Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Guangdong, China.
Soft Matter. 2021 Nov 24;17(45):10177-10185. doi: 10.1039/d0sm01558j.
In this study, we report a computational investigation on how the mechanochemical characteristics of crosslinking molecules influence the viscoelasticity of three dimensional F-actin networks, an issue of key interest in analyzing the behavior of living cells and biological gels. In particular, it was found that the continuous breakage and rebinding of cross-linkers result in a locally peaked loss modulus in the rheology spectrum of the network, reflecting the fact that maximum energy dissipation is achieved when the driving frequency of the applied oscillating shear becomes comparable to the dissociation/association rate of crosslinking molecules. In addition, we showed that when subjected to constant rate of shear, an actin network can exhibit either strain hardening or softening depending on the ratio between the loading rate and unbinding speed of cross-linkers. A criterion for predicting the transition from softening to hardening was also obtained, in agreement with recent experiments. Finally, significant structural evolution was found to occur in random networks undergoing mechanical "training" ( under a constant applied shear stress over a period of time), eventually leading to a pronounced anisotropic response of the network afterward which again is consistent with experimental observations.
在这项研究中，我们报告了一项关于交联分子的机械化学特性如何影响三维 F-肌动蛋白网络粘弹性的计算研究，这是分析活细胞和生物凝胶行为的关键问题。具体而言，研究发现交联剂的连续断裂和重新结合导致网络流变谱中损耗模量局部峰值，这反映了当施加的振荡剪切的驱动频率与交联分子的离解/结合速率相当时，最大能量耗散得以实现。此外，我们还表明，当受到恒定剪切速率作用时，肌动蛋白网络可以表现出应变硬化或软化，这取决于加载速率与交联剂解联速度的比值。还获得了一个预测从软化到硬化转变的判据，这与最近的实验结果一致。最后，发现随机网络在机械“训练”下（在一段时间内施加恒定的剪切应力）会发生显著的结构演变，最终导致网络在之后呈现出明显的各向异性响应，这再次与实验观察结果一致。
