earticle

영어

A sensitive, fluorescence based, label-free, immunoassay system, relying on emission from the dianion form of ochratoxin A (OTA2-) in the OTA/anti-OTA complex under weakly acidic conditions, was developed. Although free OTA exists in its monoanion form (OTA-) at pH 6.0, OTA in the OTA/anti-OTA complex is present in the OTA2- form predominantly at this same pH. This is caused by deprotonation of both the carboxylic acid group of a phenylalanine and the isocoumarin phenolic group in this substance. The results of the current effort show that the fluorescence intensities (λex = 390 nm, λem = 450 nm) of solutions increase with increasing concentrations of OTA at pH 6.0 owing to formation of the OTA/anti-OTA complex. With an optimized system, the fluorescence immunoassay can be used to detect OTA in a highly specific manner with a limit of detection (LOD) of 0.5 ng mL-1. In order to demonstrate a practical application of this assay, LODs for OTA in spiked red wine, white wine, and grape juice were determined and found to be 2.15, 1.23, and 2.06 ng mL-1, respectively. The new strategy, involving a simple sample preparation procedure, serves as a powerful tool for the rapid and sensitive quantitative determination of OTA in food and feed matrices.