Electrochemical immunosensor for HBe antigen detection based on a signal amplification strategy: The co-catalysis of horseradish peroxidase and nanoporous gold

Abstract

The amplification of the electrochemical signal is crucial to improving the sensing performance of an immunosensor. In this study, a signal amplification strategy based on the co-catalysis of horseradish peroxidase (HRP) and nanoporous gold (NPG) was used to fabricate an electrochemical immunosensor for the determination of Hepatitis B e antigen (HBeAg). For the resulting immunosensor, HRP catalyzed catechol and thus served as a signal label of secondary antibody. NPG with unique properties was selected as a carrier for capture antibody immobilization. Further, NPG had an efficient electrocatalytic activity towards catechol (the substrate of HRP), which thus significantly enhanced the electrochemical signal produced by the HRP-labeled secondary antibody. Based on the co-catalysis of HRP and NPG, the immunosensor exhibited a good linear relationship between peak current density and HBeAg concentration in a wide HBeAg detection range from 1 pg mL−1 to 1 ng mL−1 with a high sensitivity of 23.51 μA mL ng−1 cm−2 as well as a low detection limit of 0.064 pg mL−1 (S/N = 3). Additionally, the immunosensor presented a strong anti-interference capability against human serum, human serum/dopamine, human serum/tryptophan, human serum/NO2−, human serum/D-glucose, and human serum/IgG. For the detection of HBeAg in human serum, the concentrations detected by the immunosensor were in good agreement with the standard concentrations that added in the human serum samples. These unique properties potentially make the proposed immunosensor a good choice for HBeAg detection.