An amperometric immunosensor based on Nafion-modified electrode for the determination of Schistosoma japonicum antibody

An amperometric immunosensor is described for the assay of antibody of Schistosoma japonicum (SjAb). The polyanionic perfluorosulfonated Nafion polymer was used to modify the glassy carbon electrode as a platform for the immobilization of S. japonicum antigen (SjAg). The competitive immunoassay format was employed to detect SjAb with horseradish peroxidase (HRP)–SjAb as a tracer, o-aminophenol (o-AP) and hydrogen peroxide as enzyme substrates. The amount of HRP-labeled SjAb binding onto the electrode surface was detected by measuring the product of the enzyme catalytic reaction at −250 mV (versus Ag/AgCl reference electrode). The system was optimized with regard to parameters involved in the preparation of immunosensor and the assay process. The present immunosensor permits a reliable determination of SjAb in the range of 0.05–4.8 μg/ml with a relative standard deviation of below 7.4%. The rabbit serum samples of different infection degree were measured, which implied the immunosensor offer a promising alternative for clinical diagnosis of S. japonicum.