Zero-Background\nDual-Mode Closed Bipolar Electrode\nElectrochemiluminescence Biosensor Based on ZnCoN‑C Potential\nRegulation for Ultrasensitive Detection of Ochratoxin A

In this work, the relationship between electrochemiluminescence\n(ECL) signal and driving voltage was first studied by self-made reduced\nand oxidized closed bipolar electrodes (CBPEs). It was found that\nwhen the driving voltage was large enough, the maximum ECL signals\nfor the two kinds of CBPEs were the same but their required drive\nvoltages were different. Zinc cobalt nitrogen doped carbon material\n(ZnCoN-C) had an outstanding electric double layer (EDL) property\nand conductivity. Therefore, it could significantly reduce the driving\nvoltage of two kinds of CBPE systems, reaching the maximum ECL signal\nof Ru(bpy)<sub>3</sub><sup>2+</sup>. Interestingly, when the ZnCoN-C\nmodified electrode reached the maximum ECL signal, the bare electrode\nsignal was zero. As a proof-of-concept application, a zero-background\ndual-mode CBPE-ECL biosensor was constructed for the ultrasensitive\ndetection of ochratoxin A (OTA) in beer. Considering that beer samples\ncontained a large number of reducing substances, a reduced CBPE system\nwas selected to build the biosensor. Furthermore, a convenient ECL\nimaging platform using a smartphone was built for the detection of\nOTA. This work used a unique EDL material ZnCoN-C to regulate the\ndriving voltage of CBPE for the first time; thus, a novel zero-background\nECL sensor was constructed. Further, this work provided a deeper understanding\nof the CBPE-ECL system and opened a new door for zero-background detection.