Denatured thiolated collagen. II. Cross-linking by oxidation.

We have recently described a new method for the thiolation of denatured collagen, which allows precise amounts of SH groups to be attached onto the protein backbone. The oxidation of denatured thiolated collagen produces disulphide cross-linking. The cross-linking of these products has been studied, optimized and compared to the cross-linking of native and denatured collagen with 0.5% aqueous glutaraldehyde. Films have been prepared and their tensile mechanical properties and biodegradation rates with trypsin and collagenase have been evaluated. Our results indicate that the cross-linking in oxidized thiolated collagen depends on the number of the disulphide bridges formed and on their intermolecular versus intramolecular repartition. Since the number of disulphide bridges can be controlled by the level of thiol in the denatured collagen and by the oxidation procedure, it is possible to control the mechanical properties and the biodegradation rates of these new materials. Under optimized conditions, oxidized denatured thiolated collagen films are more resistant and rigid than glutaraldehyde-cross-linked collagen films Cross-linked thiolated collagen materials are also more resistant to collagenase degradation. However, because of the loss of the triple-helical structure, they are more susceptible to trypsin degradation relative to glutaraldehyde-cross-linked triple-helical collagen. Denatured collagen cross-linked by physiological bridges such as disulphide bridges, with controllable mechanical properties and biodegradation rates, is of considerable interest in biomedical applications.