Excessive tryptamine in food poses a significant risk to human health, emphasizing the demand for efficient, sensitive, and rapid detection technologies. Surface-enhanced Raman Spectroscopy (SERS) aptasensors are presently attracting a lot of attention due to their ability to detect targets at low concentrations. However, their inherent instability and poor anti-interference ability hinder their widespread use. Herein, a two-layer core-satellite magnetic SERS aptasensor was constructed to achieve the sensitive detection of tryptamine. The SERS aptasensor consisted of magnetic SERS recognition probes (magnetite nanoparticles coated with gold nanoparticles and aptamer: Fe3O4@Au-apt) and SERS signal probes (gold nanoparticles of two different sizes functionalized with the Raman reporter molecule 4-mercaptobenzonitrile and complimentary deoxyribonucleic acid strands). In the absence of tryptamine, the SERS signal probes attached to the aptamer on the SERS recognition probes to form a two-layer core-satellite structure with an intense SERS signal at 2226 cm− 1 in the “biological-silent” region due to the 4-Mercaptobenzonitrile. In the presence of tryptamine, tryptamine bonded to aptamer on the SERS recognition probe leading to detachment of the SERS signal probes, weakening the SERS signal at 2226 cm− 1. The aptasensor exhibited a favorable linear range from 0.001 to 100 mg L− 1, with a detection limit of 0.39 × 10− 3 mg L− 1 toward tryptamine. The fabricated sensor was practically applied to the detection of tryptamine in liquor, white wine and vinegar samples, with results highly consistent with high performance liquid chromatography data, demonstrating the broad prospects of the developed analytical method in food threat detection.

Herein, a reusable and portable surface-enhanced Raman spectroscopy (SERS) sandpaper was successfully synthesized for the sensitive detection of S-fenvalerate in foods. Commercial sandpapers were decorated with Ag@SiO2@Au nanoarrays via a liquid-liquid interface self-assembly method. The capacity of sandpaper to float directly on the cyclohexane-water interface allows nanoarrays to be formed directly on it, thereby minimizing stacking issues typically associated with nanoarray assemblies and significantly enhancing the sensitivity of S-fenvalerate detection. Moreover, the SERS sandpaper was reusable and portable due to its strong adhesion of the nanoarrays. Under optimized testing conditions, the developed SERS sandpaper method was capable of detecting S-fenvalerate, demonstrating a strong linear response within a concentration range of 10-7-103 mu mol/L, with a limit of detection of 1.92 & times; 10-8 mu mol/L. The analysis of spiked food samples containing S-fenvalerate using the developed SERS sandpaper afforded excellent recoveries (92.2%-109.7%). Additionally, the SERS sandpaper was successfully applied to quantify S-fenvalerate in real food samples, with results consistent with analyses conducted using gas chromatography.

In the agricultural sector, pesticides are widely used to enhance crop yields and protect plants from pests and diseases. However, pesticide residues pose significant threats to humans, animals, insects and ecosystems. Accordingly, the rapid, sensitive, and accurate detection of pesticide residues is of great significance for protecting human health and the wider environment. Surface-enhanced Raman spectroscopy (SERS) is increasingly being applied for the detection of hazardous substances in foods. Furthermore, biological recognition elements (such as antibodies, aptamers, etc.) are widely applied in food safety assessment due to their high specificity and low cost. Combining bio-affinity elements with SERS technology can create efficient and accurate pesticide residue detection platforms. This review summarizes recent progress in the development of SERS biosensors for the detection of pesticide residues. Strategies for integrating specific recognition elements (especially antibodies and aptamers) with the plasmonic SERS nanosystems are discussed. Then, selected case studies are introduced highlighting the advantages of such SERS biosensors for pesticide detection, before future prospects of this research field are discussed. This review guides the development novel SERS biosensors for pesticides and other target analytes.

An ultra-sensitive and specific surface-enhanced Raman scattering (SERS) sensor based on three-dimensional (3D) SERS tags was successfully developed for simultaneous detection of levamisole (LMS) and chlorpromazine (CPZ) residues in foods. The SERS sensor had three key components: (1) Aptamer-functionalized magnetic nanocomposites were used as capture probes (Fe3O4@PEI@Ag-apt), which allowed fast and accurate isolation of LMS and CPZ, whilst also significantly improving the anti-interference properties of the detection method; (2) Complementary DNA (c-DNA)-modified 3D SERS tags served as signal probes (AuNS@AuNRMBN/NT@Ag-c-DNA), which provided two different “hot spot” regions (Au-Au and Au-Ag) and greatly enhanced the Raman signal; (3) The third component was competitive attachment of the signal probe to the surface of the capture probe. When levamisole and chlorpromazine were present, they bound preferentially to the aptamers on the capture probe (thereby separating the signal probe from the capture probe). After magnetic enrichment of the capture probes, the Raman signal of the corresponding signal probe decreased significantly, providing a basis for quantitative detection of LMS and CPZ. Under optimized conditions, the sensor achieved ultra-low limits of detection of 9.3 × 10−6 mg L−1 for levamisole and 3.3 × 10−6 mg L−1 for chlorpromazine. Recoveries ranged from 89.11% to 105.43% for levamisole, and 91.44% to 109.53% for chlorpromazine, indicating good accuracy of the method. This work offers a new strategy for the construction of SERS sensors with high sensitivity and specificity for simultaneous detection of levamisole and chlorpromazine in foods.

The rapid progress in science and technology increases the demand for dyes and results in the pollution of dye wastewater. Recently, covalent organic frameworks (COFs) have been suggested as a promising candidate for wastewater treatment. The influence of inorganic salt ions on the transport and separation processes of dye wastewater is poorly understood. In this work, the transport and separation mechanisms of dyes are investigated via nonequilibrium molecular dynamics simulations (NEMD). It is found that the inorganic salts enhance the rejection rate of different dyes in TpPa-1 membranes. The fundamental reason for this phenomenon is the hindrance caused by inorganic salt ions, which change the orientation of dye molecules as they pass through the pore channels of the TpPa-1 membrane. As a result, the dye molecules show a greater tendency to form π-π interaction with the TpPa-1 membrane surface, which accelerates their adsorption.

Herein, a molecularly imprinted surface-enhanced Raman spectroscopy (SERS) sensor was developed for the selective capture and sensitive detection of tryptamine in foods. The SERS sensor exploited silver nanoparticle-decorated TiO2 (TiO2@Ag) substrates for Raman signal enhancement via synergistic effect of electromagnetic enhancement and photoinduced charge-transfer, whilst surface functionalization with the molecularly imprinted polymer ensured selective tryptamine capture. The SERS spectrum of tryptamine on the sensor closely matched that predicted by density functional simulations. The SERS intensity for tryptamine on the developed TiO2@Ag@MIP sensor increased linearly with the logarithm of the tryptamine concentration over the range of 10-6-10-2 mol L-1, with a LOD of 4.85 × 10-7 mol L-1. Tryptamine was detected in a spiked white vinegar sample, and its recoveries were in the range of 92.00%-111.40%. The SERS sensor could be used for the detection of tryptamine in actual samples.

In this study, a novel surface enhanced Raman spectroscopy (SERS) sensor was developed for the ultrasensitive determination of kanamycin in foods. The sensor used two distinct signal amplification strategies, namely the surface plasmon resonance of gold nanorods and a Zn-doped carbon quantum dots catalytic cascade oxidation-reduction reaction switch controlled by a nucleic acid aptamer. Under optimized experimental conditions, the SERS sensor demonstrated a linear range of 10-12 to 10-5 g mL-1 for the detection of kanamycin, with a limit of detection of 3.03 × 10-13 g mL-1. Experiments with antibiotics structurally similar to kanamycin and interferrants revealed that the sensor had excellent selectivity. Milkpowder and honey samples spiked with kanamycin were assayed, with recoveries ranging from 84.1% to 107.2% and a relative standard deviation of 0.74% to 2.81% being obtained. Quantification of kanamycin in milk samples revealed no significant difference between the results obtained with the sensor and by HPLC.

A highly sensitive molecularly imprinted surface-enhanced Raman scattering (SERS) sensor was developed for selective detection of histamine. A combination of two semiconductors and Ag nanoparticles (NPs) was used as the SERS substrate. The SERS was induced by Ag NPs plasmon resonances as well as charge-transfer between the semiconductors and the Ag NPs. The Raman intensity and the logarithm of the histamine concentration were linear over the range 10-8-10-3 mol L-1. The sensor exhibited good selectivity and had a sensitivity limit of 3.088 × 10-9 mol L-1. Histamine was detected in a spiked liquor sample, and its recoveries were in the range of 89.89%-109.18%.