Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
ACS Nano. 2013 Aug 27;7(8):6816-24. doi: 10.1021/nn403575n. Epub 2013 Jul 26.
Practical applications of solid-state nanopores for DNA detection and sequencing require the electrophoretic motion of DNA through the nanopores to be precisely controlled. Controlling the motion of single-stranded DNA presents a particular challenge, in part because of the multitude of conformations that a DNA strand can adopt in a nanopore. Through continuum, coarse-grained and atomistic modeling, we demonstrate that local heating of the nanopore volume can be used to alter the electrophoretic mobility and conformation of single-stranded DNA. In the nanopore systems considered, the temperature near the nanopore is modulated via a nanometer-size heater element that can be radiatively switched on and off. The local enhancement of temperature produces considerable stretching of the DNA fragment confined within the nanopore. Such stretching is reversible, so that the conformation of DNA can be toggled between compact (local heating is off) and extended (local heating is on) states. The effective thermophoretic force acting on single-stranded DNA in the vicinity of the nanopore is found to be sufficiently large (4-8 pN) to affect such changes in the DNA conformation. The local heating of the nanopore volume is observed to promote single-file translocation of DNA strands at transmembrane biases as low as 10 mV, which opens new avenues for using solid-state nanopores for detection and sequencing of DNA.
为了将固态纳米孔实际应用于 DNA 检测和测序，需要精确控制 DNA 通过纳米孔的电泳运动。控制单链 DNA 的运动特别具有挑战性，部分原因是 DNA 链在纳米孔中可以采用多种构象。通过连续体、粗粒度和原子建模，我们证明可以通过局部加热纳米孔体积来改变单链 DNA 的电泳迁移率和构象。在所考虑的纳米孔系统中，通过可以辐射打开和关闭的纳米级加热元件来调节纳米孔附近的温度。局部温度升高会导致 DNA 片段在纳米孔内产生相当大的拉伸。这种拉伸是可逆的，因此 DNA 的构象可以在紧凑（局部加热关闭）和扩展（局部加热打开）状态之间切换。发现在纳米孔附近作用于单链 DNA 的有效热泳力足够大（4-8 pN），足以影响 DNA 构象的这种变化。观察到纳米孔体积的局部加热可促进 DNA 链在跨膜偏压低至 10 mV 时的单分子线传输，这为使用固态纳米孔进行 DNA 检测和测序开辟了新途径。
