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Boundaries of the Topologically Frustrated Dynamical State in Polymer Dynamics
ACS Macro Letters ( IF 5.1 ) Pub Date : 2022-05-03 , DOI: 10.1021/acsmacrolett.2c00019 Kuo Chen 1 , Siao-Fong Li 1 , M Muthukumar 1
ACS Macro Letters ( IF 5.1 ) Pub Date : 2022-05-03 , DOI: 10.1021/acsmacrolett.2c00019 Kuo Chen 1 , Siao-Fong Li 1 , M Muthukumar 1
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Using fluorescence microscopy and single-particle tracking, we have directly observed the dynamics of λ-DNA trapped inside poly(acrylamide-co-acrylate) hydrogels under an externally applied electric field. Congruent with the recent discovery of the nondiffusive topologically frustrated dynamical state (TFDS) that emerges at intermediate confinements between the traditional entropic barrier and reptation regimes, we observe the immobility of λ-DNA in the absence of an electric field. The electrophoretic mobility of the molecule is triggered upon application of an electric field with strength above a threshold value Ec. The existence of the threshold value to elicit mobility is attributed to a large entropic barrier, arising from many entropic traps acting simultaneously on a single molecule. Using the measured Ec which depends on the extent of confinement, we have determined the net entropic barrier of up to 130 kBT, which is responsible for the long-lived metastable TFDS. The net entropic barrier from multiple entropic traps is nonmonotonic with the extent of confinement and tends to vanish at the boundaries of the TFDS with the single-entropic barrier regime at lower confinements and the reptation regime at higher confinements. We present an estimate of the mesh size of the hydrogel that switches off the nondiffusive TFDS and releases chin diffusion in the heavily entangled state.
中文翻译：
聚合物动力学中拓扑受挫动力学状态的边界
使用荧光显微镜和单粒子跟踪，我们直接观察了在外加电场下捕获在聚（丙烯酰胺-共-丙烯酸酯）水凝胶内的 λ-DNA 的动力学。与最近发现的非扩散拓扑受挫动力学状态 (TFDS) 一致，该状态出现在传统熵势垒和蠕动机制之间的中间限制中，我们观察到在没有电场的情况下 λ-DNA 的不动性。在施加强度高于阈值E c的电场时触发分子的电泳迁移率. 引发迁移率的阈值的存在归因于一个大的熵屏障，这是由许多熵陷阱同时作用于单个分子而产生的。使用取决于限制程度的测量E c，我们确定了高达 130 k B T的净熵屏障，它负责长寿命的亚稳态 TFDS。来自多个熵陷阱的净熵屏障在限制范围内是非单调的，并且趋向于在 TFDS 的边界处消失，在较低限制下为单熵屏障状态，在较高限制下为蠕动状态。我们对水凝胶的网格尺寸进行了估计，该水凝胶会关闭非扩散 TFDS 并在重度纠缠状态下释放下巴扩散。
更新日期：2022-05-03
中文翻译：
聚合物动力学中拓扑受挫动力学状态的边界
使用荧光显微镜和单粒子跟踪，我们直接观察了在外加电场下捕获在聚（丙烯酰胺-共-丙烯酸酯）水凝胶内的 λ-DNA 的动力学。与最近发现的非扩散拓扑受挫动力学状态 (TFDS) 一致，该状态出现在传统熵势垒和蠕动机制之间的中间限制中，我们观察到在没有电场的情况下 λ-DNA 的不动性。在施加强度高于阈值E c的电场时触发分子的电泳迁移率. 引发迁移率的阈值的存在归因于一个大的熵屏障，这是由许多熵陷阱同时作用于单个分子而产生的。使用取决于限制程度的测量E c，我们确定了高达 130 k B T的净熵屏障，它负责长寿命的亚稳态 TFDS。来自多个熵陷阱的净熵屏障在限制范围内是非单调的，并且趋向于在 TFDS 的边界处消失，在较低限制下为单熵屏障状态，在较高限制下为蠕动状态。我们对水凝胶的网格尺寸进行了估计，该水凝胶会关闭非扩散 TFDS 并在重度纠缠状态下释放下巴扩散。
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