Dual trace detection of hazardous substances by aptamer-functionalized gold nanofilms based on surface-enhanced Raman spectroscopy

This work proposes the application of multi-residue Surface-enhanced Raman spectroscopy (SERS) detection based on an internal standard and aptamer-functionalized gold nanofilms. First, two types of complementary DNA (cDNA) are fixed on the self-assembled monolayer of a halide ion-regulated nano-membrane through goldsulfur bonds. Then, two signal probe molecules are prepared and modified. The aptamer specifically binds to cDNA, generating SERS signals. Detection of the target analytes is achieved by measuring the Raman intensity and using the internal standard method. The results show that the concentrations of thiamethoxam and dichlorodiphenyltrichloroethane (DDT) at 10-12 M can be effectively measured under optimal experimental conditions. The Raman intensity exhibits a linear relationship at the shifts of 1085 cm-1 for 4-mercaptopyridine (4-MPY) and 1583 cm-1 and 2223 cm-1 for 4-mercaptobenzoic acid (4-MBN). When applied to the detection of thiacloprid in actual lake water samples, the results show no significant difference compared to the standard.