Fabrication and characterization of a novel collagen-catechol hydrogel

3,4-Dihydroxybenzaldehyde, a derivative of catechol and an agent with an extensive pharmacological and biological activities, was used to modify collagen and prepared hydrogels. The aldehyde group of 3,4-dihydroxybenzaldehyde interacted with the ɛ-amino group of collagen, and then the catechol group of 3,4-dihydroxybenzaldehyde was oxidized and self-polymerized. The chemical network formed due to the cross-linking bridges of polymerized catechol groups among collagen molecules, resulting in the transformation from solution to hydrogel. The results of the Fourier-transform infrared measurement indicated that the triple helix structure of collagen was integrated after cross-linking. The appearance of hydrogels changed from golden to dark brown with the increasing 3,4-dihydroxybenzaldehyde dose. When the weight ratio of 3,4-dihydroxybenzaldehyde and collagen increased from 0 to 2:1, the thermal denaturation temperature of collagen increased from 40.2 to 77.6℃ while the elastic modulus of collagen increased from 13.6 to 1061.4 Pa. The addition of 3,4-dihydroxybenzaldehyde also caused more compact morphologies and a dramatic enhancement in the enzymatic resistance of hydrogels. Moreover, the results of cell proliferation assay demonstrated the favorable biocompatibility of collagen hydrogels with 3,4-dihydroxybenzaldehyde. These promising data indicate that the novel hydrogels had significant potential for applications.