An electrochemical aptasensor for determining fumonisin B₁: A signal-on mechanism based on target-induced...

Fumonisin B₁ (FB₁) is a highly toxic mycotoxin commonly found in maize and other staple crops, posing significant threats to food safety and public health. There is an urgent need for the development of portable, on-site detection technologies to monitor contamination in agricultural environments and supply chains. In this study, we developed a simple, cost-effective electrochemical aptasensor for sensitive FB₁ detection. Molecular docking analyses and secondary structure predictions were employed to elucidate the signal transduction mechanism, suggesting that the sensor operates via a signal-on mechanism driven by target-induced conformational changes in a specific aptamer. The sensor fabrication involves a straightforward two-step immobilization of a ferrocene-labeled aptamer onto a gold nanoparticle-modified electrode, enabling rapid preparation without complex instrumentation. Upon FB₁ binding, the aptamer undergoes a structural shift that brings the redox tag close to the electrode surface, producing an enhanced current signal. The aptasensor exhibits excellent analytical performance, including a low detection limit of 1.58 ng/mL, a broad linear range of 2.5-175 ng/mL, and high selectivity against co-occurring mycotoxins. Application to real fungal-contaminated samples showed strong agreement with LC-MS results. These attributes, combined with simple and rapid fabrication, position this electrochemical aptasensor as a promising tool for in-field mycotoxin monitoring, fulfilling critical needs in food safety and environmental analysis.