Reserch Of Micro-Hydrogel Beads Prepared By Chitosan/α, β-glycerophosphate As Embolism Material

Based on the previous study of our laboratory, the chitosan with different dynamic viscosity(DV)and degree of deacetylation(DD) were used to prepare Chitosan/α,β-Glycerophosphate hydrogel , then measured the gelation temprature by inversion. The influence of the DV , the DD of chitosan, the ratio of chitosan solution andα,β-glycerophosphate solution to the gelation temperature are discussed. Through the observation by SEM and facade press method, the influence of the DV and DD of chitosan, the ratio of chitosan solution andα,β-glycerophosphate solution to the mechanical strength was also researched. The mixture of liquid paraffin and soybean oil were used as oil phase and the chitosan andα,β-glycerophosphate solution were used as water phase to prepare the micro hydrogel beads(CMs/α,β-GP). The influence of the ratio of oil phase and water phase, the species of emulsifier, stirring speed, the shape of the stirring stick and the DV of chitosan to the morphology of the CMs/α,β-GP surface and the internal structure were studied. We domestrated the capability to inject the CMs/α,β-GP through duct by the experiement of catheter- pushing injection, analyzed the IR property of CMs/α,β-GP, compared the difference of the swelling and protein adsorption between the CMs/α,β-GP and chitosan beads(CMs). Then we used the CMs/α,β-GP to load 5-fluorouracil and measure the loading efficiency, encapsulation efficiency and the in vitro release. The protein adsorption, blood compatibility and in vitro degration of CMs/α,β-GP prepared by chitosan with different DV and DD were studied.The result indicates that the higher DD the chitosan is, or the higher ratio theα,β-glycerophosphate solution(α,β-GP) in the water phase is, the lower the gelation temperature of the system is, while it has little relationship with the DV of chitosan. The SEM image shows that temperature hardly influence the hydrogel internal structure of the hydrogel after it turns to solid phase which is capable to cut. The internal structure of the hydrogel prepared by chitosan with high DV is more dense. Compared to the hydrogel prepared by the low DD chitosan, the hydrogel prepared by the high DD chitosan has more dence internal structure, smaller porous size and thicker frame wall. In the same condition, increasing theα,β-glycerophosphate ratio in the system can change the morpology of the frame, that is, the frame become thicker and porous,the size become smaller. The result of compressive strength test indicates that compressive strength of the hydrogel prepared by chitosan with the DV 100cps, 130cps, 200cps, 400cps and 560cps respectively has the same tendacy with the increasing of temperature, but appears no regularity relationship with the DV of chitosan. Compressive strength of the hydrogel prepared by chitosan with the DD of which is 69.5%, 84% and 93.7%, respectively,were all about 1.56N and has no obvious difference. The increasing of the ratio ofα,β-glycerophosphate solution can decrease the compressive strength of the hydrogel. The mechanical strength of the hydrogel is also affected by the air humidity, the higher the air humidity is, the less the water envaporate from the intenal of the hydrogel, then the higher the mechanical strength is.When the proportion of liquid paraffin and soybean oil is 4:1 or 1:0 in the oil phase, the hydrogel beads are round , uniform size and seldom adhesion. The dispersion of the beads will increase when the oil phase is increased. The addition of emulsifier could increase the dispersion of the beads, which make the beads uniform in size and smaller. Otherwise, the higher the stirring speed and the more the stirrer blades are, the smaller the beads is, while the higher the DV of chitosan is, the larger the beads are. The experiments of catheter- pushing injection indicate that the micro beads are fit for pulled by duct, as they have well property of anti-pressure. We found the stretching vibration of O-H bond and N-H bond, while the deformation vibration of oxygen bridge bond and -C=O bond and CH2 , which indicate the intertaction of chitosan andα,β-glycerophosphate during the process of gelation. The swelling ratio of the CMs/α,β-GP is 218.08%, far larger than CMs, the swelling ratio of which is 70.98%. The loading rate of 5-fluorouracil is 7.705%, and the encapsule rate is 28.3%, while the cumulative release amount in vitro is 85.94% in 36h.The protein adsorption of CMs/α,β-GP is 13.21μg/g(BSA/ Beads) and 15.68μg/g measured in 1h and 24h respectively, lower than that of chitosan beads, which is 3.71×10~3μg/g and 4.83×10~3μg/g respectively. The tendency of BSA adsorption of CMs/α,β-GP prepared by chitosan which deacetylation is 69.5%, 84% and 93.7% is almost same.The results indicate that the protein adsorption is proportional with the deacetylation of chitosan. The tendency BSA adsorption of CMs/α,β-GP prepared by chitosan which DV is 130cps, 200cps and 400cps is almost the same, which is all below 30μg/g. The BSA adsorption capability of CMs/α,β-GP prepared by higher DV chitosan is more advanced. The increase of the concentration of protein will raise the adsorption amount of it. All of the hemolysis rates of CMs/α,β-GP prepared by chitosan which DV is 130cps(DD:95.8%), 200cps(DD:69.5%,DD: 84% , DD:93.7%) and 400cps(DD:92.5%)respectively are less than 5%.The result indicates that the CMs/α,β-GP are satisfied with the standard of hemolysis of medical materials . The degration experiment in vitro indicates that the CMs/α,β-GP prepared by chitosan with deacetylation 70% had the highest degration rate. Increasing or decreasing the deacetylation of the chitosan would decline the degration rate of the CMs/α,β-GP in vitro.