Engineering Nonmechanical Protein-Based Hydrogels with Highly Mechanical Properties: Comparison with Natural Muscles

The elegant elasticity and toughness of muscles that are controlled by myofilament sliding, highly elastic springlike properties of titin, and Ca 2+ -induced conformational change of the troponin complex have been a source of inspiration to develop advanced materials for simulating elastic muscle motion. Herein, a highly stretchable protein hydrogel is developed to mimic the structure and motion of muscles through the combination of protein folding–unfolding and molecular sliding. It has been shown that the protein bovine serum albumin is covalently cross-linked, together penetrated with alginate chains to construct polyprotein-based hydrogels, where polyproteins can act as the elastic spring titin via protein folding–unfolding and also achieve tunable sliding facilitated by alginate due to their reversible noncovalent interactions, thus providing desired mechanical properties such as stretchability, resilience, and strength. Notably, these biomaterials can achieve the breaking strain of up to 1200% and show massive energy dissipation. A pronounced expansion–contraction phenomenon is also observed on the macroscopic scale, and the Ca 2+ -induced contraction process may help to improve our understanding of muscle movement. Overall, these excellent properties are comparable to or even better than those of natural muscles, making the polyprotein-based hydrogels represent a new type of muscle-mimetic biomaterial. Significantly, the prominent biocompatibility of the designed biomaterials further enables them to hold potential applications in the biomedical field and tissue engineering.

由肌丝滑动控制的肌肉优雅的弹性和韧性、肌动蛋白的高弹性弹簧特性以及Ca 2+ 诱导的肌钙蛋白复合物的构象变化一直是开发用于模拟弹性肌肉运动的先进材料的灵感来源。在此，开发了一种高度可拉伸的蛋白质水凝胶，通过蛋白质折叠-展开和分子滑动的结合来模拟肌肉的结构和运动。研究表明，牛血清白蛋白通过共价交联，与海藻酸盐链一起渗透，构建了基于多蛋白的水凝胶，其中多蛋白可以通过蛋白质折叠-展开充当弹性弹簧肌动蛋白，并且由于其可逆的非共价相互作用，还可以通过海藻酸盐实现可调节的滑动，从而提供所需的机械性能，如拉伸性、弹性和强度。值得注意的是，这些生物材料可以实现高达 1200% 的断裂应变，并表现出巨大的能量耗散。在宏观尺度上也观察到明显的膨胀-收缩现象，Ca 2+ 诱导的收缩过程可能有助于提高我们对肌肉运动的理解。总体而言，这些优异的性能可与天然肌肉相媲美甚至更好，使得基于多蛋白的水凝胶代表了一种新型的仿肌肉生物材料。值得注意的是，所设计的生物材料突出的生物相容性进一步使其在生物医学领域和组织工程中拥有潜在的应用。