Design of Molecular Pacemaker with a Built-in Self-Oscillating Circuit

在使用刺激响应凝胶的常规致动系统中，外部刺激的“开-关”切换对于激发凝胶的作用是必不可少的。在转换时，凝胶只提供一种独特的作用，要么溶胀，要么去溶胀。与这些对刺激的临时反应相反，我们体内有许多生理现象继续其自身的周期性变化;例如心跳，脑电波等。如果凝胶可以实现这种自振荡，则可能出现新的仿生智能材料，以表现出有节奏的运动，如分子起搏器。自激微泵在本项目中，我们开发了这样一种自吸收凝胶。它在恒定条件下自发地表现出周期性肿胀和去肿胀，不需要外部刺激的“开-关”切换。其作用类似于心脏搏动，凝胶的机械振荡是通过振荡化学反应产生的。别洛乌索夫号 ...更多信息 Zhabotinsky（BZ）反应。BZ反应具有类似于生命系统中代谢反应TCA循环的循环反应网络。我们制备了一种由交联聚（N-异丙基丙烯酰胺）组成的离子凝胶，它与BZ反应的催化剂三（2，2 ′-联吡啶）钌共价键合。在凝胶基质内发生的BZ反应产生催化剂部分的周期性氧化还原变化。这种化学振荡通过聚合物链亲水性的变化转化为聚合物网络的机械振荡。结果，凝胶呈现出周期性的溶胀-去溶胀变化。详细分析了凝胶的振荡行为，并利用微细加工技术制备了具有生物体自主周期运动特性的微驱动器。采用光引发剂和叠氮基聚合物两种方法控制凝胶结构。合成了几种形状与光掩模相同的微米级凝胶。研究了聚合反应的最佳合成条件。同时，利用X射线光刻技术（LIGA），制作了一种由该凝胶制成的纤毛运动驱动器。除了这些微致动器，自振荡聚合物链和纳米凝胶颗粒已被制备为仿生纳米机器。少

In conventional actuating systems using stimuli-responsive gels, "on-off" switching of external stimuli is essential to instigate the action of the gel. Upon switching, the gels provide only one unique action, either swelling or deswelling. In contrast to these temporary responses to stimuli, there are many physiological phenomena in our body that continue their own native cyclic changes ; examples are heartbeat, brain waves, etc. If such self-oscillation could be achieved for gels, possibilities would emerge for new biomimetic intelligent materials to exhibit rhythmical motion such as molecular pacemaker. self-beating micropump. etc. In this project, we have developed such a self-oscillatlng gel. It spontaneously exhibits cyclic swelling and deswelling under constant conditions, requiring no "on-off" switching of extemal stimuli. Its action is similar to that of a beating heart muscke.The mechanical oscillation of gel is produced via oscillating chemical reaction. called the Belousov- … More Zhabotinsky (BZ) reaction. The BZ reaction has a cyclic reaction network similar to TCA cycle which is the metabolic reaction in living systems. We have prepared an ionic gel consisting of the cross-linked poly (N-isopropylacrylamide) to which ruthenium tris (2, 2'-bipyridine), a catalyst for the BZ reaction, is covalently bonded. The BZ reaction occurring within the gel matrix generates periodic redox changes of the catalyst moiety. This chemical oscillation is converted into the mechanical oscillation of the polymer network through the change in hydrophilicity of polymer chains. As a result, the gel exhibits a periodical swelling-deswelling change. The oscillating behaviors of the gel have been analyzed in detail.Further, the micro-actuator to undergo autonomic and periodic motion like living organism has been prepared by micro-fabrication technique. Two photolithographic methods ; (1)using photoinitiator and (2)using the polymer with azidophenyl groups, were employed to control the gel structure. Several shapes of micrometer-sized gels with the same pattern as photomask were synthesized. Optimal synthetic condition for polymerization has been investigated. And also, by using X-ray lithography technique (LIGA), a ciliary motion actuator made of the gel has been demonstrated. As well as these microactuator, self-oscillating polymer chains and nano-gel particles have been prepared as biomimetic nano-machines. Less