Nanoscale Advances最新文献

The diffusion motions of individual polymer aggregates in disordered porous media were visualized using the single-particle tracking (SPT) method because the motions inside porous media play important roles in various fields of science and engineering. In the aggregates diffused on the surfaces of pores, continuous adsorption and desorption processes were observed. The relationship between the size of the aggregates and pore size was analysed based on diffusion coefficients, moment scaling spectrum (MSS) slope analysis, and diffusion anisotropy analysis. The obtained diffusion coefficients were different for different aggregates and pore sizes. The MSS slope analysis indicated that more than 85% of the aggregates showed confined diffusion for all the conditions investigated. The diffusion anisotropy analysis suggested that the diffusion of the aggregates exhibited anisotropic behaviour. The interactions between the aggregates and the pores were complex, causing the aggregates to exhibit motions distinct from those associated with surface diffusion on smooth surfaces.

In alignment with the global movement toward reducing animal testing, several reconstructed human epidermis (RHE) models have been created for conducting skin irritation tests. These models have undergone development, verification, validation, and integration into OECD TG 439. Our team has introduced a novel in-house RHE named GB-RHE, and we adhere to OECD TG 439 to pre-validate the model and test its potential employment for nanoparticle irritation studies. GB-RHE exhibits morphological, biochemical, and physiological attributes equivalent to the human epidermis, featuring well-differentiated multilayered viable keratinocytes with a robust barrier function. The performance of the GB-RHE model was evaluated using ten reference chemicals, following the performance standard of OECD TG 439. The results demonstrated commendable predictive capacity and showed that titanium dioxide nanoparticles (TiO₂ NPs) are 'non-irritant' to the human epidermis following the globally harmonized classification system. However, although the histological analysis did not show morphological changes, transmission electron micrographs demonstrated that TiO₂ NPs can be internalized, reaching the external viable layers of the epidermis. This study demonstrates that in addition to the potential of the GB-RHE model to evaluate skin irritation, this model also has the potential to evaluate the skin toxicity of NPs and carry out cell internalization studies.

Sensing of hazardous gases has an important role in ensuring safety in a variety of industries as well as environments. Mainly produced by the combustion of fossil fuels and other organic matter, ethanol is a dangerous gas that endangers human health and the environment. Stability and sensing sensitivity are major considerations when designing gas sensors. Here, a superior ethanol sensor with a high response and fast recovery was synthesized by "wrapping" CdS nanoparticles on metallic Ti₃C₂T _x MXene using a simple method. CdS nanoparticles were uniformly covered on the Ti₃C₂T _x MXene surface, forming a "rice crust"-like heterostructure. The sensor displayed good detection of ethanol gas at room temperature. Response signals up to 31% were obtained for ethanol molecules (20 ppm) with quick recovery (41 s). The performance of the ethanol sensor was evaluated across a range of concentrations (5-100 ppm) and relative humidity (60% and 90% RH) at room temperature. Our method could open up a new strategy for the development of ethanol sensors.

Using the first principle calculations, we propose a boron and nitrogen cluster incorporated graphene system for efficient valley polarization. The broken spatial inversion symmetry results in high Berry curvature at K and K' valleys of the hexagonal Brillouin zone in this semiconducting system. The consideration of excitonic quasiparticles within the GW approximation along with their scattering processes using the many-body Bethe-Salpeter equation gives rise to an optical gap of 1.72 eV with an excitonic binding energy of 0.65 eV. Owing to the negligible intervalley scattering, the electrons in opposite valleys are selectively excited by left- and right-handed circularly polarized light, as evident from the oscillator strength calculations. Therefore, this system can exhibit the circular-dichroism valley Hall effect in the presence of an in-plane electric field. Moreover, such excitonic qubits can be exploited for information processing.

Pt-CeO₂ nanosponges (1 wt% Pt) with high surface area (113 m² g^-1), high pore volume (0.08 cm³ g^-1) and small-sized Pt nanoparticles (1.8 ± 0.4 nm) are prepared by thermal decomposition of a cerium oxalate precursor and examined for catalytic oxidation of CO, volatile organic compounds (VOCs), and NH₃. The cerium oxalate precursor Ce₂(C₂O₄)₃·10H₂O is prepared by aqueous precipitation from Ce(NO₃)₃·6H₂O and K₂C₂O₄·H₂O and thermally converted to CeO₂ nanosponges by heating in air. Optimal conditions for decomposition in terms of surface area and porosity are observed at 350 °C for 20 min. Finally, the CeO₂ nanosponges are decorated with small-sized Pt nanoparticles, using a wet-chemical impregnation with Pt(ac)₂ in methanol. Electron microscopy with tomography, electron spectroscopy and further methods (TG, XRD, FT-IR, sorption analysis) are used to characterize the catalyst composition and especially the structure and porosity of the Pt-CeO₂ nanosponges as well as the uniform distribution of the Pt nanoparticles. The Pt-CeO₂ nanosponges show good thermal stability (up to 400 °C) and, already as a new, non-optimized catalyst, promising activity for catalytic oxidation of CO, VOCs, NH₃ as indicated by high activities in terms of low and stable light-out and light-off temperatures as well as a high selectivity to N₂ (for NH₃ oxidation) with >80% at 170-250 °C.

Photocatalytic reduction of CO₂ to produce organic fuels is a promising strategy for addressing carbon reduction and energy scarcity. Transition metal carbides (Ti₃C₂T _X ) are of particular interest due to their unique layered structures and excellent electrical conductivity. However, the practical application of Ti₃C₂T _X is limited by the poor separation efficiency of photogenerated charge carriers and the low migration ability of photogenerated electrons. Herein, Ag/Ag₂S/Ti₃C₂T _X heterojunctions were synthesized by depositing Ag/Ag₂S nanoparticles onto layered Ti₃C₂T _X substrates using a combination of co-precipitation and photoreduction methods. Fluorescence spectra, UV diffuse reflection, and photoelectric chemical characterizations demonstrated that Ag/Ag₂S/Ti₃C₂T _X heterojunctions provided effective channels for the reverse and synergistic migration of electrons and holes, leading to improved spatial separation. Notably, the Ag component in the composite acts as an electron acceptor and reactive center, significantly enhancing the migration ability of photogenerated electrons. The total alcohol yield over Ag/Ag₂S/Ti₃C₂T _X (125.3 μmol g_catal. ^-1) was 5.1 times higher than that on Ag₂S (24.7 μmol g_catal. ^-1) and 2.1 times higher than on Ti₃C₂T _X (60.7 μmol g_catal. ^-1). This study offers valuable insights into designing efficient photocatalytic CO₂ reduction catalysts.

Mesenchymal stem cell (MSC)-based bone tissue regeneration has gained significant attention due to the excellent differentiation capacity and immunomodulatory activity of MSCs. Enhancing osteogenesis regulation is crucial for improving the therapeutic efficacy of MSC-based regeneration. By utilizing the regenerative capacity of bone ECM and the functionality of nanoparticles, we recently engineered bone-based nanoparticles (BNPs) from decellularized porcine bones. The effects of internalization of BNPs on MSC viability, proliferation, and osteogenic differentiation were first investigated and compared at different time points. The phenotypic behaviors, including cell number, proliferation, and differentiation were characterized and compared. By incorporating a LNA/DNA nanobiosensor and MSC live cell imaging, we monitored and compared Notch ligand delta-like 4 (Dll4) expression dynamics in the cytoplasm and nucleus during osteogenic differentiation. Pharmacological interventions are used to inhibit Notch signaling to examine the mechanisms involved. The results suggest that Notch inhibition mediates the osteogenic process, with reduced expression of early and late stage differentiation markers (ALP and calcium mineralization). The internalization of BNPs led to an increase in Dll4 expression, exhibiting a time-dependent pattern that aligned with enhanced cell proliferation and differentiation. Our findings indicate that the observed changes in BNP-treated cells during osteogenic differentiation could be associated with elevated levels of Dll4 mRNA expression. In summary, this study provides new insights into MSC osteogenic differentiation and the molecular mechanisms through which BNPs stimulate this process. The results indicate that BNPs influence osteogenesis by modulating Notch ligand Dll4 expression, demonstrating a potential link between Notch signaling and the proteins present in BNPs.

Thin film transistors (TFTs) with InSnZnO (ITZO) and Al₂O₃ as the semiconductor and dielectric layers, respectively, were investigated, aiming to elevate the device performance. Chemically synthesized CuInS₂/ZnS core/shell colloidal quantum dots (QDs) were used to passivate the semiconductor/dielectric interface. Compared with the pristine device, the device with the integrated QDs demonstrates remarkably improved electrical performance, including a higher electron mobility and a lower leakage current. Moreover, the integration of QDs largely mitigates hysteresis in the bidirectional transfer characteristics of the device. Improved negative bias stress stability is also observed in the device with QDs. The performance enhancement is ascribed to the reduction of the trap states induced by the defects in Al₂O₃, and the screening of electrical dipoles at the Al₂O₃/ITZO interface. This work proposes a new strategy to passivate the semiconductor/dielectric interface, which not only improves TFT performance, but also holds potential for optoelectronic applications.

Since the initial publication on the first Ti₃C₂T _x MXene in 2011, there has been a significant increase in the number of reports on applications of MXenes in various domains. MXenes have emerged as highly promising materials for various biomedical applications, including photothermal therapy (PTT), drug delivery, diagnostic imaging, and biosensing, owing to their fascinating conductivity, mechanical strength, biocompatibility and hydrophilicity. Through surface modification, MXenes can mitigate cytotoxicity, enhance biological stability, and improve histocompatibility, thereby enabling their potential use in in vivo biomedical applications. MXenes are also known for their ability to absorb light in the near-infrared (NIR) region and generate heat by localised surface plasmon resonance (LSPR) effects and electron-phonon coupling. Optical excitation laser pulses result in hot photocarrier distribution in MXenes, which quickly transfers surplus energy to the crystal lattice and results in the internal conversion of light into heat with nearly 100% efficiency. The relaxation of hot carrier distribution by electron-phonon interactions leads to the cooling of the lattice by dissipating thermal energy to the surrounding environment. This heating effect of MXenes makes them potential photothermal agents (PTAs), particularly for PTT applications. The adjustable surface of MXenes and their high surface area-to-volume ratios are ideal for the combinatorial approach of PTT along with drug delivery, photodynamic therapy (PDT), bone regeneration and other applications. Since non-Ti MXenes are more biocompatible than Ti MXenes, they are promising candidates for different biomedical applications. This comprehensive review provides a concise overview of the current research patterns, properties, and biomedical applications of non-Ti MXenes, particularly in PTT and its combinatorial approaches.

This study developed a novel PbS-rGO composite counter electrode to enhance the performance of quantum dot-sensitized solar cells (QDSSCs). The composite was synthesized via a hydrothermal method by anchoring PbS nanocubes onto reduced graphene oxide (rGO) sheets. The effect of the mass ratio of rGO to PbS (0.0, 0.1, 0.3, and 0.6) on power conversion efficiency (PCE) was investigated. The optimized rGO-PbS (0.03) composite achieved a power conversion efficiency of 5.358%, V _oc of 0.540 V, J _sc of 21.157 mA cm^-2, and FF of 0.516. The rGO framework provides an interconnected conductive network that facilitates efficient charge transport, reduces charge transfer resistance, and improves overall conductivity. Electrochemical analyses confirmed the superior electrocatalytic activity of the composite in reducing the S _n ^2-/S^2- redox couple. The unique band alignment between rGO and PbS optimized the electron transfer pathways. The hierarchical structure increased the surface area and light absorption, enabling a more effective charge transfer at the electrode-electrolyte interface.