Search Results (188)

Surface-enhanced Raman scattering is highly promising for trace molecular detection but requires substrates with both ultrahigh sensitivity and macroscopic uniformity. Current bimetallic nanostructures struggle to achieve large-area structural reproducibility and high-density “hot spots” due to the lack of precise spatial control over nanoparticle arrangement and the random distribution of nanogaps, which severely limits their quantitative reliability in realistic applications. Here, we developed a simple and scalable method to fabricate a highly ordered Au/Ag composite nanoshell array via combining the gas–liquid interface self-assembly and ion sputtering. This prepared substrate is featured by abundant nanoscale openings, crevices, and interfacial junctions. The Au/Ag composite nanoshell array achieves an ultra-low limit of 10⁻¹¹ M for the standard probe Rhodamine 6G. The highly ordered array also ensures advanced large-area signal reproducibility with a relative standard deviation of 6.1%. This work successfully balances the large-area uniformity and high sensitivity in SERS detection. It also provides a robust and reliable plasmonic platform for practical food safety analysis and environmental monitoring. Full article

Current micro/nanosystems mainly rely on a planar fabrication framework, where structures are built layer-by-layer on flat surfaces. This conventional approach leaves vertical sidewalls underutilized, posing geometric limits in packaging density, three-dimensional (3D) interconnects, and multi-surface functionalization. To overcome these constraints, sidewall patterning has emerged as a promising strategy, enabling 3D integrated circuits, templates for directed nanostructure synthesis, and microfluidic drag reduction. Nevertheless, traditional photolithography and non-photolithographic techniques face challenges when applied to vertical or curved 3D surfaces. Unidirectional radiation and restricted focal depths prevent high-fidelity pattern transfer, even when using soft lithography, scanning probes, or nanoimprinting. To address these geometric and mechanical barriers, our group has developed several approaches for patterning the sidewalls of microsystems, which are the primary focus of this review. Building upon our approaches, this review further surveys related sidewall-patterning strategies, including micro-transfer printing, multi-stimuli-responsive mechanics, block copolymer self-assembly, two-photon polymerization, and laser-induced forward transfer. Collectively, these techniques expand the capabilities of sidewall engineering and provide valuable insights into next-generation 3D micro- and nanomanufacturing. Full article

Self-assembled artificial nanostructures, such as DNA origami, have attracted interest as templates for the placement of inorganic materials because their design enables the incorporation of binding sites for attaching nanocomponents with nanometer-scale precision. In this work, we introduce a lithographically defined window-array substrate as an addressable platform for dark-field spectroscopic studies of individual DNA-origami-templated metallic nanostructures. The pattern was designed using the Nanometer Pattern Generation System (NPGS) software and written by electron beam lithography (EBL) on a SiO_x/Si substrate. The role of the EBL pattern is to provide spatially separated measurement sites that facilitate the localization, selection, and optical interrogation of single-particle and dimer configurations. Metallic nanostructures created by the DNA origami technique, with programmable placement of spherical gold nanoparticles (Au NPs), are used here. The nanostructures are rectangular, measuring 70 nm × 90 nm, with an Au NP attached at one corner or at two opposite corners. These seed NPs are later enlarged by controlled coalescence via electroless silver deposition. Localized surface plasmon resonance (LSPR) studies by dark-field microscopy (DFM) are presented as a proof-of-concept application for evaluating the scattering response of individual silver-metalized nanoparticles and dimers. Full article

Noble metal nanostructures based on localized surface plasmon resonance (LSPR) can induce metal-enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS), significantly improving trace detection sensitivity for biomedical and chemical analysis. While self-assembly of noble metal nanoparticles offers simplicity and low equipment dependence, achieving large-area, uniform, and controllable nanostructures remains challenging. In this study, angle-dependent dip coating (ADDC) technology was employed to achieve efficient, controllable self-assembly of silver nanoparticles (AgNPs) on glass slides, establishing a fabrication process for MEF/SERS dual-functional substrates. A stable AgNPs-anhydrous ethanol suspension was prepared and extracted from an inclined substrate reservoir using a microfluidic syringe pump, enabling large-area uniform nanostructure assembly. Systematic investigation revealed that substrate inclination angle provides better morphology and fluorescence enhancement control than withdrawal flow rate. The silver nanostructured surface fabricated under a withdrawal flow rate of 16 mL/h and a substrate inclination angle of 30° exhibited a Cy3 detection limit as low as ${10}^{-1}$ nM, with an enhancement factor ranging from 19.14 to 28.66, as well as an R6G SERS detection limit of ${10}^{-10}$ M with an enhancement factor of 4.07 × ${10}^8$. This study confirms that ADDC technology enables simple, efficient, large-area uniform AgNPs self-assembly for superior dual-function enhancement substrates, offering a cost-effective and efficient strategy for highly sensitive trace detection. Full article

The corrosion protection of copper in acidic urban rain environments was studied using self-assembled hydrophobic layers (SAHLs) based on stearic acid (SA), with and without rosehip seed oil (RH). The limited durability of fatty acid-based self-assembled layers under acidic conditions was addressed by correlating surface wettability, morphology, and electrochemical behaviour. Contact angle and SEM analyses showed that SA alone forms a moderately hydrophobic but structurally irregular layer, whereas the addition of 2.0 wt.% RH produces a hierarchical micro/nanostructure with near-superhydrophobic characteristics (CA ≈ 149°). Electrochemical measurements in simulated acid rain solutions (pH 5, 3, and 1) revealed a strong pH dependence of protective performance. While SA-derived layers provided effective protection at pH 5, they deteriorated at lower pH due to protonation of carboxylate anchoring groups and electrolyte ingress. In contrast, SAHLs containing 2.0 wt.% RH maintained polarisation resistance in the MΩ cm² range and inhibition efficiencies above 99% at pH 3, and remained effective even at pH 1. Long-term EIS results indicate a predominantly diffusion-controlled, barrier-type inhibition mechanism associated with defects sealing and interfacial reorganisation. Notably, the rosehip seed oil used is a commercially available, bio-based material with expired shelf life, highlighting the potential of waste-derived resources for sustainable corrosion protection. Full article

Antimicrobial resistance represents one of the most formidable global health crises of the 21st century, driven by the diminishing efficacy of conventional antibiotics due to bacterial adaptation and biofilm formation. In response, antimicrobial nanoformulations have emerged as a transformative therapeutic paradigm, offering multifaceted and innovative mechanisms to combat resistant pathogens. This comprehensive review delineates the broad scope and distinct novelty of nano-enabled antimicrobial strategies, moving beyond the single-target limitations of traditional drugs. We systematically explore the diverse architectural classes of nanoformulations—including metallic, polymeric, and self-assembling nanostructures—and elucidate their unique mechanistic actions. These encompass (1) physical disruption of microbial membranes via electrostatic interactions; (2) catalytic generation of reactive oxygen and nitrogen species to induce an ‘oxidative storm’; (3) intracellular sabotage of essential metabolic pathways; (4) the ‘Trojan horse’ strategy for enhanced drug delivery and bioavailability; (5) efflux pump bypass to counteract a major resistance mechanism; (6) penetration and eradication of resilient biofilms; and (7) disarming pathogens through quorum sensing and virulence inhibition. Furthermore, this review highlights the immunomodulatory potential of nanoformulations; their activity beyond bacteria against fungi, viruses, and parasites; and the critical role of the nano-bio interface defined by surface physicochemistry. We also address the translational pathway, considering challenges in nanotoxicology, scalability, and regulatory approval, alongside the ecological impact and economic horizon of these technologies. This sector is projected to reach USD 5.4 to 8.96 billion by 2033 to 2034, with compound annual growth rates of 11 to 21% across antimicrobial nanomaterials, nanocoatings, and nanomedicine applications. By integrating insights from computational modeling and in silico design, this review underscores how nanoformulations leverage synergistic, multi-target approaches to overcome resistance, enhance therapeutic efficacy, and represent a significant leap forward in the future of infectious disease management. The novelty lies in the holistic and mechanistic synthesis of how nanotechnology is redefining antimicrobial warfare, offering a promising arsenal to avert a post-antibiotic era. Full article

The two-dimensional chiral self-assembly and chiral separation of achiral Ext-TEB molecules on a Bi(111) surface were investigated using low-temperature scanning tunneling microscopy (LT-STM). At low coverage, the molecules self-assembled into chiral clusters. As the coverage increased, a monolayer film with a non-edge-sharing honeycomb structure was formed. This supramolecular structure exhibited organizational chirality, accompanied by chiral separation. Upon annealing, part of the non-edge-sharing honeycomb structure transformed into a close-packed structure, while retaining the organizational chirality, supramolecular chirality, and pronounced chiral separation. Furthermore, applying a higher bias was found to induce a transition in the electronic state of the non-edge-sharing honeycomb structure, converting it into an edge-sharing honeycomb configuration. This study reveals that the chirality of 1,3,5-tris(4-ethynylphenyl) benzene (Ext-TEB) arises from the rotation of the side-chain phenyl rings, which is induced by the rotation of the molecular axis relative to the substrate lattice. This work presents a strategy for the preparation of chiral nanostructures from achiral molecules due to the spontaneous chiral symmetry generation. Full article

The rapid fabrication of low-cost surface-enhanced Raman scattering (SERS) substrates is highly desirable for chemical and biological sensing. Existing customized SERS substrates, such as Au or Ag nanostructures produced by physical deposition, frequently involve complex fabrication routes, which limits the scalability of SERS devices. Here, we present the hexagonal close-packed plasmonic superlattices as an efficient, low-cost and applicable SERS platform, fabricated by scalable seed-mediated growth and interfacial self-assembly methods. We systematically compared Ag, Au, and Au@Ag nanospheres (NSs) of different sizes and demonstrated that the plasmonic superlattices made by 55 nm Au@Ag NSs exhibit the strongest Raman response, highest sensitivity, lowest detection limit, good spatial uniformity, and broad applicability. Simulations and Raman mapping experiments further confirm that Au@Ag NSs achieve an optimal balance between hotspot density and plasmonic field intensity, allowing for direct identification and quantification of diverse biochemical targets. Full article

We demonstrate that gold nanoparticles (AuNPs) are capable of unwinding double-stranded (ds) DNA. Upon unwinding, the exposed nucleobases of the separated strands adsorb onto the nanoparticle surface, resulting in the coating of the particles. The unwinding process was characterized by Atomic Force Microscopy (AFM) and absorption spectroscopy. Our results show that AuNPs initially bind to single-stranded overhangs at the duplex termini, forming dsDNA–nanoparticle dumbbells. This binding event subsequently initiates the separation of the DNA strands. As the unwinding proceeds, the nanoparticles become progressively wrapped by the unwound DNA strands, which leads to a gradual reduction in the interparticle distance within the dumbbells. This process is driven by the strong affinity of nucleobases for the gold surface. The efficiency of DNA unwinding was found to depend strongly on both nanoparticle size and temperature. These findings provide new insights into DNA-nanoparticle interactions and may facilitate the rational design of DNA–AuNP hybrid nanostructures such as dumbbell-shaped conjugates for applications in DNA-based nanoelectronics, biosensing, and self-assembled nanomaterials. Full article

Tungsten oxide (WO₃) nanostructures have emerged as promising electroactive materials due to their high pseudocapacitance, structural versatility, and chemical stability, while reduced graphene oxide (rGO) provides excellent electrical conductivity and surface area. The strategic combination of these nanomaterials in hybrid electrodes has gained attention for enhancing the energy storage performance of supercapacitors. In this work, we report the fabrication and electrochemical performance of nanostructured multilayer films based on the electrostatic Layer-by-Layer (LbL) self-assembly of poly (amidoamine) (PAMAM) dendrimers alternated with tungsten oxide (WO₃) nanofibers dispersed in reduced graphene oxide (rGO). The films were deposited onto indium tin oxide (ITO) substrates and subsequently subjected to electrochemical reduction. UV-Vis spectroscopy confirmed the linear growth of the multilayers, while atomic force microscopy (AFM) revealed homogeneous surface morphology and thickness control. Electrochemical characterization by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) revealed a predominantly electrical double-layer capacitive (EDLC) behavior. From the GCD measurements (PAMAM/rGO-WO₃)₂₀ films achieved an areal capacitance of ≈2.20 mF·cm⁻², delivering an areal energy density of ≈0.17 µWh·cm⁻² and an areal power density of ≈2.10 µW·cm⁻², demonstrating efficient charge storage in an ultrathin electrode architecture. These results show that the synergistic integration of PAMAM dendrimers, reduced graphene oxide, and WO₃ nanofibers yields a promising strategy for designing high-performance electrode materials for next-generation supercapacitors. Full article

The synthesis of biocidal peptide materials using simple, low-cost, solvent-free methods is a crucial challenge for developing new antimicrobial approaches. In this study, we produced proteinoid nanostructures through simple, inexpensive, and environmentally friendly thermal reactions between glutamic acid (Glu) and tyrosine (Tyr) in various molar ratios. Mechanistically, the thermal cyclization of glutamic acid into pyroglutamic acid (pGlu) facilitated the formation of short peptide chains containing pGlu as the N-terminus moiety and subsequent L-tyrosine or glutamic acid residues, which self-assembled into nanometric spheroidal structures that exhibit blue emission. Spectroscopic (FTIR, UV-Vis, photoluminescence) and mass (LC-MS) analyses confirmed the formation of mixed pGlu-/Tyr/Glu peptides. All products exhibit dose-dependent antimicrobial activity against Methicillin-Resistant Staphylococcus aureus (MRSA), with a minimum inhibitory concentration (MIC) of 25 mg mL⁻¹ for the GluTyr 1:1 and 2:1 proteinoids. The outcomes observed following 24 h exposure of the HEK293 cell line to the materials indicate their suitability for integration into hybrid systems for antimicrobial surfaces. This work is the first to demonstrate a direct antibacterial activity of proteinoids obtained by thermal condensation, opening up the possibility of designing a new class of synthetic antimicrobial peptides. Full article

The development of metal nanostructures on large-area Gallium Nitride (GaN) surfaces has the potential to enable new, low-cost technologies for III-N semiconductor layer nanostructuring. Self-assembled nanostructures are typically formed through the thermal activation of solid-state dewetting (SSD) in thin metal layers. However, such thermal processing can induce degradation of the metal-GaN material system. This comprehensive study investigated the thermal stability of thin metal films on GaN surfaces, focusing on their morphology and nanostructuring for high-temperature processing. The research expands and systematizes the understanding of the thin metal layers on GaN surface interactions at high temperatures by categorizing metals based on their behaviour: those that exhibit self-assembly, those that catalyze GaN decomposition, and those that remain thermally stable. Depending on the annealing temperature and metal type, varying degrees of GaN layer decomposition were observed, ranging from partial surface modification to significant volumetric degradation of the material. A wide range of metals was investigated: Au, Ag, Pt, Ni, Ru, Mo, Ti, Cr, V, Nb. These materials were selected based on criteria such as high work function and chemical resistance. In this studies metal layers with a target thickness of 10 nm deposited by vacuum evaporation on 2.2 $\mathsf{\mu }$m thick GaN layers grown by metal organic vapor phase epitaxy were applied. The surface morphology and composition were analyzed using AFM, SEM, EDS, and Raman spectroscopy measurement techniques. Full article

Surface modification of nucleic acid-based electrochemical biosensors has been at the forefront of research since their inception. Effective modification ensures the optimization of the sensitivity, specificity, and stability of modern biosensors. Recent advances in DNA nanotechnology have enabled the development of novel electrochemical biosensor interfaces with precise assembly and high biocompatibility. In this review, we explore three strategies for enhancing biosensor performance: the integration of tetrahedral DNA nanostructures (TDNs), self-assembled monolayers (SAMs), and DNA-based hydrogels. TDNs offer well-defined geometry and controlled spatial presentation of capture probes, significantly reducing background noise and improving target accessibility. SAMs provide a robust and tunable platform for anchoring these nanostructures, enabling reproducible and chemically stable interfaces. DNA hydrogels serve as a responsive and flexible scaffold capable of signal amplification and analyte retention. These surface architectures enhance sensitivity and minimize non-specific adsorption (NSA). We discuss recent applications and experimental outcomes, highlighting how each component is driving the next generation of nucleic acid-based biosensors. Full article

This work presents the development of carbon nanotubes functionalised with carboxylic acid groups (CNT-COOH) as an oxygen-sensitive electrochemical platform for parallel multi-analyte enzymatic biosensing. The platform was constructed by depositing carboxylic-acid-functionalised single-walled carbon nanotubes covalently onto nanostructured gold electrodes modified with a self-assembled monolayer of 4-aminothiophenol. Atomic force microscopy characterization revealed that the nanotubes attached via their ends to the surface and had a predominantly horizontal orientation. Glucose oxidase, lactate oxidase, glutamate oxidase, and tyrosinase were immobilised onto the electrodes to create selective biosensor for lactate, glucose, glutamate, and dopamine, respectively. A key finding is that incorporating catalase significantly extends the linear detection range for analytes by mitigating the accumulation of hydrogen peroxide. The resulting multifunctional biosensor demonstrated its capability for the simultaneous and independent measurement of glucose, lactate as the key bioanalytes under uniform conditions in blood plasma samples, highlighting its potential for applications in health and food technologies. Full article

Polymeric vesicles, characterized by enhanced colloidal stability, excellent mechanical properties, controllable surface functionality, and adjustable membrane thickness, are extremely useful in nano- and bio-technology for potential applications as nanosized carriers for drugs and enzymes. However, a few preparative steps are necessary to achieve a unilamellar vesicle with a narrow size distribution. Herein, we report the spontaneous formation of unilamellar polymeric vesicles with nanometer sizes (<50 nm), fabricated by simply mixing diblock copolymers (P(EO-AGE)(2K-2K) and P(EO-AGE)(0.75K-2K)) with differing hydrophilic mass fractions in aqueous solutions. Depending on the mixing ratio of block copolymers and the temperature, the block copolymer mixtures self-assemble into various nanostructures, such as spherical and cylindrical micelles, or vesicles. The self-assembled structures of the block copolymer mixtures were characterized by small-angle neutron scattering, resulting in a phase diagram drawn as a function of temperature and the mixing condition. Notably, the critical temperature for the micelle-to-vesicle phase transition can be easily controlled by altering the mixing conditions; it decreases with an increase in the concentration of one of the block copolymers. Full article