Controlling the Mechanical Properties of Fiber Bundles through their Molecular Architecture

在自然界中，成束的生物纤维是许多机械任务的常见解决方案。由于它们表现出不同寻常的机械性能和对不断变化的要求的惊人适应能力，它们也引起了纳米技术领域的兴趣。生物学中纤维束的一个例子是微管，它是各种细胞功能所必需的。它们是由平行细丝组成的管状蛋白细丝，它们的相互作用决定了整个微管的机械结构。在自然界中，微管的确切结构受到每种细胞类型的严格控制。纤维结构的一些最严重的力学后果预计将主要影响非常短的微管。然而，这些预测很难得到证实，因为用传统技术测量的短长度区域几乎无法达到。在拟议的研究中，我们将使用基于激光散射的高速、高分辨率位置检测系统，该系统将允许在以前无法访问的微管长度区域进行测量。微管的热涨落将被用来提取它们的力学性能。此外，该项目还将研究组成纤维的数量与新出现的机械性能之间的关系。结果将与最先进的聚合物模型进行比较。拟议的研究旨在识别和量化微管分子结构和力学之间的相互作用。这些结果不仅将使人们更深入地了解细胞功能是如何在分子水平上实现的，而且还将对纳米技术产生深刻的见解，因为它们可以推广到其他纤维束，包括人造纤维束。这项研究将使学生接触到理论物理、生物化学、分子生物学、工程学和材料科学等不同科学领域之间的丰富互动，从而训练他们发展跨学科的研究方法。

In nature, bundles of biological fibers are a common solution for many mechanical tasks. Because they exhibit unusual mechanical properties and a stunning adaptability to changing requirements, they are also of interest to the field of nanotechnology.One example of a fiber bundle in biology are microtubules which are essential for a variety of cell functions. They are tubular protein filaments which consist of parallel filaments whose interactions determine the mechanics of the overall microtubule. In nature, the exact architecture of microtubules is tightly controlled for each cell type. Some of the most drastic mechanical consequences of the fiber architecture are expected to predominantly affect very short microtubules. These predictions have however been difficult to verify because the short length regime is barely accessible to measurements with conventional techniques. In the proposed research, we will employ a high speed, high resolution position detection system based on the scattering of laser light which will allow for measurements in the previously inaccessible microtubule length regime. The thermal fluctuations of microtubules will be exploited to extract their mechanical properties. In addition, the project will study the connection between the number of constituent filaments and the emergent mechanical properties. Results will be compared to state-of-the-art polymer models.The proposed research aims to identify and quantify the interplay between microtubule molecular architecture and mechanics. The results will not only allow for a deeper understanding of how cellular functions are implemented on a molecular scale, but will also yield insights into nanotechnology because they can be generalized to other fiber bundles, including artificial ones. The gained knowledge may lead to new artificially designed materials available to consumers.The research will expose students to a rich interplay between scientific fields as diverse as theoretical physics, biochemistry, molecular biology, engineering and material science, thereby training them in developing an interdisciplinary approach towards research.