Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States.
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.
ACS Appl Mater Interfaces. 2021 Jun 9;13(22):26339-26351. doi: 10.1021/acsami.1c04027. Epub 2021 May 24.
Mimicking the hierarchical assembly of natural fiber materials is an important design challenge in the manufacturing of nanostructured materials with biomolecules such as peptides. Here, we produce nanofibers with control of structure over multiple length scales, ranging from peptide molecule assembly into supramolecular building blocks called "bundlemers," to rigid-rod formation through a covalent connection of bundlemer building blocks, and, ultimately, to uniaxially oriented fibers made with the rigid-rod polymers. The peptides are designed to physically assemble into coiled-coil bundles, or bundlemers, and to covalently interact in an end-to-end fashion to produce the rigid-rod polymer. The resultant rodlike polymer exhibits a rigid, cylindrical nanostructure confirmed by transmission electron microscopy (TEM) and, correspondingly, exhibits shear-thinning behavior at low shear rates observed in many nanoscopic rod systems. The rigid-rod chains are further organized into final fiber materials via electrospinning processing, all the while preserving their unique rodlike structural characteristics. Morphological and structural investigations of the nanofibers through scanning electron microscopy, transmission electron microscopy, and X-ray scattering, as well as molecular characterization via Fourier transform infrared (FTIR) and Raman spectroscopy, show that continuous nanofibers are composed of oriented rigid-rod chains constituted by α-helical peptides within bundle building blocks. Mechanical properties of electrospun fibers are also presented. The ability to produce nanofibers from the oriented rigid-rod polymer reveals bundlemer chains as a viable tool for the development of new fiber materials with targeted structure and properties.
模拟天然纤维材料的分级组装是在制造具有生物分子（如肽）的纳米结构材料方面的一个重要设计挑战。在这里，我们通过控制结构来生产具有多个长度尺度的纳米纤维，从肽分子组装成称为“束状分子”的超分子构建块，到通过束状分子构建块的共价连接形成刚性棒，最终生产出具有刚性棒聚合物的单轴取向纤维。这些肽被设计为物理组装成螺旋束或束状分子，并以端到端的方式进行共价相互作用，从而产生刚性棒聚合物。所得的棒状聚合物通过透射电子显微镜（TEM）证实具有刚性的圆柱状纳米结构，相应地，在许多纳米棒系统中观察到的低剪切速率下表现出剪切稀化行为。刚性棒链通过静电纺丝处理进一步组织成最终的纤维材料，同时保持其独特的棒状结构特征。通过扫描电子显微镜、透射电子显微镜和 X 射线散射对纳米纤维进行形态和结构研究，以及通过傅里叶变换红外（FTIR）和拉曼光谱进行分子表征，表明连续的纳米纤维由取向的刚性棒链组成，这些链由束状构建块内的α-螺旋肽构成。还介绍了静电纺纤维的机械性能。从取向的刚性棒聚合物生产纳米纤维的能力揭示了束状分子作为开发具有目标结构和性能的新型纤维材料的可行工具。
