Amperometric magnetoimmunosensor for ErbB2 breast cancer biomarker determination in human serum, cell lysates and intact breast cancer cells.

A highly sensitive amperometric magnetoimmunosensor for the determination of ErbB2 protein, a well-known biomarker related to high-impact high-incidence diseases such as breast cancer, is described. A sandwich format involving the covalent immobilization of a specific capture antibody onto magnetic beads (MBs) and incubation of the modified MBs with a mixture solution of the antigen and a HRP-labeled detector antibody was used. The resulting modified MBs were captured on the surface of a disposable screen-printed carbon electrode (SPCE) and the amperometric responses at -0.20 V were measured. This ErbB2 magnetoimmunosensor exhibited a very low detection limit of 26 pg mL(-1) far below the established cut-off for this biomarker (15 ng mL(-1)) and was successfully applied to the quantitation of ErbB2 in human serum and cell lysates samples without any matrix effect. In addition, the developed assay allowed the assessment of ErbB2 status directly in intact breast cancer cells. The results correlated well with those obtained with a commercial ELISA method, thus demonstrating that the new magnetoimmunosensing platform offers a truthful and useful analytical tool to be easily applied in breast cancer diagnosis through either ErbB2 protein determination or breast cancer cell status detection.