Yamamoto Tatsuhiro, Murakami Yoichi, Motoyanagi Jin, Fukushima Takanori, Maruyama Shigeo, Kato Masaru
Center for NanoBio Integration, The University of Tokyo, Tokyo 113-8656, Japan.
Anal Chem. 2009 Sep 1;81(17):7336-41. doi: 10.1021/ac901197v.
Nanomaterials continue to attract widespread attention in many scientific and technological fields. The sizes and shapes of nanomaterials determine their physical and chemical properties. We have developed an analytical system for single nanomaterials that combines capillary electrophoresis (CE) with a highly sensitive detection method. In this manuscript, we combined CE with Raman spectroscopy or with scanning probe microscopy (SPM) for the analysis of individual single-walled carbon nanotubes (SWNTs). To combine CE with these detection techniques, we fabricated a fraction collection system that can collect droplets of small volume (<300 nL) in a small hydrophilic spot on a fractionation glass plate. The CE-separated fractions were concentrated by the evaporation of effluent, thus increasing the sensitivity by more than a factor of 10 in the case of Raman spectroscopic analysis. We characterized the fractionated SWNTs by means of Raman spectroscopy and SPM, both of which detected single SWNTs. Raman analysis enabled us to recognize a diameter difference of only 0.02 nm between SWNTs, and it was supposed that the separation by CE occurred based on the diameters of the SWNTs. We also observed a fibrous SWNT structure 1 nm high via SPM, and this structure was thought to be a single SWNT. These combined analytical systems enable the precise separation and characterization of individual SWNTs. We expect that methods developed herein can be applied to the analysis of many nanomaterials, because these methods offer separation and analysis with nanometer-scale precision. The characterization of nanomaterials at the single-compound level will be a necessity as the field of nanomaterials continues to evolve, and these combined methods may become indispensable techniques for the analysis of widely available nanomaterials.
纳米材料在许多科技领域持续吸引着广泛关注。纳米材料的尺寸和形状决定了它们的物理和化学性质。我们开发了一种用于单个纳米材料的分析系统，该系统将毛细管电泳（CE）与高灵敏度检测方法相结合。在本论文中，我们将CE与拉曼光谱或扫描探针显微镜（SPM）相结合，用于分析单个单壁碳纳米管（SWNTs）。为了将CE与这些检测技术相结合，我们制作了一个馏分收集系统，该系统可以在分馏玻璃板上的一个小亲水性斑点中收集小体积（<300 nL）的液滴。通过流出物的蒸发对CE分离的馏分进行浓缩，因此在拉曼光谱分析的情况下，灵敏度提高了10倍以上。我们通过拉曼光谱和SPM对分馏后的SWNTs进行了表征，这两种方法都检测到了单个SWNTs。拉曼分析使我们能够识别出SWNTs之间仅0.02 nm的直径差异，并且推测CE分离是基于SWNTs的直径发生的。我们还通过SPM观察到了一个1 nm高的纤维状SWNT结构，并且认为该结构是单个SWNT。这些组合分析系统能够对单个SWNTs进行精确分离和表征。我们期望本文开发的方法能够应用于许多纳米材料的分析，因为这些方法提供了纳米级精度的分离和分析。随着纳米材料领域的不断发展，在单化合物水平上对纳米材料进行表征将成为必要，并且这些组合方法可能会成为分析广泛可用的纳米材料不可或缺的技术。
