Relaxation dynamics in biological fiber bundles

纤维束广泛存在于自然界。它们促进了多种生物功能，并显示出不同寻常的机械性能。细胞生物学中纤维束的一个例子是参与许多细胞功能的微管。微管是管状的，由小的蛋白质细丝组成，它们的相互作用决定了整个微管的机械结构。最近的研究提供了证据表明，这种特殊的分子结构导致了意想不到的机械性能，其中最重要的是随着时间的延长，它们变得更坚硬，抗弯曲。这一发现还表明，分子结构在很大程度上决定了弯曲的微管松弛到平衡状态的速度。因此，需要进行系统的研究，以解决在广泛的灯丝长度范围内分子结构、力学和动力学性质之间的相互作用。在拟议的研究中，将用高分辨率光学显微镜分析微管自然产生的弯曲变形的松弛，并与考虑微管分子结构的理论模型进行比较。这项研究将对材料科学和工程具有重要意义，因为这些知识可以用于设计具有新的力学性能的材料。更广泛地说，人们将对细胞中的多功能纤维材料有更好的了解。该项目将使学生接触到材料科学与工程、理论物理、物理化学和分子生物学等不同科学领域之间的丰富互动，从而培养他们进行跨学科研究的方法。

Fiber bundles are widely found in nature. They facilitate a multitude of biological functions and exhibit unusual mechanical properties. An example of a fiber bundle in cell biology is the microtubule which is involved in many cell functions. Microtubules are tubular-shaped, formed of small protein filaments whose interactions determine the mechanics of the overall microtubule. Recent studies have provided evidence that this specific molecular architecture leads to unexpected mechanical properties, the most important of which is that they become stiffer against bending as they grow longer. This finding also suggests that the molecular architecture largely determines how fast a bent microtubule relaxes to its equilibrium state. Thus, a systematic study is needed to address the interplay between molecular architecture, mechanics, and dynamical properties over a wide range of filament lengths. In the proposed research, the relaxation of naturally occurring bending deformations of microtubules will be analyzed with high-resolution light microscopy and compared with theoretical models that take the molecular architecture of microtubules into account. The research will be important for material science and engineering as the knowledge can be used to design materials with novel mechanical properties. More generally a better understanding of multifunctional fiber materials in cells will be obtained. The project will expose students to a rich interplay between scientific fields as diverse as material science and engineering, theoretical physics, physical chemistry, and molecular biology, thereby educating them in an interdisciplinary approach towards research.