The Thermosensitive Hydroxybutyl Chitosan Hydrogel For The Study Of Insulin Controlled Release

Hydrogel is a water dissolution system which has a three-dimensional netstructure, it has a very strong water-absorbing and water-retaining property. We canretain a kind of hydrogel which has biodegradability, a certain mechanical strengthand sensitivity to external physical and chemical environment by chemical synthesisor by modification of natural polymer. This will expand the application range of thehydrogel. Chitosan has good biocompatibility with organs, tissues and cells. It isdigestible in animal tissue, non-toxic, and has antibacterial properties. Because ofthese excellent properties, chitosan has been widely used in biomedical materials,chemical, food, cosmetics and other fields. Currently, the temperature-sensitivehydrogel which is prepared by chitosan is a hot research field of biomaterials. In thisstudy, we synthesized the thermosensitive hydroxybutyl chitosan hydrogel bychemical modification of chitosan, explored the feasibility of hydroxybutyl chitosanhydrogel as insulin controlled release carrier.According to a modified method, hydroxybutyl chitosan (HBC) hydrogelpossessed thermal sensitivity was prepared which can form hydrogel at lower criticalsolution temperature (LCST). By infrared spectroscopy (FTIR) and molecular weightdetermination identified physical and chemical properties of hydroxybutyl chitosan.The rheological analysis determined the gelation temperature of hydroxybutylchitosan hydrogel, the gelation temperature can be changed by mixing different kindof materials. The cross-sectional morphologies of hydrogel samples were observed byscanning electron microscopy (SEM). The HBC hydrogel exhibits an open networkstructure. By adjusting the concentration of the hydrogel, it may be change the insidepore size of HBC hydrogel. The HBC hydrogel was non-cytotoxic to mouseembryonic fibroblasts (MEF). Moreover, HBC has promoting effect to MEF. Theblood compatibility test results of different concentrations of hydroxybutyl chitosanhydrogel illustrate the hemolysis rate of this hydrogel is less than0.5%, so hydroxybutyl chitosan does not cause hemolysis. The enzyme degradation of HBChydrogel results showed that lysozyme, amylase, chitosanase can decomposehydroxybutyl chitosan hydrogel. The lower the concentration is, the faster the rate ofenzymatic degradation. Insulin was100%entrapped in the hydrogel. In vitro insulinrelease studies showed that half of the insulin was released from the concentration of5%hydrogel after48h. Whereas, by enzymolysis with lysozyme,80%of the totalinsulin was released after48h. The study suggested that HBC hydrogel could beutilized for controlled release of insulin in a non-invasive manner.Based on the above findings, hydroxybutyl chitosan have good biocompatibilityand biodegradability as a temperature-sensitive hydrogels. It can pack protein drugsand control release them. Therefore, hydroxybutyl chitosan hydrogel has a potentialability to becoming insulin carrier.