conceived for high power applications. Moreover, the NTs can perform with good cycling stability and capacity retention approaching 50% of the initial value after very long-term operation along with improved durability (> 2000 cycles).

Herein we report a novel, easy, fast and reliable microwave-assisted synthesis procedure for the preparation of colloidal zinc oxide nanocrystals (ZnO NCs) optimized for biological applications. ZnO NCs are also prepared by a conventional solvo-thermal approach and the properties of the two families of NCs are compared and discussed. All of the NCs are fully characterized in terms of morphological analysis, crystalline structure, chemical composition and optical properties, both as pristine nanomaterials or after amino-propyl group functionalization. Compared to the conventional approach, the novel microwave-derived ZnO NCs demonstrate outstanding colloidal stability in ethanol and water with long shelf-life. Furthermore, together with their more uniform size, shape and chemical surface properties, this long-term colloidal stability also contributes to the highly reproducible data in terms of biocompatibility. Actually, a significantly different biological behavior of the microwave-synthesized ZnO NCs is reported with respect to NCs prepared by the conventional synthesis procedure. In particular, consistent cytotoxicity and highly reproducible cell uptake toward KB cancer cells are measured with the use of microwave-synthesized ZnO NCs, in contrast to the non-reproducible and scattered data obtained with the conventionally-synthesized ones. Thus, we demonstrate how the synthetic route and, as a consequence, the control over all the nanomaterial properties are prominent points to be considered when dealing with the biological world for the achievement of reproducible and reliable results, and how the use of commercially-available and under-characterized nanomaterials should be discouraged in this view.

In the present paper we demonstrate the efficient use of shape controlled flower-like ZnO (Zinc oxide) nanostructured particles as multifunctional electrode for both energy conversion and storage applications, i.e. Dye-sensitized Solar Cells (DSCs) and lithium-ion batteries. As regards DSC (Dye-sensitized Solar Cell) device, ZnO flower-like particles, prepared by a simple, low-cost and reliable hydrothermal method under mild reaction temperature, are efficiently used as photoanode in a microfluidic architectured cell in combination with NMBI (N-methylbenzimidazole), employed as additive of the electrolytic solution for the first time in a ZnO-based DSC. We obtain a remarkable sunlight conversion efficiency of 3.6%. As regards storage applications, a stable long-term ambient temperature cycling behavior in lithium cell is demonstrated, even at increasingly higher currents. Remarkable charge-discharge efficiency and specific capacity are obtained up to 200 cycles, which is the highest number of cycles reported so far for similar systems. Noteworthy, such results are achieved without the addition of foreign additives, nor during the synthesis process neither during the electrode preparation, and also no carbon coating on ZnO surface is used. The originality of the present paper consists not only in showing for the first time the efficient operation of such ZnO particles as anode in Li-ion batteries for prolonged cycling, but also in demonstrating the versatile and multifunctional use of the same material for two different energy related applications. The reported results enlighten indeed the promising prospects of the flower-like ZnO nanostructured material for the successful implementation as stable and long-term performing anodic material in the next generation of both energy conversion and storage devices.

Lithiated vanadium oxides with polyelectrochromic behaviour are reported here for the first time. Electrochrome was obtained by means of a simple and solvent-free solid state reaction. Clear XPS evidence indicates that the electro-generation of the red color is due to the dismutation of surface-adsorbed O2− species with subsequent formation of red colored V5+–O22− complexes. The reaction is switched electrochemically by oxidation of the surface V4+ centers.

In this work, the piezoelectric properties of BaTiO3 1D vertical nanostructures were investigated with a comparison between the macroscopic and the nanometric response. The piezoelectric nanostructured carpet was obtained by the topotactic conversion of anodic TiO2 nanotubes exploiting hydrothermal treatment in Ba-enriched water solution. The nanoscale investigation by a piezoelectric force microscope returns a detailed map of ferroelectric polarization, which is preferentially confined over the vertical nanostructure axis. The scanning probe microscopy results were then coupled to the macroscopic response of the piezo-evaluation system to compare the multiscale response of the nanostructured material. Both the local and macroscopic measurement techniques provide d33 values in the range of 5.5–7 pm/V, in agreement with the values reported in the literature for other barium titanate nanostructures. The characterization of the piezoelectric response of BaTiO3 nanostructures at the nanoscale can provide useful guidelines for the next generation of Pb-free materials to be integrated into near-future nanodevices.

An optimized thermoset gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) was prepared by facile photo-induced free radical polymerisation technique and tested for the first time in electrochromic devices (ECD) combining WO3sputtered on ITO as cathodes and V2O5electrodeposited on ITO as anodes. The behaviour of the prepared ECD was investigated electrochemically and electro-optically. The ECD transmission spectrum was monitored in the visible and near-infrared region by varying applied potential. A switching time of ca. 2 s for Li+insertion (coloring) and of ca. 1 s for Li+de-insertion (bleaching) were found. UV-VIS spectroelectrochemical measurements evidenced a considerable contrast between bleached and colored state along with a good stability over repeated cycles. The reported electrochromic devices showed a considerable enhancement of switching time with respect to the previously reported polymeric ECD indicating that they are good candidates for the implementation of intelligent windows and smart displays.

We report on an easy, fast, eco-friendly, and reliable method for the synthesis of reduced graphene oxide/SnO2 nanocomposite as cathode material for application in microbial fuel cells (MFCs). The material was prepared starting from graphene oxide that has been reduced to graphene during the hydrothermal synthesis of the nanocomposite, carried out in a microwave system. Structural and morphological characterizations evidenced the formation of nanocomposite sheets, with SnO2 crystals of few nanometers integrated in the graphene matrix. Physico-chemical analysis revealed the formation of SnO2 nanoparticles, as well as the functionalization of the graphene by the presence of nitrogen atoms. Electrochemical characterizations put in evidence the ability of such composite to exploit a cocatalysis mechanism for the oxygen reduction reaction, provided by the presence of both SnO2 and nitrogen. In addition, the novel composite catalyst was successfully employed as cathode in seawater-based MFCs, giving electrical performances comparable to those of reference devices employing Pt as catalyst.

The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.

In the field of fuel cells, oxygen plays a key role as the final electron acceptor. To facilitate its reduction (Oxygen Reduction Reaction—ORR), a proper catalyst is needed and platinum is considered the best one due to its low overpotential for this reaction. By considering the high price of platinum, alternative catalysts are needed and manganese oxides (Mn x O y ) can be considered promising substitutes. They are inexpensive, environmental friendly and can be obtained into several forms; most of them show significant electro-catalytic performance, even if strategies are needed to increase their efficiency. In particular, by developing light and high-surface area materials and by optimizing the presence of catalytic sites, we can obtain a cathode with improved electro-catalytic performance. In this case, nanofibers and xerogels are two of the most promising nanostructures that can be used in the field of catalysis. In this work, a study of the morphological and catalytic behavior of Mn x O y nanofibers and xerogels is proposed. Nanofibers were obtained by electrospinning, while xerogels were prepared by sol-gel and freeze drying techniques. Despite of the different preparation approaches, the obtained nanostructured manganese oxides exhibited similar catalytic performance for the ORR, comparable to those obtained from Pt catalysts.

In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices.

In the present paper, we use zinc oxide nanoparticles under the excitation of ultraviolet (UV) light for the generation of Reactive Oxygen Species (ROS), with the aim of further using these species for fighting cancer cells in vitro. Owing to the difficulties in obtaining highly dispersed nanoparticles (NPs) in biological media, we propose their coating with a double-lipidic layer and we evaluate their colloidal stability in comparison to the pristine zinc oxide NPs. Then, using Electron Paramagnetic Resonance (EPR) coupled with the spin-trapping technique, we demonstrate and characterize the ability of bare and lipid-coated ZnO NPs to generate ROS in water only when remotely actuated via UV light irradiation. Interestingly, our results reveal that the surface chemistry of the NPs greatly influences the type of photo-generated ROS. Finally, we show that lipid-coated ZnO NPs are effectively internalized inside human epithelial carcinoma cells (HeLa) via a lysosomal pathway and that they can generate ROS inside cancer cells, leading to enhanced cell death. The results are promising for the development of ZnO-based therapeutic systems.

Silicon is a very attractive Li-ion battery anode material due to its high theoretical capacity, but proper nanostructuring is needed to accommodate the large volume expansion/shrinkage upon reversible cycling. Hereby, novel mesoporous Si nanostructures are grown at room temperature by simple and rapid Pulsed Laser Deposition (PLD) directly on top of the Cu current collector surface. The samples are characterized from the structural/morphological viewpoint and their promising electrochemical behavior demonstrated in lab-scale lithium cells. Depending on the porosity, easily tuneable by PLD, specific capacities approaching 250 μAh cm−2 are obtained. Successively, newly elaborated bi-component silicon/carbon nanostructures are fabricated in one step by alternating PLD deposition of Si and C, thus resulting in novel multi-layered composite mesoporous films exhibiting profoundly improved performance. Alternated deposition of Si/C layers by PLD is proven to be a straightforward method to produce multi-layered anodes in one processing step. The addition of carbon and mild annealing at 400°C stabilize the electrochemical performance of the Si-based nanostructures in lab-scale lithium cells, allowing to reach very stable prolonged reversible cycling at improved specific capacity values. This opens the way to further reducing processing steps and processing time, which are key aspects when upscaling is sought