Controllable Fabrication And Application Of Zwitterionic Hydrogel Microspheres

Zwitterionic hydrogels possess many advatages such as high water content,excellent anti-biofouling properties and biocompatibility,thus they have been widely used in various applications.Among zwitterionic hydrogels,poly-carboxybetaine(pCB)hydrogel is a unique one.In this thesis,we developed a method to prepare different sized pCB hydrogel microspheres and then applied them in blood purification and enzyme immobilization.The main contents of this thesis are as follows:1.The controllable,uniform,continuous and stable preparation of poly carboxybetaine methacrylate(pCBMA)hydrogel microspheres were developed with a self-designed equipment according to the characteristics of synethesizing zwitterionic hydrogels.The impacts of fabrication conditions such as the diameter of fabrication tube,the concentration of surfactant and the velocity ratio of continuous phase and dispersed phase to the microspheres diameter was systematically investigated.The diameter distribution,swollen rate and water content of the spheres were also assessed.2.To overcome the problems of activated carbon adsorbent in blood purifcation such as poor hemocompatibility and vulnerability to protein fouling,pCBMA hydrogel microspheres embedding activated carbon(pCBMA-AC)were fabricated.The leakage rate of activated carbon was lower than 0.1%.Meanwhile its blood compatibility and cytocompatibility were significantly improved,the hemolysis rate and cytotoxity were lower than 0.09% and 4.46%,respectively.In comparison,the values of bare activated carbon were 13.9% and 28.68%,respectively.Besides,the adsorption performance of pCBMA-AC was not influenced in 100 mg/L BSA solution or 100% FBS,superior to bare activated carbon.These advantages made pCBMA-AC a promising candidate for blood purification applications.3.To overcome the problems of enzyme immobilization such as low embedding rate,poor stability and compromized enzyme activity,HRP was immobilized in pCBMA hydrogel microspheres as a novel biocatalyst HRP-pCBMA.The immobilizing rate of HRP was 91.2%.For endocrine disrupting chemicals bisphenol A(BPA),the degradation rate of immobilized HRP was 7 times to free HRP.Under the optimized condition(30 °C,pH 4),the degradation rate of immobilized HRP was 99.42%.Furthermore,HRP-pCBMA showed favourable thermal and chemical stability,the BPA removal rates were all above 90% under 30-70 °C or in several organic solvents.Besides,the storage stability and reusability were also commendable.After 10 days storage at 4 °C,the BPA removal rate remained 72.29%,while 91.32% remained after 10 times recycle.Thus it can be found pCBMA hydrogel microspheres were also a promising material for enzyme immobilization.