Permeation of Proteins through a Biodegradable Hydrogel

Abstract

The permeation of proteins of different molecular weights into a biodegradable hydrogel, a model system for controlled release of biologically active macromolecules, was investigated. The hydrogels were prepared by a crosslinking copolymerization from a biodegradable synthetic polypeptide, poly[N5-(2-hydroxyethyl)-L-glutamine] (PHEG) with methacryloylated side chains and acrylamide. The permeation of sodium azide, trypsin-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 T[and trypsin was controlled by gels with permeability coefficients ranging from 2.8 x 10−9 to 4.0 x 10−10 mmol/mL. Gels with different network densities controlled the diffusion 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 poly-α,β-[N-(2-hydroxyethyl)-DL-aspartamide]. A decrease in the gel cross-linking density due to the degradation efficiently increased the permeability to the model macromolecule.