MODULATION OF PROTEIN RELEASE FROM CHITOSAN-ALGINATE MICROCAPSULES USING THE PH-SENSITIVE POLYMER HYDROXYPROPYL METHYLCELLULOSE ACETATE SUCCINATE

The release characteristics of protein from chitosan-alginate microcap sules prepared using an electrostatic droplet generator were evaluated . The release studies were undertaken in-vitro in simulated gastrointe stinal fluids covering the pH range 1.2-8. Chitosan-alginate microcaps ules showed unsatisfactory release properties, losing 94% of the encap sulated proteins (bovine serum albumin) over a 24h period at pH 1.2. I ncorporation of a pH-sensitive polymer, hydroxypropyl methylcellulose acetate succinate (HPMCAS), in the microcapsules, by coating the capsu le membrane as well as blending with the capsule core polymer in varyi ng ratios, produced significant changes in the release profiles of the microcapsules. At pH 1.2, the modified microcapsules retained up to 6 0% of the encapsulated protein after 24 h. The results obtained highli ght the potential of HPMCAS as a release-modifier in chitosan-alginate microcapsules.