Interplay between chain stiffness and excluded volume of semiflexible polymers confined in nanochannels
Interplay between chain stiffness and excluded volume of semiflexible polymers confined in nanochannels
复制标题
限制在纳米通道中的半柔性聚合物的链刚度和排除体积之间的相互作用
DOI：
10.1063/1.4865965
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发表时间：
2014-02-28
影响因子：
4.4
通讯作者：
Dorfman, Kevin D.
中科院分区：
文献类型：
--
作者：
Muralidhar, Abhiram;Tree, Douglas R.;Dorfman, Kevin D.
通道限制半柔性聚合物的性质是由链刚度和排除体积效应的复杂相互作用决定的。利用修剪-富集Rosenbluth方法（PERM）模拟，通过系统地控制链刚度和排斥体积，研究了通道受限聚合物的平衡性质。我们的计算链的延伸和限制自由能的自由连接链和不排除体积显示出良好的协议与理论预测。对于理想的蠕虫状链，扩展被认为是交叉从Odijk行为在强约束到零拉伸，散装的行为在弱约束。相比之下，自我避免蠕虫状链，我们总是观察到的线性缩放的轮廓长度的延伸是有效的，在长链限制，无论制度的限制，由于刚度和排除体积效应的共存。我们进一步提出，延伸的长链极限对应于链长度，其中端到端距离沿着通道轴线的投影几乎等于平行于轴线的平均跨度。对于纳米通道中的DNA，使用PERM模拟确定了超过1兆碱基对的分子量;发现对于实验中常用的通道尺寸，DNA的分子量表现出几乎渐近的分数扩展。(C)2014 AIP Publishing LLC.
The properties of channel-confined semiflexible polymers are determined by a complicated interplay of chain stiffness and excluded volume effects. Using Pruned-Enriched Rosenbluth Method (PERM) simulations, we study the equilibrium properties of channel-confined polymers by systematically controlling chain stiffness and excluded volume. Our calculations of chain extension and confinement free energy for freely jointed chains with and without excluded volume show excellent agreement with theoretical predictions. For ideal wormlike chains, the extension is seen to crossover from Odijk behavior in strong confinement to zero-stretching, bulk-like behavior in weak confinement. In contrast, for self-avoiding wormlike chains, we always observe that the linear scaling of the extension with the contour length is valid in the long-chain limit irrespective of the regime of confinement, owing to the coexistence of stiffness and excluded volume effects. We further propose that the long-chain limit for the extension corresponds to chain lengths wherein the projection of the end-to-end distance along the axis of the channel is nearly equal to the mean span parallel to the axis. For DNA in nanochannels, this limit was identified using PERM simulations out to molecular weights of more than 1 megabase pairs; the molecular weight of lambda-DNA is found to exhibit nearly asymptotic fractional extension for channels sizes used commonly in experiments. (C) 2014 AIP Publishing LLC.