Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China.
J Phys Condens Matter. 2013 Nov 20;25(46):465101. doi: 10.1088/0953-8984/25/46/465101. Epub 2013 Oct 7.
The blockade ionic current inside a nanopore due to polymer translocation is studied using a three-dimensional Langevin dynamics method. The blockade current IB is dependent on the polymer length N, polymer configuration, polymer-pore interaction, and charge of the polymer. The behavior of IB can be explained using four factors: (1) the volume vacancy fraction fV inside the pore; (2) the conformation of the polymer; (3) the location of the polymer inside the pore; and (4) the total charge Ztot inside the pore. We find that IB increases with fV but decreases with increasing |Ztot|. The influence of the polymer's conformation is complex, dependent on the size of polymer RG and the cross-sectional size of the pore s. A compact conformation can decrease IB when RG > s but increase IB when RG < s. For the latter case, the conformation of the polymer is too small to block the pore, thus providing a broad passage for the ions. At the same fV, monomers will locate close to the surface with a large polymer-pore attraction, which also provides a large IB.
使用三维 Langevin 动力学方法研究了聚合物穿过后纳米孔内的阻塞离子电流。阻塞电流 IB 取决于聚合物长度 N、聚合物构象、聚合物-孔相互作用和聚合物的电荷。IB 的行为可以用四个因素来解释：（1）孔内的体积空位分数 fV；（2）聚合物的构象；（3）聚合物在孔内的位置；（4）孔内的总电荷 Ztot。我们发现，IB 随 fV 的增加而增加，但随 |Ztot| 的增加而减小。聚合物构象的影响很复杂，取决于聚合物 RG 的大小和孔的横截面积 s。当 RG > s 时，紧凑构象会降低 IB，但当 RG < s 时，IB 会增加。在后一种情况下，聚合物的构象太小而无法阻塞孔，从而为离子提供了宽阔的通道。在相同的 fV 下，单体将与具有较大聚合物-孔吸引力的表面靠近，这也提供了较大的 IB。
