Biodegradation of a poly(alpha-amino acid) hydrogel. I. In vivo.

A new hydrogel material has been prepared by crosslinking a hydrophilic, nonionic poly(amino acid), poly(2-hydroxyethyl-L-glutamine). The material properties of the hydrogel can be controlled by variation in the crosslink density, and the swelling ratio was found to be a sensitive and convenient method for measuring the extent of in vivo biodegradation of implanted specimens. Degradation of the material was observed only during the first 2 weeks of subcutaneous implantation in rats, and is attributed to hydrolysis by proteolytic enzymes released during the acute and chronic stages of the normal inflammatory response.