Development of Artificial Enzymes by Surface Molecular Imprinting

分子印迹技术是设计“定制”催化中心的一种很有前途的方法。然而，它仍然有两个根本的缺陷：很难将水溶性底物作为印迹分子引入催化中心，以及由于底物向聚合物基质中深层形成的催化中心的内扩散而导致催化动力学缓慢。为了克服这些问题，我们提出了一种在聚合物表面构建识别位点的新型分子印迹技术--表面分子印迹技术。通过聚合含有功能主体分子、印迹分子和交联剂的油包水(W/0)乳液，设计了一种具有高界面活性的新型功能主体分子，考虑到主体分子应该位于水-油界面，以产生高特异性识别。此外，我们还引入了咪唑分子作为官能团来催化底物的水解反应。利用新合成的功能主体分子，通过钴离子与咪唑基团形成络合物印迹底物类似物，制备了模拟酶的聚合物。通过与对照实验比较，考察了人工生物催化剂对氨基酸酯的催化性能。该仿酶生物催化剂具有较高的活性和较高的稳定性。

A molecular imprinting technique is one of the promising approaches to design "tailor-made" catalytic sites. However, it still has two fundamental drawbacks : difficulties to introduce water-soluble substrates as an imprinting molecule in the catalytic sites, and slow catalytic kinetics arising from the inner diffusion of substrates toward the catalytic sites formed deeply in the polymer matrix. To conquer these problems, we proposed a novel molecular imprinting technique for constructing recognition sites on the polymer surface called "surface molecular imprinting technique". An imprinted polymer was prepared by polymerizing water-in-oil (W/0) emulsions containing a functional host molecule, an imprint molecule and a cross-linking agent.In this study, we designed a novel functional host molecule possessing a high inter facial activity, considering that the host molecule should be located at water-oil interface to yield a high specific recognition. Furthermore we introduced an imidazole molecule as a functional group to catalyze the hydrolysis reaction of substrates. Using the newly synthesized functional host molecule, an enzyme-mimic polymer was prepared by imprinting a substrate analogue through the complex formation between a cobalt ion and the imidazole moiety. The catalytic properties of artificial biocatalysts were investigated on the hydrolysis reaction of an amino acid ester by comparing to control experiments. The enzyme-mimic biocatalyst showed a high activity and maintained high stability for a long time.