Living Matter Department, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
Departments of Chemical & Biomolecular Engineering, Chemistry, and Physics & Astronomy, Rice University, Houston, Texas 77005, USA.
Phys Rev Lett. 2019 May 31;122(21):218102. doi: 10.1103/PhysRevLett.122.218102.
Dynamically cross-linked semiflexible biopolymers such as the actin cytoskeleton govern the mechanical behavior of living cells. Semiflexible biopolymers nonlinearly stiffen in response to mechanical loads, whereas the cross-linker dynamics allow for stress relaxation over time. Here we show, through rheology and theoretical modeling, that the combined nonlinearity in time and stress leads to an unexpectedly slow stress relaxation, similar to the dynamics of disordered systems close to the glass transition. Our work suggests that transient cross-linking combined with internal stress can explain prior reports of soft glassy rheology of cells, in which the shear modulus increases weakly with frequency.
动态交联的半柔性生物聚合物，如肌动蛋白细胞骨架，控制着活细胞的力学行为。半柔性生物聚合物对机械载荷表现出非线性的刚度增加，而交联剂的动力学则允许随着时间的推移进行应力松弛。在这里，我们通过流变学和理论建模表明，时间和应力的综合非线性导致了出乎意料的缓慢的应力松弛，类似于接近玻璃转变的无序系统的动力学。我们的工作表明，瞬态交联与内应力相结合可以解释先前关于细胞软玻璃态流变学的报告，其中剪切模量随频率的增加而微弱增加。
