NSF-Europe: Mechanical Properties of Thin-Film Active Materials

该项目资助了理论家（马萨诸塞大学阿默斯特分校和阿姆斯特丹自由大学）和实验家（加州大学欧文分校和自由大学）之间的国际合作的美国部分，以研究分子马达驱动的生物聚合物网络（F-肌动蛋白）的材料特性。更好地了解这些系统的材料特性将有助于阐明真核细胞的细胞骨架的材料特性，并促进基于细胞骨架设计基序的新型仿生材料的开发。为了能够直接观察网络内的应变场，并从与细胞脂膜偶联的细胞骨架的数据中得出推论，这些实验将在朗缪尔单层的表面进行。为了开发所需的实验技术，该合作涉及F-肌动蛋白/分子马达和Langmuir单层的专家。他们的实验工作将与正在开发半柔性凝胶变形特性新模型的理论家密切合作。理论家将与他们的实验同事密切合作，进一步完善用于该系统的微观流变学技术（并通过扩展，在细胞内微观流变学实验），以及开发微观结构和运动活性之间的关系的预测模型活性凝胶及其流变学特性。这项工作将有一个强大的教育组成部分，因为它将作为一个新的科学家，能够跨物理学和生物学学科工作的培训基地。各个职业层次的年轻科学家，包括本科生、研究生和博士后研究人员，都将参与该项目。该项目为美欧联合合作的美国部分提供资金。在纳米科学中正在进行的令人兴奋的努力之一是适应生物机器或生物材料的技术应用。要做到这一点，首先必须了解生物系统功能背后的物理特性。这项研究集中在生物材料的一个特定子集：活性材料。在活性材料中，材料对外力或扭曲的反应取决于内部活性元素的状态，如马达蛋白。该项目将系统地研究由三部分组成的活性材料：空气-水界面上的表面活性剂单层;附着在单层上的蛋白质纤维网络，称为肌动蛋白;以及连接到肌动蛋白网络的运动蛋白。该项目的核心是理论与实验之间的相互作用，因为需要开发用于局部测量机械性能的新技术。这项工作将有一个强大的教育组成部分，因为它将作为一个新的科学家，能够跨物理学和生物学学科工作的培训基地。年轻的科学家在他们的职业生涯的各个层次，本科生，研究生和博士后研究人员，将参与该项目。

This project funds the US component of an international collaboration between theorists (University of Massaschusetts, Amherst and the Vrije Universiteit in Amsterdam) and experimentalists (University of California, Irvine and the Vrije Universiteit) to study the material properties of biopolymer networks (F-actin) driven by molecular motors. A better fundamental understanding of the material properties of such systems will help to elucidate the materials properties of the cytoskeleton of eukaryotic cells and facilitate the development of novel, biomimitic materials based on cytoskeletal design motifs. In order to both enable the direct observation of the strain field within the network and to draw inferences from the data regarding the cytoskeleton coupled to the lipid membrane of the cell, these experiments will be performed at the surface of a Langmuir monolayer. To develop the required experimental techniques the collaboration involves experts in both F-actin/molecular motors and Langmuir monolayers. Their experimental work will be done in close collaboration with theorists who are developing a new model of the deformation properties of semiflexible gels. The theorists will work closely with their experimental colleagues to further refine microrheology techniques for use in this system (and, by extension, in intracellular microrheological experiments) as well as to develop predictive models of the relationship between the microstructure and motor activity of the active gel and its rheological properties. There will be a strong educational component of this work, as it will serve as the training ground for a new breed of scientists that are capable of working across the disciplines of physics and biology. Young scientists at all levels of their career, undergraduate, graduate students, and post-doctoral researchers, will be involved in the project.This project funds the US component of a joint US-European collaboration. One of the exciting efforts underway in nanoscience is the adaptation of bio-machines or bio-materials for technological applications. To accomplish this, one must first understand the physical properties underlying the function of the biological systems. This research focuses on a particular subset of biomaterials: active materials. In active materials, the response of the material to external forces or distortions depends on the state of internal active elements, such as motor proteins. This project will systematically study an active material consisting of three parts: a surfactant monolayer at the air-water interface; a network of protein fibers, known as actin, that are attached to the monolayer; and motor proteins connected to the actin network. Central to this project is the interaction between theory and experiment, as new techniques for making local measurements of mechanical properties need to be developed. There will be a strong educational component of this work, as it will serve as the training ground for a new breed of scientists that are capable of working across the disciplines of physics and biology. Young scientists at all levels of their career, undergraduate, graduate students, and post-doctoral researchers, will be involved in the project.