F(ab’)2 Fragment of Monoclonal Antibody onto Magnetic Nanoparticles for Ochratoxin A Detection

Ochratoxin A (OTA) is a fungal metabolite found in various foods. The toxin is a public health risk. Therefore, a rapid and sensitive immunoassay for OTA determination on the base of immobilized F(ab’)2 fragments of monoclonal anti-OTA antibody onto magnetic nanoparticles (MNPs) was developed. The self-fluorescence ability of the toxin was studied. F(ab’)2 fragment was obtained by hydrolysis with the enzyme pepsin. Differences in the absorbance characteristics of whole and fragmented antibodies were determined and discussed. The conjugate OTA-OVA-ATTO620 was obtained in our laboratory and then was purified. MNPs with immobilized fragments or antibodies and the OTA-OVA-ATTO620 conjugate were used for competitive immune analysis performing. The presented assay was discussed and compared with other authors. The linear range, obtained with immobilized F(ab’)2 fragments, was from 0.002 to 100 ng/mL OTA in milk. The immunoassay with immobilized F(ab’)2 fragments had the lowest detection limit (0.001 ng/mL OTA) than that from other authors and methods available on the up-to-date web. The recovery rates and the relative standard deviations of the method were presented. The assay was precise and had good repeatability.