Nanoscale Advances最新文献

We proposed an ingenious, highly efficient TiO₂ meta-atom (MA)-based near-infrared disordered metalens structure harnessing bird's eye-inspired hyperuniform distribution and analyzed its optical and imaging properties employing the finite-difference time-domain (FDTD) method. The hyperuniform disordered MAs constructed an image at a focal length by engineering the phase shift of transmittance. We obtained a high focusing efficiency of 84.39% at a wavelength of 820 nm for disordered metalens structures. Amazingly, our proposed disordered metalens structures can mimic the optical properties of ordered metalens structures. Similar focusing efficiencies of disordered and ordered metalens structures were found in a wavelength range from 850 to 890 nm due to the long-range periodic properties of hyperuniform disordered structures. The focal length shifts and NAs of disordered metalens structures were comparable to the focal length shifts and NAs of periodic metalens structures in the entire operating region from 770 to 970 nm with a constant FWHM of 1.503 μm. Our proposed structure paves the way for designing new and innovative imaging, sensing, and spectroscopic technologies, such as lidar, medical devices, IR and machine vision cameras, display systems, and holography.

Nanocrystals are widely explored for a range of medical, imaging, sensing, and energy conversion applications. CdS nanocrystals have been reported as excellent photocatalysts, with thin film CdS also highly important in photovoltaic devices. To optimise properties of nanocrystals, control over phase, facet, and morphology are vital. Here, CdS nanocrystals were synthesised by the solvothermal decomposition of a Cd xanthate single source precursor. To attempt to control CdS nanocrystal surfaces and morphology, the solvent used in the nanocrystal synthesis was altered from pure trioctylphosphine oxide (TOPO) to a mixed TOPO : fluorinated aromatic amine (3-fluorobenzyl amine (3-FlBzAm) or 3-fluoroaniline (3-FlAn)), where ¹⁹F provides a sensitive NMR-active surface probe. Powder X-ray diffraction found that the CdS nanocrystals synthesised from TOPO : 3-FlAn solvent mixtures were predominantly cubic whilst the TOPO : 3-FlBzAm synthesised nanocrystals were predominantly hexagonal. Raman spectroscopy identified hexagonal CdS in all samples. Solid-state NMR of ¹¹³Cd, ¹⁹F, ¹³C, and ¹H was employed to investigate the local Cd environments, surface ligands, and ligand interactions. This showed there was a mixture of CdS phases present in all samples and that surfaces were capped with TOPO : fluorinated aromatic amine mixtures, but also that there was a stronger binding affinity of 3-FlBzAm compared with 3-FlAn on the CdS surface, which likely impacts growth mechanisms. This work highlights that fluorinated aromatic amines can be used to probe NC surfaces and also control NC properties through their influence during NC growth.

Here, a straightforward design is employed to synthesize a nanocatalyst based on a carbon-activated modified metal-organic framework using the solvothermal method. This work presents a simple and practical approach for producing the activated carbon derived from the Thymus plant (ACT) modified with amine-functionalized isoreticular metal-organic framework-3 (IRMOF-3) to create an ACT@IRMOF-3 core-shell structure. Successful functionalization was confirmed through N₂ adsorption isotherms, FT-IR, FE-SEM, TEM, EDS, elemental mapping, TGA, and XRD analysis. The ACT@IRMOF-3 nanocomposite demonstrated exceptional performance in the synthesis of novel benzodiazepine derivatives, facilitating high product yields using various 1,2-phenylenediamine and aromatic aldehydes under mild conditions. The obtained results demonstrated that the presence of IRMOF-3 on the surface of ACT remarkably increases the catalytic reaction yield. The present methodology offers several merits such as high catalytic activity, excellent yields, short reaction times, cleaner reactions, simple operations, and compatibility of a wide range of substrates. Furthermore, the catalyst can be easily isolated from the reaction mixture via filtration and retains remarkable reusability and catalytic activity even after six consecutive reaction cycles.

Surface-enhanced Raman spectroscopy (SERS) has shown its ability to characterize biological substances down to a single-molecule level without a specific biorecognition mechanism. Various nanofabrication technologies enable SERS substrate prototyping and mass manufacturing. This study reports a complete cycle of design, fabrication, prototyping, and metrology of SERS substrates based on two-photon polymerization (2PP). Highly controllable direct laser writing allows the fabrication of individual nanopillars with up to an aspect ratio of 4. The developed SERS substrates show up to 10⁶ Raman signal enhancement, comparable to commercial substrates. Moreover, the rapid prototyping of the 2PP-printed SERS substrates takes from a minute to less than 2 hours, depending upon the nano-printing approach and aspect ratio requirements. The process is well-controlled and reproducible for achieving a uniform distribution of nanostructure arrays, allowing the SERS substrates to be used for a broad range of applications and the characterization of different molecules.

In this study, we introduce an in situ synthesis technique for incorporating gold nanoparticles (AuNPs) into a magnetic nanocomposite made of glucosamine and alginate (GluN/Alg) via ionotropic gelation. GluN acted as a reducing agent for gold ions, leading to the formation of AuNPs which embedded in the nanocomposite Fe₃O₄@GluN/Alg. Analytical techniques confirmed the crystallite structure of the nanocomposite AuNPs/Fe₃O₄@GluN/Alg, which had an average size of 30-40 nm. This nanocomposite demonstrated high catalytic efficiency in reducing 2-, 3-, and 4-nitrophenols, exhibiting rapid kinetics with pseudo-first order rate constants between 1.16 × 10^-3 s^-1 and 2.29 × 10^-3 s^-1. The reduction rates and recyclability for nitrophenols followed the order: 4-nitrophenol > 2-nitrophenol ∼ 3-nitrophenol. These results indicate that the nanocomposite holds significant promise for customized applications in environment and medicine, positioning it as a highly versatile material.

The potential applicability of the C₂₄ nanocage and its boron nitride-doped analogs (C₁₈B₃N₃ and C₁₂B₆N₆) as pyrazinamide (PA) carriers was investigated using density functional theory. Geometry optimization and energy calculations were performed using the B3LYP functional and 6-31G(d) basis set. Besides, dispersion-corrected interaction energies were calculated at CAM (Coulomb attenuated method)-B3LYP/6-31G(d,p) and M06-2X/6-31G(d,p) levels of theory. The adsorption energy (E _ads), enthalpy (ΔH), and Gibbs free energy (ΔG) values for C₂₄-PA, C₁₈B₃N₃-PA, and C₁₂B₆N₆-PA structures were calculated. The molecular descriptors such as electrophilicity (ω), chemical potential (μ), chemical hardness (η) and chemical softness (S) of compounds were investigated. Natural bond orbital (NBO) analysis confirms the charge transfer from the drug molecule to nanocarriers upon adsorption. Based on the quantum theory of atoms in molecules (QTAIM), the nature of interactions in the complexes was determined. These findings suggest that C₂₄ and its doped analogs are promising candidates for smart drug delivery systems and PA sensing applications, offering significant potential for advancements in targeted tuberculosis treatment.

With advancements in photonic technologies, photonic crystal fibers (PCFs) have become crucial components in developing highly sensitive and efficient biosensors. This paper presents an optimized bowtie-shaped PCF biosensor that leverages surface plasmon resonance (SPR) phenomena for enhanced refractive index (RI) sensing. The proposed design uses an external sensing mechanism to effectively characterize performance across an RI range of 1.32 to 1.44. Fabrication is simplified by selecting a large pitch and gold layer height, while performance is enhanced by increasing pitch size, improving the gold layer, and optimizing air hole diameter. Simulations performed using the finite element method in COMSOL Multiphysics v5.4 demonstrate an impressive wavelength sensitivity (WS) of 143 000 nm per RIU and an amplitude sensitivity (AS) of 6242 per RIU. The sensor also exhibits a high resolution of 6.99 × 10^-7 RIU and maintains excellent full width at half maximum (FWHM) characteristics, resulting in a very high figure of merit (FOM) of 2600, indicating superior performance. These promising results suggest that the optimized bowtie-shaped PCF biosensor can be effectively applied to detect a wide range of biological and chemical substances with high precision and sensitivity.

Electrolytic glucose oxidation has garnered great interest in energy-saving hydrogen generation. However, high charge-transfer resistance and inefficient active centers have been recognized as the primary issues for poor electrochemical performance. In this study, for the first time, we offer a novel defect-rich CeO _x /β-Ni(OH)₂ composite nanosheet-decorated Ni foam electrocatalyst (denoted as Ce@NF-GA), synthesized via a unique hydrothermal approach under the co-participation of glycerol and acetic acid. The employed characterizations unveil a close CeO _x /β-Ni(OH)₂ interfacial contact and numerous surface defects (e.g., oxygen vacancies). Such features significantly result in a significant enhancement in the electrocatalytic glucose oxidation reaction. Indeed, the obtained Ce@NF-GA catalyst demands a low potential of 1.31 V to reach a current density of 10 mA cm^-2. Additionally, Ce@NF-GA exhibited a high charge transportation capability and stability for 3 consecutive working cycles, corresponding to an outstanding Faradaic efficiency of ∼100% toward hydrogen production. The exploration of such novel material discloses a potential pathway for the utilization of Ce-based electrocatalysts for the energy-saving hydrogen production-coupled glucose oxidation reaction.

Recently, interest has surged in the environmental and biomedical applications of two-dimensional transition metal borides, commonly referred to as MBenes. These materials have emerged as promising candidates for energy storage devices, such as batteries and supercapacitors. Additionally, MBenes have shown remarkable catalytic activity due to their high surface area and tunable electronic properties. They exhibit significant promise in various catalytic applications, particularly in nitrogen reduction reactions (NRRs), electrocatalytic conversion of nitrogen oxides, and several electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Notably, MBenes have shown great potential in water treatment and pollutant removal applications, such as desalination and water purification. Their high water permeability, ion selectivity, and excellent stability make them suitable for efficient water treatment processes. On the other hand, MBenes are emerging as versatile materials with significant potential in various biomedical applications, particularly in biosensing, cancer therapy, and the treatment of neurodegenerative diseases. However, several challenges hinder their practical implementation in biomedical and environmental fields. One significant issue is the scalability of synthesis methods; producing MBenes in large quantities while maintaining high purity and uniformity is often complex and costly. Moreover, the stability of MBenes and their composites under different environmental and biological conditions raises concerns, as they may undergo degradation or lose their functional properties over time, which could limit their long-term effectiveness. Additionally, there is a need for comprehensive toxicity assessments to ensure the safety of MBenes in biomedical applications, particularly when interacting with human tissues or biological systems. This review aims to systematically investigate the environmental and biomedical applications of MBenes and their composites, emphasizing their unique characteristics and potential roles in addressing pressing global challenges. Furthermore, the review will identify and discuss the existing challenges and limitations in the operational performance of MBenes and their composites, providing a critical assessment of their current state in various applications.

This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu³⁺-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu³⁺ ions using Reisfeld's approximation. Eu³⁺-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu³⁺ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu³⁺ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu³⁺), confirming the successful doping of Eu³⁺ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu³⁺ incorporation, indicating strong coupling between Eu³⁺ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions under UV excitation. Using Judd-Ofelt (JO) analysis, the intensity parameters (Ω ₂, Ω ₄, Ω ₆) were derived, providing insights into the asymmetry of the Eu³⁺ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu³⁺ dopants were examined, showing efficient sensitization of Eu³⁺ through excitation of the ZnO host, with an optimal Eu³⁺ doping level maximizing luminescence. Eu³⁺-doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging.