PREPARATION METHODS OF BIODEGRADABLE MICROSPHERES ON BOVINE SERUM-ALBUMIN LOADING EFFICIENCY AND RELEASE PROFILES

The solvent evaporation and multiple phase methods for preparing poly- (d, l) lactide microspheres of bovine serum albumin (BSA) were compare d. The effects of poly (vinyl alcohol) concentration and external aque ous phase temperature on the loading efficient of BSA microspheres pre pared by multiple phase emulsion method were evaluated as well. The BS A loading efficient of microspheres by multiple phase emulsion method was much higher than that by solvent evaporation method. The high aque ous solubility of BSA contributes to the low loading efficieny in the solvent evaporation method, suggesting that this method is inappropria te for proteins with high water solubility. The loading efficieny of m icrospheres, whcih were prepared by multiple phase emulsion method, in creased with PVA concentration but decreased with external aqueous pha se temperature. The burst phenomenon of release profiles of microspher es was influenced by poly (vinyl alcohol) concentrations and the exter nal aqueous phase temperature. Considering the duration sustained rele ase, 0.5% w/v of poly (vinyl alcohol) is most appropriate among the co ncentrations tested for preparing BSA microspheres by multiple phase e mulsion method.