Nanoporous Au Behavior in Methyl Orange Solutions

Nanoporous (NP) gold, the most extensively studied and efficient NP metal, possesses exceptional properties that make it highly attractive for advanced technological applications. Notably, its remarkable catalytic properties in various significant reactions hold enormous potential. However, the exploration of its catalytic activity in the degradation of water pollutants remains limited. Nevertheless, previous research has reported the catalytic activity of NP Au in the degradation of methyl orange (MO), a toxic azo dye commonly found in water. This study aims to investigate the behavior of nanoporous gold in MO solutions using UV-Vis absorption spectroscopy and high-performance liquid chromatography. The NP Au was prepared by chemical removal of silver atoms of an AuAg precursor alloy prepared by ball milling. Immersion tests were conducted on both pellets and powders of NP Au, followed by examination of the residual solutions. Additionally, X-ray photoelectron spectroscopy and electrochemical impedance measurements were employed to analyze NP Au after the tests. The findings reveal that the predominant and faster process involves the partially reversible adsorption of MO onto NP Au, while the catalytic degradation of the dye plays a secondary and slower role in this system.

Near Infrared Light-Emitting Diodes Based on Colloidal InAs/ZnSe Core/Thick-Shell Quantum Dots

Heavy-metal-free III-V colloidal quantum dots (QDs) exhibit promising attributes for application in optoelectronics. Among them, InAs QDs are demonstrating excellent optical performance with respect to absorption and emission in the near-infrared spectral domain. Recently, InAs QDs attained a substantial improvement in photoluminescence quantum yield, achieving 70% at a wavelength of 900 nm through the strategic overgrowth of a thick ZnSe shell atop the InAs core. In the present study, light-emitting diodes (LEDs) based on this type of InAs/ZnSe QDs are fabricated, reaching an external quantum efficiency (EQE) of 13.3%, a turn-on voltage of 1.5V, and a maximum radiance of 12 Wsr-1m-2. Importantly, the LEDs exhibit an extensive emission dynamic range, characterized by a nearly linear correlation between emission intensity and current density, which can be attributed to the efficient passivation provided by the thick ZnSe shell. The obtained results are comparable to state-of-the-art PbS QD LEDs. Furthermore, it should be stressed not only that the fabricated LEDs are fully RoHS-compliant but also that the emitting InAs QDs are prepared via a synthetic route based on a non-pyrophoric, cheap, and commercially available as precursor, namely tris(dimethylamino)-arsine.

Ultrasound-activated Piezoelectric Nanoparticles Trigger Microglia Activity against Glioblastoma Cells

Glioblastoma multiforme (GBM) is the most aggressive brain cancer, characterized by a rapid and drug-resistant progression. GBM "builds" around its primary core a genetically heterogeneous tumor-microenvironment (TME), recruiting surrounding healthy brain cells by releasing various intercellular signals. Glioma-associated microglia (GAM) represent the largest population of collaborating cells, which, in the TME, usually exhibit the anti-inflammatory M2 phenotype, thus promoting an immunosuppressing environment that helps tumor growth. Conversely, "classically activated" M1 microglia could provide pro-inflammatory and anti-tumorigenic activity, expected to exert a beneficial effect in defeating glioblastoma. In this work, we proposed an immunotherapy approach based on pro-inflammatory modulation of the GAM phenotype, through a controlled and localized electrical stimulation. The developed strategy relies on the wireless ultrasonic excitation of polymeric piezoelectric nanoparticles coated with GBM cell membrane extracts, to exploit homotypic targeting in anti-glioma applications. Such camouflaged nanotransducers locally generate electrical cues on GAM membranes, activating their M1 phenotype and ultimately triggering a promising anti-cancer activity. Collected findings open new perspectives in the modulation of immune cell activities through "smart" nanomaterials and, more specifically, provide an innovative auspicious tool in glioma immunotherapy. This article is protected by copyright. All rights reserved.

Stainless Steel Activation for Efficient Alkaline Oxygen Evolution in Advanced Electrolyzers

Designing robust and cost-effective electrocatalysts for efficient alkaline oxygen evolution reaction (OER) is of great significance in the field of water electrolysis. In this study, an electrochemical strategy to activate stainless steel (SS) electrodes for efficient OER is introduced. By cycling the SS electrode within a potential window that encompasses the Fe(II)↔Fe(III) process, its OER activity can be enhanced to a great extent compared to using a potential window that excludes this redox reaction, decreasing the overpotential at current density of 100 mA cm-2 by 40 mV. Electrochemical characterization, Inductively Coupled Plasma - Optical Emission Spectroscopy, and operando Raman measurements demonstrate that the Fe leaching at the SS surface can be accelerated through a Fe → γ-Fe2 O3 → Fe3 O4 or FeO → Fe2+ (aq.) conversion process, leading to the sustained exposure of Cr and Ni species. While Cr leaching occurs during its oxidation process, Ni species display higher resistance to leaching and gradually accumulate on the SS surface in the form of OER-active Fe-incorporated NiOOH species. Furthermore, a potential-pulse strategy is also introduced to regenerate the OER-activity of 316-type SS for stable OER, both in the three-electrode configuration (without performance decay after 300 h at 350 mA cm-2 ) and in an alkaline water electrolyzer (≈30 mV cell voltage increase after accelerated stress test-AST). The AST-stabilized cell can still reach 1000 and 4000 mA cm-2 at cell voltages of 1.69 and 2.1 V, which makes it competitive with state-of-the-art electrolyzers based on ion-exchange membrane using Ir-based anodes.

How Photogenerated I2 Induces I-Rich Phase Formation in Lead Mixed Halide Perovskites

Bandgap tunability of lead mixed halide perovskites (LMHPs) is a crucial characteristic for versatile optoelectronic applications. Nevertheless, LMHPs show the formation of iodide-rich (I-rich) phase under illumination, which destabilizes the semiconductor bandgap and impedes their exploitation. Here, it is shown that how I2 , photogenerated upon charge carrier trapping at iodine interstitials in LMHPs, can promote the formation of I-rich phase. I2 can react with bromide (Br- ) in the perovskite to form a trihalide ion I2 Br- (Iδ- -Iδ+ -Brδ- ), whose negatively charged iodide (Iδ- ) can further exchange with another lattice Br- to form the I-rich phase. Importantly, it is observed that the effectiveness of the process is dependent on the overall stability of the crystalline perovskite structure. Therefore, the bandgap instability in LMHPs is governed by two factors, i.e., the density of native defects leading to I2 production and the Br- binding strength within the crystalline unit. Eventually, this study provides rules for the design of chemical composition in LMHPs to reach their full potential for optoelectronic devices.

Microglia Polarization and Antiglioma Effects Fostered by Dual Cell Membrane-Coated Doxorubicin-Loaded Hexagonal Boron Nitride Nanoflakes

Microglial cells play a critical role in glioblastoma multiforme (GBM) progression, which is considered a highly malignant brain cancer. The activation of microglia can either promote or inhibit GBM growth depending on the stage of the tumor development and on the microenvironment conditions. The current treatments for GBM have limited efficacy; therefore, there is an urgent need to develop novel and efficient strategies for drug delivery and targeting: in this context, a promising strategy consists of using nanoplatforms. This study investigates the microglial response and the therapeutic efficacy of dual-cell membrane-coated and doxorubicin-loaded hexagonal boron nitride nanoflakes tested on human microglia and GBM cells. Obtained results show promising therapeutic effects on glioma cells and an M2 microglia polarization, which refers to a specific phenotype or activation state that is associated with anti-inflammatory and tissue repair functions, highlighted through proteomic analysis.

Azobenzene-based optoelectronic transistors for neurohybrid building blocks

Exploiting the light-matter interplay to realize advanced light responsive multimodal platforms is an emerging strategy to engineer bioinspired systems such as optoelectronic synaptic devices. However, existing neuroinspired optoelectronic devices rely on complex processing of hybrid materials which often do not exhibit the required features for biological interfacing such as biocompatibility and low Young's modulus. Recently, organic photoelectrochemical transistors (OPECTs) have paved the way towards multimodal devices that can better couple to biological systems benefiting from the characteristics of conjugated polymers. Neurohybrid OPECTs can be designed to optimally interface neuronal systems while resembling typical plasticity-driven processes to create more sophisticated integrated architectures between neuron and neuromorphic ends. Here, an innovative photo-switchable PEDOT:PSS was synthesized and successfully integrated into an OPECT. The OPECT device uses an azobenzene-based organic neuro-hybrid building block to mimic the retina's structure exhibiting the capability to emulate visual pathways. Moreover, dually operating the device with opto- and electrical functions, a light-dependent conditioning and extinction processes were achieved faithful mimicking synaptic neural functions such as short- and long-term plasticity.

Ru-Cu Nanoheterostructures for Efficient Hydrogen Evolution Reaction in Alkaline Water Electrolyzers

Combining multiple species working in tandem for different hydrogen evolution reaction (HER) steps is an effective strategy to design HER electrocatalysts. Here, we engineered a hierarchical electrode for the HER composed of amorphous-TiO2/Cu nanorods (NRs) decorated with cost-effective Ru-Cu nanoheterostructures (Ru mass loading = 52 μg/cm2). Such an electrode exhibits a stable, over 250 h, low overpotential of 74 mV at -200 mA/cm2 for the HER in 1 M NaOH. The high activity of the electrode is attributed, by structural analysis, operando X-ray absorption spectroscopy, and first-principles simulations, to synergistic functionalities: (1) mechanically robust, vertically aligned Cu NRs with high electrical conductivity and porosity provide fast charge and gas transfer channels; (2) the Ru electronic structure, regulated by the size of Cu clusters at the surface, facilitates the water dissociation (Volmer step); (3) the Cu clusters grown atop Ru exhibit a close-to-zero Gibbs free energy of the hydrogen adsorption, promoting fast Heyrovsky/Tafel steps. An alkaline electrolyzer (AEL) coupling the proposed cathode and a stainless-steel anode can stably operate in both continuous (1 A/cm2 for over 200 h) and intermittent modes (accelerated stress tests). A techno-economic analysis predicts the minimal overall hydrogen production cost of US$2.12/kg in a 1 MW AEL plant of 30 year lifetime based on our AEL single cell, hitting the worldwide targets (US$2-2.5/kgH2).

Preparation of different conjugated polymers characterized by complementary electronic properties from an identical precursor

The possibility of generating regions with different electronic properties within the same organic semiconductor thin film could offer novel opportunities for designing and fabricating organic electronic devices and circuits. This study introduces a new approach based on a novel type of highly processable polymer precursor that can yield two different conjugated polymers characterized by complementary electronic properties, i.e. promoting electron or hole transport, from the same starting material. In particular, these multipotent precursors comprise functionalized dihydroanthracene units that can offer several functionalization opportunities to improve the solubility or insert specific functionalities. This strategy also allows for the preparation of high-molecular-weight conjugated polymers comprising diethynylanthracene and anthraquinone units without the need for solubilizing side chains. Thin films of the polymer precursor can be used, after solid-state transformations, to prepare single organic layers comprising regions characterized by different chemical nature and electronic properties. Here, we present a detailed characterization of the chemical and electronic properties of the precursor and the obtained conjugated polymers, showing how it is possible to harvest their characteristics for potential applications such as electrochromic surfaces and organic field-effect transistors.

Boosting the Photoluminescence Efficiency of InAs Nanocrystals Synthesized with Aminoarsine via a ZnSe Thick-Shell Overgrowth

InAs-based nanocrystals can enable restriction of hazardous substances (RoHS) compliant optoelectronic devices, but their photoluminescence efficiency needs improvement. We report an optimized synthesis of InAs@ZnSe core@shell nanocrystals allowing to tune the ZnSe shell thickness up to seven mono-layers (ML) and to boost the emission, reaching a quantum yield of ≈70% at ≈900 nm. It is demonstrated that a high quantum yield can be attained when the shell thickness is at least ≈3ML. Notably, the photoluminescence lifetimeshows only a minor variation as a function of shell thickness, whereas the Auger recombination time (a limiting aspect in technological applications when fast) slows down from 11 to 38 ps when increasing the shell thickness from 1.5 to 7MLs. Chemical and structural analyses evidence that InAs@ZnSe nanocrystals do not exhibit any strain at the core-shell interface, likely due to the formation of an InZnSe interlayer. This is supported by atomistic modeling, which indicates the interlayer as being composed of In, Zn, Se and cation vacancies, alike to the In2 ZnSe4 crystal structure. The simulations reveal an electronic structure consistent with that of type-I heterostructures, in which localized trap states can be passivated by a thick shell (>3ML) and excitons are confined in the core.

High-performance alkaline water electrolyzers based on Ru-perturbed Cu nanoplatelets cathode

Alkaline electrolyzers generally produce hydrogen at current densities below 0.5 A/cm2. Here, we design a cost-effective and robust cathode, consisting of electrodeposited Ru nanoparticles (mass loading ~ 53 µg/cm2) on vertically oriented Cu nanoplatelet arrays grown on metallic meshes. Such cathode is coupled with an anode based on stacked stainless steel meshes, which outperform NiFe hydroxide catalysts. Our electrolyzers exhibit current densities as high as 1 A/cm2 at 1.69 V and 3.6 A/cm2 at 2 V, reaching the performances of proton-exchange membrane electrolyzers. Also, our electrolyzers stably operate in continuous (1 A/cm2 for over 300 h) and intermittent modes. A total production cost of US$2.09/kgH2 is foreseen for a 1 MW plant (30-year lifetime) based on the proposed electrode technology, meeting the worldwide targets (US$2-2.5/kgH2). Hence, the use of a small amount of Ru in cathodes (~0.04 gRu per kW) is a promising strategy to solve the dichotomy between the capital and operational expenditures of conventional alkaline electrolyzers for high-throughput operation, while facing the scarcity issues of Pt-group metals.

Nucleation and Growth of Bipyramidal Yb:LiYF4 Nanocrystals-Growing Up in a Hot Environment

Lanthanide-doped LiYF₄ (Ln:YLF) is commonly used for a broad variety of optical applications, such as lasing, photon upconversion and optical refrigeration. When synthesized as nanocrystals (NCs), this material is also of interest for biological applications and fundamental physical studies. Until now, it was unclear how Ln:YLF NCs grow from their ionic precursors into tetragonal NCs with a well-defined, bipyramidal shape and uniform dopant distribution. Here, we study the nucleation and growth of ytterbium-doped LiYF₄ (Yb:YLF), as a template for general Ln:YLF NC syntheses. We show that the formation of bipyramidal Yb:YLF NCs is a multistep process starting with the formation of amorphous Yb:YLF spheres. Over time, these spheres grow via Ostwald ripening and crystallize, resulting in bipyramidal Yb:YLF NCs. We further show that prolonged heating of the NCs results in the degradation of the NCs, observed by the presence of large LiF cubes and small, irregular Yb:YLF NCs. Due to the similarity in chemical nature of all lanthanide ions our work sheds light on the formation stages of Ln:YLF NCs in general.

Enhancing charge extraction in inverted perovskite solar cells contacts via ultrathin graphene:fullerene composite interlayers

Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs). This is utterly fundamental in an inverted (p-i-n) configuration using fullerene-based ETLs. Here, we propose a scalable strategy to improve fullerene-based ETLs by incorporating high-quality few-layer graphene flakes (GFs), industrially produced through wet-jet milling exfoliation of graphite, into phenyl-C61-butyric acid methyl ester (PCBM). Our new composite ETL (GF:PCBM) can be processed into an ultrathin (∼10 nm), pinhole-free film atop the perovskite. We find that the presence of GFs in the PCBM matrix reduces defect-mediated recombination, while creating preferential paths for the extraction of electrons towards the current collector. The use of our GF-based composite ETL resulted in a significant enhancement in the open circuit voltage and fill factor of triple cation-based inverted PSCs, boosting the power conversion efficiency from ∼19% up to 20.8% upon the incorporation of GFs into the ETL.

Cell-Membrane-Coated and Cell-Penetrating Peptide-Conjugated Trimagnetic Nanoparticles for Targeted Magnetic Hyperthermia of Prostate Cancer Cells

Prostate malignancy represents the second leading cause of cancer-specific death among the male population worldwide. Herein, enhanced intracellular magnetic fluid hyperthermia is applied in vitro to treat prostate cancer (PCa) cells with minimum invasiveness and toxicity and highly specific targeting. We designed and optimized novel shape-anisotropic magnetic core-shell-shell nanoparticles (i.e., trimagnetic nanoparticles - TMNPs) with significant magnetothermal conversion following an exchange coupling effect to an external alternating magnetic field (AMF). The functional properties of the best candidate in terms of heating efficiency (i.e., Fe₃O₄@Mn_0.5Zn_0.5Fe₂O₄@CoFe₂O₄) were exploited following surface decoration with PCa cell membranes (CM) and/or LN1 cell-penetrating peptide (CPP). We demonstrated that the combination of biomimetic dual CM-CPP targeting and AMF responsiveness significantly induces caspase 9-mediated apoptosis of PCa cells. Furthermore, a downregulation of the cell cycle progression markers and a decrease of the migration rate in surviving cells were observed in response to the TMNP-assisted magnetic hyperthermia, suggesting a reduction in cancer cell aggressiveness.

Stable Sn-Based Hybrid Perovskite-Related Structures with Tunable Color Coordinates via Organic Cations in Low-Temperature Synthesis

Organic-inorganic Pb-free layered perovskites are efficient broadband emitters and thus are promising materials for lighting applications. However, their synthetic protocols require a controlled atmosphere, high temperature, and long preparation time. This hinders the potential tunability of their emission through organic cations, as is instead common practice in Pb-based structures. Here, we present a set of Sn-Br layered perovskite-related structures that display different chromaticity coordinates and photoluminescence quantum yield (PLQY) up to 80%, depending on the choice of the organic monocation. We first develop a synthetic protocol that is performed under air and at 4 °C, requiring only a few steps. X-ray and 3D electron diffraction analyses show that the structures exhibit diverse octahedra connectivity (disconnected and face-sharing) and thus optical properties, while preserving the organic-inorganic layer intercalation. These results provide key insight into a previously underexplored strategy to tune the color coordinates of Pb-free layered perovskites through organic cations with complex molecular configurations.

The Dark Side of Lead-Free Metal Halide Nanocrystals: Substituent-Modulated Photocatalytic Activity in Benzyl Bromide Reduction

We illustrate here the high photocatalytic activity of sustainable lead-free metal halide nanocrystals (NCs), namely, Cs₃Sb₂Br₉ NCs, in the reduction of p-substituted benzyl bromides in the absence of a cocatalyst. The electronic properties of the benzyl bromide substituents and the substrate affinity to the NC surface determine the selectivity in C-C homocoupling under visible light irradiation. This photocatalyst can be reused for at least three cycles and preserves its good performance with a turnover number of ca. 105,000.

Defect Engineering to Achieve Photostable Wide Bandgap Metal Halide Perovskites

Bandgap tuning is a crucial characteristic of metal-halide perovskites, with benchmark lead-iodide compounds having a bandgap of 1.6 eV. To increase the bandgap up to 2.0 eV, a straightforward strategy is to partially substitute iodide with bromide in so-called mixed-halide lead perovskites. Such compounds are prone, however, to light-induced halide segregation resulting in bandgap instability, which limits their application in tandem solar cells and a variety of optoelectronic devices. Crystallinity improvement and surface passivation strategies can effectively slow down, but not completely stop, such light-induced instability. Here we identify the defects and the intragap electronic states that trigger the material transformation and bandgap shift. Based on such knowledge, we engineer the perovskite band edge energetics by replacing lead with tin and radically deactivate the photoactivity of such defects. This leads to metal halide perovskites with a photostable bandgap over a wide spectral range and associated solar cells with photostable open circuit voltages.

Mixed Organic Cations Promote Ambient Light-Induced Formation of Metallic Lead in Lead Halide Perovskite Crystals

One major concern toward the performance and stability of halide perovskite-based optoelectronic devices is the formation of metallic lead that promotes nonradiative recombination of charge carriers. The origin of metallic lead formation is being disputed whether it occurs during the perovskite synthesis or only after light, electron, or X-ray beam irradiation or thermal annealing. Here, we show that the quantity of metallic lead detected in perovskite crystals depends on the concentration and composition of the precursor solution. Through a controlled crystallization process, we grew black-colored mixed dimethylammonium (DMA)/methylammonium (MA) lead tribromide crystals. The black color is suggested to be due to the presence of small lead clusters. Despite the unexpected black coloring, the crystals show higher crystallinity and less defect density with respect to the standard yellow-colored DMA/MAPbBr₃ crystals, as indicated by X-ray rocking curve and dark current measurements, respectively. While the formation of metallic lead could still be induced by external factors, the precursor solution composition and concentration can facilitate the formation of metallic lead during the crystallization process. Our results indicate that additional research is required to fully understand the perovskite precursor solution chemistry.

CuFeS2 Nanoparticles Functionalized with a Thermoresponsive Polymer for Photothermia and Externally Controlled Drug Delivery

CuFeS₂ chalcopyrite nanoparticles (NPs) can generate heat under exposure to near-infrared laser irradiation. Here, we develop a protocol to decorate the surface of CuFeS₂ NPs (13 nm) with a thermoresponsive (TR) polymer based on poly(ethylene glycol methacrylate) to combine heat-mediated drug delivery and photothermal heat damage. The resulting TR-CuFeS₂ NPs feature a small hydrodynamic size (∼75 nm), along with high colloidal stability and a TR transition temperature of 41 °C in physiological conditions. Remarkably, TR-CuFeS₂ NPs, when exposed to a laser beam (in the range of 0.5 and 1.5 W/cm²) at NP concentrations as low as 40-50 μg Cu/mL, exhibit a high heating performance with a rise in the solution temperature to hyperthermia therapeutic values (42-45 °C). Furthermore, TR-CuFeS₂ NPs worked as nanocarriers, being able to load an appreciable amount of doxorubicin (90 μg DOXO/mg Cu), a chemotherapeutic agent whose release could then be triggered by exposing the NPs to a laser beam (through which a hyperthermia temperature above 42 °C could be reached). In an in vitro study performed on U87 human glioblastoma cells, bare TR-CuFeS₂ NPs were proven to be nontoxic at a Cu concentration up to 40 μg/mL, while at the same low dose, the drug-loaded TR-CuFeS₂-DOXO NPs displayed synergistic cytotoxic effects due to the combination of direct heat damage and DOXO chemotherapy, under photo-irradiation by a 808 nm laser (1.2 W/cm²). Finally, under a 808 nm laser, the TR-CuFeS₂ NPs generated a tunable amount of reactive oxygen species depending on the applied power density and NP concentration.

A Novel Patient-Personalized Nanovector Based on Homotypic Recognition and Magnetic Hyperthermia for an Efficient Treatment of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the deadliest brain tumor, characterized by an extreme genotypic and phenotypic variability, besides a high infiltrative property in healthy tissues. Apart from very invasive surgical procedures, to date, there are no effective treatments, and life expectancy is very limited. In this work, we propose an innovative therapeutic approach based on lipid-based magnetic nanovectors, owning a dual therapeutic function: chemotherapy, thanks to an antineoplastic drug (regorafenib) loaded in the core, and localised magnetic hyperthermia, thanks to the presence of iron oxide nanoparticles, remotely activated by an alternating magnetic field. The drug has been selected based on ad hoc patient-specific screenings; moreover, the nanovector is decorated with cell membranes derived from patients' cells, aiming at increasing homotypic and personalized targeting. We demonstrated that this functionalization not only enhances the selectivity of the nanovectors towards patient-derived GBM cells, but also their blood-brain barrier in vitro crossing ability. The localised magnetic hyperthermia induces both thermal and oxidative intracellular stress, that lead to lysosomal membrane permeabilization and release of proteolytic enzymes into the cytosol. Collected results show that hyperthermia and chemotherapy work in synergy to reduce GBM cell invasion properties, to induce intracellular damage and, eventually, to prompt cellular death. This article is protected by copyright. All rights reserved.

Colloidal Synthesis of Nickel Arsenide Nanocrystals for Electrochemical Water Splitting

We report a detailed study on the first colloidal synthesis of NiAs nanocrystals. By optimizing the synthesis parameters, we were able to obtain trioctylphosphine-capped NiAs nanoplatelets with an average diameter of ∼10 nm and a thickness of ca. 4 nm. We then studied the performance of such NiAs nanocrystals as electrocatalysts for electrochemical water splitting reactions, namely, acidic hydrogen evolution reaction (HER) and alkaline oxygen evolution reaction (OER). These nanocrystals were found to be the most HER active ones among the transition metal arsenides reported to date despite exhibiting less than 40 h of stability under benchmark operative conditions (i.e., -10 mA cm_geo ^-2). When tested as alkaline OER electrocatalysts, our NiAs nanocrystals behaved as a pre-catalyst and transformed superficially into an active Ni-oxy/hydroxide. As a result, NiAs nanocrystals featured an OER activity higher than that of benchmark Ni⁰ nanocrystals. Noticeably, the OER performance, in terms of , was retained for up to 60 h of continuous operation. The present study highlights how transition metal arsenides, whose structural features could be successfully controlled through a proper tuning of the synthetic parameters, might represent an emerging class of materials for electrocatalytic applications.

Surface Functionalization of Ti6Al4V-ELI Alloy with Antimicrobial Peptide Nisin

Implant-associated infections are a severe global concern, especially in the case of orthopedic implants intended for long-term or permanent use. The traditional treatment through systemic antibiotic administration is often inefficient due to biofilm formation, and concerns regarding the development of highly resistant bacteria. Therefore, there is an unfulfilled need for antibiotic-free alternatives that could simultaneously support bone regeneration and prevent bacterial infection. This study aimed to perform, optimize, and characterize the surface functionalization of Ti6Al4V-ELI discs by an FDA-approved antimicrobial peptide, nisin, known to hold a broad antibacterial spectrum. Accordingly, nisin bioactivity was also evaluated by in vitro release tests both in physiological and inflammatory pH conditions. Several methods, such as X-ray photoelectron spectroscopy (XPS), and Kelvin Probe atomic force microscopy confirmed the presence of a physisorbed nisin layer on the alloy surface. The functionalization performed at pH 6-7 was found to be especially effective due to the nisin configuration exposing its hydrophobic tail outwards, which is also responsible for its antimicrobial action. In addition, the first evidence of gradual nisin release both in physiological and inflammatory conditions was obtained: the static contact angle becomes half of the starting one after 7 days of soaking on the functionalized sample, while it becomes 0° on the control samples. Finally, the evaluation of the antibacterial performance toward the pathogen Staphylococcus aureus after 24 h of inoculation showed the ability of nisin adsorbed at pH 6 to prevent bacterial microfouling into biofilm-like aggregates in comparison with the uncoated specimens: viable bacterial colonies showed a reduction of about 40% with respect to the un-functionalized surface and the formation of (microcolonies (biofilm-like aggregates) is strongly affected.

High Open-Circuit Voltage Cs2 AgBiBr6 Carbon-Based Perovskite Solar Cells via Green Processing of Ultrasonic Spray-Coated Carbon Electrodes from Waste Tire Sources

Invited for this month cover is the group of Teresa Gatti at the Justus Liebig University (JLU) in Giessen, Germany, the group of Federico Bella at Politecnico di Torino (POLITO), Italy, and the group of Francesco Lamberti at the University of Padova (UNIPD), also in Italy. The image shows how waste tires can be converted in a conductive carbon powder that undergoes a green processing step to produce carbon electrodes for lead-free perovskite solar cells. Similar devices can be employed to harvest indoor light in order to power the Internet of Things (IoT) ecosystem. The Research Article itself is available at 10.1002/cssc.202201590.

High Open-Circuit Voltage Cs2 AgBiBr6 Carbon-Based Perovskite Solar Cells via Green Processing of Ultrasonic Spray-Coated Carbon Electrodes from Waste Tire Sources

Costs and toxicity concerns are at the center of a heated debate regarding the implementation of perovskite solar cells (PSCs) into commercial products. The first bottleneck could be overcome by eliminating the top metal electrode (generally gold) and the underlying hole transporting material and substituting both with one single thick layer of conductive carbon, as in the so-called carbon-based PSCs (C-PSCs). The second issue, related to the presence of lead, can be tackled by resorting to other perovskite structures based on less toxic metallic components. An interesting case is that of the double perovskite Cs₂ AgBiBr₆ , which at present still lacks the outstanding optoelectronic performances of the lead-based counterparts but is very stable to environmental factors. In this work, the processing of carbon electrodes onto Cs₂ AgBiBr₆ -based C-PSCs was reported, starting from an additive-free isopropanol ink of a carbon material obtained from the hydrothermal recycling of waste tires and employing a high-throughput ultrasonic spray coating method in normal environmental conditions. Through this highly sustainable approach that ensures a valuable step from an end-of-life to an end-of-waste status for used tires, devices were obtained delivering a record open circuit voltage of 1.293 V, which might in the future represent ultra-cheap solutions to power the indoor Internet of Things ecosystem.

Near-Infrared Light-Emitting Diodes Based on RoHS-Compliant InAs/ZnSe Colloidal Quantum Dots

We demonstrate efficient, stable, and fully RoHS-compliant near-infrared (NIR) light-emitting diodes (LEDs) based on InAs/ZnSe quantum dots (QDs) synthesized by employing a commercially available amino-As precursor. They have a record external quantum efficiency of 5.5% at 947 nm and an operational lifetime of ∼32 h before reaching 50% of their initial luminance. Our findings offer a new solution for developing RoHS-compliant light-emitting technologies based on Pb-free colloidal QDs.

Alloying Bi-Doped Cs2Ag1-xNaxInCl6 Nanocrystals with K+ Cations Modulates Surface Ligands Density and Photoluminescence Efficiency

We show how, in the synthesis of yellow-emissive Bi-doped Cs₂Ag_1-xNa_xInCl₆ double perovskite nanocrystals (NCs), preventing the transient formation of Ag⁰ particles increases the photoluminescence quantum yield (PLQY) of the NCs from ∼30% to ∼60%. Calculations indicate that the presence of even a single Ag⁰ species on the surface of a NC introduces deep trap states. The PL efficiency of these NCs is further increased to ∼70% by partial replacement of Na⁺ with K⁺ ions, up to a 7% K content, due to a lattice expansion that promotes a more favorable ligands packing on the NC surface, hence better surface passivation. A further increase in K⁺ lowers the PLQY, due to both the activation of nonradiative quenching channels and a lower oscillator strength of the BiCl₆→AgCl₆ transition (through which PL emission occurs). The work indicates how a deeper understanding of parameters influencing carrier trapping/relaxation can boost the PLQY of double perovskites NCs.

A colloidal route to semiconducting tungsten disulfide nanosheets with monolayer thickness

Transition metal dichalcogenides (TMDs) are a class of materials that have been extensively studied in the last decade, with molybdenum disulfide (MoS₂) being the main protagonist. Typically, the interesting TMD properties, e.g. a direct band gap transition, or broken inversion symmetry, are only present in monolayer thick TMDs, and in the absence of strong lateral confinement, we require different materials or alloys thereof when we want to obtain TMDs with varying (direct) band gap energies. With this in mind, tungsten disulfide (WS₂) is emerging as a direct competitor of MoS₂ due to its similar properties but larger band gap energy. While several colloidal strategies have been reported for the synthesis of WS₂, the synthesis of monolayer WS₂ and detailed studies on the effect of synthesis parameters on the synthesis outcome have remained elusive. In this work we therefore focused on a colloidal synthesis method for monolayer WS₂ using a design of experiment (DOE) approach. After optimization, we obtained nanosheets with a band gap transition consistent with the expected value for a monolayer. The thickness was further confirmed by Raman spectroscopy. While we could identify two temperature ranges where we could obtain a monolayer, sample characterization by XPS spectroscopy revealed the presence of different ratios of the metallic phase, with the sample synthesized at lower temperature displaying a lower concentration of the metallic phase.

Photoluminescence Intensity Enhancement in Tin Halide Perovskites

The prevalence of background hole doping in tin halide perovskites usually dominates their recombination dynamics. The addition of excess Sn halide source to the precursor solution is the most frequently used approach to reduce the hole doping and reveals photo-carrier dynamics related to defects activity. This study presents an experimental and theoretical investigation on defects under light irradiation in tin halide perovskites by combining measurements of photoluminescence with first principles computational modeling. It finds that tin perovskite thin films prepared with an excess of Sn halide sources exhibit an enhancement of the photoluminescence intensity over time under continuous excitation in inert atmosphere. The authors propose a model in which light irradiation promotes the annihilation of VSn 2- /Sni 2+ Frenkel pairs, reducing the deep carrier trapping centers associated with such defect and increasing the radiative recombination. Importantly, these observations can be traced in the open-circuit voltage dynamics of tin-based halide perovskite solar cells, implying the relevance of controlling the Sn photochemistry to stabilize tin perovskite devices.

Injectable carbon nanotube-functionalized hydrogel as a tool for cardiac tissue engineering

Background/Introduction

Heart failure (HF) is an expensive major public health problem in the United States and around the world (1). The current treatments for HF are aimed at reducing symptoms, slowing disease progression, and reducing mortality and not aimed at repairing heart muscle or restoring function. Furthermore, even with these treatments, approximately half of patients with HF will die within 5 years of diagnosis (2). Cardiac transplantation remains the only definitive treatment for those affected with end-stage HF, but availability of donor hearts remains a major limitation (3).

Purpose

The ability of the adult heart to regenerate cardiomyocytes (CMs) lost after injury is limited, generating interest in developing tissue engineering therapies to avoid progression towards HF. Rigid carbon nanotubes (CNTs) scaffolds have been used to improve CMs viability, proliferation, and maturation (4), but require undesirable invasive surgeries for implantation. To overcome this limitation, we engineered an injectable reverse thermal gel (RTG) functionalized with CNTs (RTG-CNT) that transitions from a liquid-solution to a gel-based matrix shortly after reaching body temperature allowing for a liquid-based delivery rapidly followed by a stable-gel localization (5).

Methods and results

Here we show experimental evidences the RTG-CNT hydrogel, used as a three-dimensional (3D) niche to culture human induced pluripotent stem cells (hiPSC)-CMs, promotes hiPSC-CMs alignment and elongation with increased Cx43 localization and improved contraction function when compared with traditional two-dimensional (2D) fibronectin controls and plain 3D RTG system without CNTs. Moreover, the short-term (4-week) biocompatibility of the RTG-CNT hydrogel was also assessed in a mouse model (intracardial injection). The results confirmed that the RTG-CNT hydrogel is well tolerated by the cardiac tissue.

Conclusion

Our results indicated that the injectable RTG-CNT hydrogel has the potential to be used as a minimally invasive tool for cardiac tissue engineering efforts.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): NATIONAL HEART, LUNG, AND BLOOD (NHLBI) INSTITUTE

ZnCl2 Mediated Synthesis of InAs Nanocrystals with Aminoarsine

The most developed approaches for the synthesis of InAs nanocrystals (NCs) rely on pyrophoric, toxic, and not readily available tris-trimethylsilyl (or tris-trimethylgermil) arsine precursors. Less toxic and commercially available chemicals, such as tris(dimethylamino)arsine, have recently emerged as alternative As precursors. Nevertheless, InAs NCs made with such compounds need to be further optimized in terms of size distribution and optical properties in order to meet the standard reached with tris-trimethylsilyl arsine. To this aim, in this work we investigated the role of ZnCl₂ used as an additive in the synthesis of InAs NCs with tris(dimethylamino)arsine and alane N,N-dimethylethylamine as the reducing agent. We discovered that ZnCl₂ helps not only to improve the size distribution of InAs NCs but also to passivate their surface acting as a Z-type ligand. The presence of ZnCl₂ on the surface of the NCs and the excess of Zn precursor used in the synthesis enable the subsequent in situ growth of a ZnSe shell, which is realized by simply adding the Se precursor to the crude reaction mixture. The resulting InAs@ZnSe core@shell NCs exhibit photoluminescence emission at ∼860 nm with a quantum yield as high as 42±4%, which is a record for such heterostructures, given the relatively high mismatch (6%) between InAs and ZnSe. Such bright emission was ascribed to the formation, under our peculiar reaction conditions, of an In–Zn–Se intermediate layer between the core and the shell, as indicated by X-ray photoelectron spectroscopy and elemental analyses, which helps to release the strain between the two materials.

Colloidal Bismuth Chalcohalide Nanocrystals

Here we present a colloidal approach to synthesize bismuth chalcohalide nanocrystals (BiEX NCs, in which E=S, Se and X=Cl, Br, I). Our method yields orthorhombic elongated BiEX NCs, with BiSCl crystallizing in a previously unknown polymorph. The BiEX NCs display a composition‐dependent band gap spanning the visible spectral range and absorption coefficients exceeding 10⁵ cm⁻¹. The BiEX NCs show chemical stability at standard laboratory conditions and form colloidal inks in different solvents. These features enable the solution processing of the NCs into robust solid films yielding stable photoelectrochemical current densities under solar‐simulated irradiation. Overall, our versatile synthetic protocol may prove valuable in accessing colloidal metal chalcohalide nanomaterials at large and contributes to establish metal chalcohalides as a promising complement to metal chalcogenides and halides for applied nanotechnology.

Mixed Dimethylammonium/Methylammonium Lead Halide Perovskite Crystals for Improved Structural Stability and Enhanced Photodetection

The solvent acidolysis crystallization technique is utilized to grow mixed dimethylammonium/methylammonium lead tribromide (DMA/MAPbBr₃ ) crystals reaching the highest dimethylammonium incorporation of 44% while maintaining the 3D cubic perovskite phase. These mixed perovskite crystals show suppression of the orthorhombic phase and a lower tetragonal-to-cubic phase-transition temperature compared to MAPbBr₃ . A distinct behavior is observed in the temperature-dependent photoluminescence properties of MAPbBr₃ and mixed DMA/MAPbBr₃ crystals due to the different organic cation dynamics governing the phase transition(s). Furthermore, lateral photodetectors based on these crystals show that, at room temperature, the mixed crystals possess higher detectivity compared to MAPbBr₃ crystals caused by structural compression and reduced surface trap density. Remarkably, the mixed-crystal devices exhibit large enhancement in their detectivity below the phase-transition temperature (at 200 K), while for the MAPbBr₃ devices only insignificant changes are observed. The high detectivity of the mixed crystals makes them attractive for visible-light communication and for space applications. The results highlight the importance of the synthetic technique for compositional engineering of halide perovskites that governs their structural and optoelectronic properties.

One-step functionalization of mildly and strongly reduced graphene oxide with maleimide: an experimental and theoretical investigation of the Diels-Alder [4+2] cycloaddition reaction

For large-scale graphene applications, such as the production of polymer-graphene nanocomposites, exfoliated graphene oxide (GO) and its reduced form (rGO) are presently considered to be very suitable starting materials, showing enhanced chemical reactivity with respect to pristine graphene, in addition to suitable electronic properties (i.e., tunable band gap). Among other chemical processes, a suitable way to obtain surface decoration of graphene is through a direct one-step Diels-Alder (DA) reaction, e.g. through the use of dienophile or diene moieties. However, the feasibility and extent of decoration largely depends on the specific graphene microstructure that in the case of rGO sheets is not easy to control and generally presents a high degree of inhomogeneity owing to various on-plane functionalization (e.g., epoxide and hydroxyl groups) or in-plane lattice defects. In an effort to gain some insights into the covalent functionalization of variably reduced GO samples, we present a combined experimental and theoretical study on the DA cycloaddition reaction of maleimide, a dienophile functional unit well-suited for chemical conjugation of polymers and macromolecules. In particular, we considered both mildly and strongly reduced GOs. Using thermogravimetry, Raman and X-Ray photoelectron spectroscopy, and elemental analysis we show evidence of variable chemical reactivity of rGO as a function of the residual oxygen content. Moreover, from quantum mechanical calculations carried out at the DFT level on different graphene reaction sites, we provide a more detailed molecular view to interpret experimental findings and to assess the reactivity series of different graphene modifications.

Artificially altered gravity elicits cell homeostasis imbalance in planarian worms, and cerium oxide nanoparticles counteract this effect

Gravity alterations elicit complex and mostly detrimental effects on biological systems. Among these, a prominent role is occupied by oxidative stress, with consequences for tissue homeostasis and development. Studies in altered gravity are relevant for both Earth and space biomedicine, but their implementation using whole organisms is often troublesome. Here we utilize planarians, simple worm model for stem cell and regeneration biology, to characterize the pathogenic mechanisms brought by artificial gravity alterations. In particular, we provide a comprehensive evaluation of molecular responses in intact and regenerating specimens, and demonstrate a protective action from the space-apt for nanotechnological antioxidant cerium oxide nanoparticles.

Cerium Oxide Nanoparticle Administration to Skeletal Muscle Cells under Different Gravity and Radiation Conditions

For their remarkable biomimetic properties implying strong modulation of the intracellular and extracellular redox state, cerium oxide nanoparticles (also termed "nanoceria") were hypothesized to exert a protective role against oxidative stress associated with the harsh environmental conditions of spaceflight, characterized by microgravity and highly energetic radiations. Nanoparticles were supplied to proliferating C2C12 mouse skeletal muscle cells under different gravity and radiation levels. Biological responses were thus investigated at a transcriptional level by RNA next-generation sequencing. Lists of differentially expressed genes (DEGs) were generated and intersected by taking into consideration relevant comparisons, which led to the observation of prevailing effects of the space environment over those induced by nanoceria. In space, upregulation of transcription was slightly preponderant over downregulation, implying involvement of intracellular compartments, with the majority of DEGs consistently over- or under-expressed whenever present. Cosmic radiations regulated a higher number of DEGs than microgravity and seemed to promote increased cellular catabolism. By taking into consideration space physical stressors alone, microgravity and cosmic radiations appeared to have opposite effects at transcriptional levels despite partial sharing of molecular pathways. Interestingly, gene ontology denoted some enrichment in terms related to vision, when only effects of radiations were assessed. The transcriptional regulation of mitochondrial uncoupling protein 2 in space-relevant samples suggests perturbation of the intracellular redox homeostasis, and leaves open opportunities for antioxidant treatment for oxidative stress reduction in harsh environments.

Two-Step Thermal Annealing: An Effective Route for 15 % Efficient Quasi-2D Perovskite Solar Cells

Invited for this month's cover are collaborators from University of Pavia, École Polytechnique Fédérale de Lausanne, University of Messina and Istituto Italiano di Tecnologia. The cover picture shows the crystal structure of a Ruddlesden-Popper quasi-2D perovskite with chemical formula (PEA)₂ MA₃₉ Pb₄₀ I₁₂₁ (with PEA: phenylethylammonium and MA: methylammonium). The subscript 40 indicates the number of PbI₆ octahedra separated by a double layer of PEA cations. Such quasi-2D perovskites exhibit efficient photovoltaic performances and higher stability with respect to the pure 3D counterpart (MAPbI₃ ). This article is part of the Special Collection on "Perovskite Materials and Devices". Read the full text of the article at 10.1002/cplu.202000777.

Two-Dimensional Gallium Sulfide Nanoflakes for UV-Selective Photoelectrochemical-type Photodetectors

Two-dimensional (2D) transition-metal monochalcogenides have been recently predicted to be potential photo(electro)catalysts for water splitting and photoelectrochemical (PEC) reactions. Differently from the most established InSe, GaSe, GeSe, and many other monochalcogenides, bulk GaS has a large band gap of ∼2.5 eV, which increases up to more than 3.0 eV with decreasing its thickness due to quantum confinement effects. Therefore, 2D GaS fills the void between 2D small-band-gap semiconductors and insulators, resulting of interest for the realization of van der Waals type-I heterojunctions in photocatalysis, as well as the development of UV light-emitting diodes, quantum wells, and other optoelectronic devices. Based on theoretical calculations of the electronic structure of GaS as a function of layer number reported in the literature, we experimentally demonstrate, for the first time, the PEC properties of liquid-phase exfoliated GaS nanoflakes. Our results indicate that solution-processed 2D GaS-based PEC-type photodetectors outperform the corresponding solid-state photodetectors. In fact, the 2D morphology of the GaS flakes intrinsically minimizes the distance between the photogenerated charges and the surface area at which the redox reactions occur, limiting electron-hole recombination losses. The latter are instead deleterious for standard solid-state configurations. Consequently, PEC-type 2D GaS photodetectors display a relevant UV-selective photoresponse. In particular, they attain responsivities of 1.8 mA W^-1 in 1 M H₂SO₄ [at 0.8 V vs reversible hydrogen electrode (RHE)], 4.6 mA W^-1 in 1 M Na₂SO₄ (at 0.9 V vs RHE), and 6.8 mA W^-1 in 1 M KOH (at 1.1. V vs RHE) under 275 nm illumination wavelength with an intensity of 1.3 mW cm^-2. Beyond the photodetector application, 2D GaS-based PEC-type devices may find application in tandem solar PEC cells in combination with other visible-sensitive low-band-gap materials, including transition-metal monochalcogenides recently established for PEC solar energy conversion applications.

Graphene-Based Electrodes in a Vanadium Redox Flow Battery Produced by Rapid Low-Pressure Combined Gas Plasma Treatments

The development of high-power density vanadium redox flow batteries (VRFBs) with high energy efficiencies (EEs) is crucial for the widespread dissemination of this energy storage technology. In this work, we report the production of novel hierarchical carbonaceous nanomaterials for VRFB electrodes with high catalytic activity toward the vanadium redox reactions (VO²⁺/VO₂ ⁺ and V²⁺/V³⁺). The electrode materials are produced through a rapid (minute timescale) low-pressure combined gas plasma treatment of graphite felts (GFs) in an inductively coupled radio frequency reactor. By systematically studying the effects of either pure gases (O₂ and N₂) or their combination at different gas plasma pressures, the electrodes are optimized to reduce their kinetic polarization for the VRFB redox reactions. To further enhance the catalytic surface area of the electrodes, single-/few-layer graphene, produced by highly scalable wet-jet milling exfoliation of graphite, is incorporated into the GFs through an infiltration method in the presence of a polymeric binder. Depending on the thickness of the proton-exchange membrane (Nafion 115 or Nafion XL), our optimized VRFB configurations can efficiently operate within a wide range of charge/discharge current densities, exhibiting energy efficiencies up to 93.9%, 90.8%, 88.3%, 85.6%, 77.6%, and 69.5% at 25, 50, 75, 100, 200, and 300 mA cm^-2, respectively. Our technology is cost-competitive when compared to commercial ones (additional electrode costs < 100 € m^-2) and shows EEs rivalling the record-high values reported for efficient systems to date. Our work remarks on the importance to study modified plasma conditions or plasma methods alternative to those reported previously (e.g., atmospheric plasmas) to improve further the electrode performances of the current VRFB systems.

Inverted perovskite solar cells with enhanced lifetime and thermal stability enabled by a metallic tantalum disulfide buffer layer

Perovskite solar cells (PSCs) have proved their potential for delivering high power conversion efficiencies (PCE) alongside low fabrication cost and high versatility. The stability and the PCE of PSCs can readily be improved by implementing engineering approaches that entail the incorporation of two-dimensional (2D) materials across the device's layered configuration. In this work, two-dimensional (2D) 6R-TaS₂ flakes were exfoliated and incorporated as a buffer layer in inverted PSCs, enhancing the device's PCE, lifetime and thermal stability. A thin buffer layer of 6R-TaS₂ flakes was formed on top of the electron transport layer to facilitate electron extraction, thus improving the overall device performance. The optimized devices reach a PCE of 18.45%, representing a 12% improvement compared to the reference cell. The lifetime stability measurements of the devices under ISOS-L2, ISOS-D1, ISOS-D1I and ISOS-D2I protocols revealed that the TaS₂ buffer layer retards the intrinsic, thermally activated degradation processes of the PSCs. Notably, the devices retain more than the 80% of their initial PCE over 330 h under continuous 1 Sun illumination at 65 °C.

Engineering the Optical Emission and Robustness of Metal-Halide Layered Perovskites through Ligand Accommodation

The unique combination of organic and inorganic layers in 2D layered perovskites offers promise for the design of a variety of materials for mechatronics, flexoelectrics, energy conversion, and lighting. However, the potential tailoring of their properties through the organic building blocks is not yet well understood. Here, different classes of organoammonium molecules are exploited to engineer the optical emission and robustness of a new set of Ruddlesden-Popper metal-halide layered perovskites. It is shown that the type of molecule regulates the number of hydrogen bonds that it forms with the edge-sharing [PbBr₆ ]^4- octahedra layers, leading to strong differences in the material emission and tunability of the color coordinates, from deep-blue to pure-white. Also, the emission intensity strongly depends on the length of the molecules, thereby providing an additional parameter to optimize their emission efficiency. The combined experimental and computational study provides a detailed understanding of the impact of lattice distortions, compositional defects, and the anisotropic crystal structure on the emission of such layered materials. It is foreseen that this rational design can be extended to other types of organic linkers, providing a yet unexplored path to tailor the optical and mechanical properties of these materials and to unlock new functionalities.

Two-Step Thermal Annealing: An Effective Route for 15 % Efficient Quasi-2D Perovskite Solar Cells

Low-dimensional perovskites (LDP) are nowadays recognized as promising materials for the realization of highly performing photovoltaic cells. However, issues related to film morphology, composition, crystal quality and material homogeneity limit the device performances and reproducibility. In this work, we implement a robust method for the deposition of a LDP mixing methylammonium (MA) and phenylethylammonium (PEA) cations to create the mixed system (PEA)₂ MA₃₉ Pb₄₀ I₁₂₁ by using a two-step thermal annealing treatment (at 60 and 100 °C). Our approach results in LDP films with high crystal quality and enhanced carrier lifetime, which double the power conversion efficiency of reference devices, reaching up to 15 %.

Biomimetic keratin gold nanoparticle-mediated in vitro photothermal therapy on glioblastoma multiforme

Aim: To realize and characterize a new generation of keratin-coated gold nanoparticles (Ker-AuNPs) as highly efficient photosensitive nanosized therapeutics for plasmonic photothermal (PPT) therapy. Materials & methods: The chemical, physical, morphological and photothermal properties of Ker-AuNPs are investigated using dynamic light scattering, ζ-potential, UV-Visible, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy and high-resolution thermography. In vitro experiments are performed on a human glioblastoma cell line (i.e., U87-MG), using viability assays, transmission electron microscopy, fluorescence microscopy, cytometric analyses and PPT experiments. Results: Experiments confirm the excellent biocompatibility of Ker-AuNPs, their efficient cellular uptake and localized photothermal heating capabilities. Conclusion: The reported structural and functional properties pointed out these Ker-AuNPs as a promising new tool in the field of biocompatible photothermal agents for PPT treatments against cancer-related diseases.

Photo-electrical properties of 2D quantum confined metal-organic chalcogenide nanocrystal films

Hybrid quantum wells are electronic structures where charge carriers are confined along stacked inorganic planes, separated by insulating organic moieties. 2D quantum-confined hybrid materials are of great interest from a solid-state physics standpoint because of the rich many-body phenomena they host, their tunability and easy synthesis, allowing the creation of material libraries. In addition, from a technological point of view, 2D hybrids are promising candidates for efficient, tunable, low-cost materials impacting a broad range of optoelectronic devices. Different approaches and materials have, therefore, been investigated, with the notable example of 2D metal halide hybrid perovskites. Despite the remarkable properties of such materials, the presence of toxic elements like lead is not desirable in applications and their ionic lattices may represent a limiting factor for stability under operating conditions. Therefore, non-ionic 2D materials made with non-toxic elements are preferable. In order to expand the library of possible hybrid quantum well materials, herein, we consider an alternative platform based on non-toxic, self-assembled, metal-organic chalcogenides. While the optical properties have been recently explored and some unique excitonic characters highlighted, photo-generation of carriers and their transport in these lamellar inorganic/organic nanostructures and critical optoelectronic aspects remain totally unexplored. We hereby report the first investigation on the electrical properties of the air-stable [AgSePh]_∞ 2D coordination polymer in the form of nanocrystal (NC) films readily synthesized in situ and at low temperature, compatible with flexible plastic substrates. The wavelength-dependent photo-response of the NC films suggests the possible use of this material as a near-UV photodetector. We therefore built a lateral photo-detector, achieving a sensitivity of 0.8 A W^-1 at 370 nm, thanks to a photoconduction mechanism, and a cut-off frequency of ∼400 Hz, and validated its reliability as an air-stable UV detector on flexible substrates.