Collaborative Research: Mechanics and Structural Polymorphism of Bacterial Flagellar Assemblies

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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.