Cross-linking Reaction between Genipin and Porcine Acellular Dermal Matrix

Genipin(GP) has been used as a sort of perfect natural cross-linking agent for collagenous biomaterials, but the cross-linking mechanism between collagen and GP is not clear. The aldehyde groups can be formed in aqueous solution of Genipin (GP), which can react with Cu(OH)2 and be used in the silver mirror reaction. About 0.2506 mol aldehyde groups were determined by Decolor Fuchsin Spectrophotometry in 1mol GP. In neutral solution, the ultraviolet absorption peak of GP appeared at 242.10nm, whereas in alkaline solution, it GP moved to 271.70nm due to the generation of enolates structure. Compared with the neutral condition, the GP molecular size almost doubled in alkaline solution, therefore it was speculated that dimers were formed. In this work, porcine acellular dermal matrix (pADM) was employed as a model of collagen to react with Genipin. The colour of GP cross-linked pADM (GP-pADM) turned into yellow from white initially and finally into dark blue and a new absorption peak was found at 2358.79cm(-1). With an increasing amount of GP, the shrinkage temperature (Ts) of GP-pADM increased slowly from 58.4 degrees C to 80 degrees C (6% dosage). Regarding the formation of dimers, the size of GP molecule was increased which fitted the distance of two aminos of the collagen for cross-linking. Furthermore, due to the ring structure of genipin and cross-linking bonds, the amount of rigid structures of collagen increased, consequently improved collagen stability was achieved. Fibroblasts grew well on GP-pADM with great morphology, and the vitro cytotoxicity was grade o.