Growth process and molecular packing of a self-assembled lipid nanotube: Phase-contrast transmission electron microscopy and XRD analyses
Growth process and molecular packing of a self-assembled lipid nanotube: Phase-contrast transmission electron microscopy and XRD analyses
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DOI：
10.1021/la702488u
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发表时间：
2008-02-05
期刊：
影响因子：
3.9
通讯作者：
Shimizu, Toshimi
中科院分区：
文献类型：
--
作者：
Yui, Hiroharu;Minamikawa, Hiroyuki;Shimizu, Toshimi
相衬透射电子显微镜（PC-TEM）和快速冷冻方法相结合，研究了自组装脂质纳米管在水中的初始生长过程。 PC-TEM 使我们能够检测薄层状边缘结构以及新生边缘非常快速地生长成具有高对比度的细管。细管充当核心结构，用于进一步生长成厚的完整脂质纳米管。最初形成的纳米管结构被称为“芯管”。芯管具有均匀的壁结构，由五层层组成，芯管的内径和外径分别为130和180 nm。评估的层间距为 4.6 nm，与 X 射线衍射测量的层间距非常一致。我们还根据 PC-TEM 图像、广角区域的 X 射线衍射图和红外光谱确定的螺距角讨论了纳米管的分子堆积。纳米管的亚晶格结构属于斜方晶系类型。相邻脂质分子之间的扭转角被确定为约。首次0.26度；它是手性堆积中脂质纳米管形成的关键参数，但之前尚未得到阐明。
Phase-contrast transmission electron microscopy (PC-TEM) and quick freezing method have been combined to study the initial growing process of a self-assembled lipid nanotube in water. The PC-TEM enabled us to detect thin lamellar edge structure and the very fast growth of the newborn edge to a thin tube with high contrast. The thin tube acts as a core structure for further growth into, thick complete lipid nanotube. The initially formed nanotube structure is denoted as a "core tube". The core tube has uniform wall structure that consists of five lamellar layers and the inner and outer diameters of the core tube are 130 and 180 nm, respectively. The evaluated lamellar spacing of 4.6 nm is well compatible with that measured by X-ray diffraction. We also discussed the molecular packing of the nanotube from the pitch angle determined by the PC-TEM images, X-ray diffraction pattern in wide-angle region, and IR spectroscopy. The subcell structure of the nanotube is assigned to an orthorhombic type. The twisting angle between the neighboring lipid molecules is determined as ca. 0.26 degrees for the first time; it is a crucial parameter for the formation of a lipid nanotube in chiral packing but has not been elucidated before.