嵌段共聚物纳米纤维固定化脂肪酶的制备及其在杂环合成中的催化性能研究

Lipase has been widely used in organic synthesis due to their high efficiency, selectivity, and mild reaction conditions. In practice, owing to the intrinsic nature of lipase, such catalyzer suffers from the stability and recycling problem. To resolve this issue, lipase immobilization is proposed. However, the substrate may have influence on the activity of the lipase. Therefore, it is still a challenge to fabricate immobilized lipase with a high activity. In this project, we plan to immobilize the lipase on a novel PEO-b-PAA copolymer nanofiber prepared by electrospinning and explore its application in the synthesis of heterocyclic compound. In the fabrication of such lipase catalyzer, a two-step procedure will be employed. The copolymer nanofibers will be firstly fabricated and then the lipases will be immobilized onto them. To improve the quantities of the immobilized lipases on nanofibers and keep their structure on high activity, the size and composition as well as the morphology of the nanofiber are systematically investigated. A mild, recyclable and environmental-friendly method to synthesis heterocyclic compound efficiently will be realized from the as-prepared catalyzer with an optimized reaction condition including the solvent and pH as well as the temperature. Finally, a lipase reactor will be designed to study its industrial application.

脂肪酶催化具有高效、专一、条件温和及环境友好等优点，在有机合成中有重要应用前景，但游离酶不稳定、易失活且难回收限制了其应用。酶固定化是很好的解决方案，而固定化脂肪酶的活性与载体的性质密切相关，如何保持甚至提高脂肪酶活性和稳定性是其催化应用的难点与关键。本项目拟基于静电纺丝技术制备聚氧乙烯嵌段聚丙烯酸共聚物（PEO-b-PAA）纳米纤维固定脂肪酶，从根本上解决脂肪酶在单组份纳米纤维上不能兼具高固载量和高活性的难题；探究纳米纤维组成、尺寸和形态对酶固载量、稳定性和活性的调控规律，优化脂肪酶固定化条件。在此基础上，将固定化脂肪酶应用于有机杂环合成，探明溶剂极性、溶剂亲疏水性、体系pH值、反应时间和温度等参数对固定化脂肪酶催化性能的影响规律，实现脂肪酶对杂环合成的高效催化。最后，尝试研制纳米纤维固定化脂肪酶微反应器，研究其循环催化性能和运行稳定性，为实现脂肪酶催化有机反应产业化提供理论和实验基础。

脂肪酶催化具有高效、专一、条件温和及环境友好等优点，在有机反应中有重要应用前景，但游离酶不稳定、易失活且难回收限制了其应用。酶固定化是良好的解决方案，而固定化脂肪酶的活性与载体的性质密切相关，如何保持甚至提高脂肪酶的活性和稳定性是其催化应用的难点与关键。.1、基于静电纺丝技术制备四种载体，用于接枝生物酶，获得了4种固定化酶，我们进行了不同条件下载体的结构调控，得到的固定化酶具有更高的温度稳定性、pH稳定性和储存稳定性。其中一例壳聚糖改性纳米纤维载体接枝酶，酶担载量达到170mg/g。有望在有机污染物降解和有机合成中得到应用。.2、利用固定化酶催化降解对硝基苯酚，催化合成苯并呋喃和苯并吡喃衍生物等化合物。我们进行了反应条件的优化，其中一例纳米纤维膜固定脂肪酶催化苯并呋喃衍生物的合成，产率可达70%左右；在第3次催化有机反应时，产率仍可保持在42%左右。该化合物的合成对其他杂环的合成研究具有重要的意义。.3、初步研制了纳米纤维固定化脂肪酶微反应器，利用蠕动泵实现循环催化。该反应器的性能优化还在探索中。该反应器的研制有望于实现固定化酶在工业领域的应用。.4、采用静电纺丝技术制备三种二氧化钛复合纳米纤维材料并研究了其光电转换性能和光催化性能。与单一材料相比，复合材料对光的吸收性能明显提高，光催化效率和光电转换效率有较大幅度提高。该复合材料的合成对于光电复合材料的设计制备研究有重要的意义。