ADSORPTION OF PROTEIN ON THE SURFACE OF THERMOSENSITIVE POLY(METHYL METHACRYLATE) MICROSPHERES MODIFIED WITH THE N-(2-HYDROXYPROPYL)METHACRYLAMIDE AND 2-(METHACRYLOYLOXY)ETHYL PHOSPHORYLCHOLINE MOIETIES

A series of microspheres composed of methyl methacrylate (MMA) and N(2 -hydroxypropyl) methacrylamide (HPMA), and/or 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), i.e., binary copolymer microspheres [poly(HP MA-co-MMA)(KPS) and poly(HPMA-co-MMA)(ABIP)] and ternary ones [poly(HP MA/MPC-co-MMA)(KPS) and poly(HPMA/MPC-co-MMA)(ABIP)], were prepared by emulsifier-free emulsion copolymerization using potassium peroxodisul fate (KPS) or 2,2'-azobis [2-(imidazolin-2-yl)propane]dihydrochloride (ABIP) as initiators. The decrease in zeta-potential of the polymer mi crospheres is caused by the addition of the HPMA and/or MPC moieties. Equilibrium water content of poly(HPMA-co-MMA)(ABIP) showed a remarkab le swelling change with a change in response to temperature: the hydra ted conformation at 28 degrees C and the dehydrated one at above 40 de grees C. The adsorption of protein on the polymer microspheres also ch anged in response to change in temperature. The ternary polymer micros pheres effectively suppressed the adsorption both of Alb and Glo, less than binary ones. A series of polymer microspheres are expected to ap ply as a novel drug carrier with both thermosensitive and nonthromboge nic functions. (C) 1997 John Wiley & Sons, Inc.