Materials Advances最新文献

[This corrects the article DOI: 10.1039/D0MA00642D.].

Here we present a nanopatterning strategy utilising thermal scanning probe lithography (t-SPL) for the precise organisation of DNA origami into nanoarrays. The aim of this approach is to demonstrate control in the fabrication of nanoarray platforms exhibiting single-molecule accuracy. Combining the inherent programmability of DNA origami structures with t-SPL nanopatterning, we demonstrated the controlled immobilisation on surfaces of functionalised DNA origami - as proof of concept we employed gold nanoparticles (AuNPs) and quantum dots (QDs) - at predefined positions and in nanoarray configurations. This method holds great potential for the construction of hetero-functionalised biomolecular nanoarrays with single-molecule control, with applications in bionanotechnology and (nano)materials science.

Ni–Zn-based ferrites (NZFO) need to possess the ideal ratio of dielectric and magnetic characteristics for uses involving electromagnetic fields. Consequently, the NZFO system has been modified by Ti⁴⁺ substitution at Fe³⁺ producing Ni_0.5Zn_0.5Ti_xFe_2−xO₄ (x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) and a conventional sol–gel process was followed for the synthesis. The structure of the synthesized samples was evaluated from the X-ray diffraction (XRD) patterns. Fourier transform infrared (FTIR) measurement provided information on chemical interaction with thermodynamic conditions. In addition, the grain sizes were obtained from scanning electron microscopy (SEM). Furthermore, the studied samples exhibit a notable light absorption in the visible spectrum with band gaps between 3.8 and 4.8 eV. The magneto-dielectric properties were analyzed by field (H) dependent magnetization (M), frequency-dependent permeability (μ), and permittivity (ε) measurements. Ti⁴⁺ substitution in NZFO led to a decrease in magnetic saturation (M_s) and μ while the values of creased and improved the mismatching impedance (Z/η₀ = (μ′/ε′)^1/2). The lowest value of M_s (14 emu g⁻¹) is achieved for the sample with x = 0.1 for which μ is also the lowest. Finally, a stable value of Z/η₀ (∼4.0) has been obtained for the x = 0.10 sample over a wide range of frequencies (1–10 MHz), making it suitable as a miniaturizing device material in this frequency range.

Carbon dot-based radiocontrast agents have recently sparked the interest of researchers owing to their better contrasting capabilities, simple synthesis protocols, high colloidal stability, and good biocompatibility. In this study, we propose for the first time the synthesis of iodine-doped carbon dots (I-CDs) using low-cost reagents such as citric acid (C₆H₈O₇), urea (CH₄N₂O) and potassium iodide (KI). The as-prepared I-CDs demonstrated excellent colloidal stability (with a zeta potential value of −64.7 mV), excitation-dependent fluorescent properties (with a maximum quantum yield of ∼8.9%), and a mean iodine concentration of ∼4.67 wt%. Notably, the as-prepared I-CDs displayed greater X-ray attenuation efficiency (42.87 HU mL mg⁻¹) as compared to the commercially employed iopromide radiocontrast agent (30.98 HU mL mg⁻¹). Furthermore, ATPase activity, cytotoxicity analysis with HeLa, NHDF, HEK293, and A549 cell lines, and live-cell imaging experiments of the Drosophila neuroblasts in intact brain lobes suggested high biocompatibility and nontoxicity of the prepared I-CDs. Overall, biocompatible and low-cost I-CDs show great promise as bifunctional radiocontrast and fluorescent agents for biomedical applications.

Efficiency improvement of heterogeneous silicon thin-film solar cells (SiTFSCs) remains challenging. Thus, single-walled carbon nanotube (SWCNT) and zinc oxide nanostructures (ZnO NCs) were integrated into Si thin films using the spray-spin coating approach to realize such solar cells. The effect of various annealing temperatures (100–175 °C) on the solar cells’ efficiency, structure, morphology, and absorbance was assessed. X-ray diffraction analysis confirmed the existence of highly crystalline wurtzite and hexagonal structures corresponding to ZnO and graphite with maximum nanocrystallite sizes of 51.92 nm. Scanning electron microscopy images of the samples showed uniform surface morphology without any aggregation. In addition, with the increase of the annealing temperature from 100 to 175 °C, the efficiency, porosity, optical absorbance bands, and band gap energy of the films were increased from 17.0–18.6%, 70–74.8%, 246–326 nm, and 2.0–2.5 eV, respectively. It was asserted that by controlling the annealing temperature, the overall performance of the proposed SWCNT/ZnO NC-integrated SiTFSC can be enhanced, contributing to the further advancement of high-performance Si-based photovoltaics.

Eumelanin is a black-brown biopigment that provides photoprotection and pigmentation in mammals, insects, and invertebrates. It can be obtained by oxidative polymerisation of 5,6-dihydroxyindole (DHI) and its 2-carboxylic acid (DHICA). Due to its unique physical and chemical properties and its biocompatibility, eumelanin is a promising biomaterial for applications in energy storage, biomedicine, and sensing. However, poor solubility in water and lack of sustainable and low-cost sources of eumelanin have so far limited the full exploitation of this biomaterial. Insect farming is rapidly emerging as an alternative source of eumelanin. Unlike other types of eumelanin, BSF eumelanin, which is extracted from the exoskeleton of the black soldier fly (BSF, Hermetia illucens), is water-dispersible; however, its fundamental chemical properties are not completely understood. Here, we report the characterisation of BSF eumelanin using various spectroscopy techniques. Contrary to what is known about other insect eumelanins, which are believed to contain exclusively DHI, our results indicate that BSF eumelanin may contain both DHI and DHICA moieties. We discuss the potential reasons for this discrepancy.

This study examines the spiking response of a proteinoid–actin–kombucha system when exposed to varying frequency of yellow light pulses. The objective is to understand the frequency-dependent characteristics of this system's response and explore the possibility of using light pulses to regulate and manipulate how it functions. The kombucha samples, which contained proteinoid–actin complexes, were exposed to several stimulation conditions. These settings included no light (blank) and yellow light pulses at frequencies of 2 Hz, 4 Hz, 10 Hz, 20 Hz, and 100 Hz. The spiking response was analyzed in terms of potential (mV) over time (s), and the characteristics of the response, such as amplitude and period, were examined. The findings indicate that the spiking patterns and characteristics fluctuate according on the stimulation frequency, with higher frequencies generally leading to more distinct and numerous spikes compared to lower frequencies and the absence of stimulation. The skewness and kurtosis values of the potential data indicate different levels of asymmetry and tail tendency in the probability distributions, which further supports the fact that the response is based on frequency. The study emphasises the capacity to manipulate and regulate the functions of the proteinoid–actin–kombucha system using light pulses, hence creating opportunities for future usage in several domains, including biosensors and biocomputing.

The utilization of hydrogen as a sustainable alternative to fossil fuels is gaining momentum due to its environmental compatibility and recyclability. In this study, we present a novel approach employing a NiO–Ni(OH)₂ hybrid decorated on VS₂ nanosheets, synthesized through a facile one-pot hydrothermal method, for enhancing the photocatalytic activity in the hydrogen evolution reaction (HER) from a methanol–water mixture under visible light irradiation. The synthesized samples underwent comprehensive characterization via XRD, FT-IR, SEM, TEM, XPS, BET, optical bandgap determination, and electrochemical analyses including CV, LSV, Tafel slope, and EIS Nyquist plot. Characterization results revealed that the presence of a minor quantity of NiO–Ni(OH)₂ effectively restrained the growth of VS₂ crystallites, leading to a reduction in average crystallite size with increasing NiO–Ni(OH)₂ content. XPS analysis confirmed the presence of NiO–Ni(OH)₂ on VS₂ and the oxidation states of V⁴⁺ and Ni²⁺ cations. Notably, the photocatalytic experiments demonstrated that NiO–Ni(OH)₂ served as an excellent co-catalyst for enhancing H₂ production over VS₂, with the H₂ production rate of 41642.2 μmol g⁻¹ h⁻¹ achieved with a loading of 0.8 mol% of NiO–Ni(OH)₂ to VS₂, surpassing the pristine VS₂ by over fourfold. The enhanced H₂ production activity was attributed to the accumulation of NiO–Ni(OH)₂ particles on the VS₂ surface, facilitating efficient movement of photoexcitons and minimizing photogenerated electron–hole pair recombination, thereby reducing hydrogen production overpotential and enhancing catalytic hydrogen generation. The outstanding performance and durability of the NiO–Ni(OH)₂/VS₂ photocatalyst suggest its potential as a cost-effective and promising candidate for hydrogen evolution reaction photocatalysis.

Crystal size engineering is an emerging strategy to modulate mechanical and gas adsorption properties of metal–organic frameworks (MOFs). Fundamental principles on how the properties of these materials change with size remain to be understood and explored. Here, supermicron-, micro-, and nano-sized single crystals of a prototypical MOF zeolitic imidazolate framework-7 (ZIF-7) were generated using a solvothermal method. Atomic force microscopy (AFM) imaging revealed that nano- and micro-sized crystals exhibited rounded and prism-like morphologies, respectively. AFM nanoindentation was used to assess the stiffness (Young's modulus) of the rounded and prism-like crystals as a function of crystal size. We demonstrate that the framework flexibility increases (Young's modulus decreases) with crystal size reduction for both morphologies, which can be attributed to a larger number of point defects (missing metal nodes and/or missing linkers) for smaller crystals. Remarkably, scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy measurements on individual prism-like micro-sized crystals of various sizes revealed a decreasing trend in the Zn/C ratio with crystal size reduction. Collectively, the size-dependent SEM and AFM characterization studies suggest that smaller crystals have lower relative metal content via a larger number of missing metal node defects. Our findings highlight how the mechanical properties of MOFs can vary significantly as a function of crystal size likely due to a variable and size-dependent number of missing metal node defects. Such size-dependent behavior especially towards the nanoscale is thus important to consider for the rational design of various functional crystalline materials.

In the pursuit of commercializing electronic and optoelectronic devices, researchers have turned their attention to non-toxic inorganic cubic metal halide perovskites. This study focuses on novel lead-free compounds—specifically AlGeX₃ (where X = F, Cl, and Br) and examines their structural, electronic, optical, and mechanical properties under the application of hydrostatic pressure through density functional theory (DFT). The mechanical stability of all compounds is rigorously assessed using Born stability criteria and formation energy. The elastic investigations reveal that the materials have anisotropy, ductility, and good Machinenabilty index depending on the halide type and applied pressure. The pressure-dependent electronic band structures are calculated by GGA-PBE functional to demonstrate the intriguing behavior of the compounds. Band structures are also calculated by HSE06 functional without pressure. Further, the substitution of the halide F with Cl/Br leads to an indirect to direct band gap transformation. Additionally, increasing positive hydrostatic pressure results in a tunable band gap with decreasing trends for all the compounds leading them to transit from semiconductor to metallic state. This phenomenon is explained by the partial and total density of states (PDOS and TDOS). The improvement of pressure-dependent optical properties in both visible and UV regions makes them valuable contenders in the quest for efficient solar cells and other electronic and optoelectronic devices.