Temporal Sensing Platform Based on Bipolar Electrode for the Ultrasensitive Detection of Cancer Cells

We report a bipolar electrode (BPE) sensing platform for the temporal detection of cancer cells. Combining the advantages of anodic dissolution and electrochemiluminescence (ECL), this strategy shows an ultralow detection limit down to 5 cells/cm(2). At the anode working as the reporting pole, Au NPs were assembled through DNA double strand, which served as both catalyzer for the ECL reaction of luminol/H2O2 and seeds for the chemical reduction of Ag, the anodic dissolution probe. The duration of Ag layer dissolution was positively correlated with the amount of Ag but negatively related to the controlled potential and the conductivity of the circuit. Therefore, it was possible to amplify a slight conductivity change through tuning the other two factors. As the formation of Ag@Au completely quenched the ECL emission of luminol, the ECL emission recovery reflected the extent of anodic dissolution. Through monitoring the ECL recovery time before and after the incubation of cells on the cathode, a few number of cells could be quantified due to slight difference of the conductivity. This method shows several merits. First, the combination of anodic dissolution and ECL significantly increases the detection sensitivity of BPE device. In addition, this strategy broadens the application of BPE for the ultrasensitive monitoring of cancer cells, which was applied to investigate the capture efficiencies of antibodies and aptamers toward MCF-7 and A549.