A New Fluorescence Immunoassay Based on Magnetic Nanoparticles for Schistosoma Japonicum Antibodies
A fluorescence immunoassay using magnetic nanoparticles as the immobilization substrate was proposed for Schistosoma japonicum antibodies(SjAb).The SjAb in serum samples reacted with the bound Schistosoma japonicum antigens(SjAg) on the magnetic particles of core-shell structure,and the horserash peroxide labeled secondary.Antibodies were then bound to the magnetic particles by a sandwich reaction.Using 3,3′,5,5′-tetramethyl benzidine(TMB) as a fluorescent substrate,the SjAb was determined indirectly by measuring the decrease in fluorescent intensity resulting from the catalytic oxidation of TMB.Using the fluorescence immunoassay method,the fluorescence intensity(If) of the TMB substrate solution is linearly related to the SjAb concentration(C) in rabbit serum in the range of 5.0-100 μg/L with a regression equation of If=225.8-1.6C(r=0.9976),and the detection limit reaches 1.5 μg/L,which shows good detection sensitivity.