Study on the release of invertase from enzymatically degradable dextran hydrogels

Abstract

Abstract Chemically crosslinked dextran hydrogels were prepared for application in the controlled delivery of bioactive proteins. Dextran was functionalized by reacting with glycidyl acrylate to introduce reactive double bonds. Upon exposure to γ-irradiation the functionalized dextran formed a crosslinked gel which could be degraded by dextranase. The effect of dextranase-induced degradation on the swelling kinetics of the prepared hydrogels was examined. Enzymatic degradation of the gels became slower as the γ-irradiation dose increased for the formation of the gels. The dextran hydrogels were examined as a potential delivery system for proteins by using invertase as a model protein. Invertase was incorporated into the hydrogel by mixing it with the purified, functionalized dextran before exposure to γ-irradiation. The effect of γ-irradiation on the bioactivity of the incorporated invertase was determined. The γ-irradiation did not change the bioactivity of the incorporated invertase as long as the total γ-irradiation dose was limited below 0.4 Mrad. The release study showed that the release of invertase from the dextran gel was controlled by dextranase-induced 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 molecular weight, and γ-irradiation dose can be adjusted to prepare delivery systems which meet the desired degradation kinetics and protein release profiles.