Poly(3,4-ethylendioxythiophene) (PEDOT) films have been electrochemically polymerized on graphene (GR) modified glassy carbon electrode (GCE) simply by a one-step cyclic voltammetry (CV) method in an aqueous media in the absence of any surfactant. The PEDOT/GR composite films were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). This composite film provided an excellent platform for immobilization of antibody with good bioactivity, and conductivity through Au nanoparticles (AuNPs) as a linker. With a sandwich-type immunoassay format, the analyte and then the CdTe quantum dots coated carbon nanosphere (CNS@CdTe)-labeled antibody were successively bound to the immunosensor. The dual-amplification strategy greatly enhanced the sensitivity for point-of-care testing (POCT) of prostate-specific antigen (PSA). Under optimal conditions, the proposed method could detect PSA with a linear range of 0.001–10 ng mL−1 and a detection limit down to 0.8 pg mL−1. The assay results of PSA in clinical serum samples from the Tumor Hospital were in acceptable agreement with the reference values from enzyme-linked immunosorbent assay. The proposed ECL immunosensor exhibited high sensitivity and stability, and could be applied in POCT of other tumor markers for remote regions and developing countries.
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This work was financially supported by Natural Science Research Foundation of China (21277058, 21207048, 51273084), Natural Science Foundation of Shandong Province, China (ZR2012BZ002), Technology Development Plan of Shandong Province, China (Grant No. 2011GGB01153).