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.