中文摘要：

为了揭示高浓度盐溶液中DNA穿过纳米孔时的动力学行为,实验研究了poly（dT）20电泳穿过α溶血素纳米孔的输运机理.实验结果表明,阻塞电流主要由DNA的过孔事件和碰撞事件引起.2种事件引发的阻塞电流都随着外加电势的增加而线性增加.尽管外加电势存在差异,归一化之后的阻塞电流幅值却都保持不变.此外,poly（dT）20的碰撞事件持续时间并不受电压影响,而过孔时间却随着外加电势的增加而相应延长.这是由于胸腺嘧啶的堆叠效应较差,相比较其他碱基而言,在强电场力作用下,poly（dT）20更容易发生蜷曲,导致过孔阻力增加.分子动力学模拟也进一步对实验结果进行了验证.研究结果表明,增加跨膜电势差有助于降低柔性poly（dT）20的过孔速度,从而提高单分子的检测精度.

英文摘要：

Experiments of poly（dT）20 electrophoresis throughα-hemolysin nanopores were performed to unveil the electrophoretic transport mechanism of DNA through nanopores in high concentration potassium chloride solution. It is found that there are two obvious current blockades induced by poly（dT）20 translocation and collision events. Both blockade currents increase linearly with the applied bias voltage. However, the normalized blockade currents are almost kept the same although variable bias voltages are applied. The collision time of poly（dT）20 in the luminal site of the pore remains constant for different voltages. The translocation speed of poly（dT）20through the nanopore decreases with the increase of bias voltage. It is because as the potential increases, the drag force on the homopolymer helps it to crumple into a cluster much easier due to the poor stacking of thymine residues compared with homopolymers consisting of other nucleotides. Molecular dynamics simulations further confirm the experimental results. Increasing the applied bias voltage can slowdown the translocation velocity of the flexible poly（dT）20, which favors increasing the precision of single molecule detection by using nanopores.