THE INFLUENCE OF BIODEGRADABLE MICROCAPSULE FORMULATIONS ON THE CONTROLLED-RELEASE OF A PROTEIN

Biodegradable microcapsules were prepared from various polymer composi tions such as poly-D,L-lactic acid or poly-L-lactic acid and poly-D,L- lactide-co-glycolide for the controlled release of a model protein Bov ine Serum Albumin (BSA). ELISA data indicated that the binding activit y of BSA toward anti-BSA antibody was not lost during the microencapsu lation process and the release from microcapsules. The effect of diffe rent microcapsule formulations on release profiles of the protein was investigated. It was found that the polymer composition, total amount of polymers and protein loading were factors involved in the determina tion of release profiles of BSA. The degradation of various microcapsu les was also investigated. Factors such as degrees of the hydrolytic c hain scission of ester linkages, water content and internal structures were compared. The microcapsule formulation influenced the porosity a nd the degree of concentration gradient of BSA. These were related to the initial burst effects and release patterns. All these factors inte rplayed their roles on the release characteristics of BSA. Depending o n the microcapsule formulation, controllable and predictable release p rofiles of BSA that could be described by either zero- or first-order kinetics were observed.