Construction of Biomimetic Moving Systems Using Polymer Gels

为了创造仿生运动系统，已经采用聚合物凝胶，利用其可逆的尺寸和形状变化，从而通过在分子水平上整合变形来实现运动。沿着这条路线，人们利用合成高分子凝胶构建了几种人工软机器，如gelooper（凝胶-回路器）、gelf（凝胶高尔夫）、凝胶阀、化学马达、形状记忆凝胶、人工肌肉、人工心脏。受这些研究结果的启发，我们成功地获得了具有10 MPa的高机械强度的水凝胶，由于其极低的摩擦系数，可以承受数百万次连续磨损试验，磨损很小。通过对凝胶机与固体机性能的比较，阐明了软湿机的特点。例如，如果凝胶在其表面上具有自由悬挂的带电聚合物链，则摩擦系数低至10^<-4>，这低于动物关节软骨的摩擦系数。我们已经成功地创建了由肌动蛋白和肌球蛋白的肌肉蛋白重构的ATP燃料软凝胶机器。化学交联的肌动蛋白凝胶细丝，体积是天然肌动蛋白细丝（F-肌动蛋白）的几千倍，通过与ATP水解偶联，沿着化学交联的肌球蛋白纤维凝胶（1 cm长，直径50 μ m）以与天然F-肌动蛋白一样高的速度移动。肌肉蛋白质凝胶表明，人们可以通过使用肌动蛋白和肌球蛋白分子作为基本元素，重建一个以化学能为燃料的软机器。

In order to create biomimetic motility systems, polymer gels have been employed using their reversible size and shape change, thereby realizing the motion by integrating the deformation on a molecular level. Along this line, several kinds of artificial soft machines have been constructed using synthetic polymer gels, such as gelooper (gel-looper), gelf (gel golf), gel valves, chemical motor, shape memory gel, artificial muscle, artificial heart. Motivated by these research results, we have succeeded in obtaining hydrogels with a high mechanical strength as 10 MPa sustaining more than millions of continuous wearing test with little wearing due to their extremely low frictional coefficient. These gels might open new era of soft ＆ wet materials for substituting articular cartilage and other tissues of human body.By comparing the behaviors of gel machine with the solid machine, the specific features of the soft and wet machine have been elucidated. For example, if a gel has free dangling charged polymer chains on its surface, the frictional coefficient becomes as low as 10^<-4>, which is lower than that of animal articular cartilage.We have successfully created an ATP fueled soft gel machine reconstructed from muscle proteins of actin and myosin. Chemically cross-linked actin gel filaments, several thousand times the volume of native actin filaments (F-actin) move along a chemically cross-linked myosin fibrous gel (1 cm long and 50 μ m in diameter) with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The muscle protein-gel demonstrates that one can reconstruct a soft machine fueled by chemical energy by using actin and myosin molecules as elementary elements.