Collaborative Research: Mechanics and Microrheology of Biomimetic Materials

合作研究：仿生材料的力学和微观流变学

• 批准号: 0907212
• 负责人: Alexander Levine
• 金额: $ 33万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907212&HistoricalAwards=false
• 关键词: Collaborative; Research; Mechanics; Microrheology; Biomimetic

This award by the Biomaterials program in the Division of Materials Research in support of the collaborative efforts by University of California Los Angeles and University of California Irvine is to study the interaction between the nonequilibrium dynamics of molecular motors and the elastic nonlinearities of filamentous actin (F-actin) and determine the collective mechanical properties of the network, with coordinated experimental/theoretical approaches to address each of these challenges. The cytoskeleton of living cells is built primarily from cross-linked F-actin that, in living cells, is generically tensed by molecular motors such as myosin. The mechanical properties of this filament network have been shown to have a complex dependence on the state of activity of these molecular motors, and depend on a combination of the mechanics of the individual filaments, their network structure, and the non-equilibrium steady-state of the network. Understanding in detail how the mechanics of this network can be controlled by its internal stress state (imposed by the endogenous molecular motors) will enable us to better understand how cells control their mechanics and morphology, develop an understanding how cells sense and exert forces on their surroundings. To date, this field has focused on relating the equilibrium collective (non-)linear response properties of a material to the molecular structure of its constituents. With this award, F-actin networks associated with the air/water interface of a Langmuir monolayer will be studied. These 2D networks will then be tensed by molecular motors, and studied using both macro- and microrheology to elucidate the underlying relationship of network architecture (observed through fluorescent labeling of some of the filaments) and non-equilibrium stress state to its collective mechanics. The (quasi-) two-dimensional nature of the network allows for the direct observation of the local network structure, strain state, and provides a way to rapid in situ chemical modification of the system. Experiments on these biopolymer networks could provide insight about the active control of the nonequilibrium steady-state of biopolymer networks that allow the creation of a gel having reversibly tunable mechanical properties. Understanding this prototypical cytoskeletal biopolymer network may allow the development of novel biomimetic active materials with addressable mechanics. Teaching and training of graduate and undergraduate students in experimental and theoretical aspects of biophysics of soft materials, and developing a web site for the interpretation of microrheology are other parts of this award.Human cells are pervaded by a stiff biopolymer network that acts, much like the skeleton of our bodies, to maintain cellular shape and to allow the cell to exert forces on its environment through the action of molecular motors acting on this cytoskeleton. Recent advances have made it possible to deconstruct and then rebuild the principal structural elements of the cytoskeleton in the laboratory. With this award, the mechanical properties of this biopolymer network are measured, and will explore the relationship between network structure, molecular motor activity and large scale mechanics in these protein filament networks. The principal importance of this work is that these studies would provide better understanding how cells use molecular motors to exert forces on their environment and how the activity of these motors can modify the stiffness of the network in a reversible way. This understanding will help to elucidate fundamental design principles by which one may build artificial active materials that use nanomachines (i.e. molecular motors) to actively control their mechanical properties. Students, both graduate and undergraduate, will be trained in research activities that are related to biopolymer networks and their reversibly tunable mechanical properties.

该奖项由材料研究部生物材料项目颁发，支持加州大学洛杉矶分校和加州大学欧文分校的合作努力，旨在研究分子马达的非平衡动力学与丝状肌动蛋白的弹性非线性之间的相互作用（F -肌动蛋白）并确定网络的集体机械特性，并采用协调的实验/理论方法来解决这些挑战。活细胞的细胞骨架主要由交联的 F-肌动蛋白构成，在活细胞中，F-肌动蛋白通常由肌球蛋白等分子马达拉紧。该细丝网络的机械性能已被证明对这些分子马达的活​​动状态具有复杂的依赖性，并且取决于单个细丝的力学、其网络结构和非平衡稳态的组合网络的。详细了解该网络的力学如何通过其内部应力状态（由内源性分子马达施加）控制，将使我们能够更好地了解细胞如何控制其力学和形态，了解细胞如何感知并向其施加力。周围环境。迄今为止，该领域的重点是将材料的平衡集体（非线性）线性响应特性与其成分的分子结构联系起来。 凭借该奖项，我们将研究与 Langmuir 单层空气/水界面相关的 F-肌动蛋白网络。 然后，这些二维网络将通过分子马达张紧，并使用宏观和微观流变学进行研究，以阐明网络结构（通过一些细丝的荧光标记观察）和非平衡应力状态与其集体力学的基本关系。网络的（准）二维性质允许直接观察局部网络结构、应变状态，并提供了一种快速原位化学修饰系统的方法。 对这些生物聚合物网络的实验可以提供对生物聚合物网络非平衡稳态的主动控制的见解，从而允许创建具有可逆可调机械性能的凝胶。了解这种原型细胞骨架生物聚合物网络可能有助于开发具有可寻址力学的新型仿生活性材料。 该奖项的其他部分还包括对研究生和本科生进行软材料生物物理学实验和理论方面的教学和培训，以及开发一个解释微流变学的网站。人体细胞遍布着坚硬的生物聚合物网络，其作用就像我们身体的骨架，以维持细胞形状并允许细胞通过作用于该细胞骨架的分子马达的作用对其环境施加力。最近的进展使得在实验室中解构然后重建细胞骨架的主要结构元素成为可能。通过该奖项，可以测量该生物聚合物网络的机械性能，并将探索这些蛋白质丝网络中的网络结构、分子运动活动和大规模力学之间的关系。这项工作的主要重要性在于，这些研究将提供更好的理解细胞如何使用分子马达对其环境施加力，以及这些马达的活动如何以可逆的方式改变网络的刚度。这种理解将有助于阐明基本设计原则，通过这些原则，人们可以构建使用纳米机器（即分子马达）主动控制其机械性能的人造活性材料。 研究生和本科生将接受与生物聚合物网络及其可逆可调机械性能相关的研究活动培训。