Materials Science and Engineering Department , University of Delaware , Newark , Delaware 19716 , United States.
Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States.
Biomacromolecules. 2018 Nov 12;19(11):4286-4298. doi: 10.1021/acs.biomac.8b01163. Epub 2018 Oct 9.
Computationally designed peptides form desired antiparallel, tetrameric coiled-coil bundles that hierarchically assemble into a variety of well-controlled nanostructures depending on aqueous solution conditions. The bundles selectively self-assemble into different structures: nanotubes, platelets, or needle-like structures at solution pH values of 4.5, 7, and 10, respectively. The self-assembly produces hollow tubes or elongated needle-like structures at pH conditions associated with charged bundles (pH 4.5 or 10); at neutral pH, near the pI of the bundle, a plate-like self-assembled structure forms. Transmission electron microscopy and small-angle X-ray scattering show the nanotubes to be uniform with a tube diameter of ∼13 nm and lengths of up to several μm, yielding aspect ratios >1000. Combining the measured nanostructure geometry with the apparent charged states of the constituent amino acids, a tilted-bundle packing model is proposed for the formation of the homogeneous nanotubes. This work demonstrates the successful use of assembly pathway control for the construction of nanostructures with diverse, well-structured morphologies associated with the folding and self-association of a single type of molecule.
通过计算设计的肽形成所需的反平行、四聚体螺旋卷曲束，根据水溶液条件，这些卷曲束会分层组装成各种具有良好控制的纳米结构。在溶液 pH 值为 4.5、7 和 10 时，束选择性地自组装成不同的结构：纳米管、血小板或针状结构。自组装在与带电荷束相关的 pH 值条件下（pH 值为 4.5 或 10）产生空心管或拉长的针状结构；在中性 pH 值下，即接近束的等电点时，形成板状自组装结构。透射电子显微镜和小角 X 射线散射表明，纳米管均匀，管直径约为 13nm，长度可达数 μm，纵横比>1000。将测量的纳米结构几何形状与组成氨基酸的明显带电状态相结合，提出了一种倾斜束堆积模型，用于形成均匀的纳米管。这项工作成功地展示了利用组装途径控制来构建具有不同、结构良好形态的纳米结构的方法，这些形态与单一类型分子的折叠和自组装有关。
