Ultrasensitive electrochemical immunosensor of carcinoembryonic antigen based on gold-label silver-stain signal amplification

A novel gold-label silver-stain electrochemical immunosensor was developed based on polythioninegold nanoparticles (PTh-Au) modified glassy carbon electrode (GCE) as a platform and secondary antibody labeled Au NPs (Ab₂-Au) as immumoprobe for carcinoembryonic antigen (CEA) detection. The sandwich-type biosensor adopted anodic stripping voltammetry to detect silver stripping signal when the Ab₂-Au of the formed immunocomplexes were stained with silver. The optimized detection conditions were investigated. The effect of different electrochemical responses at various concentrations of CEA was checked by anodic stripping voltammetry. This immunosensor showed a low detection limit of 0.055 ng/mL and a wide linear calibration of 0.1-120 ng/mL (R²=0.99856). Moreover, this immunoassay also existed the advantages of good reproducibility, stability and selectivity. Thus, this immunosensing protocol may provide a potential application for effective clinical detection of CEA.