Sugimoto Manabu, Kato Yuta, Ishida Kentaro, Hyun Changbae, Li Jiali, Mitsui Toshiyuki
Department of Mathematics and Physics, Aoyama-Gakuin University 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa, 252-5258, Japan.
Nanotechnology. 2015 Feb 13;26(6):065502. doi: 10.1088/0957-4484/26/6/065502. Epub 2015 Jan 22.
We used fluorescence microscopy to investigate the diffusion and drift motion of λ DNA molecules on an Au-coated membrane surface near nanopores, prior to their translocation through solid-state nanopores. With the capability of controlling electric potential at the Au surface as a gate voltage, Vgate, the motions of DNA molecules, which are presumably generated by electrokinetic flow, vary dramatically near the nanopores in our observations. We carefully investigate these DNA motions with different values of Vgate in order to alter the densities and polarities of the counterions, which are expected to change the flow speed or direction, respectively. Depending on Vgate, our observations have revealed the critical distance from a nanopore for DNA molecules to be attracted or repelled-DNA's anisotropic and unsteady drifting motions and accumulations of DNA molecules near the nanopore entrance. Further finite element method (FEM) numerical simulations indicate that the electrokinetic flow could qualitatively explain these unusual DNA motions near metal-collated gated nanopores. Finally, we demonstrate the possibility of controlling the speed and direction of DNA motion near or through a nanopore, as in the case of recapturing a single DNA molecule multiple times with alternating current voltages on the Vgate.
在λ DNA分子通过固态纳米孔转运之前，我们使用荧光显微镜研究了其在纳米孔附近金涂层膜表面的扩散和漂移运动。通过将金表面的电势作为栅极电压Vgate进行控制，在我们的观察中，推测由电动流产生的DNA分子运动在纳米孔附近发生了显著变化。我们仔细研究了不同Vgate值下的这些DNA运动，以改变抗衡离子的密度和极性，预计这将分别改变流速或流向。根据Vgate，我们的观察揭示了DNA分子被吸引或排斥的纳米孔临界距离——DNA的各向异性和不稳定漂移运动以及DNA分子在纳米孔入口附近的聚集。进一步的有限元方法（FEM）数值模拟表明，电动流可以定性地解释金属排列的栅控纳米孔附近这些不寻常的DNA运动。最后，我们证明了控制DNA在纳米孔附近或通过纳米孔运动的速度和方向的可能性，例如在Vgate上施加交流电压多次捕获单个DNA分子的情况。
