Nanoscale Advances最新文献

We report on the evolution of tritium-induced sp³-defects in monolayer graphene on a Si/SiO₂ substrate, by comparing large-area Raman maps of the same two samples, acquired just after fabrication and twice thereafter, about 9-12 months apart. In-between measurements the samples were kept under standard laboratory conditions. Using a conservative classification of sp³-type spectra, based on the D/D' peak intensity ratio, we observed almost complete depletion of sp³-type defects over the investigation period of about two years. This by far exceeds the ∼5.5% annual reduction expected from tritium decay alone (≥3× larger). This change in the defect composition is accompanied by a recovery of the 2D-band of graphene and an overall decrease in defect-density, as determined via the D/G intensity ratio. Hydrogenated graphene is reported to be reasonably stable over several months, when kept under vacuum, but suffers substantial hydrogen loss under laboratory air conditions. While the results shown here for tritiated graphene exhibit similarities with hydrogenated graphene, however, some distinct differences are observed.

Dopamine (DA) is an important biomolecule of the central nervous system (CNS) as well as a monomer incorporated into melanin, a macromolecule often associated with skin pigmentation. Herein, we have investigated the electropolymerization of DA to form polydopamine (PDA) at a micro interface between two immiscible electrolyte solutions (micro-ITIES) between water|1,2-dichloroethane (w|DCE) under external, electrochemical control. DA oxidation to form PDA was achieved via the use of an ionic liquid composed of trihexyltetradecylphosphonium (P₆₆₆₁₄) paired with AuCl₄ ^- and dissolved in the DCE phase. AuCl₄ ^- acts as a strong oxidizer, accepting electrons from DA to form Au nanoparticles (NPs) that become incorporated into the growing PDA matrix. Au NP/PDA electrosynthesis was found to improve with increasing aqueous phase pH and was discovered to create a delicate, free-standing film. Au NP/PDA was used to modify a glassy-carbon electrode (GCE) and employed as a platform for DA detection. This proof-of-concept DA-biosensor demonstrated quasi-reversible DA oxidation and a good limit-of-detection (LOD) and linear-dynamic-range of 0.27 µM and 0.2-20 µM, respectively, using differential pulse voltammetry (DPV).

This study investigates the modification of adhesive properties in UV-cured thin films, commonly used in many fields ranging from protective coatings to primer layers for printing. We incorporated two types of additives into a 12 µm thick polymer film: one additive containing silicone-modified polyethers and another additive containing silicone-free modified polyethers. Our findings indicate that both additives segregate towards the film's surface, altering the surface properties without affecting the bulk. Using atomic force microscopy, we measured the adhesive work from force-distance curves, observing improved adhesive properties up to an optimal concentration of 10 wt%. Beyond this concentration, the film's adhesion plateau, with excess additives assimilating into the film's bulk which we interpret as being consistent with a change in the near-surface polymer ordering. Concentration-dependent measurements suggest a change in nanomechanical response above 10 wt%. This indicates that the films above this concentration undergo a drastic change, which we attribute to either capillary interaction, molecular ordering or additional crosslinking between the additive and base polymer mixture. Our results provide a deeper understanding of polymeric surface modification, which is paramount for flexographic printing of metallic surfaces using 2D flakes and thin polymer films.

Photodetectors play a pivotal role in recently developed optical communication and imaging systems. Metal chalcogenide-based photodetectors are widely used for visible light photodetection. In this regard, a combined heterostructure of In₂Se₃ and Ag₂S is a promising candidate for visible light photodetection. The annealing-induced Ag₂S diffusion into the In₂Se₃ layer resulted in a high-performance photo detectivity performance of 7.32 × 10⁹ Jones. It showed the highest photocurrent of 62.35 nA during the rise phase and 67.74 nA during the decay phase, coupled with strong I _on/I _off ratios of 3.96 (rise) and 3.18 (decay). Its rise and fall times (τ _r = 7.15 and τ _d = 6.35 s) were moderate and well-balanced, suggesting efficient charge separation and recombination kinetics. The bandgap of the annealed film increased with reduction in structural disorder, as evidenced by UV-visible spectroscopy and well supported by DFT results. The amorphous to polycrystalline phase transformation induced a change in surface morphology and reduced the contact angle, thereby decreasing hydrophobicity. The refractive index decreased with an increase in optical transmission and skin depth, while optical density reduced upon annealing. X-ray photoelectron spectroscopy revealed the oxidation states of the elements, while energy-dispersive X-ray analysis presented the elemental composition of the films. The heterostructure formation and its mixing upon annealing were evident from the cross-sectional FESEM images, and the presence of the planes was confirmed through HRTEM images. The observed optical properties, along with enhanced photodetection, pave the way toward the construction of novel III-VI metal chalcogenide-based heterojunctions for high-performance and broadband photodetectors.

Inkjet-printed gold nanotape (AuNTp) structures embedded in polyvinyl alcohol (PVA) hydrogels provide a reusable, high-surface-area platform for catalytic degradation of phenol and 4-nitrophenol (4-NP) under ambient conditions. AuNTps, featuring distinct three-dimensional "heads" and atomically thin quasi-one-dimensional "tails", enhanced catalytic activity in both reduction and oxidation reactions. Compared to spherical gold nanoparticles (AuNPs), AuNTps are nearly twice as catalytically efficient for 4-NP reduction on a per-mass basis, reflecting the influence of anisotropic morphology on surface-sensitive electron transfer. In contrast, phenol oxidation shows weaker morphology dependence, likely proceeding through hydroxyl radical-mediated pathways that are less sensitive to catalyst shape or facet structure. To enable rapid substrate diffusion and facilitate reuse, AuNTps were formulated into PVA inks and inkjet-printed into micrometre-thick hydrogel mesh architectures (8 to 15 µm thick). Although printed meshes show reduced activity relative to free AuNTps in solution, they achieve a nearly fourfold increase in mass-normalised rate constants for 4-NP reduction compared to drop-cast gels (0.24 × 10⁴ vs. 0.07 × 10⁴ min^-1 g^-1) and achieve 26% phenol, a common water pollutant, in 4 hours at room temperature, with consistent performance over multiple cycles. These findings demonstrate the potential of inkjet-printed nanozyme hydrogels as scalable, heterogeneous catalysts. Further improvements may be achieved by optimising catalyst-matrix interactions to reduce diffusion and accessibility barriers. This work addresses a significant challenge in nanozyme catalysis: translating high-performance nanomaterials into practical, reusable formats suitable for environmental remediation.

Upconversion nanoparticles (UCNPs) have emerged as promising tools for deep tissue optogenetics because they can convert near-infrared (NIR) light, which has high biopermeability, into ultraviolet (UV) or visible light. In optogenetics, microbially derived photoreceptor proteins such as channelrhodopsin (ChR) have been widely used. G protein-coupled receptor (GPCR)-type opsins have signal amplification capabilities and are emerging as promising candidates for high-sensitivity optogenetic tools. Since many GPCR-type opsins are so-called "bistable opsins" that can be switched between active and inactive states using light, it is not obvious whether multi-wavelength light from UCNPs can control bistable opsins. In this study, we constructed HEK293T cells expressing OPN5, a type of bistable opsin, and bound NaYF₄:Yb,Tm@NaLuF₄ core-shell UCNPs onto the cells. It was then demonstrated that light emitted from UCNPs upon NIR irradiation can control OPN5 even when the wavelengths that activate and deactivate OPN5 are simultaneously emitted.

Lipid nanoparticle (LNP) formulations have emerged as a versatile platform for the delivery of therapeutics. However, achieving long-term stability and effective delivery of water-soluble small molecule drugs remains a challenge. In this study, we demonstrate a cryopreservable LNP formulation incorporating a hydrophobically modified bis-prodrug of lamivudine. By systematically varying the surfactant composition by combining a PEGylated surfactant (Brij S20) with an unPEGylated, zwitterionic lipid (Lipoid S100), we identify formulations that maintain colloidal stability following freeze–drying and redispersion in the presence of 10% w/v sucrose. Particle size measurements before and after lyophilisation indicate that surfactant ratio significantly impacts redispersibility, with 50/50 Brij/lipoid compositions offering the best performance. A core composition comprising the prodrug and tricaprin at either 1 : 1 or 3 : 1 ratio was evaluated, with the 3 : 1 formulation achieving redispersed particle sizes below 150 nm and low polydispersity. Enzymatic studies using porcine liver esterase confirm slow, sustained conversion of the bis-prodrug to active lamivudine over up to 9 weeks. This work highlights the opportunity of a prodrug-based strategy to formulate water-soluble APIs into stable, freeze-dried LNPs, enabling controlled, enzyme-responsive release. These findings offer insight into how surfactant composition influences freeze–drying compatibility and provide a platform for the development of LNP systems for small molecule delivery.

We designed a multifunctional all-dielectric metasurface employing cuboid structures patterned with bow-tie-shaped nanoholes; it exhibits multiple Fano resonances induced by quasi-bound states in the continuum (quasi-BICs) through structural asymmetry. Among them, several resonant modes demonstrated high quality factors in the range of 10³-10⁴, along with near-unity modulation depth and strong spectral contrast. The optical responses were analyzed utilizing the finite-difference time-domain (FDTD) method, with Fano profiles fitted to theoretical models and the BIC-governed modes validated via the inverse-square ratio law. Furthermore, multipolar decomposition and electromagnetic spatial field profiles revealed the origins of the resonance, while LC circuit modeling provided additional physical insight into the Fano profiles. The proposed metasurface also exhibited strong polarization dependence, indicating its potential for active optical switching. Finally, the refractive-index sensing performance, including the potential for detecting Vibrio cholerae in an appropriate environment, reached a sensitivity of 342 nm per RIU and a figure of merit of 217.14 RIU^-1. Advancing the control of high-Q quasi-BIC Fano resonances, this study highlights Fano resonators' potential for refractive-index sensing and active switching.

Pristine and noble metal-decorated ZnO nanostructures were synthesized via a simple chemical reduction approach using hydrazine hydrate to deposit silver (Ag) and gold (Au) nanoparticles. Comprehensive characterization using PXRD, FESEM, HRTEM, XPS, FTIR, Raman, BET, and UV-vis spectroscopy revealed high-surface-area nanostructures with enhanced optical properties. Photocatalytic evaluation demonstrated that Au- and Ag-decorated ZnO exhibited significantly improved degradation efficiencies compared to bare ZnO under visible-light irradiation, attributed to improved charge carrier separation and extended visible-light absorption via plasmonic resonance effects. Notably, the catalysts showed excellent reusability over multiple cycles. Most significantly, the as-synthesized nanocomposite exhibited remarkable capability for the simultaneous co-degradation of two structurally and chemically distinct pollutants: tetracycline (TC, pharmaceutical antibiotic) and methylene blue (MB, textile dye). Under identical visible-light conditions at pH 7, Au-ZnO achieved 95% degradation of TC (2.0 × 10^-3 M) and 80% degradation of MB (1.0 × 10^-5 M) within 120 min using only 20 mg catalyst. This simultaneous removal of pharmaceuticals and dyes in a single photocatalytic process demonstrates the potential of dual-pollutant degradation. The single-platform capability for degrading structurally diverse pollutants suggests that noble metal-modified ZnO warrants further investigation as a multifunctional photocatalyst for treating complex wastewater containing mixed organic contaminants.