Laser-induced CdS/TiO₂/graphene dual photoanodes for ratiometric self-powered photoelectrochemical sensor: an innovative approach for aflatoxin B1 detection

A ratiometric self-powered photoelectrochemical sensor based on laser direct writing technology was constructed to address the problem that the conventional single-signal detection mode was susceptible to the influence of instrumentation and environmental factors, which interfered with the detection results. Laser-induced CdS/TiO₂/Graphene was prepared as dual photoanodes (PA1 and PA2), which were controlled by multiplexed switches to form a photocatalytic fuel cell with Pt cathode. By modifying the aptamer of aflatoxin B1 (AFB1) on the photoanode surface, the target was specifically captured to the electrode surface to form a biological complex, which increased the steric hindrance and affected the electron transfer, thus reducing the output signal of the sensor. Targets with different concentrations were incubated on the surface of PA1, and targets with fixed concentrations were incubated on the surface of PA2. Under the control of the multiplex switch, the output signals of the two photoanodes were recorded, and the ratio of these two signals was used as the basis for the quantitative detection of AFB1. The sensor output was linearly increasing with the logarithm of AFB1 concentration from 1.0 to 150 ng mL⁻¹ and the detection limit was 0.0974 ng mL⁻¹. Additionally, this method had good stability, fast response, and good selectivity to real samples, providing an effective method for food safety monitoring.