Novel Dual-Potential Color-Resolved Luminophore Ru(bpy)<sub>3</sub><sup>2+</sup>-Doped CdSe QDs for Bipolar Electrode Electrochemiluminescence\nBiosensing

The\nclassical electrochemiluminescence (ECL) reagent Ru(bpy)<sub>3</sub><sup>2+</sup> was first doped into CdSe QDs to prepare novel\ndual-potential color-resolved luminophore Ru-CdSe QDs. Ru-CdSe QDs\nemitted a strong red ECL signal at a positive potential with coreactant\nTPrA and a strong green ECL signal at a negative potential with coreactant\nK<sub>2</sub>S<sub>2</sub>O<sub>8</sub>. As a proof-of-concept application,\nthis work introduced Ru-CdSe QDs into a dual-channel closed bipolar\nelectrode (CBPE) system to construct an ECL biosensor for simultaneous\ndetection of chloramphenicol (CAP) and kanamycin (KAN). Ru-CdSe QDs\nwere dropped on BPE holes A and B for ECL emission. Cobalt single-atom\ncatalysts (Co–N–C SACs) had superior electric double\nlayer (EDL) performance and conductivity. It could greatly promote\nthe electron transfer of the CBPE system and realize ECL signal amplification.\nBased on this characteristic, Co–N–C SACs were introduced\ninto BPE hole C and driving electrode hole D, respectively, using\nthe CAP and KAN split dual-aptamer sandwich strategy. During positive\npotential scanning, the polarity of BPE hole A was anode, and Ru-CdSe\nQDs emitted a red ECL signal. With the increase of CAP concentration,\nabundant Co–N–C SACs were introduced to the electrode\nsurface. The positive potential ECL signal was increased for CAP detection.\nDuring negative potential scanning, the polarity of the BPE hole B\nwas cathode, and Ru-CdSe QDs emitted a green ECL signal for KAN detection.\nFinally, a zero-background spatial-potential color-resolved CBPE–ECL\nbiosensor was developed for dual-mode detection of CAP and KAN. This\nwork explored a novel ECL luminophore to construct a CBPE–ECL\nsensor, which greatly facilitated the development of the ECL assay.