Bipolar Electrode Based Multicolor Electrochemiluminescence Biosensor.

We report a multicolor ECL device based on closed bipolar electrode (BPE) for the visualized sensing of prostate-specific antigen (PSA) in human blood serum. As the emission color of concomitant electrochemiluminophores is potential resolved, similar to a three-electrode system, selective excitation of ECL could be achieved by tuning the interfacial potential at the poles of BPE. Via modulating the resistance of BPE, multicolor ECL emission of [Ru(bpy)3]2+ and [Ir(ppy)3] mixture using tripropylamine (TPrA) as the co-reactant was observed at the anode and the principle was elaborated. The concept was utilized to the quantification of clinical biomarkers with the color variation. A PSA concentration dependent silver bridge was constructed in the gap of the BPEs as an electric conductivity modulator. On the basis of a multicolor BPE-ECL device, the cutoff values (4.0 and 10.0 ng/mL) of human PSA could be recognized with naked eyes by the green-yellow-red ECL emission changing. As the first multicolor ECL device in biological analysis, BPE may raise the application of potential-resolved ECL to a new level.