PERMEATION OF PROTEINS THROUGH A BIODEGRADABLE HYDROGEL

The permeation of proteins of different molecular weights into a biode gradable hydrogel, a model system for controlled release of biological ly active macromolecules, was investigated. The hydrogels were prepare d by a crosslinking copolymerization from a biodegradable synthetic po lypeptide, poly[N-5-(2-hydroxyethyl)-L-glutamine] (PHEG) with methacry loylated side chains and acrylamide. The permeation of sodium azide, t rypsin-kallikrein inhibitor (TKI), trypsin, and albumin into the gels with network densities between 0.04 and 0.226 mmol/mL were determined. The permeation of sodium azide was not influenced by the gel network density. The permeability of TKI and trypsin was controlled by gels wi th permeability coefficients ranging from 2.8 x 10(-9) to 4.0 x 10(-10 ) mmol/mL. Gels with different network densities controlled the diffus ion of peptides and proteins with molecular weights between 6,000 and 60,000. The combined effect of diffusion and biodegradation of the gel on the permeation rate of macromolecules was determined for ly-alpha, beta-[N-(2-hydroxyethyl)-DL-aspartamide]. A decrease in the gel cross- linking density due to the degradation efficiently increased the perme ability to the model macromolecule.