Construction of Biomimetic Moving Systems Using Polymer Gels

为了创建仿生运动系统，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，使用合成聚合物凝胶构建了几种人造软体机器，如gelooper（凝胶环），ggolf（凝胶高尔夫），凝胶阀，化学马达，形状记忆凝胶，人造肌肉，人造心脏。在这些研究成果的激励下，我们成功地获得了机械强度高达10 MPa的水凝胶，由于其极低的摩擦系数，可以承受超过百万次的连续磨损试验，而且磨损很小。这些凝胶可能会为替代关节软骨和其他人体组织开启柔软湿材料的新时代。通过对凝胶机和固体机性能的比较，阐明了软湿机的具体特点。例如，如果凝胶表面有自由悬垂的带电聚合物链，其摩擦系数就会低至10^<-4>，低于动物关节软骨的摩擦系数。我们成功地制造了一种以肌动蛋白和肌凝蛋白为原料的以ATP为燃料的软凝胶机器。化学交联的肌动蛋白凝胶丝，体积是天然肌动蛋白丝（F-actin）的几千倍，通过偶联ATP水解，以与天然F-actin一样高的速度沿着化学交联的肌球蛋白纤维凝胶（长1厘米，直径50 μ m）移动。肌肉蛋白凝胶表明，人们可以利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.