Rapid dual-modal detection of two types of pesticides in fruits using SERS-based immunoassay

Abstract

Pesticide residue is a harmful chemical residue produced in agricultural production, posing a threat to human health. To detect mixed pesticide residues in food rapidly and simultaneously, we present a dual-channel dual-modal test strip immunoassay. According to the standard colorimetric bar, the naked-eye test can achieve semi-quantitative detection. By collecting the Raman spectra of the signal probes, surface-enhanced Raman scattering (SERS) detection can achieve accurate quantification of pesticide residues. Specifically, a double-layer 4-mercaptobenzoic acid (4-MBA) molecule-labeled bimetallic core-shell material (AuMBA@AgMBA) was conjugated with target antibodies to obtain signal probes. Here, antibody bonding was achieved by the dehydrated condensation of its amino group with the carboxyl group of the outer 4-MBA. In addition, the Au nanoparticles were connected to rabbit IgG by electrostatic adsorption as indicating probes to ensure the normal operation of the test strips. Under the optimal parameters, the detection ranges of acetamiprid and carbendazim were 0.3 - 2μg/kg and 3 - 30μg/kg, respectively. Furthermore, the recovery experiments showed that the results of the SERS method matched well with the high-performance liquid chromatography method. The SERS immunoassay is characterized by high sensitivity, rapidity and reliability, which has potential to simultaneously detect mixed pesticides in the field.