Liu Dani, Feng Shi, Huang Qingqiu, Sun Shuofei, Dong Gening, Long Feifei, Milazzo Mario, Wang Mingkun
School of Aeronautic Science and Engineering, Beihang University, Beijing, 100191, China.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
Adv Funct Mater. 2023 Jul 11;33(28). doi: 10.1002/adfm.202300426. Epub 2023 Apr 18.
Load-bearing soft tissues are soft but strong, strong yet tough. These properties can only be replicated in synthetic hydrogels, which do not have the biocomplexity required by many biomedical applications. By contrast, natural hydrogels, although retaining the native complexity, are weak and fragile. Here we present a thermomechanical casting method to achieve the mechanical capabilities of synthetic materials in biopolymer hydrogels. The thermomechanical cast and chemically crosslinked biopolymer chains form a short-range disordered but long-range ordered structure in water. Upon stretch, the disordered structure transforms to a hierarchically ordered structure. This disorder-order transformation resembles the synergy of the disordered elastin and ordered collagen in load-bearing soft tissues. As entropy drives a reverse order-disorder transformation, the hydrogels can resist repeated cycles of loads without deterioration in mechanical properties. Gelatin hydrogels produced by this method combine tissue-like tunable mechanical properties that outperform the gelatin prepared by synthetic approaches, and biocomplexity beyond current natural systems. Unlike polymer engineering approaches, which rely on specific crosslinks provided by special polymers, this strategy utilizes the entropy of swollen chains and is generalizable to many other biopolymers. It could thus significantly accelerate translational success of biomaterials.
承重软组织柔软且坚韧，坚韧而有韧性。这些特性只能在合成水凝胶中复制，而合成水凝胶并不具备许多生物医学应用所需的生物复杂性。相比之下，天然水凝胶虽然保留了天然的复杂性，但却脆弱易碎。在此，我们提出一种热机械铸造方法，以实现生物聚合物水凝胶具备合成材料的机械性能。热机械铸造和化学交联的生物聚合物链在水中形成短程无序但长程有序的结构。在拉伸时，无序结构转变为分级有序结构。这种无序-有序转变类似于承重软组织中无序弹性蛋白和有序胶原蛋白的协同作用。由于熵驱动反向的有序-无序转变，水凝胶能够抵抗反复的加载循环而机械性能不会恶化。通过这种方法制备的明胶水凝胶兼具类似组织的可调机械性能，其性能优于通过合成方法制备的明胶，并且具有超越当前天然系统的生物复杂性。与依赖特殊聚合物提供的特定交联的聚合物工程方法不同，该策略利用了溶胀链的熵，并且可推广到许多其他生物聚合物。因此，它可以显著加速生物材料的转化成功。
