Biofunctional nanogold microsphere doped with Prussian blue nanoparticles for sensitive electrochemical immunoassay of cancer marker

Abstract

A novel signal-amplified strategy for sensitive electrochemical immunoassay of cancer marker (human tissue polypeptide antigen, TPA, used in this case) is developed by using Prussian blue nanoparticles-doped nanogold microsphere (AuPB) as the promoter. To construct such an immunoassay, the AuPB was initially synthesized by using the reverse micelle method, and the as-synthesized AuPB was then heavily functionalized with horseradish peroxidase (HRP) and anti-TPA antibody. Based on a specific sandwich-type immunoassay format, target TPA was monitored on anti-TPA-functionalized glassy carbon electrode by using the biofunctional AuPB as the signal tag. Compared with conventional nanogold labeling, the as-prepared AuPB possessed good redox activity, which could be employed as an electron mediator for improvement of catalytic efficiency of the labeled HRP. Under optimal conditions, the electrochemical immunoassay presents good electrochemical responses toward target TPA, and allowed the detection of TPA at a concentration as low as 5 pg mL⁻¹. The precision, reproducibility, specificity and stability of the electrochemical immunoassay are acceptable. In addition, the methodology is validated for the analysis of 8 clinic human serum specimens and 8 spiked serum samples, receiving in good accordance with the results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.