Preparation And Application To Immobilization Of Glucose Oxidase Of Gold Magnetic Particles

Gold Magnetic Particles is magnetic multiplex nanoparticles which surface material is gold nanoparticles coating.Due to the different structures and compositions.Gold Magnetic Particles can be divided into assembling-type and core-shell type.Because Gold Magnetic Particles combines the ability of the rapid biological immobilization were separated from the reaction system with the aid of an external magnetic field easily.The synthesis,properties and applications of Gold Magnetic Particles are one of the most active research fields.Glucose oxidase is one of aerobic dehydrogenase.By glucose oxidaseβ-D-glucose is oxidized toδ-gluconic acid lactone and hydrogen peroxide specifically under aerobic conditions.Glucose oxidase has the important application value in the medical science and environments detect fields.Immobilization technology of enzyme is an effective measure to achieve using repeatly of enzyme and improve stability.Moreover magnetic particles has the huge development potential because it was beneficial to separation and recovery compared with other carriers.The preparation processes and physical and chemical properties of assembling-type and core-shell type Gold Magnetic Particles were described in this paper.It studying two kinds of Gold Magnetic Particles on the immobilization of glucose oxidase.The optimal conditions of immobilization were studied in detail. The enzymology properties and catalytic effect were contrasted between immobilization of glucose oxidase and free glucose oxidase in detail.1.Fe₃O₄ nanoparticles were prepared by chemical precipitation method. Meanwhile,seed-mediated growth synthesis of core-shell type Gold Magnetic Particles in this paper.Then used APTES to amino-modified Fe₃O₄ nanoparticles, and the content of amino content in the amino-modified Fe₃O₄ nanoparticles is 0.15mmol/g,which is tested by base titrations.The particle size of nano-sized colloidal gold was about 20nm which was synthesized of by using Frens method. We assembled gold nanoparticles to the surface of Fe₃O₄ nanoparticles by using great bonding properties of AuCl₄^- and AuCl₂^- to RNH₂.2.The saturation magnetization of core-shell type Gold Magnetic Particles was 41 emu/g,It was showed by Atomic Absorption Spectrometry that Fe₃O₄ was binding to gold nanoparticles in surface,and amount of substance ratio of Fe₃O₄:Au was 1:1.61.By using infrared analysis showed that Fe₃O₄ nano-particles combined with Si-O and amino layers.Practical structure was accord with theoretical model.The saturation magnetization of assembling-type Gold Magnetic Particles was 58emu/g, and amount of substance ratio of Fe₃O₄:Au was 1:0.97.Both characteristic absorption peaks of Gold Magnetic Particles were 550nm,the average diameter were around 50nm.The dispersion of core-shell type Gold Magnetic Particles get better than assembling-type.3.The optimal conditions of core-shell type Gold Magnetic Particles immobilized enzyme's volume ratio of 5g/L Fe₃O₄ and 0.1%HAuCl₄ was 1:1.93 immobilize 2h in 23.42℃,pH=5.71.In this condition,immobilized enzyme activity was 583U/g,specific activity was 38.7U/mg,and enzyme recovery was 56.4%.The optimal conditions of assembling-type Gold Magnetic Particles immobilized enzyme's volume ratio of 5g/L Fe₃O₄ and 0.1%HuCl₄ was 1:1.89 immobilize 2h in 27.83℃,pH=5.53.In this condition,immobilized enzyme activity was 501U/g, specific activity was 30.1U/mg,and enzyme recovery was 47.3%. 4.Characterization analysis results show that Gold Magnetic Particles immobilized GOD and free GOD have some optimum temperature that was 24℃. The optimum pH was decreased by 0.5 assembling-type Gold Magnetic Particles immobilized enzyme contrast with free GOD.There was some increasing in thermal and pH stabilities.Moreover assembling-type Gold Magnetic Particles immobilized enzyme has better operational and storage stabilities than core-shell type.