Signal amplified enzyme-linked immunosorbent assay with gold nanoparticles for sensitive detection of trace furaltadone metabolite

Enzyme-linked immunosorbent assay (ELISA) provides a convenient means for detection of furaltadone metabolite 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ). However, conventional ELISA bears drawback of unsatisfactory sensitivity. Hence, development of high-performance ELISA is of great significance for food safety. We report a signal amplified ELISA strategy for sensitive detection of AMOZ by incorporating gold nanoparticles (AuNPs) into conventional ELISA. In this system, AMOZ competes with bovine serum albumin-AMOZ (BSA-AMOZ) to bind to limited amount of monoclonal antibody; and a large amount of reporter antibody and horseradish peroxidase molecules are loaded onto AuNPs to amplify colorimetric signals. Under the optimized conditions, the signal amplified ELISA achieves a limit of detection of 10−2 ng/mL, which is 500-fold improvement than traditional ELISA in sensitivity. Moreover, pork liver samples spiked with different amount of AMOZ are successfully measured, suggesting this signal amplified ELISA can be used as a general signal enhancement strategy for determination of low-molecular weight contaminants in various foods.