Positively Charged Nanogold Combined with Expanded Mesoporous Silica-Based Immunoassay for the Detection of Avermectin

Avermectin (AVM) has been widely used in agriculture and animal husbandry for the treatment of broad spectrum parasitic diseases, but it has a harmful effect on human body through food chain. In this paper, on the basis of anti-AVM specific antibody, expanded mesoporous silica-encapsulated gold nanoparticles (EMSN-AuNPs)-based enzyme-linked immunosorbent assay (ELISA) for the detection of AVM was developed. Under the optimized conditions, the linear range of the developed EMSN-AuNPs-based ELISA was from 2.53 to 184.28 ng/mL, with the limit of detection (LOD) of 2.17 ng/mL. In addition, the cross-reactivity to macrolide antibiotic analogues was less than 0.1%. Therefore, the established EMSN-AuNPs-based ELISA was used to detect the AVM residues in the spiked samples, with the recovery from 99.5 to 101.5%, and the results was further validated by high-performance liquid chromatography (HPLC) and ELISA. Therefore, the constructed EMSN-AuNPs-based ELISA is suitable for monitoring AVM in biological samples with its sensitivity, accuracy, and real-timing.