Boundaries of the Topologically Frustrated Dynamical State in Polymer Dynamics
Boundaries of the Topologically Frustrated Dynamical State in Polymer Dynamics
复制标题
聚合物动力学中拓扑受阻动力学状态的边界
DOI：
10.1021/acsmacrolett.2c00019
复制
发表时间：
2022
影响因子：
7.015
通讯作者：
Muthukumar, M.
中科院分区：
文献类型：
--
作者：
Chen, Kuo;Li, Siao-Fong;Muthukumar, M.
利用荧光显微镜和单粒子跟踪技术，我们直接观察了在外加电场作用下，λ-DNA被捕获在聚（丙烯酰胺-丙烯酸酯）水凝胶中的动力学过程。与最近发现的非扩散拓扑阻挫动力学态（TFDS）相一致，它出现在传统的熵垒和爬行状态之间的中间限制，我们观察到λ-DNA在没有电场的情况下的不动性。在施加强度高于阈值Ec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势垒，所产生的许多熵陷阱同时作用于单个分子。使用measuredEC取决于禁闭的程度，我们已经确定了高达130 kBT，这是负责长寿命的亚稳态TFDS的净熵势垒。从多个熵陷阱的净熵势垒是非单调的限制的程度，往往消失在边界的TFDS与单熵势垒制度在较低的限制和爬行制度在较高的限制。我们对水凝胶的网格尺寸进行了估计，该水凝胶关闭了非扩散性TFDS并在严重纠缠状态下释放了下巴扩散。
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 valueEc. 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 measuredEcwhich depends on the extent of confinement, we have determined the net entropic barrier of up to 130kBT, 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.