BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology Centre, Singapore 117543, Singapore.
Phys Rev Lett. 2013 Apr 19;110(16):168105. doi: 10.1103/PhysRevLett.110.168105.
Blob theory has been widely applied to describe polymer conformations and dynamics in nanoconfinement. In slit confinement, blob theory predicts a scaling exponent of 2/3 for polymer diffusivity as a function of slit height, yet a large body of experimental studies using DNA produce a scaling exponent significantly less than 2/3. In this work, we develop a theory that predicts that this discrepancy occurs because the segment correlation function for a semiflexible chain such as DNA does not follow the Flory exponent for length scales smaller than the persistence length. We show that these short length scale effects contribute significantly to the scaling for the DNA diffusivity, but do not appreciably affect the scalings for static properties. Our theory is fully supported by Monte Carlo simulations, quantitative agreement with DNA experiments, and the results reconcile this outstanding problem for confined polymers.
液滴理论已广泛应用于描述纳米受限环境中的聚合物构象和动力学。在狭缝限制中，液滴理论预测聚合物扩散率作为狭缝高度的函数的标度指数为 2/3，但使用 DNA 的大量实验研究产生的标度指数明显小于 2/3。在这项工作中，我们提出了一个理论，该理论预测这种差异的发生是因为对于 DNA 等半柔性链，片段相关函数并不遵循比持久长度小的长度尺度的 Flory 指数。我们表明，这些短尺度效应对 DNA 扩散率的标度有很大贡献，但对静态特性的标度没有明显影响。我们的理论得到了蒙特卡罗模拟的充分支持，与 DNA 实验定量一致，结果解决了受限聚合物中这一突出问题。
