DEVELOPMENT OF A POLYMER-ENZYME IMMUNOASSAY METHOD AND ITS APPLICATION

Both poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)-antib ody (PINP-Ab)-labelled enzyme adhered quickly and tightly to cellulose acetate/nitrate membrane either below (less efficiently) or above (mo re efficiently) the lower critical solution temperature, and the reten tion of PINP-Ab on the membrane increased over 30-fold when compared w ith the unconjugated Ab. These characteristics were used to develop a novel polymer-enzyme-linked immunoassay method: homogeneous antigen-an tibody immune-complexation reaction and a heterogeneous separation pro cess. By using a simple horseradish-peroxidase-labelled antibody as a probe, we applied this method to the detection of human serum hepatiti s B surface antigen (HBsAg). This immunoassay system can detect as lit tle as 1 ng/ml of HBsAg. The advantages of this method are: (a) fast h omogeneous immune complexation; (b) a rapid heterogeneous separation p rocess; (c) high sensitivity; and (d) low non-specific background.