Preparation of a high-performance thermally shrinkable polystyrene SERS substrate via Au@Ag nanorods self-assembled to detect pesticide residues

This paper reports a bottom-up substrate preparation method using a two-phase interface self-assembly technology that combines silver-coated gold core-shell nanorods with the thermally shrinkable polystyrene (TSP) support material for surface-enhanced Raman spectroscopy (SERS), that is, TSP-SERS substrate. The gold nanorods with long absorption wavelength were used as the core, and the silver shells were coated to obtain the core-shell nanostructures with a stronger resonance with the wavelength of the light source. The density of the nanostructures and numbers of hot spots within the light spot increased via the three-dimensional folding feature formed by thermal shrinkage. The combined effect of the two factors increases the enhancement factor by an order of magnitude to 10(7) after thermal contraction. The detection concentration of 4-mercaptobenzoic acid can reach 10(-9) M, and the maximum relative standard deviation is only 8.9%. In fact, the detection limit of benzimidazole on the surface of apple can reach 0.5 mg/L, and the recovery deviation is controlled within the range of 11.7%. The practical detection of benzimidazole pesticide residues showed that this method has wide application prospects in the detection of pesticide residues.