Swank Zoe, Deshpande Siddharth, Pfohl Thomas
Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
Soft Matter. 2016 Jan 7;12(1):87-92. doi: 10.1039/c5sm02304a.
The physical properties of polymeric actin facilitate many mechanical processes within the cell, including cellular deformation and locomotion, whereby the polymers can be confined to a range of different geometries. As actin polymers often form entangled solutions in the cell, we have investigated the effect of confinement on the evolution of entangled semiflexible polymer solutions. Using a microfluidic platform, we examined the physical dynamics of actin polymers confined within narrow (2-4 μm) rectangular channels. Focusing on the entanglement process of two actin polymers, we found that their prolonged entrainment leads to synchronized horizontal undulations and decreased translational diffusion. In the absence of cross-linking molecules or proteins, the long-range entrainment interactions are predominantly controlled by the geometric boundaries. We directly measure the deflection length Λ for an individual polymer, either solitarily confined within a channel or confined in the presence of a second filament, enabling the determination of the change in free energy associated with polymer entanglement. Our results indicate that geometrical confinement can serve as a solitary variable influencing the physical dynamics of entangled semiflexible polymers.
聚合肌动蛋白的物理性质有助于细胞内的许多机械过程，包括细胞变形和运动，在此过程中，聚合物可以被限制在一系列不同的几何形状中。由于肌动蛋白聚合物在细胞中常常形成缠结溶液，我们研究了限制条件对缠结半柔性聚合物溶液演化的影响。使用微流控平台，我们研究了限制在狭窄（2-4μm）矩形通道内的肌动蛋白聚合物的物理动力学。聚焦于两种肌动蛋白聚合物的缠结过程，我们发现它们的长时间夹带会导致同步的水平波动并降低平移扩散。在没有交联分子或蛋白质的情况下，长程夹带相互作用主要由几何边界控制。我们直接测量单个聚合物的偏转长度Λ，该聚合物要么单独限制在通道内，要么在存在第二根细丝的情况下受到限制，从而能够确定与聚合物缠结相关的自由能变化。我们的结果表明，几何限制可以作为一个单独的变量影响缠结半柔性聚合物的物理动力学。
