Collaborative Research: Multiscale engineering of active stress in biomaterials

摘要：生物系统表现出非凡的行为，包括自愈、繁殖和自我运动的能力。传统的合成材料没有表现出这种特性，因为它们是由无生命的分子组成的。相反，生物系统由活跃的能量传导分子组成，这些分子不断地相互推动和拉动，产生活跃的应力。这些活跃的压力使生物系统成为活跃物质的例子，并最终导致了它们许多不寻常的行为。创造人工活性物质为构建具有逼真功能的材料开辟了一条新途径。然而，实现这种可能性的一个重大障碍是缺乏对活动应力如何产生的理解：给定特定的元素构建块，目前没有工具来测量或理论上预测活动应力的大小、类型，甚至是标志。该项目将利用实验、模拟和理论的协同结合来阐明主动应力产生的基本原理。这项工作将导致创造新的实验工具来测量活性应力，新的合成程序来创造活性材料，以及新的多尺度建模技术来研究活性物质。综合推广计划将通过互动演示、先进的跨学科培训和密集的夏季课程，为K-12教育、本科生和毕业生带来活跃物质的兴奋。技术摘要：本课题主要研究微管和动力蛋白-14分子马达的组合。这项工作解决了理解这些活性材料产生的主动应力的三个基本挑战。首先是开发工具，利用光学镊子、流体流量测量、微流体和3D打印，结合理论和模拟，测量不同长度尺度下的主动应力。其次，一种新的系统将被创建，其中主动应力的产生将通过直接将驱动蛋白-14以预定的模式附着在微管上来调节。理论和模拟将用于指导创建哪种模式，反过来，测量这些设计材料中产生的活性应力将提供严格的理论和模拟测试。第三，将开发和测试一个多尺度建模框架。随后，这些将通过分析计算和模拟相结合而相互关联。所得到的模型将根据实验的持续反馈来建立。综上所述，这项工作将为研究、理解和设计活性材料中的主动应力建立新的范式。这项DMR拨款支持研究，以了解微管和激酶-14分子马达的组装，资金来自数学和物理科学理事会材料研究部的凝聚态物理（CMP）和生物材料（BMAT）项目。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Abstract:Biological systems exhibit remarkable behaviors, including the ability to heal, reproduce, and be self-motile. Conventional synthetic materials do not display such properties because they are composed of inanimate molecules. In contrast, biological systems consist of active, energy transducing molecules which continuously push and pull on each other, producing active stresses. These active stresses make biological systems examples of active matter, and are ultimately are responsible for many of their unusual behaviors. Creating artificial active matter opens up a new route towards constructing materials with lifelike functionalities. However, a significant obstacle to realizing this possibility is an absence of understanding of how active stresses are produced: given specific elemental building blocks, there are not currently tools to either measure or theoretically predict the magnitude, type, or even the sign of the active stresses. The project will elucidate the foundational principles of active stress generation using a synergistic combination of experiments, simulations, and theory. The work will result in the creation of new experimental tools for measuring active stresses, new synthesis procedures for creating active materials, and new multi-scale modeling techniques for studying active matter. An integrated outreach program will bring the excitement of active matter to K-12 education, undergraduates, and graduates by combining interactive demonstrations, advanced interdisciplinary training, and intensive summer courses.Technical Abstract:The research focuses on studying assemblages of microtubules and kinesin-14 molecular motors. The work addresses three fundamental challenges in understanding active stresses generated by such active materials. First is the development of tools to measure active stresses at different length scales using optical tweezers, fluid flow measurements, microfluidics, and 3D printing, in combination with theory and simulations. Second, a novel system will be created in which active stress generation will be modulated by directly affixing kinesin-14 to microtubules in predetermined patterns. Theory and simulations will be used to guide which patterns to create, and conversely, measuring the resulting active stress generation in these designed materials will provide a stringent test of theory and simulations. Third, a multi-scale modeling framework will be developed and tested. These will be subsequently related to each other through a combination of analytical calculations and simulations. The resulting models will be made with continual feedback from experiments. Taken together, this work will establish new paradigms to study, understand, and engineer active stresses in active materials.This DMR grant supports research to understand the assemblages of microtubules and kinesin-14 molecular motors with funding from the Condensed Matter Physics (CMP) and Biomaterials (BMAT) Programs in the Division of Materials Research of the Mathematical and Physical Sciences Directorate.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.