Bias-Modulated Dual-Channel Photoelectrochemical Immunosensor Enabled by a Dual-Responsive Nanolabel

Photoelectrochemical (PEC) immunosensors have attracted extensive attention in biomarker detection owing to their high sensitivity, operational simplicity, and low cost. However, conventional PEC sensors are susceptible to generate false-positive results in complex biological matrices, due to nonspecific binding at the sensing interfaces. The dual-channel design can reduce the false detection rate and improve detection accuracy through mutual verification and complementation of the two signals, we demonstrate herein a novel bias-modulated dual-channel PEC immunosensor for the efficient detection of the breast cancer biomarker CA15-3. Two photoactive materials, In₄SnS₈/Bi₂O₂S and BiOBr_0.8I_0.2, are separately assembled on an indium tin oxide (ITO) electrode and act as anode and cathode sensing regions, respectively. By precisely tuning the bias of the electrode, anode and cathode PEC signals can be acquired independently. Furthermore, ZnFe₂O₄ is exploited as a dual-responsive nanolabel, which can enhance the anode signal but reduce the cathode signal when attached to the electrode by immunorecognition. The two independent noninterfering signals on one electrode were integrated to enhance both sensitivity and accuracy. This work offers a new strategy for early breast cancer screening and holds significant promise for clinical diagnostic applications.