Visual Color-Switch Electrochemiluminescence Biosensing of Cancer Cell Based on Multichannel Bipolar Electrode Chip

In this work, we developed a visual electrochemiluminescence (ECL) sensing platform based on a dual-bipolar electrode (D-BPE) array chip. The chip was composed of two arrays of BPEs and three separated arrays of reservoirs filled with buffer, Ru­(bpy)3 2+-TPrA and luminol solutions, respectively. Both BPEs served as ECL reporting platforms. By applying 6.0 V voltage, an array of orange electrochemiluminescence (ECL) signals belonging to Ru­(bpy)3 2+ turned on. After adding DNAzyme and H2O2 in Ru­(bpy)3 2+ and luminol reservoirs, the orange Ru­(bpy)3 2+ signals decreased until vanished due to the quenching effect; meanwhile, a new array of blue ECL signals turned on because of the luminol-H2O2 ECL reaction. The designed D-BPE owns superior properties compared with the three-electrode system benefiting from the quantitative relation of bipolar systems, which greatly enhanced the ECL detection sensitivity. Meanwhile, the visual color-switch ECL and the ratiometric detecting principle made the results easier to evaluate and more accurate. Quantitative detection of HL-60 cancer cells from 320 cells/mL to 2.5 × 105 cells/mL with two linear ranges was achieved. The detection limit was down to 80 cells/mL. Finally, this D-BPE chip could distinguish the tumor cells from normal cells and provide a prospect for cancer diagnosis in a high-throughput, visual way.