Water-soluble 2-methacryloyloxyethyl phosphorylcholine copolymer as a novel synthetic blocking reagent in immunoassay system

The purpose of this study is the development of a novel synthetic blocking reagent for the enzymelinked immunosorbent assay (ELISA) method. The water- soluble amphiphilic phospholipid polymer, poly[2-methacryloyloxyethyl phosp horylcholine (MPC)-co-styrene (St)], was synthesized, and the function of t he poly(MPC-co-St) as a blocking reagent was compared with conventional blo cking reagents which are made of proteins such as bovine serum albumin (BSA ) and casein. The poly(MPC-co-St) solution functioned at the same level as BSA solution and casein solution for preventing non-specific antibody adsor ption (p >0.01). When the 1.0 wt% BSA solution and 1.0 wt% casein solution were used as a blocking reagent, the remaining activity of the immobilized antibody decreased about 50% after 20 days. On the other hand, in 0.01 wt% and 0.1 wt% poly(MPC-co-St) solutions, the activity remained 76% and 91% of the initial value, respectively. The effects of poly(MPC-co-St) on the sta bilization of the immobilized antibody depended on its concentration. These results indicated that the poly(MPC-co-St) had the ability to inhibit dena turation of protein, that is, proteins in the ELISA system kept their nativ e structure. We concluded that the water-soluble amphiphilic poly(MPC-co-St ) is an effective synthetic blocking reagent in the ELISA method.