BDT mediated asymmetric deposition of Ag on gold nanobipyramids for SERS detection of drug residues in aquaculture water

Surface deposition of metal on plasmonic nanoparticles is a powerful technique to enhance their Raman activity. In this paper, we demonstrated a sensitive surface-enhanced Raman scattering (SERS) substrate based on asymmetric deposition of Ag on gold nanobipyramids (Au NBP@BDT@Ag), which was applied to detect the drug residues of malachite green (MG), methylene blue (MB), and crystal violet (CV) in aquaculture water. By tuning the concentrations of 1,4-benzenedithiol (BDT) and AgNO 3 , the deposited Ag component showed an asymmetric growth on the two ends of Au NBPs, forming Au@Ag nanodarts. The Au@Ag nanodarts exhibited the most outstanding SERS performance and was thus used to detect the drug residues. Comparing with the original Au NBP, the SERS enhancement of Au@Ag nanodart has been dramatically improved with the maximum enhancement factor (EF) of 8 × 10 6 . The limit of detection (LOD) of the three drugs are respectively 8.4 × 10 −11 M for MG, 8.5 × 10 −9 M for MB, and 6.7 × 10 −9 M for CV, while the broad linear detection range is 1.0 × 10 −10 M ∼ 1.0 × 10 −6 M for MG, 1.0 × 10 −8 M ∼ 1.0 × 10 −5 M for MB, and 1.0 × 10 −8 M ∼ 1.0 × 10 −5 M for CV, respectively. And the detection of real clam feeding water samples also showed the potential of this detection strategy. We believed the detection strategy could have an application in the field of the detection of drug residues in aquaculture water and the asymmetric deposition will be meaningful in the field of dimer synthesis using Au NBP as core.