Multiphase Intelligent Materials for Biomimetic Sensors

由于膜结合大分子提供了最普遍和最强大的生物离子传感和通道机制，设计了一种新型聚合物修饰电极：由聚（苯乙烯-共丙烯腈）和聚（谷氨酸）组成的多相材料作为嵌段共聚物。这种材料使我们能够通过蘸料将合成多肽固定在电极上。因此，在铂丝上制备了一种以多肽为化学接受成分的稳定聚合物膜。以氧化还原活性偶离子的渗透率变化为指标，得到了10^<-6> M Ca^<2+>离子的电化学响应。在Mg^<2+>中也观察到这种离子浓度依赖性的响应变化，但在Na^+， K^+和四丁基铵离子中则没有。另一方面，在相同的电极上得到了对尿素的电化学响应。这似乎是电化学传感器对尿素反应而不依赖于酶（脲酶）的第一个例子。此外，由于乙烯基聚合物链作为膜的构建块，修饰电极具有显着的稳定性。多相结构具有易于改性和优异的稳定性；乙烯基制成的膜支持“合成离子通道”。合成多肽作为蛋白质的模型已被广泛研究，尽管它们在实际用途上的应用相当有限。目前的策略将促进合成多肽用于先进智能材料的使用。

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.