Collaborative Research: Mechanics and Structural Polymorphism of Bacterial Flagellar Assemblies

该奖项的目的是组装自限结构和材料，这些结构和材料会随着环境条件的变化而发生大规模的结构变化，如温度、溶液性质或施加的力。作为基本的构建模块，该项目将利用细菌鞭毛，一种螺旋聚合物，作为纳米级弹簧，并表现出非单调的力-延伸关系，这在合成材料中并不常见。为了实现这一目标，该项目将利用实验，计算和理论工具的组合，以阐明鞭毛为基础的材料在三个层次的行为。首先，该项目将表征和模拟单个鞭毛的机制，以及嵌合鞭毛工程，以实现新的多态转换反应。第二，将产生，表征和控制一对鞭毛之间的吸引力相互作用。最后，这些相同的吸引相互作用将用于组装鞭毛束或由数千个鞭毛组成的绳。这项研究有望产生纳米结构的，响应性纤维材料，具有良好的控制机械和结构性能，其中单个单体单元在埃尺度上的构象变化在多个长度尺度上协同级联，以产生毫米级材料的宏观机械变化。该项目的教育和研究部分将通过扩大REU计划进行整合，为参加马萨诸塞州布兰代斯大学和大学夏季研究的本科生举办年度“理论与实验”研讨会，让新手研究人员了解软材料理论和实验研究的独特和互补方法。此外，还将与宾夕法尼亚大学设计学院的建筑师、设计师和讲师Jennifer Sabin建立合作伙伴关系，以探索复杂的生物聚合物组装图案与最先进的纺织品设计和制造工艺之间的关系。

The objective of this award is to assemble self-limited structures and material that undergo large-scale structural changes in response to changing environmental conditions such as temperature, solution properties, or imposed force. As a basic building block the project will utilize bacterial flagella, a helical polymer which acts as a nanoscale spring and exhibits non-monotonic force-extension relationship that is not commonly found in synthetic materials. To achieve the goal the project will utilize a combination of experimental, computational and theoretical tools to elucidate the behavior of flagella based materials at three levels of hierarchy. First, the project will characterize and model the mechanics of individual flagella, as well as chimeric flagella engineered to achieve new polymorphic switching responses. Second, will be to generate, characterize, and control attractive interactions between a pair of flagella. Finally, these same attractive interactions will be used to assemble flagellar bundles or ropes consisting of thousands of flagella. This study holds the promise to generate nano-structured, responsive fibrous materials with well-controlled mechanical and structural properties, in which conformational changes of individual monomeric units at Angstrom scales cooperatively cascade across multiple lengthscales to produce macroscopic mechanical changes in millimeter-sized materials. The educational and research component of this project will be integrated by expanding an REU program to hold an annual "Theory Meets Experiment" symposium for undergraduates participating in summer research at Brandeis and University of Massachusetts, to expose novice researchers to the distinct and complementary methods of theoretical and experimental research in soft materials. In addition, a partnership will be explored with Jennifer Sabin, architect, designer, and lecturer at the University of Pennsylvania School of Design in order to explore the relationship between complex biopolymer assembly motifs and a state-of-the-art textile design and fabrication process.