Levine Alex J, MacKintosh F C
Department of Chemistry & Biochemistry, University of California, Los Angeles, California 90095, USA.
J Phys Chem B. 2009 Mar 26;113(12):3820-30. doi: 10.1021/jp808192w.
Recent experiments on molecular motor driven in vitro F-Actin networks have found anomalously large strain fluctuations at low frequency. In addition, the shear modulus of these active networks becomes as much as one hundred times larger than that of the same system in equilibrium. We develop a two-fluid model of a low-density semiflexible network driven by molecular motors to explore these effects and show that, relying on only simple assumptions regarding the motor activity in the system we can quantitatively understand both the low-frequency fluctuation enhancement and the nonequilibrium stiffening of the network. These results have implications for the interpretation of microrheology in such active networks including the cytoskeleton of living cells. In addition, they may form the basis for theoretical studies of biomimetic nonequilibrium gels whose mechanical properties are tunable through the control of their nonequilibrium steady-state.
最近对分子马达驱动的体外F-肌动蛋白网络进行的实验发现，在低频下存在异常大的应变波动。此外，这些活性网络的剪切模量比处于平衡状态的同一系统大出多达一百倍。我们开发了一种由分子马达驱动的低密度半柔性网络的双流体模型，以探究这些效应，并表明，仅依靠关于系统中马达活性的简单假设，我们就能定量理解网络的低频波动增强和非平衡硬化现象。这些结果对于解释此类活性网络（包括活细胞的细胞骨架）中的微观流变学具有重要意义。此外，它们可能为仿生非平衡凝胶的理论研究奠定基础，这种凝胶的机械性能可通过控制其非平衡稳态来调节。
