Stabilization of an antibody conjugated with enzyme by 2-methacryloyloxyethyl phosphorylcholine copolymer in enzyme-linked immunosorbent assay

The purpose of this study was to develop a novel synthetic stabilizer of en zyme-linked antibody in the enzyme-linked immunosorbent assay (ELISA). The water-soluble amphiphilic phospholipid polymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-styrene (St)] was synthesized, and its stabiliz ing functions for the antibody were compared with conventional stabilizers of the antibody conjugated with enzyme (enzyme-antibody conjugate), such as bovine serum albumin (BSA) and casein. In the absence of the stabilizer, t he remaining immunologic activity decreased to about 10% of its initial val ue after 37 days. The same tendency was observed even when the enzyme-antib ody conjugate in 1.0 wt % BSA solution was used as a stabilizer. In 1.0 wt % casein solution, the immunologic activity decreased to 29% of the initial value after 37 days. On the other hand, in 0.1 wt % and 1.0 wt % poly(MPC- co-St) solution, the activity remained 74% and 92% of the initial value, re spectively. The effects of poly(MPC-co-St) on the stabilization of the enzy me-antibody conjugate depended on the concentration of poly(MPC-co-St). Dur ing the ELISA procedure, not only did poly(MPC-co-St) have no effect on the reaction between the antigen and the antibody, but it also had no effect o n the reaction between the enzyme and the substrate. These results indicate that poly(MPC-co-St) has the ability to suppress the denaturation of prote in, enzyme, and antibody. We concluded that water-soluble po ly(MPC-co-St) is an effective synthetic stabilizer in the ELISA. (C) 1999 John Wiley & So ns, Inc.