Biodegradable Hydrogel for Controlled Release of Biologically Active Macromolecules

Abstract

The preparation, swelling and mechanical behavior and in vitro biodegradation of a novel hydrogel suitable for controlled release of biologically active macromolecules were investigated. The hydrogel was based on the biode gradable polypeptide, poly[ N ⁵-(2-hydroxyethyl)-L-glutamide] with methacryl oylated side chains (mole fraction 0.02-0.10). These were used as a "macro monomer crosslinker" in the crosslinking polymerization of acrylamide. The polymerization can be carried out under conditions that avoid loss of the biolog ical activity of proteins. The network density of the gels was controlled by the number of methacryloylated side chains in the macromonomers and by the amount of diluent during gel formation. It was found that the network density decreases with increasing dilution and decreasing concentration of the double bonds in the macromonomer. The enzymatic degradation of the hydrogels by papain increased with decreasing network density. The release of a model pro tein entrapped in the gel was also influenced by the network density of the gel. All the gels can be fully degraded to soluble products.