Immobilization Of Laccase By Surface Modified Magnetic Nanoparticles And Its Property

The application of immobilized enzyme has indisputably advantageous in comparison with their soluble form.The complete elimination of enzyme from the reaction mixture,the absence of mixing and dilution problems,and the possibility of re-using are the distinct advantages.Therefore,to exploited adaptive supports and immobilization methods has been an attractive work for enzyme engineering.In this paper,we prepare magnetic nanoparticles with sodium alginate,which is well known for its biocompatibility in biomedical applications.In this study,magnetic alginate nanoparticles with small diameter(10-20μm) were prepared by on emulsification-internal gelation method.In order to covalent immobilization of enzyme on the surface of calcium alginate nanoparticles with amide linkage,we modified acyl chloride group for immobilized laccase.Some parameters of the immobilization were optimized using orthogonal design method: the duration,concention of laccase and volume of laccase per 30 mg carrier were 30 min,100 U/mL and 5 mL respectively.The immobilized laccase have lower affinity with the substrate and more stability compare with free laccase.The optimum pH and temperature of both free and immobilized laccase were 3,50℃. Thermal stability property of immobilized laccase was more stable than the free laccase.After incubation at 70℃for 7 h,the enzyme activity of immobilized laccase was 82.6%,where the activity of free laccase was 10%.The free and immobilized laccase were store at room temperature for 30 days.The rapid decrease of enzyme activity of free laccase during long term storage was significant(19%).However,the storage stability of immobilized laccase was superior(66%).The immobilized enzyme has good recycled use stability and the residual activity remained about 50%after 10 cycles.Both free and immobilized laccase could efficiently decolorize Congo red without additional medium,the immobilized laccase shows superior due to its endurance for the environment of azo dye.The decolorization of free and immobilized laccase after 12 h was 22.59%and 39.92%,respectively.The immobilized laccase shows superior due to its endurance for the environment of azo dye.The result shows that the modified magnetic alginate nanoparticles were good carrier for laccase immobilization,and will have widespread use in biomedical applications.