A SERS-based competitive immunoassay for highly sensitive and specific detection of ochratoxin A

Ochratoxin A (OTA) is a well-known carcinogenic contaminant in food commodities. The highly sensitive and specific detection of the OTA level is an essential way to prevent the health risks to humans/animals. In this work, an SERS-based competitive immunoassay platform has been developed for the detection of OTA. This assay contains two compartments: OTA-BSA-immobilized SERS nanotags and anti-OTA antibody-functionalized magnetic beads. In the presence of target OTA, a competitive reaction towards magnetic beads occurs between the target OTA and SERS nanotags. The characteristic peaks of SERS nanotags adsorbed onto magnetic beads were used for the quantitative analysis of OTA. Under optimized conditions, a good linear relationship was obtained in the range of 1 pg mL-1 to1000 pg mL-1. The limit of detection (LOD) was estimated to be 0.61 pg mL-1 using the IUPAC standard method. In addition, this proposed method was also successfully applied for the detection of OTA in wine samples and satisfactory recovery rates were obtained in the range of 90.60% to 103.3%. It is believed that this SERS-based competitive method holds great potential for highly sensitive and specific detection of mycotoxins.