Controlling the Mechanical Properties of Fiber Bundles through their Molecular Architecture

在自然界中，生物纤维束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性，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，它对各种细胞功能至关重要。它们是由平行细丝组成的管状蛋白质细丝，其相互作用决定了整个微管的力学。在自然界中，微管的确切结构对于每种细胞类型都是严格控制的。纤维结构的一些最剧烈的机械后果预计将主要影响非常短的微管。然而，这些预测很难验证，因为短的长度制度几乎无法使用传统技术进行测量。在拟议的研究中，我们将采用基于激光散射的高速，高分辨率位置检测系统，这将允许在以前无法访问的微管长度制度的测量。微管的热涨落将被用来提取它们的力学性质。此外，该项目还将研究构成纤维的数量与新兴机械性能之间的联系。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。这些结果不仅可以更深入地了解细胞功能是如何在分子尺度上实现的，而且还可以深入了解纳米技术，因为它们可以推广到其他纤维束，包括人造纤维束。 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相互作用，从而培养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.