磁响应型分子印迹多孔膜的制备及蛋白质提取机制研究

Molecularly imprinted polymers (MIPs) have great potentials in purification of proteins. However, it is difficult to extract proteins from template-bounded MIPs. The extreme extraction conditions such as strong acid and alkali could denature proteins. This proposal intends to introduce magnetic nanoparticles to MIPs in order to solve the above problem. A magnetic responsive surface molecularly imprinted porous membrane will be prepared, using proteins as template molecules and the porous polymer membrane as a substrate. Through controlling the external magnetic field during the protein extraction process, magnetic nanoparticles will twist due to their supermagnetism, which will drive a nano-scaled deformation of the surrounded polymers. It is expected that the relative displacement between protein binding sites in the imprinted holes caused by the nano-scaled deformation, will destroy the shape matches between the template protein and the imprinted holes. In this case, the protein could be extracted with mild eluting solution without losing its bioactivity. In addition, the nano-scaled deformation of the imprinted polymer could be reversibly recovered, simply by removing the external magnetic field. The protein imprinted membrane could be reused for protein rebinding. Using this technique, gentle and smart protein extraction could be achieved, besides, the application of MIPs in the field of biomacromolecules will be greatly expanded.

分子印迹聚合物在蛋白质的纯化分离领域有广阔的应用前景。然而蛋白质从中脱离存在困难，强酸强碱等苛刻的提取条件易使蛋白质变性。本项目拟以蛋白质为模板，聚合物多孔膜为载体，引入磁性纳米颗粒，制备具有磁响应性能的表面分子印迹多孔膜。调控磁性纳米颗粒的尺寸、形貌及表面修饰的官能团使其在印迹膜中均匀分布。在蛋白质洗脱过程中，通过调控外磁场使纳米颗粒因磁感应而偏转，驱动周边聚合物形变，使印迹膜表面形貌在纳米尺度上发生改变。通过磁场的改变，使印迹空穴中聚合物与蛋白质的多个结合位点之间产生相对位移，从而打破印迹空穴与模板蛋白质在空间形状上的匹配性，辅以温和的洗脱条件，使蛋白质解吸附，实现对蛋白质结构与活性的保护。去除外加磁场，磁感应消失，印迹聚合物形变可逆恢复，可以再次用于对模板分子的特异性识别。磁响应印迹膜材料的制备，将为蛋白质的温和提取提供智能化的解决途径，拓展印迹聚合物材料在生物大分子分离领域的应用。

分子印迹聚合物在亲和分离、化学传感等许多领域有广阔的应用前景。然而在生物大分子的分离中仍存在模板蛋白质易被包埋，难于洗脱的挑战。传统洗脱方法容易破坏模板与印迹聚合物之间的结合作用，易使蛋白质的结构发生改变，失去生物活性。为解决上述问题，本项目从三个方面展开了研究。（1）采用水凝胶作为分子印迹基体，水凝胶较大的孔尺寸可以为蛋白质提供更大的活动空间，降低洗脱提取难度；（2）将表面印迹技术用在多孔膜载体上，一方面将实现连续性过滤式分离，避免了回收印迹聚合物的繁琐步骤，使分离更加便捷；另一方面，膜的多孔结构将使印迹层的比表面积增大，提高吸附和分离效率采用膜分离的方式；（3）在分子印迹水凝胶和分子印迹多孔膜中引入磁性纳米颗粒，在外磁场驱动下，磁性颗粒位移带动周围的聚合物基体发生形变，从而使分子印迹凝胶和分子印迹多孔膜上的印迹位点与模板分子的结合位点之间发生相对位移，结合位点位置匹配失效，从而实现了对蛋白质的温和提取。磁响应表面印迹凝胶和印迹膜材料的制备，为蛋白质的温和提取提供了智能化的解决途径，拓展了印迹聚合物材料在生物大分子分离领域的应用。