Rechargeable battery-based constant-potential electroluminescence multiplexed immunoassay on single working electrode for sequentially anodic and cathodic detection through a self-assembly toggle switch

A common rechargeable battery with an output voltage of 1.20 V was used to develop a constant potential-triggered electroluminescence (ECL) protocol, and a low-cost toggle switch was self-assembled to convert the anodic or cathodic applied potential on working electrode by simply rotating. Based on the potential-resolution strategy, a facile ECL multiplexed immunoassay was constructed on single indium tin oxide working electrode for sequential detection of carcinoma antigen 153 and carcinoma antigen 199 (one working electrode for two analytes) by employing an anodic ECL label (Ru(bpy)32+-conjugated silica nanoparticles, +1.20 V) and a cathodic one (carbon nanocrystals dotted silica nanoparticles, −1.20 V). Under the optimal condition, the proposed multiplexed immunoassay displayed wide linear range with low detection limit, and the assay results for two tumor markers in human serum samples obtained by this system were in acceptable agreements with the reference values from commercially used method in Cancer Research Center of Shandong Tumor Hospital. The rechargeable battery-based ECL system and potential-resolution strategy equipped with a self-assembly toggle switch provided a low-cost, promising multiplexed immunoassay for point-of-care diagnosis.