Research On The Scaffold In Bone Tissue Engineering Formed By Injectable And Temperature Sensible Chitosan Hydrogel

The common method of tissue engineering is to plant seed cells on one kind ofbiomaterials, which is biocompatible and absorbable, then implanted back into bodyto repair injured tissues after forming structure of cells and biomaterials. Injectablehydrogel, as a kind of biomaterial scaffold, can be formed in situ to avoid surgicalhurt. Bone is a biocomposite composed of bone cells, i.e. osteoblast and osteoclastand extracellular matrixes made up of collagen protein fibers, a bundled array ofcrosslinked helical polypeptide strands, threading through hydroxyapatite(HA). Theinjectable biocomposite was fabricated in combination with chitosanhydrochloride(CH) based hydrogel and β-tricalcium phosohate(TCP), which is similarto natural bone in components.The machanism of sol-gel phase transition is discussedpreliminarily.The water soluble CH was synthesized and characterized by many kinds of testmeans. The cytocompatibility of CH was estimated with cell lines. The injectable CHscaffold in bone tissue engineering was fabricated through mixing CH and β-glycerolphosphate disodium(GP) with β-TCP, whose pH responsibility, temperaturedependence, swelling and rheologic behaviour are evaluated as well. The dynamicbehaviour of water in chitosan based hydrogel and sol-gel phase transition areinvestigated with NMR technology.The results show, the primary amine groups were turned into quaternaryammonium ones while chitosan was changed into CH, which turned the densechitosan molecular packages into loose ones. CH were soluble and exhibited the goodcompatibility to cells and improvement in cell adhesion and viability. Sol-gel phasetransitions and gel rations of the injectable CH based hydrogel were modulated viaoptimization of supramolecular interactions of CH,GP andβ-TCP, i.e. hydrogenbonding, electrostatic and hydrogen bonding, electrostatic and hydrophobicinteraction. Dynamic behavior of water in CH based hydrogel can be described as thefollowing two processes: physical movement along free volume cavities of networkand formation of bound water with hydrophilic groups of network. Which processdominates swelling depends on the structure of the hydrogel. 1H NMR research onsol-gel phase transition indicated the water state changed when sol-gel transitionoccurred.