Ultrasensitive detection of thiram based on surface-enhanced Raman scattering via Au@Ag@Ag core/shell/shell bimetallic nanorods

A highly sensitive and selective SERS sensors based on Au@PATP@Ag@ZIF-8 for the detection of phosphate in water

Rapid and sensitive detection of phosphate is of great significance for ensuring water safety and preventing eutrophication. In this study, we prepared Au@PATP@Ag NRs core-shell structures using 4-aminothiophenol (PATP) as an internal standard signal molecule to enhance the stability of the SERS signal. Based on the protective effect of ZIF-8 on the internal Au@PATP@Ag NRs and the phosphate-induced decomposition of ZIF-8, a phosphate SERS sensor (Au@PATP@Ag@ZIF-8) with high sensitivity, selectivity and stability was designed. This method exhibited a good linear range of 0.1-125 μM and a detection limit of 30 nM. Furthermore, the developed sensor (Au@PATP@Ag@ZIF-8) was effectively applied to assess PO43- in tap water samples, achieving recoveries between 97.44 % and 104.54 %. With its simple, fast and sensitive features, this method of phosphate detection in water provides a direction for the research and practical application of phosphate detection.

Detection of pesticide residue using an Fe3O4/GO/Ag nanocomposite as a SERS substrate and mechanism investigation

Considering that pesticide residues cause significant harm to health and the environment, it is crucial and urgent to fabricate surface-enhanced Raman scattering (SERS) substrates with high sensitivity to detect pesticide residues. In this study, a three-layer structure of multifunctional Fe3O4/GO/Ag nanoparticles (NPs) as an active substrate for SERS was fabricated and comprehensively characterized through X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), elemental mapping, and X-ray photoelectron spectroscopy (XPS). The active substrate was used to detect thiram pesticide through SERS. Combined with the synergistic effect, Ag NPs and graphene oxide (GO) possessed high-density and ordered hot spots to enhance the electromagnetic field; therefore, signal amplification and fascinating sensitivity were achieved. The lowest concentration of thiram for clear presentation of the peak was 10-12 mol L-1. There was a satisfactory linear relationship, ranging from 10-10 to 10-4 mol L-1, with a low limit of detection, high sensitivity, satisfactory enhancement factor (EF), stability, and repeatability. In addition, Fe3O4/GO/Ag was successfully applied to identify pesticide residues in a practical sample. Furthermore, the enhancement mechanism, including electromagnetic enhancement and chemical reinforcement, is discussed in detail. Fe3O4/GO/Ag is a potential active substrate for SERS and can be applied for rapid detection in the food industry, environmental fields and biomedicine with fascinating sensitivity.

Construction and Application of Au NRs/4-MBA/PAM Ratiometric Surface-Enhanced Raman Scattering Substrate for Fish Veterinary Drug Residue Detection

Surface-enhanced Raman scattering (SERS) is widely used for trace detection of substances, and the key to this technology lies in the preparation of the substrate material. In this study, a composite SERS material of Au NRs/4-MBA/PAM was constructed and characterized to better immobilize the reference molecule 4-mercaptobenzoic acid (4-MBA). Electron transmission microscopy results demonstrated that the PAM film helps Au NRs to pack closely, enhancing the stability of the material structure and reducing the interference of external environmental factors on the response of 4-MBA, thus improving the accuracy of quantitative determination. Comparative experimental results with the Au NRs/4-MBA substrate showed that the relative standard deviations (RSDs) of the detection results for MG on different batches of Au NRs/4-MBA/PAM were less than 8.0%, and the RSDs of different points on the same material were less than 10.0%, indicating that the Au NRs/4-MBA/PAM has higher uniformity, better reproducibility, and higher sensitivity in detecting malachite green (MG). Applying this material in the recovery determination of fish extract showed that the recovery rates of MG were between 75.60% and 83.24%. Therefore, the Au NRs/4-MBA/PAM substrate can accurately detect and quantify veterinary drug residue in complex matrices such as food tissue.

High performance and recyclable Ag/ZnO/PM substrate for the detection of organic pollutants

A sensitive and recyclable substrate was fabricated through in situ reduction of silver nanoparticles (NPs) on zinc oxide nanorods (NRs). The prepared silver nanoparticles/zinc oxide nanorods/polyamide mesh (Ag/ZnO/PM) substrate exhibited not only excellent surface-enhanced Raman scattering (SERS) performance to R6G with a limit of detection (LOD) of 10-12 M, mainly attributed to the synergistic effect of the suitable size and the nanoscale gaps of the Ag NPs to produce local surface plasmon resonance (LSPR), but also outstanding self-cleaning property via UV irradiation due to its significant photocatalytic property based on the non-equilibrium carriers generated by ZnO and the presence of Schottky junctions between Ag and ZnO. The substrate showed good recycling stability even after five cycles. Furthermore, the successful recyclable application of Ag/ZnO/PM for tetracycline hydrochloride (TC) detection with high sensitivity further suggested that it is a promising candidate for constructing a portable SERS platform to detect organic pollutants.