An Ultra-Sensitive Aflatoxin B₁ Electrochemical Immunosensor Based on a Site-Directed Antibody Conjugation Strategy

Aflatoxin B1 (AFB1) is one of the most carcinogenic and highly toxic mycotoxins, posing significant risks to human and animal health. Accurate and sensitive detection of AFB1 is essential for ensuring food safety. In this study, we designed an ultrasensitive electrochemical immunosensor based on an AuNP-TDN-SPA-mAb immunoprobe for AFB1 detection. This immunoprobe was developed using a site-directed antibody conjugation strategy, which enables dual modulation of antibody orientation and programmable surface distribution, thereby enhancing detection performance. Experimental results showed that the developed immunosensor exhibited a linear response range from 0.05 to 5000 pg/mL, with a limit of detection as low as 0.042 pg/mL. The immunosensor was successfully applied to the analysis of wheat and rice bran oil samples, yielding results consistent with those obtained using ultraperformance liquid chromatography (UPLC). Therefore, this site-directed antibody conjugation approach shows significant potential for broad application in the sensitive detection of mycotoxins to guarantee food safety.