Influence of cross-linking on physicochemical and biological properties of collagen-phospholipid polymer hybrid gel

To adopt collagen as a biomaterial, collagen should be modified due to disadvantages such as poor mechanical strength and high thrombogenicity. Preparation of collagen-polymer hybrid gel for application as an artificial vascular graft was executed by immobilizing 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, poly(MPC-co-methacrylic acid) (PMA), using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide and N-hydroxysuccinimide as cross-linkers. In order to alter the density of interchain cross-links (intermolecular bonding) between collagen fibrils and the MPC polymer chains, collagen-polymer hybrid gel was prepared by changing the mole ratio of MPC moiety of PMA. The intra- and interhelical cross-links made the gel thermodynamically stable. The interchain cross-links made the gel mechanically and dimensionally stable by supporting the network structure of the hybrid gel, which is thought to be achieved by connecting collagen fibrils. Enzymatic stability was depending on the density of interchain cross-links, because the adsorption of collagenase was prohibited. Increase in the MPC moiety made the gel cell adhesion property decrease. This implies that the interaction between cells and surface of the hybrid gel is being regulated by the MPC groups, making the hybrid gel much efficient for artificial vascular graft use.