Bipolar electrode ratiometric electrochemiluminescence biosensing analysis based on boron nitride quantum dots and biological release system

Abstract In this article, we developed a novel ECL ratiometry on a closed bipolar electrode (BPE) for the sensitively and accurately detection of miRNA-21. High quantum yield and low toxicity BNQDs was synthesized and coated at BPE cathode as an ECL emitter, while the anode of BPE was calibrated via another ECL material, Ir(df-ppy)2(pic) (Firpic). The electron neutrality at both ends of the BPE electrically coupled the reactions on each pole of the BPE. Therefore, one electrochemical sensing reaction could be quantified at one end of the BPE. By the hybridization of target miRNA-21 and hairpin, the glucose blocked in MSNs by the hairpin was released and reacted with glucose oxidase (GOD) to generate H2O2, thereby reducing the ECL signal of the cathode BNQDs/K2S2O8 system and promoting ECL signal of anode Firpic/TPrA. Further, the G-quadruplex formed by unreacted hairpin bases consumed H2O2, which not only recovered the ECL of BNQDs, but also further improved the ECL emission of Firpic. Therefore, the concentration of miRNA-21 could be measured by the ECL ratio of BNQDs and Firpic. The data showed that the detection limit was 10−15 M (S/N = 3) with the linear range of 10−15 M to 10−9 M. The strategy of the BPE-ECL ratio method based on BNQDs showed a good prospect in clinical application.