Fluoresence immunoassay of alpha-fetoprotein with iron(III) tetrasulfonatophthalocyanine as a mimetic enzyme labeling reagent

A new fluorimetric immunoassay for a-fetoprotein (AFP) has been developed u sing a novel promising mimetic peroxidase, iron(III) tetrasulfonatophthaloc yanine (FeTSPc). as a labeling reagent to catalyze the fluorescence reactio n of P-hydroxyphenylacetic acid (P-HPA) and hydrogen peroxide (H2O2) In the competitive immunoassay, anti-AFP antibody was coated on a 96-well plate ( polystyrene) and a constant amount of FeTSPc-labeled AFP and a known amount of test solution were added. Non-labeled and FeTSPc-labeled AFP compete fo r binding to the plate-bound antibody. After the immunoreaction, the immuno chemically adsorbed FeTSPc-AFP conjugate moiety was determined by measuring the fluorescence produced in a solution containing P-HPA and H2O2. AFP can be determined in the concentration range of 1-300 ng mL(-1) with a detecti on limit of 0.5 ng mL(-1).