Preparation And Performance Evaluation Of Gleditsia Sinensis Polysaccharide-g-NIPAM Hydrogel For Controlled Drug Delivery

Controlled drug delivery system is a new system for controlled drug which can response to the environmental stimuli. In this study, the thermo/pH-sensitive graft-polymer of Gleditsia Sinensis polysaccharide with N-Isopropyl Acrylamide (NIPAM) was prepared and cross linked with glutaraldehyde to form the hydrogel. The hydrogel is capable to use in drug delivery as drug carrier. The release characteristics of Gleditsia Sinensis polysaccharide-g-NIPAM for controlled drug release were studied, and the physical properties were also detected. FT-IR, DTG, XRD, SEM and 13C NMR were employed to analyse the structure and character of Gleditsia Sinensis polysaccharide-g-NIPAM hydrogelThe graft rate of Gleditsia Sinensis polysaccharide reached the highest value with the initiator of 0.025%(ratio of initiator to hydrogel, w/w) at 75℃for 5 hours. The gel strength of hydrogel, generated by the graft-polymer using glutaraldehyde as cross linker, had a negative correlation with the grafting rate of polymer. Influences of ionic strength and concentration of cross linker on gel strength, contractibility and Equilibrium Degree of Swelling (EDS) were investigated. The contractibility and gel strength increased with increment of cross linker and NaCl concentration, while EDS decreased with the increasing amount of cross linker and NaCl concentration. The viscosity of polymer solution jumped up rapidly at 35.5℃which was called the Lower Critical Solution Temperature (LCST) of the polymer. It was found that the properties of polymer exhibited an apparently difference at temperatures below and above 35.5℃, which indicates that the polymer has an obvious temperature dependency and could be used on organism as controlled drug release materials.The Sinomenine hydrochloride (SM) was used to estimate the release characteristics of Gledi-tsia Sinensis polysaccharide-g-N-Isopropyl Acrylamide (NIPAM) as model drug. The system has good thermo/pH sensitivity. The amount of SM released from the polymer was much more at 38℃than it at 30℃. The drug was released faster in 0.1mol/L HC1 than in 0.1mol/L pH 6.8 PBS. Furthermore, the ion strength, the amount of glutaraldehyde and the concentration of Gleditsia Sinensis polysaccharide-g-NIPAM all had significant effect on the release of SM.FT-IR, TGA and 13C NMR were employed to confirm the grafting reaction between NIPAM and Gleditsia Sinensis polysaccharide. It is revealed by the XRD analyzation that the crystilnity of grafted polymer is slightly lower than Gleditsia Sinensis polysaccharide, however, the grafting don't have a considerable effect on the crystal structure of Gleditsia Sinensis polysaccharide. SEM was employed to analyse the structure of Gleditsia Sinensis polysaccharide-g-NIPAM hydrogel. Great differences of surface structure between the Gleditsia Sinensis polysaccharide-g-NIPAM hydrogel and Gleditsia Sinensis polysaccharide hydrogel can be found.