Search Results (1,016)

Noble metal nanostructures provide versatile platforms for light manipulation through localized surface plasmon resonances (LSPRs). Among them, triangular silver nanoplates (AgNPTs) exhibit strong field-enhancement and spectral tunability, yet assembling them reproducibly on solids is challenging. We report a two-step functionalization strategy for constructing ordered AgNPT dimers on silica substrates, combining 3-aminopropyltriethoxysilane (APTES) anchoring with 1,4-butanedithiol bridging. AFM reveals face-to-face dimers with well-defined sub-nanometer gaps. Large-area AFM statistics collected over multiple regions (N = 80 nanoplates per condition) confirm reproducible and selective vertical dimerization. Extinction spectroscopy reveals sequential dielectric and coupling effects: thiol adsorption red-shifts the main resonance from 700 to 780 nm because of increased local refractive index and near-field damping, whereas dimerization partially restores it to ≈750 nm, consistent with plasmon hybridization within rigid ∼0.7 nm molecular gaps, where nonclassical moderation may occur but classical hybridization fully explains the observed shifts. Concomitantly, the extinction intensity doubles, following an exponential growth toward saturation during assembly. Surface-enhanced Raman scattering (SERS) measurements using 4-mercaptobenzoic acid (4-MBA) confirm a fourfold increase in the SERS enhancement factor from monolayer to bilayer, consistent with near-field coupling and hotspot formation at interplate junctions. Quantitative plasmon sensitivity analysis yields comparable results between experiments and finite-difference-time-domain simulations, confirming that the observed spectral shifts arise from near-field coupling and dielectric modulation rather than ensemble effects. This reproducible methodology enables precise tuning of NPT orientation, spacing, and optical response, providing a robust platform for enhanced sensing, SERS, and nanophotonic device engineering. Full article

Surface-enhanced Raman spectroscopy (SERS) amplifies Raman scattering by placing molecules in the near-field of plasmonic nanostructures, enabling label-free molecular fingerprinting. While attractive for living cell phenotyping, many cellular SERS works rely on internalized colloidal nanoparticles, leading to variable uptake/localization, aggregation-driven hotspot fluctuations, and potential cellular perturbation. Here, we report a chip-like Au/SiO₂ nanolaminate SERS substrate that supports direct culture and label-free measurements of living cells on spatially defined hotspots without nanoparticle uptake. The periodic nanolaminate forms dense nanogaps and is engineered for 785 nm excitation, providing uniform enhancement over a large, culture-compatible area with high hotspot uniformity. By engineering the cell–substrate nano–bio interface, the platform enables reproducible acquisition of intrinsic cellular vibrational fingerprints under physiological conditions without Raman tags. Using MCF-7 and MDA-MB-231 breast cancer cells, we collected hundreds of spectra per line, and MDA-MB-231 exhibited broader spectral variations, indicating greater heterogeneity. Principal component analysis and linear discriminant analysis achieved 99% classification accuracy for MCF-7 and MDA-MB-231, and bright-field imaging confirmed preserved adhesion and canonical morphologies. This chip-based, label-free living cell SERS platform enables scalable, nonperturbative phenotyping and may support rapid malignancy classification and treatment response screening across subtle cancer states. Full article

Antibiotic residues in aquatic products pose a serious food safety concern, whereas conventional laboratory methods often fail to meet the demand for on-site rapid screening. This study systematically reviews the research progress from 2021 to 2025 on both the risks of antibiotic residues in aquatic products and the development of rapid on-site detection technologies. First, based on a literature survey covering major aquatic products (e.g., fish, shrimp, and shellfish), the widespread occurrence of multiple antibiotics at high concentrations was documented, with quinolones and sulfonamides identified as the most frequently detected classes. To address the need for on-site testing, this review focuses on six rapid detection techniques: fluorescent sensor (FRS), lateral flow immunoassay (LFIA), surface-enhanced Raman scattering (SERS), enzyme-linked immunosorbent assay (ELISA), electrochemical sensor (ECRS), and colorimetric sensor (CRS). The core principles, technical advantages, recent application cases (e.g., integration with smartphones and novel nanomaterials), and development trends for each method are analyzed. Finally, it discusses the current challenges faced by existing on-site detection approaches and their potential solutions. Technology selection strategies tailored to different application scenarios (e.g., aquaculture farms, distribution channels, and consumer-level use) are also proposed. Full article

Raman spectroscopy offers unique molecular fingerprinting capability for cancer diagnosis and monitoring, yet its biomedical application is fundamentally limited by weak intrinsic signals and complex biological backgrounds. Composite Raman probes, particularly surface-enhanced Raman scattering (SERS)—based systems, overcome these limitations through synergistic electromagnetic and chemical enhancement combined with functional integration. By engineering plasmonic nanostructures, interfacial electronic states, and molecular architectures, composite Raman probes achieve synergistic electromagnetic and chemical enhancement while incorporating biorecognition units, reporter molecules, and protective coatings to improve stability, specificity, and biocompatibility. In recent years, these probes have evolved from simple signal tags into multifunctional platforms capable of ultrasensitive tumor biomarker detection, high-contrast imaging, surgical guidance, therapy monitoring, and dynamic analysis of the tumor microenvironment (TME). This review systematically summarizes recent advances in composite Raman probes for oncological applications, with an emphasis on material design strategies, enhancement mechanisms, and stimulus-responsive regulation. Representative applications at both molecular and tissue levels are highlighted, including nucleic acid, protein, and exosome detection, as well as in vivo imaging and microenvironmental sensing. Finally, current challenges and future perspectives toward clinical translation are discussed, aiming to provide guidance for the rational design of next-generation Raman probes for precision oncology. 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

Surface-enhanced Raman scattering (SERS) holds great promise for ultrasensitive chemical analysis but is often limited by the trade-off between performance and fabrication simplicity. This work presents a facile strategy to prepare monolayer silver microplates combining the top-down and bottom-up fabrication concepts. Silver microplates with uniform nanoscale thickness (~93.5 nm) and micron-scale lateral size (D₅₀ = 3.33 µm) are prepared via a scalable mechanical ball-milling process. These silver microplates served as building blocks for spontaneous interfacial self-assembly at the air/water interface to form a macroscopically continuous monolayer film. The silver microplate monolayer film is transferred onto a plasma-treated silicon wafer as a SERS substrate. The resulting SERS substrate exhibits a porous, network-like microstructure composed of densely packed microplates, which generates a high density of electromagnetic hot spots at the nanogaps. Using Rhodamine 6G as a probe molecule, the substrate demonstrates a SERS detection limit of as low as 1 nM and good spatial uniformity with a relative standard deviation of ~9.94%. This study provides a cost-effective and scalable self-assembly route of physically reshaped silver microplates to fabricate high-performance SERS substrates. Full article

Surface-enhanced Raman scattering (SERS) has become an effective and sensitive analysis tool for the detection of various molecules. Nevertheless, it is a challenge to fabricate reusable SERS substrates for detecting gaseous molecules. Here, a self-calibrated and reusable SERS substrate has been developed for the quantitative analysis of n-butylamine. The obtained substrate enhances gas enrichment capability through the coordination interaction of Fe₂O₃ with the porous structure of ZIF-8, and strengthens the Raman signal intensity by the localized surface plasmon resonance of Ag nanoparticles. Ethanethiol is employed as an internal standard to enhance analysis accuracy. The substrate exhibits excellent quantitative analysis (linear correlation coefficient, R² = 0.996), signal uniformity (RSD = 6.3%), and batch reproducibility (RSD = 4.8%). Moreover, the substrate achieves self-cleaning through photocatalysis. After five cycles, the substrate retains high SERS activity (RSD = 3.13%), exhibiting excellent reusability. Full article

Sensitive and on-site detection of pesticide residues remains a critical challenge for food safety, particularly in developing regions where rapid screening tools are urgently needed. Herein, we report a flexible surface-enhanced Raman scattering (SERS) platform based on triangular silver nanoplates (TSNPs) integrated onto a polydimethylsiloxane (PDMS) substrate, enabling sensitive and conformal detection of paraquat residues on agricultural surfaces. TSNPs were synthesized via a seed-mediated photochemical growth method and formulated into a TSNP ink, which was directly deposited onto oxygen-plasma-treated and thiol-functionalized PDMS substrates. Owing to the highly anisotropic geometry and sharp edges of TSNPs, the flexible SERS substrate exhibits strong localized surface plasmon resonance (LSPR) enhancement and mechanically stable electromagnetic hot spots. Systematic optimization of TSNP optical absorbance revealed that uniform nanoplate distribution and optimal hotspot density were achieved at an absorbance of 2.0. The SERS performance was evaluated using rhodamine 6G under front-side and back-side illumination configurations, demonstrating good signal reproducibility and a detection limit of approximately 10⁻⁵ M. Notably, back-side illumination through the PDMS layer provided superior SERS responses due to improved optical transmission and light–matter interaction. The practical applicability was further demonstrated through back-side SERS detection of paraquat on aluminum foil as a model surface, achieving a lowest detectable concentration of 5 × 10⁻⁶ M, followed by damage-free detection on Chinese pear peels. This work highlights a reliable and nondestructive flexible SERS platform for on-site pesticide residue monitoring. Full article

Francisella tularensis, the causative agent of tularemia, is a highly infectious Category A biothreat agent characterized by an exceptionally low infectious dose and diverse transmission routes. Due to the pathogen’s fastidious growth requirements and the high risk of laboratory-acquired infections, traditional cultivation methods are often protracted and hazardous. Consequently, the development of rapid and sensitive diagnostic tools is paramount. This manuscript provides a comprehensive overview of the current landscape of immunoassays, with a specific focus on the evolution from standard laboratory techniques to advanced biosensors. We detail the critical phases of antigen preparation, including high-pressure homogenization and sonication, and the generation of high-affinity polyclonal and monoclonal antibodies. Furthermore, we evaluate the implementation of novel biosensor-like devices, such as electrochemiluminescence and Surface-Enhanced Raman Scattering platforms, designed for point-of-care and field-ready scenarios. By synthesizing recent advancements in nanomaterial-enhanced recognition and microfluidic integration, this review emphasizes the pivotal role of these technologies in achieving early detection and mitigating the impact of both natural outbreaks and potential deliberate misuse of F. tularensis. Full article

Reliable detection of microplastics by surface-enhanced Raman scattering (SERS) is often hindered by poor particle–substrate contact and limited access to plasmonic hotspots on conventional planar substrates optimized for molecular adsorption. Here, we report a rapid microwave-assisted carbothermal shock strategy to fabricate silver nanoparticle-decorated electrospun carbon fibers (AgNPs@ECF) as a three-dimensional plasmonic platform tailored for solid microplastic sensing. Localized microwave-induced heating in a mixed ethanol–hexane system enables Ag nanoparticle nucleation and anchoring on conductive carbon fibers within 45 s, yielding a mechanically compliant, junction-rich architecture without chemical reductants or vacuum processing. The AgNPs@ECF composite was evaluated using morphologically weathered polystyrene (PS) and polyethylene terephthalate (PET) microplastics, along with size-controlled PS bead standards ranging from ~50 nm to 45 μm. Across these models, SERS response is governed primarily by particle–substrate contact geometry and near-field accessibility rather than polymer type. The strongest enhancement occurs in the sub-micrometer regime, where particles can engage multiple AgNP-decorated fiber junctions, while ultrasmall and large, smooth particles show reduced enhancement due to limited contact or rapid field decay. Spatially resolved Raman mapping and finite-difference time-domain simulations support a contact-dominated enhancement mechanism, revealing localized field confinement at particle–fiber interfaces. These results establish the design principles for three-dimensional SERS substrates targeting heterogeneous solid particulates, demonstrating that contact-accessible plasmonic architectures are critical for reliable microplastic detection under realistic solid-particle measurement conditions. Full article

Surface-enhanced Raman scattering (SERS) technology, with its high sensitivity and fingerprinting capability, has shown broad application prospects in environmental monitoring, food safety, biomedicine, and other fields. Electrospinning technology can produce flexible nanofiber membranes with high specific surface area and three-dimensional porous structures, providing an ideal platform for constructing high-performance SERS substrates for multiphasic analysis. This review systematically summarizes the fabrication strategies of fiber-based SERS substrates by using electrospinning technology, classified from three perspectives: material composition (polymer-based, ceramic-based, carbon fiber-based, and metal-based), spatial configuration (inner, surface, and inner-surface), and temporal sequence of plasmonic nanostructure (pre-synthesis, pre-reduction, post-reduction, post-modification, etc.). Furthermore, the sampling methods and measurement approaches of such substrates in liquid-phase, solid-phase, and gas-phase detection are discussed, with a focus on their applications in environmental pollution monitoring, food safety inspection, microbial identification, and biomedical diagnostics. Finally, the comparison of different preparation strategies and potential future directions are discussed, which could offer helpful guidance for the design and application of high-performance flexible SERS substrates. Full article

This study investigates the development and characterization of bioactive films incorporating silver nanoparticles (AgNPs) into biocompatible polymers, namely alginate and chitosan, fabricated using two methods, spin-coating and drop-casting, and aiming to enhance their antimicrobial properties. Dynamic light scattering (DLS) and electrophoretic mobility (EM) of the film precursor solutions revealed significant changes in the nanoparticles’ size and Zeta potential (ZP), reflecting the influence of polymer coatings. Alginate contributed to high electrostatic stability due to its negative charge, while chitosan facilitated specific interactions with negatively charged surfaces. Raman spectroscopy revealed that spin-coating conditions did not successfully result in film formation, highlighting the need for further optimization. Therefore, subsequent characterization studies were conducted only for the films formed by drop-casting. Topographical and nanomechanical assessments of these drop-cast films, using atomic force microscopy (AFM) and force spectroscopy, demonstrated that AgNPs reduced adhesion and elasticity in alginate films, while increasing rigidity and adhesion in chitosan-based films. Antimicrobial tests confirmed the efficacy of AgNPs in both precursor solutions and polymer films, with chitosan-based films that retained structural integrity, which makes them suitable for prolonged applications, while alginate films displayed rapid gelation upon hydration, potentially advantageous in short-term applications. The findings underscore the potential of these biopolymer-AgNP composites in creating antimicrobial materials for food packaging, wound dressings, and other biomedical applications. However, challenges related to film deposition methods, such as spin-coating, require further optimization to improve film formation and reproducibility. Full article

Background: The development of plasmonic photothermal therapy (PPTT) to trigger cancer cells is often hindered by uncontrolled overheating and the lack of real-time feedback. Methods: In this study, we report the synthesis of gold nanorod-embedded mesoporous silica nanoshells (AuNR@Si) as a multifunctional theranostic platform designed for controlled hyperthermia and surface-enhanced Raman spectroscopy (SERS) monitoring. Using a layer-by-layer templating strategy, AuNRs were successfully obtained within a hollow silica architecture. Results: While AuNRs alone exhibited rapid photothermal spikes reaching 64 °C, the AuNR@Si platform moderated the photothermal response, maintaining a stable therapeutic window (41–45 °C). In vitro assays using T47D breast cancer cells demonstrated a 33% reduction in viability following irradiation. Furthermore, the structural stability of the AuNR@Si platform enabled SERS monitoring of cellular damage, identifying specific biochemical fingerprints of protein denaturation, cytochrome c release and DNA fragmentation. Conclusions: These results suggest that AuNR@Si nanoshells provide a safer, regulated approach to photothermal ablation with the added benefit of molecular detection, demonstrating proof-of-concept theranostic functionality in a luminal breast cancer model. Full article

In the modernization of traditional Chinese medicine (TCM), trace detection of pharmacodynamic substances faces a critical challenge: insufficient sensitivity, which significantly hinders accurate quality assessment and standardization. Conventional techniques often fail to measure trace components in complex sample matrices. Therefore, the development of a rapid, effective, sensitive, and reliable analytical method, along with a corresponding quality evaluation system, is of great importance. This study used moth wing (MW) scales as a template to fabricate an Ag/MW SERS substrate via magnetron sputtering. The optimal Ag₃₀/MW SERS substrate (30 min sputtering) achieved an enhancement factor of 6.47 × 10⁶ and good reproducibility (minimum RSD: 7.03%). Principal component analysis (PCA) was integrated with four deep learning algorithms (MLP, Transformer, ResNet, DNN) to detect three typical TCM pharmacodynamic substances in pure standard solutions: atractylon, cimifugin, and timosaponin A-III. The models enabled rapid identification, with the MLP model reaching 95.00% accuracy. This research provides a novel, highly accurate, and efficient detection method with potential for TCM pharmacodynamic substances, demonstrating feasibility for bioactive compound identification in model systems, and shows promising potential for future application in TCM composition analysis and quality control. Full article

Microbial imbalance and the spread of pathogenic microorganisms pose severe threats to human health and ecological security. Traditional microbial detection methods suffer from several drawbacks such as long detection time, low sensitivity, and insufficient specificity. As an emerging fluorescent probe, carbon dots (CDs) offer an innovative direction for microbial labeling and detection due to their ultra-small particle size, unique optical properties, excellent biocompatibility, and facile surface modifiability. Herein, this article reviews the research progress of CDs on microbial labeling and detection. The content covers a brief introduction of CDs and explores the main recognition strategies including non-covalent interactions and biomolecule-mediated targeted binding. It also elaborates on the application status of multi-modal sensing technologies for microbial detection, such as CDs-based fluorescent sensing, electrochemical sensing, and surface-enhanced Raman scattering (SERS) sensing. Additionally, the challenges faced in current research, such as achieving simultaneous detection of multiple pathogens and in vivo dynamic tracking, are analyzed, and the development prospects of CDs in fields like clinical diagnosis and public health monitoring are prospected. This review aims to provide comprehensive references for further research and application of CDs in the field of microbial detection. Full article