Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Chem Phys. 2020 Nov 14;153(18):184904. doi: 10.1063/5.0027049.
The transport of polyelectrolytes confined by oppositely charged surfaces and driven by a constant electric field is of interest in studies of DNA separation according to size. Using molecular dynamics simulations that include the surface polarization effect, we find that the mobilities of the polyelectrolytes and their counterions change non-monotonically with the confinement surface charge density. For an optimum value of the confinement charge density, efficient separation of polyelectrolytes can be achieved over a wide range of polyelectrolyte charge due to the differential friction imparted by oppositely charged confinement on the polyelectrolyte chains. Furthermore, by altering the placement of the charged confinement counterions, enhanced polyelectrolyte separation can be achieved by utilizing the surface polarization effect due to dielectric mismatch between the media inside and outside the confinement.
在根据大小对 DNA 进行分离的研究中，受到相反电荷表面限制并由恒定电场驱动的聚电解质的传输引起了人们的兴趣。使用包括表面极化效应的分子动力学模拟，我们发现聚电解质及其抗衡离子的迁移率随限制表面电荷密度的变化是非单调的。对于限制电荷密度的最佳值，由于相反电荷的限制对聚电解质链施加的不同摩擦，可以在聚电解质电荷的广泛范围内实现聚电解质的有效分离。此外，通过改变带电荷的限制反离子的位置，可以通过利用限制内外介质之间的介电失配产生的表面极化效应来实现增强的聚电解质分离。
