An electrochemical immunoassay based on trepang-like gold electrodes and nanogold functionalized flower-like hierarchical carbon materials with improved sensitivity

A novel electrochemical immunosensor for the detection of carcinoembryonic antigens (CEAs) was developed by using nanogold functionalized flower-like hierarchical carbon material (AuNPs/FCM) labeled with horseradish peroxidase-secondary antibodies as a signal amplification label. The amplified detection was achieved by the increased HRP-electrocatalyzed reduction of hydrogen peroxide. In order to construct the base of the immunosensor, a hybrid platform was generated by the electrostatic attraction between poly(diallyldimethylammonium chloride) functionalized graphene (G-PDDA) and three-dimensional trepang-like gold (3D-TG). The platform with excellent electronic properties, stability, bioactivity and large surface area served as an effective matrix for CEA-primary monoclonal antibodies. Subsequently, a sandwich-type immunocomplex of 3D-TG/G-PDDA and AuNPs/FCM was formed based on the immunoreaction of antibody–antigen in the presence of CEA. Enhanced sensitivity was obtained by combining the advantages of excellent electrical conductivity and bioactivity of the hybrid sensor platform with multilabel signal amplification. Under optimal conditions, our strategy displayed excellent analytical performance for the detection of CEA ranging from 0.0001 to 50 ng mL−1 with a detection limit of 0.026 pg mL−1. The new proposed method provides a new promising platform for the design of the highly sensitive detection method, showing great promise for clinical immunoassays.