Interface engineering of dual-photoelectrode heterostructure for self-powered biosensing with triple-mode output

Sensing platforms based on multiple response mechanisms for multimode analysis have received widespread attention for their effectiveness in improving detection accuracy. Since different detection modes have different signal transduction mechanisms, the selection of materials that can accommodate multiple detection mechanisms is critical. This study employs fumonisin B1 (FB1), a key adulterant in food safety, as a model compound, and triple-mode detection of photoelectrochemical (PEC)-colorimetric (CL)-fluorescent (FL) for FB1 was achieved based on the synergistic effect of NC-Cu/Cu₂O and NH₂-MIL-88B(Fe). In particular, signal enhancement of the NC-Cu/Cu₂O photocathode can be achieved using the photoanode Ti₃C₂T_x Mxene@Bi₂S₃. In addition, NH₂-MIL-88B(Fe) can be decomposed by pyrophosphate (PPi) to free 2-aminoterephthalic acid (NH₂-BDC) and Fe³⁺. Consequently, the detection of FB1 can be achieved highly sensitive by employing the self-powered bi-electrodes enhanced PEC signals (PEC mode), Fe³⁺ induced Prussian blue (PB) (CL mode), and fluorescence signals from NH₂-BDC (FL mode). The PEC-CL-FL triple-mode sensing platform with a wide linear detection range (PEC: 100 fg/mL-100 ng/mL; CL: 1 fg/mL-1 ng/mL; FL: 1 fg/mL-1 ng/mL) and low detection limits (PEC: 13.3 fg/mL; CL: 0.66 fg/mL; FL: 0.37 fg/mL). This multimode sensing platform will have great potential for application in the detection of mycotoxins.