Macromolecular release from collagen monolithic devices.

Collagen monolithic devices varying in crosslinking density, collagen structure, and crosslinker were fabricated. In vitro release rates of a model macromolecule, inulin, were found to be linear with t1/2 and were affected by crosslinking density, nature of crosslinker, and collagen structure. The biodegradation of the collagen matrix was also examined. Proteolytic enzymes did not degrade the collagen devices; the degradation rate with collagenase was dependent on collagen structure, crosslinker, crosslinking density, and enzyme concentration. In vivo biocompatibility, degradation, and 14C-inulin release rates were evaluated subcutaneously in rats. After 3 weeks, none of the collagen discs induced any severe cellular response. Dacron induced a stronger fibroblast response but fewer inflammatory cells as compared to the collagen discs. No significant degradation of the collagen discs occurred within 3 weeks. In vivo release of 14C-inulin from collagen monolithic devices was diffusion controlled.