Preparation And Characterization Of Cs/β-GP Thermosensitive Hydrogel

Injectable thermosensitive hydrogels based on natural polymers are currently receiving a great deal of interest, notably due to their potential applications in the controlled release of drug and tissue engineering. The purpose of this thesis is to prepare a degradable thermosensitive hydrogel using the nature polymers, which possess a physiological pH and can be held liquid at low temperature for encapsulating drug, living cells and therapeutic proteins, and can be formed monolithic gel rapidly at body temperature.The studies mainly focus on the preparation of CS/β-GP and CS-GP-HEC temperature-sensitive hydrogel, and the effect of molecular weight of chitosan (CS), deacetylate degree, the concentration ofβ-Glycerophosphate disodium (P-GP) and the hydroxyethyl cellulose (HCE) on the gelation time. Furthermore, both of the degradation and drug release of CS/β-GP and CS-GP-HEC were discussed in vitro.The results show the gelling time of CS/β-GP solution increase at37℃when the molecular weight or the deacetylation degree of chitosan is decreased. The pH of the CS/β-GP solution can be increased to the physiological pH when the concentration of β-GP or HEC increased, and the gelling time will shorten in37℃as well. The gelling time and the amount ofβ-GP can be significantly reduces by using of HEC. The costs will be reduced, while the biocompatibility of hydrogels is promisingly improved.IR spectra of the lyophilized CS/β-GP hydrogel indcate that the gel formation results from the hydrogen bonding and the hydrophobic interaction between CS and β-GP. IR spectra of lyophilized CS-GP-HEC hydrogel indicate that HEC maybe interact with CS or P-GP through hydrogen bonding. SEM images indicate that the porous network structure forms in the lyophilized CS/β-GP and CS-GP-HEC hydrogel. The degradation of CS/β-GP and CS-GP-HEC hydrogels was investigated in PBS solution at37℃by enzymatic degradation method, respectively. The results indicate the hydrogels have good degradation property.The chlorhexidine (Cx) model was established. The results show that the release rate of Cx unloaded in CS-GP-HEC is more rapid than that of hydrogel with Cx loaded in β-Cyclodextrin (β-CD). The IR spectra of Cx/β-CD inclusion complex show the benzene rings'characteristic peaks of Cx are red-shift. It indicates Cx enter into the hydrophobic cavity of β-CD and a new complex formation. The CS-GP-HEC drug-loaded temperature-sensitive hydrogel with Cx/β-CD complex has appropriate gelling time, long release time and good degradation, so it has prospect in drug delivery and tissue engineering.