Simultaneous acquisition of potential-resolved multimode signals to boost electrochemical and photoelectrochemical dual-ratiometric biosensor for aflatoxin B1 detection in corn

Dual-modal sensing has revealed significant advantages on the analytical performance compared with that based on a single mode; yet, simultaneous collection of multimode signals remains challenging. In this work, a dual-ratiometric aptasensor for detecting aflatoxin B1 (AFB1) was developed by using a smart strategy to simultaneously record the electrochemical (EC) and photoelectrochemical (PEC) signals. The key point is to collect redox current and photocurrent at different voltages with the programmed light illumination. Methylene blue (MB), a bifunctional probe, was used to produce the redox current (IEC-MB) and photocurrent (IPEC-MB), acting as response signals, while the redox current of [Fe(CN)6]3−/4− (I[Fe(CN)6]3-/4-) served as reference signal. Specific recognition event of AFB1 by aptamer was designed to decrease IEC-MB and IPEC-MB based on the adsorption and desorption of MB in DNA duplex, and I[Fe(CN)6]3-/4- kept stable. Using I[Fe(CN)6]3-/4-/IPEC-MB and I[Fe(CN)6]3-/4-/IEC-MB as yardsticks, the PEC-EC dual-modal aptasensor offered two sets of linear range, i.e., 5 pg mL−1–100 ng mL−1 and 10 pg mL−1–100 ng mL−1, with high selectivity and stability for AFB1 detection. This work offers a new way for simultaneous acquisition of multimode signals to improve the applicability of PEC-EC dual-ratiometric sensing.