Protein release microparticles based on the blend of poly(D,L-lactic-co-glycolic acid) and oligo-ethylene glycol grafted poly(L-lactide)

Bovine serum albumin (BSA), a model protein drug, was encapsulated with a microparticle based on the blend of poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactide)-g-oligo(ethylene glycol) (PLLA-g-oligoEG). Effects of PLLA-g-oligoEG in the blend on degradation, characteristic properties, and release behavior of the microparticle were studied. Drug loading efficiency increased with increase in the graft frequency of oligoEG in the graft copolymer in the blend. The release of BSA was found to be more efficient for microparticles based on the blend than on the PLGA. which is due to the faster protein diffusion through the swollen phase of the hydrogel-like structure. The microparticles based on the blend showed a slower degradation and a lower PH shift compared to that of PLGA. (C) 2001 Elsevier Science B.V. All rights reserved.