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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Departments of Materials, University of California, Santa Barbara, CA 93106
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Departments of Materials, University of California, Santa Barbara, CA 93106

机译：加利福尼亚大学材料系，加利福尼亚州圣塔芭芭拉分校93106

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Cellular factors tightly regulate the architecture of bundles of filamentous cytoskeletal proteins, giving rise to assemblies with distinct morphologies and physical properties, and a similar control of the supramolecular organization of nanotubes and nanorods in synthetic materials is highly desirable. However, it is unknown what principles determine how macromolecular interactions lead to assemblies with defined morphologies. In particular, electrostatic interactions between highly charged polyelectrolytes, which are ubiquitous in biological and synthetic self-assembled structures, are poorly understood. We have used a model system consisting of microtubules (MTs) and multivalent cations to examine how microscopic interactions can give rise to distinct bundle phases in biological polyelectrolytes. The structure of these supramolecular assemblies was elucidated on length scales from subnanometer to micrometer with synchrotron x-ray diffraction, transmission electron microscopy, and differential interference contrast microscopy. Tightly packed hexagonal bundles with controllable diameters were observed for large trivalent, tetravalent, and pentavalent counterions. Unexpectedly, in the presence of small divalent cations, we have discovered a living necklace bundle phase, comprised of 2D dynamic assemblies of MTs with linear, branched, and loop topologies. This new bundle phase is an experimental example of nematic membranes. The morphologically distinct MT assemblies give insight into general features of bundle formation and may be used as templates for miniaturized materials with applications in nanotechnology and biotechnology.
机译：细胞因子紧密调节丝状细胞骨架蛋白束的结构，从而产生具有不同形态和物理特性的组装，并且非常需要合成材料中纳米管和纳米棒的超分子组织的类似控制。然而，尚不清楚什么原理决定大分子相互作用如何导致具有确定形态的组装。尤其是，人们对在生物和合成自组装结构中普遍存在的高电荷聚电解质之间的静电相互作用了解甚少。我们已经使用由微管（MTs）和多价阳离子组成的模型系统来检查微观相互作用如何在生物聚电解质中产生不同的束相。通过同步加速器X射线衍射，透射电子显微镜和微分干涉对比显微镜，从亚纳米到微米的长度尺度阐明了这些超分子组装体的结构。对于大的三价，四价和五价抗衡离子，观察到了直径可控的紧密堆积的六边形束。出乎意料的是，在存在小的二价阳离子的情况下，我们发现了一条活的项链束相，该相由具有线性，分支和环状拓扑的MT的2D动态组装组成。这个新的束相是向列膜的实验实例。形态学上不同的MT组件可洞悉束形成的一般特征，并可作为纳米技术和生物技术中应用的小型化材料的模板。

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