【作者】 张小强；

【导师】 谭天伟；

【作者基本信息】 北京化工大学 ， 生物化工， 2009， 硕士

【摘要】 磁学作为一门真正的科学来研究始于17世纪,随着磁学技术的发展,磁性材料如今在生物学、材料学等领域正越来越多地得到应用。磁性高分子微球作为一种磁性分离载体,是从上个世纪七十年代开始发展起来的一种新型功能高分子材料。磁性高分子微球既具有高分子微球的表面特性,可以通过共聚、表面改性的手段赋予表面多种反应性功能基团（如:-COOH、-OH、-NH₂）,从而与生物活性物质具有较大的交联吸附能力;同时也具有对外加磁场的磁响应性,可以借助磁场对磁性材料施加作用力。本论文合成了高分子磁性微球以及高分子磁性颗粒,并研究了两种磁性材料在脂肪酶固定化方面的应用,优化了磁性材料的合成条件。主要工作如下:1、利用化学共沉淀法、油酸改性相结合的“一步法”制备了均匀分散于有机相苯乙烯（St）中的Fe3O₄油基磁流体。制得的Fe₃O₄纳米粒子的饱和磁化强度为72.60emu/g,Fe₃O₄的平均晶粒粒径为13.3nm。油酸改性反应中,油酸与Fe³⁺的摩尔比大于0.1时,可以形成油酸对Fe₃O₄的完全包覆。沉淀剂使用氨水得到的Fe₃O₄纳米微粒的饱和磁化强度优于使用氢氧化钠。2、采用悬浮聚合方法,以St-Fe₃O₄磁流体和GMA为共聚单体,以DVB为交联剂制备了P（St-GMA-DVB）高分子磁性微球,制备出的磁性微球呈球形,具有很好的分散度,具备较好的刚性。根据不同的搅拌转速和油水比可以制备出粒径可以控制的磁性微球,粒径范围为55.300μm,磁性微球的饱和磁化强度可达6.52emu/g,表面环氧基团含量可以达到17μmol/g。3、利用悬浮聚合制备的磁性微球应用于酵母脂肪酶的固定化,液体致孔剂正庚烷加入体积分数为5%时固定化酶活力达到135U/g,用体积分数为1%的改性剂KH-550改性磁性微球后,固定化脂肪酶的酶活力最高达到445U/g。实验结果也表明了戊二醛通过先交联再吸附的方式固定化脂肪酶优于先吸附再交联的固定化方式,最优的固定化时间为3小时。4、采用本体聚合的方法,以St、DVB为单体,以碳酸钙为致孔剂制备了大孔磁性载体材料,通过L₉（3⁴）正交试验得到直接吸附固定化酶活力的四个因素的最优水平组合为St和DVB的体积比为9:1、四氧化三铁的质量分数为2.5%、固体致孔剂碳酸钙的质量分数为1%、甲苯和正庚烷的体积比为4:1。载体先经乙二胺改性再用戊二醛复合交联的载体能够取得比较好的效果,固定化酶活力达到340U/g。更多还原

【Abstract】 Magnetism studied as a true science to study started from the 17th century.With the development of magnetic technology,the magnetic materials are applied in more and more fields,such as biology,materials science and so on.Magnetic polymer microspheres as one kind of magnetic separation carriers have developed since 1970s to be a new type of functional polymer materials.Magnetic polymer microspheres not only have the surface properties of polymer microspheres,but also have the magnetic response under external magnetic fields.The magnetic polymer microspheres can endow the surface a variety of reactive functional groups（such as -COOH,-OH,-NH₂） by copolymerization,surface modification and thus have larger adsorption capacity of cross-linking with the biological activity material while they can make use of magnetic fields exert forces on magnetic materials.In this paper,the synthesis and applications in the immobilized lipase of magnetic polymer microspheres and magnetic polymer particles were studied.The synthesis processes of the magnetic material were optimized.The experimental results are obtained as follows: 1.Using the combination of chemical co-precipitation method and oleic acid modified which named "one-step" method,the homogeneous dispersing Oil-based Fe₃O₄ magnetic fluid in the organic phase of styrene was prepared.The saturation magnetization of the Fe₃O₄ nanoparticles is 72.60emu/g and the average size of the Fe₃O₄ nanoparticles is 13.3nm. Complete coating of Fe₃O₄ by oleic acid can be formed when the oleic acid and Fe³⁺ molar ratio is greater than 0.1 in the reaction of oleic acid modification.NH₃·H₂O had been used as precipitant to prepare Fe₃O₄ nanoparticles,obtaining better saturation magnetization than NaOH.2.P（St-GMA-DVB） polymer magnetic microspheres were prepared by suspension polymerization method using St-Fe₃O₄ magnetic fluid, GMA as comonomer and DVB as crosslinker.The magnetic microspheres showed spherical beads with good dispersion and good rigidity.The particle sizes of magnetic microspheres kept at 55-300μm which were controlled by different stirring speed and oil-water ratio.The saturation magnetization of the magnetic microspheres could reach 6.52emu/g and the surface epoxy group content could be achieved 17μmol/g.3.The magnetic microspheres prepared by suspension polymerization were applied in immobilization of yeast lipase,and the immobilized enzyme activity could reach 135U/g when n-heptane（liquid porogen） was added with volume fraction of 5%.With the volume fraction of 1%of modifying agent KH-550 modifying magnetic microspheres,the immobilized lipase enzyme activity was up to 445U/g. The experimental results also showed that the glutaraldehyde cross-linked first adsorption second way of immobilized lipase was better than first adsorption then cross-linked.The optimal time of lipase immobilization is 3h.4.The magnetic macroporous carrier materials P（St-co-DVB） were prepared by bulk polymerization method using multiple porogens which consisted of nano-granules of calcium carbonate as solid porogen and the mixture of toluene and n-heptane as liquid porogen.The optimal combination of four factors in the immobilized lipase enzyme activity effect were obtained by L₉（3⁴） orthogonal test.The volume ratio of St:DVB and toluene:n-heptane was respectively 9:1 and 4:1.The mass fraction of Fe₃O₄ and CaCO₃ was 2.5%and 1%respectively.The enzyme activity of immobilized lipase could reached good results of 340U/g when the cartier was modified by ethylenediamine first then cross-linked by glutaraldehyde.更多还原