Modification Of Electro Spinning Nanofibers By ATRP Approach And Their Application Of Enzyme Immobilization

As a kind of polyphenol oxidase with excellent catalytic performance,laccase still faces many difficulties and challenges in practical application.Due to the high water-solubility of free laccase molecules,it is difficult to be separated from the reaction system,and it is not recyclable,resulting in a waste of resources.Therefore,immobilization of laccase is of great significance.Electrospinning nanofibers are suitable for immobilization of laccase because of their high porosity and large specific surface area.However,the physical adsorption between the electrospinning nanofibers and laccase is poor,so it is necessary to modify the surface.The ATRP method can prepare polymer molecular chains with controllable density and length,and form a three-dimensional polymer molecular brush on the surface of the material.In this paper,electrospinning technology was used to prepare electrospinning membrane(CA/PAN),and regenerated cellulose membrane(RC)was obtained after hydrolysis.DMAEMA was selected as monomer,RC-PDMAEMA nanofiber membrane was prepared by ATRP method,and characterized by SEM and FTIR.After surface modification by ATRP,RC-PDMAEMA nanofibers were successfully grafted with polymer chains of different densities and lengths.RC and RC-PDMAEMA nanofibers were used as carriers to immobilize laccase by physical adsorption.The effects of ATRP reaction conditions and the pH of laccase fixation solution on the amount of laccase fixation were investigated.The results showed that the maximum amount of laccase fixation was 95.04±4.35 mg/g when the initiation time was 1h,the polymer grafting time was 2h,and the pH of laccase fixation solution was 5.That is 3.3 times of the RC nanofiber membrane(28.57±3.95 mg/g)of the initial ungrafted polymer.The catalytic performance of free laccase and immobilized laccase was compared by catalytic ABTS solution,and the results showed that all immobilized laccases showed higher pH and temperature tolerance than the free laccase.NFAs-PDMAEMA aerogel was prepared by three-dimensional network reconstruction using RC-Br-lh-PDMAEMA membrane with different polymer grafting time as raw material for immobilization of laccase.Studies on the immobilization of laccase showed that the length of polymer chain in the ATRP reaction would affect the immobilization amount of laccase.When the initiation time was 1h and the grafting time of DMAEMA was 2h,the maximum immobilization amount of laccase was(77.78±6.22 mg/g).It was 2.65 times of the fixed amount of aerogel laccase(29.32±5.46 mg/g)of ungrafted polymer chain.Compared with free laccase,NFAs-PDMAEMA-2h aerogel immobilized laccase has higher acid and base tolerance,temperature tolerance and excellent recycling performance.