Fast response cathodic electrochemiluminescence sensor based on closed bipolar electrode for point-of-care blood glucose testing

Glucose detection is vital for managing diabetes, monitoring metabolic disorders, and developing advanced biosensors. Electrochemical methods are widely used for glucose detection due to their sensitivity, portability, and low cost. However, these methods also have several limitations, such as interference from non-specific molecules, fouling of electrodes, and enzyme stability. Herein, to avoid external interference, we report a fast response cathodic electrochemiluminescence (ECL) glucose biosensor using a closed bipolar electrode (BPE) system with two separate cells (reporting cell and sensing cell). In this platform, Tris(2,2'-bipyridyl) ruthenium and K₂S₂O₈ were used as the luminophore and co-reagent, respectively, to generate the cathodic ECL in the reporting cell, and a commercial test strip modified with GO_x (glucose oxidase) and mediator served as the BPE anode to detect glucose in the sensing cell. The developed technique was able to determine glucose with a good correlation in the quantification of glucose in human serum samples with a fast response under a low potential, which avoided side reactions and was comparable to the commercial blood glucose meter. In addition, the sensing mechanism and working principle have been thoroughly studied, with the detailed discussion of the effect of oxygen and acetonitrile in influencing the ECL generation. Using this platform, glucose in the buffer was successfully quantified up to 18 mM, achieving a limit of detection of 3.8 mM and a linear concentration range between 4 and 12 mM. This electrochemical technique offers a simple and cost-effective strategy for point-of-care blood glucose testing without external interference, thereby opening up emerging opportunities in a broad range of sensing applications.