Multiphase Intelligent Materials for Biomimetic Sensors

由于膜结合的大分子为生物离子传感和通道提供了最普遍和最强大的机制，因此设计了一种新型的聚合物修饰电极：合成了一种由聚苯乙烯-丙烯腈和聚谷氨酸组成的多相材料作为嵌段共聚物。这种材料允许我们只需浸泡就可以将合成多肽固定在电极上。因此，在铂丝上制备了以多肽为化学感受性成分的稳定的聚合物膜。以氧化还原活性离子的渗透率变化为指标，得到了Ca~(2+)&lt；~(-6)&gt；M对10^&lt；-6&gt；M的电化学响应。这种与离子浓度相关的响应变化对镁离子也有影响，但对钠离子、钾离子和四丁基铵离子则不存在。另一方面，同一电极对尿素有较好的电化学响应。这似乎是第一个不依赖于酶(尿素酶)而响应尿素的电化学传感器的例子。此外，由于乙烯基高聚物链是膜的组成单元，修饰电极具有显著的稳定性。修饰的简便性和良好的稳定性应归因于多相结构；乙烯基膜支撑着合成离子通道。合成多肽作为蛋白质的模型已经得到了广泛的研究，尽管它们在实际用途上的应用相当有限。目前的战略将促进合成多肽用于先进的智能材料。

Since the membrane-bound macromolecules provide the most general and Powerful mechanisms for biological ion-sensing and -channeling, a new type of polymer-modified electrode was designed : A multiphase material consisting of poly(styrene-co-acrylonitrile)and poly(Lglutamate)was synthesized as the block copolymer. The material has allowed us to immobilize synthetic polypeptides on a electrode just by dipping. A stable polymer membrane bearing the polypeptide as a chemoreceptive component was thus prepared on a Pt wire. Electrochemical responses toward 10^<-6> M of Ca^<2+> ion were obtained based on the permeability change of the redox active couple ions as the indicator. Such ion concentration-dependent changes in responses were seen also for Mg^<2+>, but not for Na^+, K^+, and tetrabutylammonium ions. On the other hand, electrochemical response towards urea was obtained by the same electrode. This seems to be the first example of an electrochemical sensor responsive to urea without depending upon the enzyme(urease). In addition, the modified electrode has a remarkable stability due to the vinyl polymer chains which serve as the building blocks of the membrane.The facile modification as well as the excellent stability should be ascribed to the multiphase structure ; vinyl-made membrane supporting 'synthetic ion channels'. Synthetic polypeptides have been studied extensively as models of proteins, though their use-in practical purposes has been rather limited. The present strategy would facilitate the use of synthetic polypeptides for advanced, intelligent materials.