A sandwich-type photoelectrochemical biosensor based on Ru(bpy)₃²⁺ sensitized In₂S₃ for aflatoxin B₁ detection

Aflatoxin B₁ (AFB₁), classified as a class I carcinogen, is a widespread mycotoxin that poses a serious threat to public health and economic development, and the food safety problems caused by AFB₁ have aroused worldwide concern. The development of accurate and sensitive methods for the detection of AFB₁ is significant for food safety monitoring. In this work, a sandwich-type photoelectrochemical (PEC) biosensor for AFB₁ detection was constructed on the basis of an aptamer-antibody structure. A good photocurrent response was obtained due to the sensitization of In₂S₃ by Ru(bpy)₃²⁺. In addition, this sandwich-type sensor constructed by modification with the antibody, target detector, and aptamer layer by layer attenuated the migration hindering effect of photogenerated carriers caused by the double antibody structure. The aptamer and antibody synergistically recognized and captured the target analyte, resulting in more reliable PEC response signals. CdSe@CdS QDs-Apt were modified as a signal-off probe onto the sensor platform to quantitatively detect AFB₁ with a "signal-off" response, which enhanced the sensitivity of the sensor. The PEC biosensor showed a linear response range from 10^-12 to 10^-6 g mL^-1 with a detection limit of 0.023 pg mL^-1, providing a feasible approach for the quantitative detection of AFB₁ in food samples.