Strain history dependence of the nonlinear stress response of fibrin and collagen networks
Strain history dependence of the nonlinear stress response of fibrin and collagen networks
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DOI：
10.1073/pnas.1222787110
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发表时间：
2013-07-23
影响因子：
11.1
通讯作者：
Weitz, David A.
中科院分区：
文献类型：
--
作者：
Muenster, Stefan;Jawerth, Louise M.;Weitz, David A.
我们表明，非交联纤维蛋白或I型胶原蛋白形成的网络的非线性力学响应不断变化，响应于重复的大应变负荷。我们表明，这种动态演变的机械响应产生的一个特征的非线性应力-应变关系的转移到更高的应变。因此，施加的载荷不会削弱底层基质，而是延迟应变刚化的发生。使用共聚焦显微镜，我们提出了直接的证据表明，这种行为的结果，从持续延长个别纤维之间的相互作用引起的纤维拉伸和纤维屈曲时，网络反复应变。此外，我们发现，共价交联的纤维蛋白或胶原蛋白抑制移位的非线性材料的响应，这表明个别纤维延长的分子起源可能是滑的纤维内的单体。因此，纤维结构与表现出内部可塑性的成分结合产生了一种材料，其机械响应适应外部负载条件。这种设计原理可能有助于设计具有这种能力的新型材料。
We show that the nonlinear mechanical response of networks formed from un-cross-linked fibrin or collagen type I continually changes in response to repeated large-strain loading. We demonstrate that this dynamic evolution of the mechanical response arises from a shift of a characteristic nonlinear stress-strain relationship to higher strains. Therefore, the imposed loading does not weaken the underlying matrices but instead delays the occurrence of the strain stiffening. Using confocal microscopy, we present direct evidence that this behavior results from persistent lengthening of individual fibers caused by an interplay between fiber stretching and fiber buckling when the networks are repeatedly strained. Moreover, we show that covalent cross-linking of fibrin or collagen inhibits the shift of the nonlinear material response, suggesting that the molecular origin of individual fiber lengthening may be slip of monomers within the fibers. Thus, a fibrous architecture in combination with constituents that exhibit internal plasticity creates a material whose mechanical response adapts to external loading conditions. This design principle may be useful to engineer novel materials with this capability.