A ratiometric electrochemiluminescence sensing platform for robust ascorbic acid analysis based on a molecularly imprinted polymer modified bipolar electrode.

Herein, a novel molecularly imprinted polymer (MIP) modified spatial-resolved "on-off" ratiometric electrochemiluminescence (ECL) sensing platform based on a closed bipolar electrode (BPE) has been reported for highly accurate and selective detection of ascorbic acid (AA). AA-imprinted MIP was decorated on the anode of the BPE, and Ru (bpy) in the anode electrolyte served as anode-emitter, while ZnInS as the other ECL emitter was coated on the cathode. Rebinding of AA at anode promoted ECL response of ZnInS (440 nm) at cathode. Meanwhile, the ECL response at 605 nm decreased, arising from the hindered reaction of Ru (bpy) on the anode surface. Therefore, an "on-off" BPE-ECL sensing platform was fabricated and showed distinguished performance in repeatability and selectivity thanks to the ratio correction effect and the specific recognition from MIP. The linear range for AA detection is from 50 nM to 3 μM with a low detection limit of 20 nM (S/N = 3). The assay deviation of the ratio responses largely declined by about 15 and 5 times compared with the ones from single pole in the aspect of repeatability and long-term stability, respectively. This work provides a reliable and stable sensing pattern for practical application, which also furnishes a strategy for designing simple and low-cost ECL sensing devices.