Immobilization of laccase enzyme onto cellulose coated magnetic nanoparticles

In this study, Fe3O4 nanoparticles were coated with cellulose by reversed-phase suspension method. The prepared cellulose coated magnetic nanoparticles (Fe3O4-CC) were characterized by transmission electrode microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction method (XRD), termogravimetric analysis (TGA), ? (Zeta)-potential analysis, electron paramagnetic resonance spectroscopy (EPR) and vibrating sample magnetometry (VSM). It was determined that the particle sizes of cellulose coated magnetic nanoparticles are smaller than 50 nm, the thickness of cellulose on the Fe3O4 nanoparticles were 4,7-7,0 nm, no change occured in spinel structure, isoelectronic point was 2,71, the saturation magnetization was 45,2 emu/g and they demonstrate superparamagnetic property. Trametes versicolor laccase enyzme, immobilized on to Fe3O4-CC nanoparticles by adsorption and by two kind of covalent binding methods; either by oxidization or activation with cyanuric chloride. The presence of enzyme was detected by SEM/EDS analysis.The effect of pH, temperature, substrate concentration, storage time on the activities of immobilized laccases were investigated. It was obtained that the optimum pH was 3,5 and optimum temperature 40 °C for all immobilized systems and after using these immobilized systems repeatedly 25 times in a day, they retained 65% of their initial activities. It was obtained that catalytic effect of immobilized laccase Fe3O4-CC-L, Fe3O4-CC-Y-L, Fe3O4-CC-SC-L was close to free laccase which was 1,35 and the values were determined as, 1,28; 1,29 and 1,30, respectively. Science Code : 201.1.117 Key Words : Magnetite, cellulose, enzyme immobilization, laccasePage Number : 142Adviser : Prof. Dr. Serpil AKSOY