Iridium oxide film-enhanced impedance immunosensor for rapid detection of carcinoembyronic antigen

A simple, rapid and sensitive impedance immunosensor based on iridium oxide (IrOx) thin film for the detection of carcinoembyronic antigen (CEA) in human sera has been proposed. Gold electrode was electrochemically modified with IrOx thin film and simultaneously functionalized with protein A (PA) to bind anti-CEA antibodies in an orientated way. It has been found that the antibody loading amount was dependent on the PA concentration and the deposition time of IrOx matrix. Under the optimized experimental conditions, the electron transfer resistances obtained were linearly related-to the CEA concentration ranging from 36.2 to 460.0 ng/mL, with a detection limit of 28.0 ng/mL. Analytical results of clinical samples from cancer patients show that the proposed immunoassay is reasonably comparable with the chemiluminescence immunoassay (CLIA), indicating the feasibility of using the proposed method for CEA immunoassay in clinical laboratory.