Surface-enhanced Raman scattering (SERS), a precise vibrational molecule spectroscopy technique, is widely utilized for rapid qualitative and quantitative analytical detection of hazardous substances. Here, we combined the integration of machine learning algorithms with calibration functionalized gold core and silver shell nanoparticles containing adenine (Au@Ade@Ag NPs) to improve the datasets quality of label-free SERS detection of thiacloprid. The core-shell structures were fabricated using only hydroxylamine hydrochloride for minimizing background interference derived from reducing agents. Electromagnetic field simulations reveal that electromagnetic field enhancement exhibited non-uniformity across different positions in nanoparticle aggregates. Noteworthy, the internal standard (730 cm−1) of adenine can significantly reduce the intra-group difference (from 25.2% to 10.3%) caused by the uneven distribution of hotspots on SERS substrates. In the concentration range of 0 μM to 20 μM, the R2 of conventional linear fitting is increased from 0.8518 to 0.9275 after calibration. Compared with all spectra dataset without 700–780 cm−1, the fitting effects of 16 of the 24 machine learning regression models have been improved, while the fitting effect of only SVR-poly algorithm has significantly decreased. The cross-validation R2 of 7 algorithms was the lowest at 0.9590. The Extra Trees presented as a pragmatic analytical choice based on its performance at low concentration levels, stability, interpretability, and prediction time. The SERS platform was applied to spiked Prunus persica (L.) Batsch and Brassica chinensis L. samples, indicating a recovery rate ranging from 85.8% to 103.5%, and a coincidence rate of high-performance liquid chromatography (HPLC) ranging from 88.4% to 112.5%. The excellent analytical performances and reliable observed suggest the potential of the machine learning-assisted self-calibrating Au@Ade@Ag NPs sensing strategy for hazardous substances of Prunus persica (L.) Batsch and Brassica chinensis L. samples.

The coral thicket-structured silver nanoparticles (CTS-Ag) were in situ grown on the surface of nanocellulose hydrogel (NC-HG) to form 3D flexible CTS-Ag@NC-HG SERS substrates through precise control of silver ion concentration. Due to the high density of hotspots formed by the unique 3D porous structure of CTS-Ag, CTS-Ag@NC-HG SERS substrates exhibit prominent detection sensitivity of 10-12 M and signal homogeneity for 4-mercaptobenzoic acid (4-MBA). In addition, due to the good flexibility, mechanical strength and adsorption properties of NC-HG, the CTS-Ag@NC-HG SERS substrate is capable of detecting preservatives on irregular food surfaces via a simple paste-read method. The detection sensitivities of 10-9, 10-8 and 10-11 M were obtained by CTS-Ag@NC-HG SERS substrate for food preservatives of sodium dehydroacetate, methylparaben, and potassium sorbate. The exceptional linear response reveals that the CTS-Ag@NC-HG SERS substrate has promising applications in the quantitative detection of food preservatives.

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique offering simplicity, ultra-high sensitivity, molecular fingerprint specificity, and rapid detection. The development of Raman probes is crucial for advancing SERS performance. Notably, 3,3′,5,5′-Tetramethylbenzidine (TMB), a widely used chromogenic substrate, possesses distinct redox, electrochemical properties and spectroscopic properties. The oxidized forms of TMB (ox-TMB) act as SERS probes, enabling sensitive and reliable SERS detection. Integration of TMB-SERS with other analytical techniques allows multimodal sensing, improving detection accuracy in applications such as disease diagnosis, environmental monitoring, and food safety. Although TMB has been mentioned in reviews on SERS substrates, probes, nanozyme-assisted SERS, and catalytic sensing, a comprehensive, substrate-focused review of TMB-mediated catalytic SERS is still lacking. This review systematically summarizes the chemical and redox properties of TMB, clarifies the mechanism of Raman activation, and highlights key applications. Design principles, current challenges, and future directions for TMB-mediated SERS systems.

The assurance of food safety is essential for public health and environmental sustainability [...]

Addressing the limitations of traditional food safety testing requires rapid, sensitive, and portable analytical innovations. Nanosensors have surfaced as powerful tools for detecting pathogens and contaminants by exploiting the specific physicochemical properties of nanomaterials. This review outlines recent strides in nanosensor technology, covering material design and applications in monitoring diverse food safety indicators. Crucially, it explores the fusion of nanosensing with emerging technologies like Artificial Intelligence (AI), the Internet of Things (IoT), and Lab-on-a-Chip (LOC) systems. However, this review critically identifies that the practical transition of nanosensors from laboratory settings to complex food matrices is still hindered by significant signal interference and insufficient long-term stability of functionalized nanomaterials. While these smart platforms offer real-time decision-making potential, they introduce new complexities regarding data reliability, standardization, and regulatory acceptance. By evaluating current sensor performance against global safety standards, this work emphasizes that future trajectories must prioritize the development of robust, cost-effective, and sustainable sensing platforms that can be rigorously validated under real-world food-processing conditions.

The rising prevalence of foodborne risks has generated an urgent demand for portable analytical instruments across the agri-food supply chain. This review systematically examines recent developments in nanosensor technologies by classifying progress according to three key parameters: transduction mechanism (optical, electrochemical, thermal, and magnetic), target analyte (pathogens, toxins, miRNAs), and application context (agri-food chain versus clinical matrices). Advanced plasmonic nanostructures, quantum-dot Förster resonance energy transfer (FRET) systems, and photonic-crystal microcavities enable sub-minute detection of food pollutants. Nanowire field-effect transistors (FETs) with nanoparticle-modified electrodes achieve femtomolar detection limits. Core-shell heteronanoparticles and smartphone-compatible nanopaper devices translate these laboratory capabilities into low-cost, field-ready platforms. Future avenues include self‑powered functionality via triboelectric/piezoelectric energy harvesters, on‑device AI for signal processing, and Internet of Nano Things (IoNT)‑enabled federated analytics—all developed under green chemistry principles and evolving regulatory standards. The convergence of nanomaterials with edge intelligence promises next‑generation autonomous sensors for global food safety assurance.

The co-contamination of aflatoxin B1 (AFB1) and ochratoxin A (OTA) in environmental foods has attracted widespread attention. A particle counting biosensor was developed for the simultaneous detection of AFB1 and OTA, utilizing polystyrene (PS) microspheres with diameters of 4 μm and 6 μm (PS4μm and PS6μm) as signal probes and aptamers as biological recognition elements. In this method, the concentration information of AFB1 and OTA was converted into changes in guide DNA (gDNA) concentration. Biotinylated single-stranded DNA (ssDNA) was immobilized on the surfaces of PS4μm and PS6μm, and the specific cleavage function of the Clostridium butyricum argonaute (CbAgo) Protein was utilized. The binding between aptamers and targets regulated the gDNA concentration, which in turn mediated the cleavage of ssDNA on the PS microspheres by CbAgo. By combining the biotin-streptavidin system with magnetic separation technology, changes in particle numbers were achieved and detected using a handheld cell counter. A linear relationship was established between particle number and the concentrations of AFB1 and OTA. The experimental results showed good linear ranges: 100 pg/mL-200 ng/mL for AFB1 and 200 pg/mL-200 ng/mL for OTA. The limits of detection were 56.3 pg/mL for AFB1 and 176.3 pg/mL for OTA. Recoveries ranged from 79.60% to 96.52%. Practical detection in corn samples verified the feasibility and accuracy of this method for the simultaneous detection of AFB1 and OTA, providing an effective approach for the synchronous analysis of trace contaminants in environmental foods.

Achieving controllable nanostructures and tunable molecular adsorption/orientation remains a key challenge in advancing surface-enhanced Raman spectroscopy (SERS) toward efficient enhancement and ultrasensitive detection. This work reports nanoporous pAg-Au-SPE substrates combined with a pH-regulated electrostatic capture electrochemical SERS (EC-SERS) strategy for sensitive detection of thiacloprid (THIA). Ag7O8NO3 micropyramids on Au-SPE were reduced with NaBH4 to form nanoporous Ag micropyramids with precisely tunable pore sizes, resulting in controllable nanostructures with dense and uniformly distributed hotspots. Under acidic conditions, THIA is protonated, and applying a potential of -0.7 V renders the pAg-Au-SPE surface negatively charged, driving electrostatic capture and enrichment of THIA at hotspots. Experimental and theoretical results reveal that protonated THIA anchors its positively charged nitrogen atoms near the Ag surface, reorienting from near-planar to more perpendicular adsorption and enhancing SERS signals. Using the intrinsic band of pAg-Au-SPE as an internal standard, the EC-SERS strategy achieves a detection limit of 1.36 nM, three orders of magnitude lower than conventional SERS (1.41 μM), and yields results in real samples that agree well with HPLC. This work can be extended to sensitive detection of diverse hazardous analytes and offers new perspectives for advancing SERS applications.

Rapid, ultrasensitive, and nondestructive detection of pesticide residues on fruit surfaces remains a significant challenge. Herein, we developed a series of flexible silver nanoparticles@chitosan hydrogel (AgNPs@CSHG) SERS substrates by a controllable in-situ growth strategy, creating uniformly distributed SERS hot spots through electrostatic interactions between silver ions and the hydroxyl/amino groups in chitosan molecules. Hydrophilic CSHG exhibits excellent adsorption and permeability properties, enabling effective enrichment of probe molecules within hotspot regions to further improve detection sensitivity. The optimal AgNPs-45@CSHG SERS substrate achieves a remarkable detection sensitivity of 10-8 M and exceptional reproducibility (RSD = 8.14%) for 4-mercaptobenzoic acid (4-MBA). Importantly, the flexible and robust AgNPs@CSHG SERS substrates realize rapid, simple and nondestructive thiram detection at a concentration as low as 10-7 M on fruit peel by a simple stick-and-read method. The flexible, ultrasensitive and nondestructive AgNPs@CSHG SERS substrate presents significant potential for applications in food safety monitoring.

Tea proteins from tea-processing by-products are sustainable resources, but their application is constrained by poor solubility and functionality. This review highlights interfacial engineering as a key strategy to improve tea protein performance and establishes a framework linking molecular structure, interfacial behavior, and functionality. The characteristics of tea residue protein and tea seed protein are first summarized in terms of source, composition, and interfacial properties. Modification strategies are then discussed from physical, chemical, biological, and combined perspectives. Representative applications include functional stabilizers for plant-based foods and edible packaging, precursors of bioactive peptides, and colloidal particles for Pickering emulsions and structured foods. Industrialization challenges, including scalability, safety, sensory quality, and regulatory issues, are critically evaluated. Future directions focus on rational modification, targeted nutrition, advanced food systems, and sustainable biomaterials, highlighting tea proteins as multifunctional ingredients for circular food systems.

Surface-enhanced Raman spectroscopy (SERS) for small, weakly adsorbing pesticides is limited by insufficient analyte enrichment and poor field deployability. To address this limitation, we present a portable electrochemical SERS (EC-SERS) platform that integrates a redox-roughened screen-printed silver electrode (SPE-Ag) with a smartphone-controlled mini-potentiostat. At pH 2, imidacloprid (IMI) is protonated, and applying -1.0 V drives IMI toward plasmonic "hot spots", yielding a 27-fold signal enhancement and a limit of detection (LOD) of 1.5 nM, four orders of magnitude lower than conventional SERS (13.5 μM). The self-fabricated, renewable SPE-Ag tolerates more than 15 adsorption-desorption cycles and exhibits good reproducibility (inter-batch RSD 5.6%), uniformity (intra-chip RSD 5.8%), and stability (90% signal retention over 10 weeks). Spiked samples of Pisum sativum L. and Allium fistulosum L. showed recoveries of 90.65%-103.04%. Overall, this low-cost, portable EC-SERS platform enables rapid screening of pesticide residues in real food matrices, showing strong potential for food safety monitoring.

Saxitoxin (STX) is a highly potent phycotoxin that poses a severe threat to both human health and aquatic ecosystems. Given its extremely low permissible level in food products, there is an urgent need for a sensitive, specific, and cost-effective screening method. In this study, an electrochemiluminescence (ECL)-based method was developed for STX detection, capitalizing on the inherent advantages of ECL, including high sensitivity and minimal background interference. To achieve selective recognition of STX, molecularly imprinted polymers (MIPs) featuring specific memory cavities were modified onto MAPB QDs@SiO2. Benefiting from the label-free nature of MIPs and the unique electronic properties of MAPB QDs, the fabricated ECL sensor exhibited excellent sensitivity with a low detection limit of 1.2 fg/mL and high selectivity against other biotoxins. With its simplicity, outstanding sensitivity, and reliable specificity, this sensor represents a promising tool for STX monitoring in environmental and food safety applications.

A scalable strategy for in-situ growth of silver nanoparticles (AgNPs) on flexible polydimethylsiloxane (PDMS) films to construct a highly sensitive AgNPs@PDMS surface-enhanced Raman scattering (SERS) substrate for the determination of malachite green is proposed. The substrate exhibits excellent uniformity and performance, with an enhancement factor of 4.5 × 107 for 4-mercaptobenzoic acid (4-MBA) and a detection limit of 10− 11 M. Moreover, it can detect malachite green in aquaculture wastewater and on irregular aquatic surfaces. Its strong linear correlation between SERS intensity and logarithmic concentration indicates good quantitative potential. UV-vis spectroscopy and spike-recovery experiments further verify its reliability. The AgNPs@PDMS substrate thus offers a reliable and promising platform for rapid on-site detection of illegal additives in aquaculture.

Surface-enhanced Raman scattering (SERS) remains hampered in complex matrices by the difficulty of selectively capturing trace analytes. In this study, we address this bottleneck with a simple electrochemical surfaceenhanced Raman scattering (EC-SERS) platform built on titanium dioxide (TiO2) nanotube arrays. Applying -0.5 V vs. Ag/AgCl recruits additional binding sites for carbendazim (CBZ) on the Ag/Au-TiO2 surface, which boosts the Raman signal 3.1-fold and delivers a 12.7-fold enhancement in sensitivity over conventional, zeropotential SERS method. After measurement, 365-nm UV illumination photocatalytically degrades the retained CBZ, restoring the substrate for reuse. Spiked vegetable extracts gave recoveries of 83.4-108.8%, values that coincide with HPLC-MS data within 80.2-101.0%. This regenerable semiconductor architecture expands the scope of TiO2-based SERS and establishes a practical route to sensitive, on-site pesticide screening.

The peels of rambutan (Nephelium lappaceum L.), constituting up to 60% of the fruit mass, are largely discarded despite being rich in ellagitannins (geraniin, corilagin, ellagic acid), anthocyanins, flavonoids, organic acids, and tocopherols. Recent studies have systematically characterized the phytochemical profile of rambutan peel and revealed its potent antioxidant, antimicrobial, anti-diabetic, anti-inflammatory, anti-osteoporotic, and anti-photoaging activities. This review synthesizes current knowledge on i) green and scalable extraction methods ranging from conventional Soxhlet and heat-assisted extraction to advanced ohmic heating, microwave/ultrasound-assisted, and supercritical fluid extraction; ii) purification strategies that enable the enrichment of geraniin (>95%) and other ellagitannins; iii) structural and stability analyses under thermal, pH, and enzymatic stresses; and iv) practical applications in functional bread, edible films/coatings, sunscreen, anti-aging creams, and natural preservatives. Compiled safety data from the reviewed literature indicate a high oral LD50 (>2000 mg/kg) for rambutan peel extract (RPE) and an absence of cytotoxicity in normal cells at therapeutic concentrations. The review further identifies several critical gaps, including limited in vivo bioavailability data, a lack of standardized cultivar-specific studies, and the need for integrated pilot-scale extraction and purification processes. Overall, rambutan peel presents an underexploited resource with multi-sectoral potential within the circular bioeconomy.

Surface-enhanced Raman scattering (SERS) is a promising alternative for trace analysis, but its potential is largely limited by weak target-substrate affinity, complex matrix interference, and signal fluctuations. This study develops a ratiometric electrochemical (EC)-SERS platform for carbendazim (CBZ) detection and fabricates a silver@gold nanoflowers/prussian blue/screen-printed electrode (Ag@AuNFs/PB/SPE) substrate. Leveraging the multifunctionality of Ag@AuNFs/PB/SPE, the EC-SERS platform realizes electro-enhanced adsorption and self-calibrating detection of CBZ. Both experiments and theoretical simulations show that an applied potential of -0.6 V significantly boosts van der Waals (vdW) forces between CBZ and Ag nanoparticles, promoting efficient CBZ enrichment at "hot spots". Compared to conventional ratiometric SERS methods, this optimal potential boosts the CBZ SERS signal by 3.8-fold. Correspondingly, the low detection limit of the ratiometric EC-SERS platform is 3.7 nM, representing a 9.3-fold improvement in sensitivity over ratiometric SERS (34.5 nM). Thus, multifunctional Ag@AuNFs/PB/SPE substrates have promoted the development of SERS technology for practical application scenarios.

Global demands for food safety and environmental monitoring have revealed that conventional pesticide detection methods lack the speed and portability required for on-site analysis. Electrochemical surface-enhanced Raman spectroscopy (EC-SERS) offers rapid enrichment, high sensitivity, exceptional selectivity, and ease of integration, effectively addressing these limitations and enabling widespread application in the detection of pesticide residues. This review examines the application of EC-SERS sensors in pesticide residue detection, emphasizing the critical factors that govern detection performance, the active substrate materials and their fabrication strategies, and the distinct roles they play within EC-SERS-based analytical platforms. In addition, it delineates four strategic approaches to improve the performance of pesticide residue detection, including the development of novel SERS substrates, optimized electrode designs, consideration of pesticide physicochemical properties, and enhanced system integration. Nevertheless, challenges persist with respect to substrate stability, signal reproducibility, spectral resolution, and application costs. Future research may therefore focus on advanced SERS substrates, miniaturized sensing platforms, and portable low-cost screen printed electrodes. Ultimately, this review aims to contribute to the ongoing refinement of EC-SERS technology for pesticide residue analysis while also offering insights applicable to the detection of other contaminants.

The detection performance of surface-enhanced Raman scattering (SERS) substrates is closely related to their three-dimensional plasmonic nanostructures. In this work, a series of three-dimensional porous hovenia acerba-like silver nanostructure-decorated polyvinyl alcohol hydrogel (HA-AgNPs@PVA) SERS substrates were fabricated by a facile in-situ chemical reduction strategy. Three-dimensional porous plasmonic nanostructures possess numerous nanopores, capable of forming multi-level and high-density hot spots. Additionally, the porous nanostructures can accommodate a greater number of probe molecules, significantly enhancing SERS performance. Using crystal violet as probe molecule, the optimized HA-AgNPs@PVA SERS substrate achieves a detection sensitivity of 10-10 M and an enhancement factor of 1.6 × 108. Moreover, flexible HA-AgNPs@PVA SERS substrate was applied for the detection of thiram on various fruit surfaces using a "stick-and-read" approach, delivering a high detection sensitivity of 10-8 M and demonstrating excellent quantitative detection capability. The developed flexible SERS platform exhibits great potential for on-site food safety monitoring.

Acetamiprid (AAP) is a renowned neonicotinoid insecticide for swift insect control that is prone to residue in agricultural products and threatens human health. Magnetic electrochemical sensor (MES) was developed for high-precision detection of AAP based on silver nanoparticle (AgNPs) and polydopamine (PDA) modified Fe3O4 nanocomposites (Ag@PDA@Fe3O4). The electrochemical signals generated by AAP hydrolysis and AgNPs oxidation are respectively used as two special signal sources. An increase in AAP concentration led to a proportional increase in the signal from AAP hydrolysis at +0.9 V (IAAP), while the signal from AgNPs oxidation at +0.27 V (IAg) correspondingly decreased. The output signal Delta I AAP / Delta I Ag (R2=0.9890) demonstrates a superior linear relationship compared to Delta I AAP (R2=0.9790) or Delta I Ag (R2=0.9740) alone. MES demonstrated a broad linear detection range from 0.01 to 2.00 mg L- 1 and an impressive limit of detection (LOD, 3S/M) at 3.6 mu g L- 1 . The incorporation of magnetic glassy carbon electrodes (MGCE) significantly mitigates the detachment of nano- materials. MES has excellent stability and selectivity, and can successfully detect AAP in actual cowpea samples. This study provides pivotal insights into the design of nanomaterial-based ratiometric electrochemical sensors for the sensitive and selective detection of AAP.

In agriculture, the spread of pesticides, especially neonicotinoid acetamiprid (AAP), has raised concerns about food residues which are of relevance to public health and safety. To solve this problem, we have developed a high-throughput detection method, electrochemical surface-enhanced Raman Spectroscopy (EC-SERS), which can detect AAP quickly and sensitively in fruit and vegetables. Our method involves the creation of a new labelfree substrate, SPE-PB-Ag, by means of an in situ electrodeposition process that is directly applicable to the detection of pesticide residues in EC-SERS. This substrate demonstrated a broad linear range of detection from 0.1 mu M to 100 mu M at a potential of -0.6 V and a low limit of detection (LOD) of 0.038 mu M, which is 10-fold higher than the conventional SERS method (LOD, 0.366 mu M). The potential used effectively modulated the stable physical adsorption interactions between the AAP molecules and the substrate surface, thus optimising the ECSERS detection process. Moreover, the SPE-PB-Ag EC-SERS substrate exhibits the ability to be regenerated through simple washing with pure water, thus sustaining its high enhancement effect over multiple uses. Therefore, this study presents an innovative, convenient, rapid, and reliable strategy for the detection of pesticide residues in fruits and vegetables, advancing the field of food safety and environmental monitoring.