Microrheology of highly crosslinked microtubule networks is dominated by force-induced crosslinker unbinding.
Microrheology of highly crosslinked microtubule networks is dominated by force-induced crosslinker unbinding.
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DOI：
10.1039/c2sm26934a
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发表时间：
2013-01-14
期刊：
影响因子：
3.4
通讯作者：
Valentine MT
中科院分区：
文献类型：
--
作者：
Yang Y;Bai M;Klug WS;Levine AJ;Valentine MT
我们确定的时间和力依赖性的粘弹性反应的重组网络的微管，已强烈交联的生物素-链霉亲和素键。为了测量这种网络的微尺度粘弹性，我们使用磁镊装置施加局部力。在短的时间尺度上，网络响应非线性施加的力，在小的力与硬化，其次是在高的力，这是我们归因于力引起的交联解除约束的硬化响应减少。在长时间尺度下，力诱导的键解束缚导致局部网络重排和显著的珠蠕变。有趣的是，即使在显著塑性流动的条件下，网络仍保持其弹性模量，这表明交联剂断裂通过形成新键来平衡。为了更好地理解这种效应，我们开发了一个有限元模型，这样一个刚性的长丝网络与不稳定的交联剂服从力依赖贝尔模型的解约束动力学。由于每根长丝具有许多交联剂，因此由于键断裂引起的耗散和网络的弹性恢复是可能的。只要在加载期内保留足够数量的原始交联剂，就可以发生回收。当这些剩余的原始交联剂被破坏时，产生塑性流动。
We determine the time- and force-dependent viscoelastic responses of reconstituted networks of microtubules that have been strongly crosslinked by biotin-streptavidin bonds. To measure the microscale viscoelasticity of such networks, we use a magnetic tweezers device to apply localized forces. At short time scales, the networks respond nonlinearly to applied force, with stiffening at small forces, followed by a reduction in the stiffening response at high forces, which we attribute to the force-induced unbinding of crosslinks. At long time scales, force-induced bond unbinding leads to local network rearrangement and significant bead creep. Interestingly, the network retains its elastic modulus even under conditions of significant plastic flow, suggesting that crosslinker breakage is balanced by the formation of new bonds. To better understand this effect, we developed a finite element model of such a stiff filament network with labile crosslinkers obeying force-dependent Bell model unbinding dynamics. The coexistence of dissipation, due to bond breakage, and the elastic recovery of the network is possible because each filament has many crosslinkers. Recovery can occur as long as a sufficient number of the original crosslinkers are preserved under the loading period. When these remaining original crosslinkers are broken, plastic flow results.