Creation of Soft & Wet Artificial Muscles and Their Application as Biomotion Systems

(1)软湿人工肌肉水凝胶的合成通过在水凝胶中引入双网络结构，我们成功地获得了具有超高机械韧性(断裂强度约为几Mpa)的水凝胶，并通过将第一网络结构的不均匀结构从几个10 nm改变为微米，成功地控制了DN凝胶的力学行为，从脆性变为延展性。韧性状的DN凝胶在失效前表现出高达20倍的伸长率。为了将该凝胶应用于人工软骨，我们进一步将该凝胶的接枝结构引入到该凝胶表面，成功地获得了断裂应力为10 Mpa，断裂能为1000J/cm~2，滑动摩擦系数为10^~(-5)~10^~(-4)的凝胶。(Ii)水凝胶作为生物组织替代物的应用研究几种不同类型的DN凝胶在总滑动距离为50公里的情况下进行了100万次循环销平试验，磨损率为10^&lt；-8；-10^&lt；-7&gt；mm^3/Nm。该凝胶的耐磨性高于高密度聚乙烯(磨损率为10~(-7)mm~(-3)/Nm)。兔体内植入试验表明，PAMPS/PDMAAm生物凝胶最适合生物持久性。将PAMPS/PDMAAm人工软骨植入兔关节内，发现凝胶具有良好的生物相容性；将PAMPS/PDMAA凝胶作为人工软骨植入关节表面数mm处，可原位再生正常软骨。这一伟大发现将导致一种全新的方法来原位修复受损的软骨。

(I) Synthesis of hydrogel as soft and wet artificial musclesBy introducing the double network structure into hydrogel, we succeeded in obtaining the hydrogel with extra-ordinary high mechanical toughness (Fracture strength of about several Mpa).In addition, by changing the inhomogeous structure of the first network from several 10nm to micrometer, we succeeded in controlling the mechanical behavior of the DN gel from brittle-like to ductile-like. The ductile-like DN gel exhibits an elongation as high as 20 times before failure. To apply this gel as artificial cartilage, we further introduced the graft structure to the DN gel surface and succeeded in obtaining the gel with a fracture stress of several 10MPa, fracture energy of 1000 J/cm^2, and sliding friction coefficient of 10^<-5>〜10^<-4>.(II) Application of hydrogel as substitutes of bio-organsTo apply the gel with excellent mechanical properties as artificial cartilage, wear property, bio-durability and biocompatibility were investigated. Several kinds of DN gels sustained cyclic pin-on-flat test for one million times with a total sliding distance of 50 km, and showed a wearing rate of 10^<-8>-10^<-7>mm^3/Nm. This wear resistance is higher than that of the high density polyethylene (wearing rate of 10^<-7>mm^3/Nm).Implantation test of DN gel in the rabbits showed that among several kinds of DN gels, the PAMPS/PDMAAm DN gel was the most suitable for bio-durability. Moreover, it was found that the gel showed a good biocompatibility when artificial cartilage made of PAMPS/PDMAAm was implanted in the articular joints of rabbits.Furthermore, we discovered that normal cartilage was regenerated in situ when the PAMPS/PDMAA gel was imbedded into the articular joint several mm from the surface as artificial cartilage. This great discovery will lead to a completely new method to repair the damaged cartilage in situ.