Abstract
This paper reports a new polarographic immunoassay with sensitized erythrocyte for the determination of α-fetoprotein(AFP). In this assay, the erythrocyte sensitized with anti-AFP antibody was used as the alternative of second antibody in sandwich immunoassay. After immune reaction, the sensitized erythrocyte hemolyzed in low osmotic solution releases hemoglobin(Hb). Hb catalyzes the conversion of the substrate o-phenylenediamine (OPD) to an electroactive product 2,3′-diaminophenazine (DAP). The enzymatic product DAP was quantified by linear-potential scan polarography. The proposed assay can detect AFP concentration as low as 0.5 ng/mL, the sensitivity approximate to that of radioimmunoassay (RIA).