ABSTRACT
Collagen is a multifunctional family of proteins of unique structural characteristics. Material degradation can result from biological processes such as enzymatic degradation or environmentally induced degradation from mechanical, metal-catalyzed oxidation, and from the permeation of body fluids into the polymeric devices. Thus, the method commonly used to solubilize the collagen molecules from crosslinked fibrils with proteolytic enzymes such as pepsin removes the telopeptides from the collagen molecule. Collagen does not appear to exist as isolated molecules in the extracellular space in the body. In fact, the result of molecular packing of collagen in a fibril is such that the nonpolar groups are also clustered, forming hydrophobic regions within collagen brils. The electrostatic state within a collagen fibril can be altered by changing the pH of the environment. Salt extraction removes the newly synthesized collagen molecules that have not been covalently incorporated into the collagen fibrils.
