Current blockade mechanism for DNA translocation through solid-state nanopore with different membrane thickness

不同薄膜厚度下的DNA分子通过固态纳米孔的相对堵塞电流机理（英文）

The current blockade mechanism for λ -DNA translocation under electrical field is investigated through solid-state nanopores with different pore thicknesses. The conductance of a nanopore system mainly consists of the contribution of the pore and access region, and the latter becomes dominant when the nanopore thickness gradually decreases to atomic layer thickness. Based on the existing model of nanopore resistance, a simplified model which describes the relative current blockade during the X-DNA translocation through the nanopores is deduced to quantitatively present the relationship between nanopore thickness and relative current blockade. Results show that the relative current blockade is effectively increased by reducing the nanopore diameter but it decreases with the decreasing nanopore thickness. A two-stage schematic is proposed to increase the relative current blockade by setting a much smaller resistance region. Experimental results show a 21. 9% increase in the relative current blockade with the proposed schematic.

通过改变固态纳米孔薄膜厚度,揭示了λ-DNA在电场作用下通过纳米孔时堵塞离子电流的作用机理.纳米孔的电导主要由孔内电阻和孔口电阻构成,当纳米孔长度逐渐减小到与原子层厚度相等时,电导主要由孔口电阻主导.根据已有的纳米孔孔口电阻模型,推导出一个简化的DNA分子堵塞纳米孔的相对离子电流模型,定量地描述了纳米孔薄膜厚度与相对堵塞电流大小之间的关系.结果表明,相对堵塞电流随着纳米孔直径的减小而增加,但随着纳米孔厚度的减小而减小.为提高相对堵塞电流,提出了一种二级结构,该结构设置了一个更小的纳米孔孔口电阻区域.实验结果显示,该结构使相对堵塞电流提高了21.9%.