Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, China.
Department of Radiation Oncology, Jiangxi Cancer Hospital, Nanchang 330029, China.
Langmuir. 2024 Mar 19;40(11):5799-5808. doi: 10.1021/acs.langmuir.3c03596. Epub 2024 Mar 5.
Nanopores are powerful single-molecule sensors for analyzing biomolecules such as DNA and proteins. Understanding the dynamics of DNA capture and translocation through nanopores is essential for optimizing their performance. In this study, we examine the effects of applied voltage and pore diameter on current blockage, translocation time, collision, and capture location by translocating λ-DNA through 5.7 and 16 nm solid-state nanopores. Ionic current changes are used to infer DNA conformations during translocation. We find that translocation time increases with pore diameter, which can be attributed to the decrease of the stall force. Linear and exponential decreases of collision frequency with voltage are observed in the 16 and 5.7 nm pores, respectively, indicating a free energy barrier in the small pore. Moreover, the results reveal a voltage-dependent bias in the capture location toward the DNA ends, which is explained by a "pulley effect" deforming the DNA as it approaches the pore. This study provides insights into the physics governing DNA capture and translocation, which can be useful for promoting single-file translocation to enhance nanopore sensing.
纳米孔是分析生物分子（如 DNA 和蛋白质）的强大单分子传感器。了解 DNA 通过纳米孔的捕获和迁移动力学对于优化其性能至关重要。在这项研究中，我们通过将 λ-DNA 穿过 5.7nm 和 16nm 的固态纳米孔，研究了外加电压和孔径对电流阻塞、迁移时间、碰撞和捕获位置的影响。我们使用离子电流变化来推断 DNA 在迁移过程中的构象。我们发现迁移时间随孔径的增大而增加，这可以归因于阻滞力的减小。在 16nm 和 5.7nm 孔中，分别观察到碰撞频率与电压呈线性和指数下降，表明在小孔中存在自由能势垒。此外，结果揭示了捕获位置对 DNA 末端的电压依赖性偏向，这可以通过“滑轮效应”来解释，即在 DNA 接近孔时，它会变形。这项研究提供了对 DNA 捕获和迁移物理规律的深入了解，这对于促进单分子迁移以增强纳米孔传感是有用的。
