FIG. 5.

Schematic representation of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)–mediated conjugation of FN to collagen. The carbodiimide EDC was added to basal lamina analogs at a 5:1 molar ratio (EDC molecules to carboxylic acids in collagen). The EDC reacts with a carboxylic acid from the collagen molecule to form an unstable reactive o-acylisourea ester that can either couple with an amine group in collagen from the basal lamina analog or an amide group in FN that is added to the collagen membrane. If the unstable reactive o-acylisourea ester does not interact with an amine, it hydrolyzes and the carboxyl group is regenerated, thus returning back to its native state.