Preparation Of Chitosan Magnetic Microsphere And The Application To Enzyme Immobilization

Magnetic polymeric microspheres are a special structural magnetic microsphere by combining the magnetic beads with organic polymers. According to the surface modification of magnetic microsphere, it can capable of combining with protein, then utilize their magnetic properties to immobilize and separate the protein.The thesis consists of four parts. The first part is the syntheses of Fe₃O₄ and CoFe₂O₄ magnetic nanoparticles; The second part is the synthesis of chitosan magnetic microspheres by reverse suspension cross-linker; The third part is connected the chitosan microspheres with thiocyanate groups; Last but not least, comparing the effect of the adsorption in glucose oxidase between the chitosan magnetic microspheres and the chitosan magnetic microspheres with thiocyanate groups and the stability between two of them.The sizes of magnetic particle of Fe₃O₄ and CoFe₂O₄ are 13 nm and 20 nm respectively. The saturation magnetization of Fe₃O₄ is 34.19 emu/g. And the saturation magnetization of CoFe₂O₄ is 54.19 emu/g.Microscope photos of chitosan magnetic microspheres with Fe₃O₄ magnetic particle indicate the particle size is 27μm. Microscope photos of chitosan magnetic microspheres with CoFe₂O₄ magnetic particles indicate the particle size is 30μm.Analyze of the reaction product of chitosan magnetic microspheres with 4-Nitrobenzyl bromide by fluorescence spectroscopy. The reduction of 4-Nitrobenzyl bromide are characterized by infrared spectroscopy. The figure shows nitryl has been reductived.According to the peak of N=C=S in infrared spectroscopy, it indicates the chitosan magnetic microspheres have reaction with thiophosgen.Compared the adsorption of glucose oxidase of chitosan magnetic microspheres with chitosan magnetic microspheres with thiophosgen. The results indicate that the adsorption reaches saturation in 3 hours. The maximum adsorption of chitosan magnetic microsphere with Fe₃O₄ and thiophosgen is 83%, the adsorption capacity is 8622 U/g. The maximum adsorption of chitosan magnetic microsphere with Fe₃O₄ and without thiophosgen is 63%, the adsorption capacity is 6296 U/g. The maximum adsorption of chitosan magnetic microsphere with CoFe₂O₄ and thiophosgen is 88%, the adsorption capacity is 8895 U/g. The maximum adsorption of chitosan magnetic microsphere with CoFe₂O₄ and without thiophosgen is 62%, the adsorption capacity is 6401 U/g. Then, evaluate the enzyme activity between the microspheres I made. The result indicates the microsphere with thiophosgen applying in fixed glucose oxidase has a steady property and higer activity.