Beilstein Journal of Nanotechnology最新文献

In the ballistic regime at finite temperatures, the proximity effect diminishes following an exponential pattern; however, at low or zero temperatures, this transition alters to a decay characterized by a power law with a dimensionality-dependent exponent. Here, we extend the current understanding of the proximity effect by exploring the role of normal metal-superconductor (NS) junction geometry in altering the spatial propagation of the superconducting order. Specifically, we demonstrate that geometric factors, such as interface curvature, significantly affect the decay exponent of the Cooper pair wave function, with negative curvature increasing the proximity range exponent and positive curvature shortening it. Furthermore, we discuss how the geometry of the NS interface governs the transparency of the clean NS junction and thus influences the proximity effect. These results deepen our understanding of how geometry and the proximity effect interact, which is important for the design and optimization of superconducting hybrid devices.

Solvated supramolecular hydrogels present unique challenges in nanoscale morphological characterization because of their fragile fibrous nature and low concentration of the solid component. In this study, imidazolium-based hydrogels containing either diketopyrrolopyrrole (DPP) or zinc(II) phthalocyanine (ZnPc) fluorophores were imaged using confocal laser scanning microscopy (CLSM) of fully solvated gels and cryogenic scanning electron microscopy (cryo-SEM) was used to observe the corresponding xerogels. The DPP@Gel systems exhibit strong fluorescence and are effectively imaged using CLSM, with fibre morphologies that closely correlate with those seen with cryo-SEM. In contrast, the analogous imidazolium gel system containing a sulfonated zinc phthalocyanine (ZnPc@Gel) yields poor CLSM images because of the relatively weak emission and sample disruption during compression, whereas cryo-SEM enables clear visualization of the native fibrous network. These results demonstrate the complementary nature of CLSM and cryo-SEM and highlight the value of cryo-SEM as a very useful tool for imaging soft nanomaterials with low fluorescence or limited optical contrast.

Chiral plasmonic nanostructures (cPNSs) have garnered extensive interest across disciplines due to their strong interaction with circularly polarized light (CPL). Numerous fundamental studies have demonstrated the enhancement of chiroptic effects in molecular systems and quantum emitters facilitated by chiral metal nanostructures; for example, the detection of DNA at attomolar concentrations has been achieved using cPNSs. In recent years, significant advancements have been made in the colloidal synthesis of chiral plasmonic nanostructures. A noteworthy breakthrough involves the use of CPL to fabricate cPNSs. As a traceless chiral agent, CPL holds great potential for integration with nanofabrication technologies. In this review, we will summarize the progress made in fabricating cPNSs using CPL. We will discuss the mechanisms involved in the CPL-based fabrication process and share our insights regarding the outstanding questions related to cPNSs produced by CPL. Additionally, we will outline common techniques for characterizing the chiroptic effects of cPNSs in both the far field and the near field. Last, we will review the various applications of cPNSs and highlight the most promising applications of cPNSs fabricated using CPL.

We present an electromagnetic study of a metamaterial receiver based on split-ring resonators with integrated cold-electron bolometers. We suggest a modified antenna design that allows one to significantly increase the absorbed power and the bandwidth. The trade-off between the bandwidth expansion due to miniaturization and the reduction in absorption efficiency determined by the Airy spot size of the coupling lens is investigated. To solve this issue, a simultaneous miniaturization of the size of the entire structure with an increase in the number of array elements is proposed. The design with a 37-element array demonstrates an increase in power absorption by a factor of 1.4 compared to the original 19-element single-ring array, as well as an increase in operating bandwidth from 160 to 820 GHz.

Vitamin B₁₂ (VB₁₂) is an essential Co²⁺-containing nutrient for neurological function, DNA synthesis, and red blood cell formation. Accurate and efficient VB₁₂ quantification in food and pharmaceutical products is crucial due to its animal-derived dietary sources and the significant health implications of VB₁₂ deficiency. Traditional methods for VB₁₂ analysis, such as high-performance liquid chromatography and enzyme-linked immunosorbent assay, are often troublesome and time-consuming, and require high-tech laboratory setups. The current overview highlights the latest optical biosensing platforms in detecting Co²⁺ ions and VB₁₂ using RNA aptamer-gold nanoparticles colorimetric sensors, surface plasmon resonance sensors, chemiluminescence and electrochemiluminescence biosensors, and fluorescence biosensors (i.e., chemosensors, nanoclusters/nanoparticles-based sensors, and carbon dot (CD)- and quantum dot (QD)-based sensors). The advent of optical biosensing technologies has resulted in a new era for VB₁₂ analysis, characterized by the development of innovative CD- and QD-based sensors. These nanomaterials offer several advantages over conventional methods, including enhanced sensitivity, specificity, rapid detection, and the ability for real-time analysis. CD- and QD-based biosensors with excellent optical properties such as photoluminescence enable the detection of VB₁₂ at negligible concentrations and in real-world samples with complex matrices. Furthermore, integrating these biosensors into cellular bioimaging and the potential for non-invasive in vitro and in vivo analysis demonstrate their versatility and applicability across a broad spectrum of biomedical research, diagnostics, and nutrient analysis.

We investigated the effect of air humidity on two gold nanoparticle systems, one functionalized with an oligo(ethylene glycol) ligand, and one functionalized with a mixture of the same with a dimannoside ligand. The dimannoside ligand was chosen to mimic the surface chemistry of viral spike proteins. We characterized the particles by electron microscopy, dynamic light scattering, and infrared spectroscopy. We probed particles adsorbed on hydrophilic and hydrophobic surfaces with atomic force microscopy (AFM) and vibrational sum frequency generation (VSFG) spectroscopy, both operated under variable air humidity. For AFM, we additionally tested hydrophilic and hydrophobic tips. While VSFG indicated preferential hydration of the dimannoside and proved conformational changes in the organic ligands, AFM provided sub-nanometer changes in particle topography due to water adsorption. In general, the dimannoside nanoparticles condense ultrathin water layers upon humidity increase. In contrast, we found that the water adsorption on the oligo(ethylene glycol) particles depends little on humidity. Our insights into structural changes on glyconanoparticles and the hydration properties of glycosylated particles are of application value for biosensors and help model the transmission of airborne viruses, such as influenza.

It is well known that the Hartree-Fock (HF) interaction does not alter observables in conventional superconductors as its effect is mainly reduced to a chemical potential shift. Deviations from this behavior can only arise in situations of translational symmetry breaking, for example, caused by the presence of external fields that induce spatial variations of the order parameter and electron density. We demonstrate that this scenario changes fundamentally in quasicrystalline systems, where the intrinsic lack of translational symmetry leads to a fractal spatial distribution of the superconducting condensate and electron density. By investigating a Fibonacci chain as a prototype quasicrystal, we numerically solve the Bogoliubov-de Gennes equations and show that, beyond the half-filling, the HF potential significantly enhances the self-similar spatial oscillations of the order parameter while simultaneously reducing its average value and altering its critical exponent. Consequently, the critical temperature is suppressed; for our chosen microscopic parameters, this suppression can reach up to 20%. Therefore, an accurate analysis of condensate distribution and related quantities in quasicrystalline superconductors requires the comparison of results obtained with and without the HF interaction.

Herein we point out critical yet often overlooked barriers restraining the real-world impact and commercial viability of nanomaterials research. In spite of decades of scientific progress, nanotechnology remains underutilized in public-facing applications. A major issue is the limited engagement of leading tech industries in developing nanotechnology-based products, prompting concerns about tangible societal and industrial outcomes. Far away, funding challenges, the field is hindered by fragmented regulations, ambiguous safety guidelines designed for bulk materials, and the absence of globally harmonized standards. These systemic limitations, coupled with persistent misconceptions, have stalled translation from lab to market. In contrast to numerous productive technologies like generative AI, machine learning, and related progress, nanotechnology has not achieved autonomous societal integration. The author argues that without a unified, transparent, and science-driven global regulatory framework, the transformative potential of nanotechnology will remain unrealized, despite over decades of excellent discoveries. This perspective calls for carefully considerations linked to productivity perception, true funding utility, and foundational reform to unlock nanotechnology's full promise across sectors.

Microplastic contamination is a newly emerging environmental problem in the ecologically sensitive Himalayan lakes, posing a threat to biodiversity, water quality, and human habitation. These high-altitude freshwater ecosystems are being increasingly polluted through human use, tourism, glacier melt, and atmospheric deposition. Microplastic quantification in such isolated locations is, however, limited by factors such as harsh climatic conditions, logistical challenges, and the need for expert analytical techniques like microscopy and spectroscopy. The present review considers sources, pathways, and ecological impacts of microplastics in Himalayan lakes compared to other sensitive aquatic ecosystems. The review describes existing remediation technologies, categorizing these into physical, chemical, and biological interventions, and takes into account emerging sustainable approaches, including biofilm-mediated degradation and nanotechnology-based solutions. The application of nanomaterials for microplastic removal is elaborated in detail, and case studies validated their effectiveness, especially in cold environments with strong UV irradiation. In the face of increasing worldwide research into microplastic contamination, there remains a huge knowledge gap concerning its behavior in distant, elevated lake systems such as the Himalayas. The most important areas to focus with regard to the ecotoxicological impact of microplastics are the bioaccumulation of microplastics in the Himalayan food web, plasticizer toxicity, and long-term potential health and ecological threats. This review addresses the imperatives of enhanced governance, monitoring, legislation, and community-based mitigation measures. This research makes a contribution by integrating region-specific data, defining priority research needs, and provoking sustainable, multidisciplinary solutions specific to freshwater cold-climate ecosystems. This contribution serves to address the imperative of adopting multidisciplinary research, region-specific remedial measures, and judicious estimation of microplastic contamination of high-altitude lakes through by describing research gaps. It distills the present scenario and promotes novel, environmentally friendly remedial measures, regulatory policies, cooperative initiatives to combat microplastic pollution, and vulnerabilities in the fragile Himalayan freshwater aquatic ecosystems.

In this study, we employ the non-equilibrium Green's function (NEGF) method combined with density functional theory (DFT) to compare electron transport through several layers of nanoscale graphene and hexagonal boron nitride (h-BN). Calculations were performed for one to six layers, corresponding to thicknesses of 0.5-3.0 nm, respectively. Electron transport was computed perpendicular to the layers in the stacking direction. We compared the decay of the current with the number of layers and evaluated the ability of h-BN to filter currents as a material coating. To investigate the effect of disorder, we included two major defects in the graphene lattice, namely, nitrogen doping and Stone-Wales defects. Nitrogen doping transforms graphene from a zero-bandgap semiconductor to a metal, while Stone-Wales defects open the bandgap. For h-BN, we considered Stone-Wales defects. A detailed comparison of electron transport through five materials, that is, multilayer nanoscale graphene, N-doped multilayer nanoscale graphene, Stone-Wales-defective multilayer nanoscale graphene, h-BN, and Stone-Wales-defective h-BN allowed us to understand the currents at the nanoscale and the chemical and structural control over the electron transport. The slopes of the current decay with thickness enabled us to extrapolate trends for electron transport in thicker multilayer carbon and h-BN materials.