Creating Dynamic and Adaptive Force-Producing Nanostructures

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Creating dynamic and adaptive force-producing nanostructuresNon-Technical Abstract: The heart muscle can operate reliably for more than a hundred years, but the molecules which generate the force to contract are replaced every few days. Muscle also responds to exercise with growth and will shrink if not used. Clearly, nature has developed ways to produce force very reliably and efficiently by dynamically organizing the molecules in this biological material. The goal of the proposed project is to take the first steps towards creating such materials in the laboratory. To this end, this project will investigate the approaches used by nature in the construction of muscles, and translate them to the engineering of man-made materials assembled from the same type of molecules used in muscles. The goal is to show that structures can be created "similar to muscle" that can be long-lived by automatically replacing their aging parts and can adapt to changing conditions by adding and releasing parts as needed. Compared to the traditional engineering approach where, for example, a long-lasting car is assembled from even more durable components, this bio-inspired approach may offer great benefits for engineering. At the same time it will help us to better understand the natural way of constructing muscles and other tissues. This understanding in turn can contribute to efforts to combat aging and restore bodily functions in medicine. In addition to obtaining new research insights, the aim is to inspire and train students at all levels. For example, teams of high school and undergraduate students will be mentored to compete in the BIOMOD biomolecular design competition.Technical Abstract: Future active materials that assemble molecular motors into structures with macroscopic force output will have to be engineered based on self-organization principles supporting the extraction of work, constant regeneration, and adaptation. The goal of this project is to discover these principles and investigate their application in a minimal model system utilizing motor proteins as the force- producing molecular components. In order to maintain these active nanostructures in a functional state beyond the limited lifetime of their active molecular components, this project will abstract the mechanisms which allow biological materials to maintain their function for a duration far beyond the lifetime of the components. In particular the roles of self-organization and continuous turnover, and the balance between desired structural stability and ease of component replacement will be investigated. The specific objectives of this research are (1) to create a structure in dynamic equilibrium where microtubules are propelled by kinesin motors weakly and reversibly bound to a surface, (2) to demonstrate that adaptation to changing loading conditions is possible due to the dynamic equilibrium established, and (3) to demonstrate that the dynamic recruitment of kinesin motors to microtubules lowers the number of motors required for stable microtubule gliding relative to a static configuration where motors are permanently adhered everywhere on the surface. The insights from these experiments will in return assist in developing a theoretical understanding of how biological materials both prevent and heal damage, and will be generalizable for the design of novel synthetic and hybrid materials. The project will integrate undergraduate and high school students in the research process and aim to recruit graduate students from underrepresented groups. Various outreach activities to local K-12 students are planned. The outcome of the project will be potentially transformational in that it aims to assist in a paradigm shift from durable man-made structures assembled from equally durable nanoscale components to durable and adaptive engineered structures composed of short-lived nanoscale components with continuous replacement.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.