Novel Dual-Potential Color-Resolved Luminophore Ru(bpy)32+-Doped CdSe QDs for Bipolar Electrode Electrochemiluminescence Biosensing

The classical electrochemiluminescence (ECL) reagent Ru(bpy)32+ was first doped into CdSe QDs to prepare novel dual-potential color-resolved luminophore Ru-CdSe QDs. Ru-CdSe QDs emitted a strong red ECL signal at a positive potential with coreactant TPrA and a strong green ECL signal at a negative potential with coreactant K2S2O8. As a proof-of-concept application, this work introduced Ru-CdSe QDs into a dual-channel closed bipolar electrode (CBPE) system to construct an ECL biosensor for simultaneous detection of chloramphenicol (CAP) and kanamycin (KAN). Ru-CdSe QDs were dropped on BPE holes A and B for ECL emission. Cobalt single-atom catalysts (Co–N–C SACs) had superior electric double layer (EDL) performance and conductivity. It could greatly promote the electron transfer of the CBPE system and realize ECL signal amplification. Based on this characteristic, Co–N–C SACs were introduced into BPE hole C and driving electrode hole D, respectively, using the CAP and KAN split dual-aptamer sandwich strategy. During positive potential scanning, the polarity of BPE hole A was anode, and Ru-CdSe QDs emitted a red ECL signal. With the increase of CAP concentration, abundant Co–N–C SACs were introduced to the electrode surface. The positive potential ECL signal was increased for CAP detection. During negative potential scanning, the polarity of the BPE hole B was cathode, and Ru-CdSe QDs emitted a green ECL signal for KAN detection. Finally, a zero-background spatial-potential color-resolved CBPE–ECL biosensor was developed for dual-mode detection of CAP and KAN. This work explored a novel ECL luminophore to construct a CBPE–ECL sensor, which greatly facilitated the development of the ECL assay.