An exampleof a simple closed bipolar electrodes-based ECL (BPEs-ECL) imagingstrategy was developed utilizing functional nanoprobes of heterogeneousRu(bpy)32+@SiO2/Au nanoparticlesfor a visual immunoassay of prostate specific antigen (PSA) in theserum samples and on the surface of an individual cancer cell. Here, KLK3 is linked to cancer.