Wong C T A, Muthukumar M
Polymer Science and Engineering Department, Materials Research Science and Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003, USA.
J Chem Phys. 2007 Apr 28;126(16):164903. doi: 10.1063/1.2723088.
The authors have addressed theoretically the hydrodynamic effect on the translocation of DNA through nanopores. They consider the cases of nanopore surface charge being opposite to the charge of the translocating polymer. The authors show that, because of the high electric field across the nanopore in DNA translocation experiments, electro-osmotic flow is able to create an absorbing region comparable to the size of the polymer around the nanopore. Within this capturing region, the velocity gradient of the fluid flow is high enough for the polymer to undergo coil-stretch transition. The stretched conformation reduces the entropic barrier of translocation. The diffusion limited translocation rate is found to be proportional to the applied voltage. In the authors' theory, many experimental variables (electric field, surface potential, pore radius, dielectric constant, temperature, and salt concentration) appear through a single universal parameter. They have made quantitative predictions on the size of the adsorption region near the pore for the polymer and on the rate of translocation.
作者从理论上探讨了流体动力学对DNA通过纳米孔转运的影响。他们考虑了纳米孔表面电荷与转运聚合物电荷相反的情况。作者表明，由于DNA转运实验中纳米孔两端存在高电场，电渗流能够在纳米孔周围形成一个与聚合物尺寸相当的吸附区域。在这个捕获区域内，流体流动的速度梯度足够高，使聚合物能够发生线圈-伸展转变。伸展构象降低了转运的熵垒。发现扩散限制的转运速率与施加电压成正比。在作者的理论中，许多实验变量（电场、表面电位、孔径、介电常数、温度和盐浓度）通过一个单一的通用参数体现出来。他们对聚合物在孔附近吸附区域的大小以及转运速率进行了定量预测。
