Abstract The structural constituents of tissues in organisms are composed primarily of minerals and proteins. Collagen is the most common protein used to construct such natural materials in vertebrates; among these structures, a wide variety of hierarchical architectures with structural and property gradients have evolved to induce desired combinations of stiffness, strength, ductility and toughness for a diverse range of mechanical functionalities. The soft collagen provides biological materials the ability to resist tensile tractions and to dissipate energy under mechanical deformation. Here we seek to understand the structure, deformation and toughening mechanisms of collagenous materials from the perspective of the hierarchical assembly of individual collagen molecules, fibrils, fibers, as well as the other nature-designed hierarchical structural elements. This review summarizes the structural designs of collagenous materials focusing on Type-I collagen, the most abundant extracellular protein that forms linear arrays, as well as examining its deformation and toughening mechanisms by illustrating how nature uses hierarchical structures and gradients, at nano-, micro- to macro-levels, to confer different functions to its organisms. The organization of collagen is discussed for different structures in order to illustrate the broad range of its functional and mechanical properties: specifically, skin, arteries, eye cornea, fish scales, bone, ligaments and tendons. We conclude by highlighting important developments in tissue engineering where synthetic and natural collagen has been incorporated into the architecture of the body. We trust that such insight may provide guidance for the design of the next-generation of synthetic structural materials with unprecedented functionality.

中文翻译：

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Nature中具有增韧机制的结构体系：I型胶原材料的材料科学综述

摘要 生物体组织的结构成分主要由矿物质和蛋白质组成。胶原蛋白是用于在脊椎动物中构建此类天然材料的最常见蛋白质。在这些结构中，具有结构和性能梯度的各种层次结构已经发展到可以为各种机械功能引入所需的刚度、强度、延展性和韧性组合。柔软的胶原蛋白为生物材料提供了抵抗拉伸牵引力和在机械变形下耗散能量的能力。在这里，我们试图从单个胶原分子、原纤维、纤维、以及其他自然设计的分层结构元素。这篇综述总结了胶原材料的结构设计，重点是 I 型胶原蛋白，这是形成线性阵列的最丰富的细胞外蛋白，并通过说明自然如何使用纳米级、微米级的分层结构和梯度来检查其变形和增韧机制。 - 宏观层面，赋予其有机体不同的功能。针对不同结构讨论了胶原蛋白的组织，以说明其广泛的功能和机械特性：特别是皮肤、动脉、眼角膜、鱼鳞、骨骼、韧带和肌腱。最后，我们强调了组织工程的重要发展，其中合成和天然胶原蛋白已被纳入人体结构。