Kirkwood diffusivity of long semiflexible chains in nanochannel confinement.
Kirkwood diffusivity of long semiflexible chains in nanochannel confinement.
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DOI：
10.1021/acs.macromol.5b00377
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发表时间：
2015-04-28
期刊：
影响因子：
5.5
通讯作者：
Dorfman, Kevin D.
中科院分区：
文献类型：
--
作者：
Muralidhar, Abhiram;Dorfman, Kevin D.
我们计算了正方形通道中渐近长半柔性聚合物的轴向扩散系数。我们的计算使用了迁移率张量的Kirkwood近似，将计算流体动力学张量的计算流体力学(CFD)计算与离散蠕虫链模型的剪枝强化RosenBluth方法(PERM)模拟相结合。我们的研究得出了三个关键结果。首先，对于经典的De Gennes系统，我们证实了Brochard和De Gennes的斑点理论正确地预测了轴向扩散系数的标度，这与以前的分析结论相反。其次，对于扩展的De Gennes体系，我们证明了一个修正的斑点理论解释了与经典斑点理论在纳米通道中扩散的预测的偏差，该斑点理论已经被用来考虑局部刚性对DNA在纳米狭缝中扩散的影响。第三，我们提供了一个类似于修正的斑点理论的计算来解释在扩展的De Gennes区域和Odijk区域之间的通道的扩散系数对通道尺寸的相对不敏感性，该区域是DNA限制在纳米通道中的实验和技术应用最相关的区域。我们的结果不仅与受限半柔性聚合物(如DNA)的动力学有关，而且还揭示了通道和狭缝中的限制之间有趣的相似之处。
We compute the axial diffusivity of asymptotically long semiflexible polymers confined in square channels. Our calculations employ the Kirkwood approximation of the mobility tensor by combining computational fluid dynamics (CFD) calculations of the hydrodynamic tensor in channel confinement with pruned-enriched Rosenbluth method (PERM) simulations of a discrete wormlike chain model. Three key results emerge from our study. First, for the classic de Gennes regime, we confirm that Brochard and de Gennes’ blob theory correctly predicts the scaling of the axial diffusivity, contrary to the conclusions of previous analyses. Second, for the extended de Gennes regime, we show that a modified blob theory, which has been used to incorporate the effect of local stiffness on DNA diffusion in nanoslits, explains the deviation from the prediction of classic blob theory for diffusion in nanochannels. Third, we provide a calculation similar to the modified blob theory to explain the relative insensitivity of the diffusivity to channel size for channels between the extended de Gennes regime and the Odijk regime, which is the most relevant regime for experiments and technological applications of DNA confinement in nanochannels. Our results are not only relevant to the dynamics of confined semiflexible polymers such as DNA, but also reveal interesting analogies between confinement in channels and slits.
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