Preparation Of Injectable Hydrogel Scaffolds And Studies On Their Properties

As a viscoelastic and bimimetic "wet material", polymeric hydrogels now constitute an important issue of research in the field of biomedical materials. It may served as the carrier of protein bioactive molecule used for tissue engineering due to it was high watery, injectable and good biocompatibility. But it was still have many problems on how to modified the properties of the materials according to the need of tissue engineering and reduce the cytotoxicity in the process of gelation.This thesis is focused on synthetic polymer hydrogels and their underlying applications in tissue engineering. We concerns the hydrogels based on dextran and chitosan which was demonstrated good biocompatibility. Otherwise, it has plenty of functional groups which can modificated by other group. Reactive vinyl sulfone (VS) and mercapto (SH) groups were incorporated into dextran and chitosan, respectively. Chemical crosslinking could be occurred depending on the Michael addition between-VS and-SH groups, thus generated hydrogel network. This can reduce the cytotoxicity of hydrogls by not adopt the crosslinking agent.Series of Dex-VS with different degree of substitutions (DS) were synthesized in the dissertation. Two kinds of mercapto reagents, dithioerythritol (DTE) and thiolated chitosan, were selected to serve as crosslinking agent to form Dex-VS/DTE hydrogels and Dex-VS/CS-SH hydrogels. Effects of preparation conditions on gelation process were investigated. Initial assessment of cell cytotoxicity showed the good biocompatibility of the hydrogel. In addition, we studied on the ectopic bone capability induced by rhBMP-2in vivo at4week used12.5wt%and4wt%hydrogels. Mass of neo-bone was notablely observed compared to control group. Consequently, such kind of hydrogel might give promising application in tissue regeneration and delivery of growth factors.