Collagen is a well-known protein that has been widely used in biomedical research and development. 28 known types of collagen have been identified, which are extracellular and have a mainly structural role. The collagen molecule consists of three polypeptide chains twined around one another and each chain has an individual twist in the opposite directions. Collagen can form stronger and more stable fibers through its self-aggregation and cross-linking.
Collagen has various advantages as a biomaterial, one of which is that collagen demonstrates its ability to penetrate a lipid-free interface. The characteristics of collagen differ from those of synthetic polymers mainly in its mode of interaction in vivo. Compared with other natural polymers such as albumin and gelatin, collagen exhibits biodegradability, weak antigenicity, and superior biocompatibility.