Preparation And Research Of Injectable Chitosan And Sodium Alginate Composite Hydrogels

Cartilages are poor in spontaneous regeneration because of no blood vessels and lymph. Recently, people have been working hard to seek for some good methods in the repairing and rebuilding of the cartilages. The mainly used methods for those included:allograft cartilage transplantation, autologous chondrocyte transplantation, synthetic substitutes. However, these methods can lead to immune or foreign body reaction. Therefore, currently, tissue engineering is paid a great attantion in cartilage repair. Many natural or synthetic polymers have been used to prepare cartilage tissue engineering scaffolds, among which the injectable polymer hydrogel is one of the most potential candidates.Chitosan is one of the abundant natural alkaline polysaccharides and the most optimal medical polymer materials due to its facile sources and good biocompatibility. Most recent research showed that injectable chitosan hydrogels can form in suit at the body temperature by hydrogen bond interactions with multiple aldehydes or hydroxyl, such as glycerophosphate solution. However, the strength of pure injectable chitosan hydrogel is generally low and degradation is also rapid, which greatly limits its application in tissue engineering. Consequently, compounding chitosan hydrogel with other biocompatible materials will be the best choice.Considering the problems from chitosan hydrogels such as fast degradation and low strength, we have carried out some modification to chitosan hydrogel using physical and chemical methods, and prepared injectable physical and chemical cross-linked chitosan hydrogels. The effect of the components in the hydrogels on the physical and chemical properties of the hydrogel composites such as gelation time, equilibrium swelling, compressive strength and degradation in vitro etc. was studyed. The results showed that the sodium alginate/chitosan hydrogels formed by using physical cross-linking were improved in the mechanical strength and degradation compared to chitosan hydrogels. The gel time of the chemical cross-linked N-succinyl-chitosan/oxidation hydrogel (8/2) of about 7 mins, and compression strength of 30.7 kPa were obtained. The mechanical and in-vitro degradation properties of those hydrogels have been further improved compared to physical cross-linked hydrogel. the achieved gelation time can meet the needs of surgical operations well. The results from the culture of osteoblasts and bone marrow mesenchymal stem cells showed that both of the physical crosslinking and chemical crosslinking injectable hydrogels not only had good biocompatibility but also promoted the cell growth and proliferation, indicating that the present hydrogels can act as a good scaffold which can be used in the cartilage and other soft tissue engineering.