Synthesis of novel magnetic cellulose-chitosan composite microspheres and their application in laccase immobilization

Novel magnetic cellulose-chitosan composite microspheres were prepared by sol-gel transition method using ionic liquids as solvent for dissolution and regeneration. Subsequently, the composite microspheres activated by glutaradehyde to immobilize enzyme. Which of their structure, properties and morphology were studied by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating-sample magnetometer showed Fe3O4 nanoparticles with mean size of -10 nm were successfully embedded in the composite microspheres. The microshpheres were examined to be with the mean size of 20 μm and good magnetic property with saturation magnetization of 30.1 emu g(-1). The effect of pH and temperature on the immobilization of laccase was also investigated. Compared with free laccase, the pH, thermal and operational stabilities of the immobilized laccase were improved and the activity recovery of immobilized laccase reached 80.6%. Immobilized laccase retained 88.9% activity after 12 reaction cycles. Therefore, the cellulose-chitosan composite microspheres were expected to be a novel support for enzyme immobilization.