Engineering Cytoskeletal Active Materials

生命有机体自发地进行复杂的形状变化和运动。这些特性是由生物有机体内部的独特材料实现的。许多生物分子，其中一些具有分子马达的功能将化学能转化为机械能。当这些马达协同工作时，它们会产生具有内力的流体和固体，这些内力会自发流动并改变形状。在这项提议中，研究人员将使用分子工程来创造自然界中没有的合成分子马达，目的是发现新型的行为和对活性材料的控制。这项工作将使新型材料能够重现活细胞的行为，包括定向运动和分裂。技术摘要：本课题的科学目标是通过调整组分的活性来控制活性软材料的结构、力学和输运特性。活性材料构成了一个广泛的系统，其中包含分布的应力产生元素，这些元素是其自发运动、图案形成和形状变化的基础。在活细胞内，机械化学活性蛋白的集合支持细胞和组织尺度上的形态形成过程，具有精确的时空控制。细胞骨架材料的常见结构基序是生物聚合物和分子马达的集合（例如肌动蛋白丝与肌球蛋白马达和微管与运动蛋白马达）。这项工作将利用分子运动工程的最新进展来构建具有可控主动应力源的活性材料，这些活性应力源可以在时空上进行修改。这将有助于理解机械酶的分子尺度特性如何调节由此产生的可收缩凝胶和可拉伸流体的新兴生物物理和材料行为。这里提出的工作将开发多功能的新实验平台来设计和研究空间结构的活性材料。这项工作的应用被设想为构建新型的自主和力敏感材料。此外，这些研究将阐明材料的设计原理，细胞运动，分裂和形状的基本特性。这项工作的广泛影响将在材料科学、合成生物学和细胞生物学之间的界面创造新的知识，培养跨学科的工作队伍，提高STEM劳动力的多样性。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。

Non-technical Abstract Living organisms spontaneously execute complex shape changes and motions. These properties are enabled by the unique materials within biological organisms. Many of the biological molecules, some of which have the capability to act as molecular motors to convert chemical energy into mechanical work. When these motors work in concert, they build fluids and solids with internal forces that spontaneously flow and change shape. In this proposal, the investigators will use molecular engineering to create synthetic molecular motors not found in nature with the goal to discover new types of behaviors and control over active materials. This work will enable new classes of materials that can recapitulate behaviors of living cells, including directed motion and division.Technical AbstractThe scientific goal of this proposal is to engineer active soft materials whose structure, mechanics and transport properties can be controlled by tuning the activity of constituents. Active materials constitute a broad class of systems that contain distributed stress-generating elements which underlie their spontaneous motion, pattern formation and shape changes. Within living cells, ensembles of mechanochemically active proteins support morphogenic processes at cellular and tissue scales with precise spatiotemporal control. A common structural motif of cytoskeletal materials are collections of biopolymers and molecular motors (e.g. actin filaments with myosin motors and microtubules with kinesin motors). The proposed work will exploit recent advances in molecular motor engineering to construct active materials with controllable sources of active stress that can be spatiotemporally modified. This will enable understanding of how molecular-scale properties of mechanoenzymes regulate the emergent biophysical and material behaviors of the resultant contractile gels and extensile fluids. The work proposed here will develop versatile new experimental platforms to engineer and study spatially structured active materials. Applications of this work is envisioned to construct new classes of autonomous and force-sensitive materials. Moreover, these studies will shed light on the materials design principles properties that underlie cell motility, division and shape. The broader impacts of this work will create new knowledge at the interface between materials science, synthetic biology and cell biology, train an interdisciplinary work force and improve diversity in the STEM workforce.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.