Studies Of Enzyme Immobilization On Biologic Carbon Fiber

Carbon fiber has been extensively applied in the sewage disposal field as absorbing materials for its excellent biocompatibility, high specific surface area, stable physical and chemical properties and diversification of application situation, but it's seldom reported as the carrier material of biologic enzyme.Enzyme is one kind of highly undivided catalytical protein. Because of the water-soluble and unstable properties of the free state enzyme, it usually needs to be immobilized on the carrier to improve the diffusion of the zymolyte molecule, enhance the thermodynamic stability of enzyme and facilitate the separation and reusage of the enzyme. At present, the developments of the physical and chemical performances, mechanical properties, temperature tolerance, activity range and recycling of enzyme carrier cannot satisfy the demands of practical applications, which limit the popularization and application of bioreaction technology. In this thesis, we try to explore a novel enzyme immobilization technology which can enhance the thermalstability, recycling, activity of immobilized enzyme and enzyme content with a kind of new carbon fiber immobilization carrier to provide a new kind of heat-resistant, efficient, expeditious and stable carrier and technique for biochemical reaction field.In this thesis, lipase was chose as the immobilized object of the immobilization study after plentiful comparative experiments between lipase and pectase, and then the performances of a series of different carbon fibers carriers were contrasted to that of chitosan which was the traditional carrier during the enzyme immobilization studies. The performances of immobilized lipase with the novel carbon fiber carrier, especially the optimum conditions of the lipase immobilization experiment and changes of lipase properties after immobilization were investigated in this paper. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were used to research and analyze the surface morphologies and structural changes of the immobilization samples, discuss the variations of enzyme activities, enzyme content, the change law of thermalstability and its restraining factors.The results showed that adsorption method is the best way to immobilize the lipase and pectase on the carbon fibers and obtain the highest activity of immobilized enzyme. At the same time, the residual activity of immobilized lipase was higher than that of immobilized pectase,1.27% and 0.90% respectively, which indicates that the effective rate of utilization of lipase was higher than pectase. From the comparative experiments of lipase immobilization with different carriers and immobilization methods, it can be seen that the adsorption method can obtain the highest activity of immobilized lipase. The investigations of the enzyme content and immobilized enzyme activities of T300 carbon fiber carrier indicated that the T300 carbon fiber carrier can enhance the utilization of the lipase. Meanwhile, the result also showed that the immobilized lipase can keep high activity under the temperature of 50℃, especially those immobilized on the T300 carbon fiber which devitalized very slowly. The immobilization of the sigma lipase on the T300 carbon fiber was investigated systematically and obtained the optimum immobilization conditions:the amount of enzyme was 0.1g; reaction temperature was 25℃and reacted for 2 h. Compared to free state enzyme, the reaction PH value of the immobilization sigma enzyme deviated to alkalescence environment, the optimum reaction temperature increased to 50℃and under the 50℃reaction environment, the immobilized lipase can still keep high activity and stable thermalstability after 1 h reaction.The creative results of the systemic investigations demonstrated the feasibility of the carbon fiber as the immobilization carrier of biologic enzyme. Carbon fiber is a new kind of quality biologic enzyme immobilization carrier. Up to now, there's no similar result reported in the world, and this paper is an original work and has applied relative patent protection. This novel technique can not only be hopefully used to biochemical reaction and reactor, but also promote the development of our national biochemical reaction technology.