STUDY ON THE RELEASE OF INVERTASE FROM ENZYMATICALLY DEGRADABLE DEXTRAN HYDROGELS

Chemically crosslinked dextran hydrogels were prepared for application in the controlled delivery of bioactive proteins. Dextran was functio nalized by reacting with glycidyl acrylate to introduce reactive doubl e bonds. Upon exposure to gamma-irradiation the functionalized dextran formed a crosslinked gel which could be degraded by dextranase. The e ffect of dextranase-induced degradation on the swelling kinetics of th e prepared hydrogels was examined. Enzymatic degradation of the gels b ecame slower as the gamma-irradiation dose increased for the formation of the gels. The dextran hydrogels were examined as a potential deliv ery system for proteins by using invertase as a model protein. Inverta se was incorporated into the hydrogel by mixing it with the purified, functionalized dextran before exposure to gamma-irradiation. Tile effe ct of gamma-irradiation on the bioactivity of the incorporated inverta se was determined. The gamma-irradiation did not change the bioactivit y of the incorporated invertase as long as the total gamma-irradiation dose was limited below 0.4 Mrad. The release study showed that the re lease of invertase from the dextran gel was controlled by dextranase-i nduced degradation rather than diffusion through the dextran network. The release study also showed that the invertase release was pulsatile . Parameters such as the degree of functionalization, dextran molecula r weight, and gamma-irradiation dose can be adjusted to prepare delive ry systems which meet the desired degradation kinetics and protein rel ease profiles.