Measurement of the Docking Time of a DNA Molecule onto a Solid-State Nanopore
Measurement of the Docking Time of a DNA Molecule onto a Solid-State Nanopore
复制标题
DOI：
10.1021/nl301719a
复制
发表时间：
2012-08-01
期刊：
影响因子：
10.8
通讯作者：
Dekker, Cees
中科院分区：
文献类型：
--
作者：
Kowalczyk, Stefan W.;Dekker, Cees
我们提出了在低盐（100 rnM KCl）下通过小（6 nm直径）纳米孔进行双链DNA易位的离子电导变化的测量。在两个低电压（600 mV）下，我们观察到DNA易位过程中的电流增强，类似于先前的报道。然而，有趣的是，在中间电压范围内，我们观察到一种新型的复合事件，在每个单一事件中，电流先减小后增大。从这些电流变化的幅度和时间的电压依赖性来看，我们得出结论，电流的减少是由DNA随机线圈对接到纳米孔上引起的。出乎意料的是，我们发现对接时间与电压呈指数关系（t与e（-V/V0）成正比）。我们讨论了一个物理图像，其中对接时间是由DNA末端需要从DNA线圈内的随机位置移动到纳米孔的时间设定的。进入孔后，由于反离子沿DNA流动增强，电流随之增加。有趣的是，这些复合事件因此可以独立地测量实际的易位时间以及易位前的对接时间。
We present measurements of the change in ionic conductance due to double-stranded (ds) DNA translocation through small (6 nm diameter) nanopores at low salt (100 rnM KCl). At both low (600 mV) voltages we observe a current enhancement during DNA translocation, similar to earlier reports. Intriguingly, however, in the intermediate voltage range, we observe a new type of composite events, where within each single event the current first decreases and then increases. From the voltage dependence of the magnitude and timing of these current changes, we conclude that the current decrease is caused by the docking of the DNA random coil onto the nanopore. Unexpectedly, we find that the docking time is exponentially dependent on voltage (t proportional to e(-V/V0)). We discuss a physical picture where the docking time is set by the time that a DNA end needs to move from a random location within the DNA coil to the nanopore. Upon entrance of the pore, the current subsequently increases due to enhanced flow of counterions along the DNA. Interestingly, these composite events thus allow to independently measure the actual translocation time as well as the docking time before translocation.