Electrochemical detection of Schistosoma japonicum antibody using biocatalytic deposition

摘要

An ultrasensitive electrochemical immunoassay based on biocatalytic deposition has been proposed for the detection of Schistosoma japonicum antibody (SjAb) in infected rabbit serum. Schistosoma japonicum antigen (SjAg) was immobilized on the gold electrode surface via glutaraldehyde crosslink and then incubated with infected rabbit serum containing SjAb; finally, the goat anti-rabbit IgG labeled with alkaline phosphatase was sandwiched to form the immunocomplex on the gold electrode surface. The alkaline phosphatase converted nonelectroactive substrate into the reducing agent and the latter, in turn, reduced metal ions to form electroactive metallic product on the electrode surface. Linear sweep voltammetry (LSV) was used to quantify the amount of the deposited silver and give the analytical signal for SjAb. Assay conditions such as the antigen concentration and enzymatic silver deposition time were optimized. The electrochemical immunosensor was able to realize a reliable determination of SjAb in the dilution range from 1: 5000 to 1: 100 with a detection limit of 1: 6457 of dilution ratio. The feasibility of the proposed immunosensor for possible clinical applications was also investigated by analyzing real serum samples.