INITIAL BURST RELEASE FROM BIODEGRADABLE MICROSPHERES IS CAUSED BY FREEZING AND/OR DRYING PROCESS

摘要

The mechanism of initial burst release of drags from biodegradable polymeric microspheres was investigated. Poly(D,L-lactic-co-glycolic acid) microspheres encapsulating fluorescein isothiocyanate (FTTC)-labled dextran were prepared by a double emulsion solvent evaporation method. Confocal microscopic analysis revealed that the freeze-drying process generated water-escaping micro-channels, through which the encapsulated molecules were presumably to be dumped out. Vacuum drying was a good alternative choice in reducing the initial burst, compared to the freeze-drying.