Sensitive electrochemical immunoassay of carcinoembryonic antigen with signal dual-amplification using glucose oxidase and an artificial catalase

A new dual-amplification strategy of electrochemical signal based on the catalytic recycling of the product was developed for the antigen–antibody interaction by glucose oxidase (GOD)- conjugated gold–silver hollow microspheres (AuAgHSs) coupled with an artificial catalase, Prussian blue nanoparticles (PB), on a graphene-based immunosensing platform. The first signal amplification introduced in this study was based on the labeled GOD on the AuAgHSs toward the catalytic oxidation of glucose. The generated H2O2 was catalytically reduced by the immobilized PB on the graphene nanosheets with the second amplification. With a sandwich-type immunoassay format, carcinoembryonic antigen (CEA) was monitored as a model analyte by using the synthesized AuAgHSs as labels in pH 6.0 phosphate buffer containing 10 mM glucose. Under optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range of 0.005–50 ng mL−1 with a low detection limit (LOD) of 1.0 pg mL−1 CEA (at 3σ). Both the intra- and inter-assay coefficients of variation (CVs) were lower than 10%. The specificity and stability of the immunosensor were acceptable. In addition, the assay was evaluated for clinical serum specimens, and received a good correlation with those obtained by the referenced electrochemiluminescent (ECL).

A new dual-amplification strategy of electrochemical signal based on the catalytic recycling of the product was developed for the antigen–antibody interaction by glucose oxidase-conjugated gold–silver hollow microspheres coupled with an artificial catalase, Prussian blue nanoparticles, on a graphene-based immunosensing platform.Figure optionsDownload as PowerPoint slideHighlights
► We designed an electrochemical immunoassay of carcinoembryonic antigen with signal dual-amplification.
► A new signal tag with glucose oxidase-conjugated gold–silver hollow microspheres.
► An artificial catalase, Prussian blue nanoparticles, on a graphene-based sensing platform.
► Comparative study of the electrochemical immunoassay by using various signal tags and sensing platforms.