Immunoassay for SKOV-3 human ovarian carcinoma cells using a graphene oxide-modified electrode

We describe a highly sensitive electrochemical immunoassay for the tumor maker HER2 on the surface of SKOV-3 human ovarian cancer cells. Following the binding of the cancer cells, ssDNA-labeled anti-HER2 antibody (ssDNA-Ab; the detection antibody) was added to conjugate unbound antigen on the target cells. Following hybridization of ssDNA with its complementary DNA, daunorubicin was injected in order to intercalate into the duplex. This enables electron transfer between daunorubicin and electrode to take place. The GO film strongly amplifies the redox signal of daunorubicin. This new assay has a detection limit of 5.2 cells per mL and in our opinion holds great promise for clinical screening of cancer biomarkers and point-of-care diagnostics.