Simultaneous detection of acetamiprid and carbendazim based on Raman-silent spectral window tags-mediated surface-enhanced Raman scattering aptasensor coupled with magnetic separation

Surface-enhanced Raman scattering (SERS) has been widely used for detecting pesticide residues. Nevertheless, the spectral interference of sample matrix still exists, and the simultaneous detection of multiple pesticides is challenging. In this work, specific simultaneous detection of acetamiprid (ACE) and carbendazim (CBZ) in complex sample matrix was achieved by using two Raman tag molecules (prussian blue, PB; 4-(mercaptomethyl) benzonitrile, MBN) whose peaks were in the Raman-silent spectral window. Two Raman nanoprobes were synthesized by adding MBN and PB into the Au and Ag core-shell gap and coupled with two complementary DNA (cDNA), respectively. Meanwhile, two aptamer-incubated Fe3O4/Au nanoparticles were used as capture molecules. Results showed that the Raman intensity at 2077 cm(-1) and 2228 cm(-1) had an inverse tendency with ACE and CBZ concentrations, respectively. Under the optimal conditions of aptamer, cDNA concentration, and reaction volume ratio, the SERS aptasensor showed a wide linear range of 0.01 similar to 1 mg/kg with limit of detection of 9.43 mu g/kg to ACE and 9.17 mu g/kg to CBZ. The result of recovery experiment showed that there was no significant difference between SERS method and HPLC method (p > 0.05). It turned out that the SERS aptasensor had a good resistance to spectral interference of matrix and easy separation, which can specifically detect ACE and CBZ in complex matrix simultaneously. SERS combined with nano-sensor elements will be conducive to the on-site detection of various hazardous substances in food safety.