Development of a Measurement Technique for Ion Distribution in an Extended Nanochannel by Super-Resolution-Laser-Induced Fluorescence
Development of a Measurement Technique for Ion Distribution in an Extended Nanochannel by Super-Resolution-Laser-Induced Fluorescence
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DOI：
10.1021/ac201654r
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发表时间：
2011-11-01
影响因子：
7.4
通讯作者：
Kitamori, Takehiko
中科院分区：
文献类型：
--
作者：
Kazoe, Yutaka;Mawatari, Kazuma;Kitamori, Takehiko
在扩展的纳米空间（10（1）-10（3）nm）中的离子行为对于具有主导表面效应的纳米流体和纳米化学是重要的。本文发展了一种新的纳米通道内离子分布的超分辨激光诱导荧光测量技术。使用受激发射耗尽显微镜实现高于衍射极限的87 nm的空间分辨率。黄绿素用于在两个激发波长下比率测量pH。成功地测量了宽度为410 nm、深度为405 nm的二维纳米通道中的pH分布，不确定度为0.05。过量的质子，显示出比本体更低的pH，不均匀地分布在纳米通道中以抵消玻璃壁的负电荷，特别是当双电层与通道尺寸相比较厚时。本研究首次揭示了纳米通道内或表面附近的离子分布，这与双电层直接相关。此外，所获得的质子分布对于理解单分子和连续相之间的纳米级水结构是重要的。这项技术将极大地有助于理解纳米尺度和界面动力学的基础科学，这是开发用于生化分析和进一步应用的新型小型化系统所迫切需要的。
Ion behavior confined in extended nanospace (10(1)-10(3) nm) is important for nanofluidics and nanochemistry with dominant surface effects. In this paper, we developed a new measurement technique of ion distribution in the nanochannel by super-resolution-laser-induced fluorescence. Stimulated emission depletion microscopy was used to achieve a spatial resolution of 87 nm higher than the diffraction limit. Fluorescein was used for ratiometric measurement of pH with two excitation wavelengths. The pH profile in a 2D nanochannel of 410 nm width and 405 nm depth was successfully measured at an uncertainty of 0.05. The excess protons, showing lower pH than the bulk, nonuniformly distributed in the nanochannel to cancel the negative charge of glass wall, especially when the electric double layer is thick compared to the channel size. The present study first revealed the ion distribution near the surface or in the nanochannel, which is directly related to the electric double layer. In addition, the obtained proton distribution is important to understand the nanoscale water structure between single molecules and continuum phase. This technique will greatly contribute to understanding the basic science in nanoscale and interfacial dynamics, which are strongly required to develop novel miniaturized systems for biochemical analysis and further applications.