Probing Access Resistance of Solid-state Nanopores with a Scanning Probe Microscope Tip.
Probing Access Resistance of Solid-state Nanopores with a Scanning Probe Microscope Tip.
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DOI：
10.1002/smll.201101337
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发表时间：
2012-02-06
期刊：
影响因子：
13.3
通讯作者：
Li, Jiali
中科院分区：
文献类型：
--
作者：
Hyun, Changbae;Rollings, Ryan;Li, Jiali
关键词：
已经开发了一种将固态纳米孔离子电流测量与扫描探针显微镜集成的装置。当微米级扫描探针尖端靠近电压偏置的纳米级孔（10-100 nm）时，尖端部分地阻挡离子流到孔并增加孔进入电阻。该装置同时记录由探针尖端引起的电流阻塞和尖端的位置。通过测量在盐溶液中作为3D空间中的尖端位置的函数的纳米孔附近的电流阻塞图，我们估计由于尖端引起的相对孔电阻增加ΔR/R 0，作为尖端位置、纳米孔几何形状和盐浓度的函数。如欧姆定律所预测的，ΔR/R 0的幅度还取决于孔长度与其半径的比率。当针尖非常接近孔表面时，约10 nm，我们的实验表明ΔR/R 0取决于泊松和能斯特-普朗克方程预测的盐浓度。此外，我们的测量表明，当尖端距离孔入口中心约5倍孔径时，ΔR/R 0趋于零。这项工作的结果不仅展示了一种通过实验探测纳米孔的接入电阻的方法，它们还提供了一种在盐溶液中定位纳米孔的方法，并为未来的纳米孔实验打开了大门，用于检测附着在探针尖端上的单个生物分子。
An apparatus that integrates solid-state nanopore ionic current measurement with a Scanning Probe Microscope has been developed. When a micrometer-scale scanning probe tip is near a voltage biased nanometer-scale pore (10–100 nm), the tip partially blocks the flow of ions to the pore and increases the pore access resistance. The apparatus records the current blockage caused by the probe tip and the location of the tip simultaneously. By measuring the current blockage map near a nanopore as a function of the tip position in 3D space in salt solution, we estimate the relative pore resistance increase due to the tip, ΔR/R0, as a function of the tip location, nanopore geometry, and salt concentration. The amplitude of ΔR/R0 also depends on the ratio of the pore length to its radius as Ohm’s law predicts. When the tip is very close to the pore surface, ~10 nm, our experiments show that ΔR/R0 depends on salt concentration as predicted by the Poisson and Nernst-Planck equations. Furthermore, our measurements show that ΔR/R0 goes to zero when the tip is about five times the pore diameter away from the center of the pore entrance. The results in this work not only demonstrate a way to probe the access resistance of nanopores experimentally, they also provide a way to locate the nanopore in salt solution, and open the door to future nanopore experiments for detecting single biomolecules attached to a probe tip.
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DOI：
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