A facile and effective electrochemical immunosensor based on controlled and oriented immobilization of natural antibodies for sensitive detection of aflatoxin B1

Aflatoxin B₁ (AFB₁) is one of the most common and harmful toxins in agricultural products, and the development of a sensitive, simple, and accurate detection method for AFB₁ is crucial for ensuring continuous monitoring and safeguarding food safety. Herein, we describe a facile and effective electrochemical immunosensor for ultrasensitive detection of AFB₁. In this framework, a novel Fc-specific cysteine (Cys)-modified antibody was first fabricated by employing photoaffinity labeling technique, which enables antibodies to be directionally immobilized onto a bare gold electrode via Au-sulfhydryl interaction. The proposed immunosensor exhibited detection limits (LODs) of 0.054 and 0.019 ng mL⁻¹ for direct competitive and sandwich-type competitive assays, respectively. Notably, these LODs were approximately 8-fold and 10-fold lower, respectively, compared to those achieved with randomly immobilized antibodies. The proposed immunosensor demonstrated excellent stability and reproducibility, along with high sensitivity, accuracy, and precision in AFB₁ detection, suggesting its significant potential for applications in food safety applications.