用于脂肪酶固定化的新型超顺磁性微球的合成、表征

应用悬浮聚合技术合成了以油酸稳定化纳米磁粒子为磁核的聚乙酸乙烯酯-二乙烯苯疏水磁性微球。利用透射电子显微镜(TEM)对磁粒子进行表征的结果显示磁粒子的平均粒径为10．09nm，最大粒径为18．41nm。利用扫描电子显微镜(SEM)和粒径分布仪对测定了微球有关参数和表面特征。振动探针式磁强计(VSM)的测定结果和拟合曲线良好的一致性表明微球的磁学特性可以用Langevin方程来描述。所有这一切都证明合成微球具有超顺磁性。对微球固定化脂肪酶的研究结果表明，固定化脂肪酶都具有很强的磁响应性和良好的分离效率，微球固定化酶既具有较大的活性负载量(最高可达6750IU)；又具有较高的活性保持率。固定于微球上的脂肪酶在催化橄榄油水解时活性的改善说明发生了界面活化作用。对温度、pH对固定化酶活性的影响以及其它相关的研究还表明固定化酶具有良好的热稳定性和持续重复使用性。

Fabrication and Characteristics of a Novel Type of Supermagnetic Microspheres for Immobilization of Candida Rugosa Lipase

A novel magnetic poly(vinyl acetate-divinyl benzene)material was synthesized by suspended copolymerization of vinyl acetate and divinyl benzene using oleic acid-stabilized magnetic colloids as magnetic cores.TEM was used to examine the sizes of magnetic colloids to give the result of maximum diameter 18.41 nm and mean diameter 10.09 nm.Parameters and surface features were characterized by SEM and diameter analyzer.Good agreement between the curves determined by VSM and simulated curves illustrated that magnetization of the microspheres could be described by the langevin function.All the observations indicated that the microspheres were superparamagnetic.The results showed that the immobilized lipase exhibited a big activity loading capacity(maximum,6750 IU/g)and a good activity recovery.The pH and temperature dependencies of the immobilized CCL as well as related research results also indicated that the immobilized lipase possessed good thermal stability and good durability in repeated use after recovery by magnetic separations.