Seeing is believing: Submicroscopic visualization of semiflexible polymer networks and extraction of structural and mechanical parameters

非技术：生物纤维是一种多功能材料，可以形成多种结构，具有独特的性能，一段时间以来一直是材料科学家的灵感来源。构成细胞骨架和细胞外基质的纤维在细胞间传递信号，并决定细胞的命运。这种细胞反应对环境的机械特性和结构的强烈依赖为通过精心设计的生物相容性和可生物降解材料来控制细胞生长和组织形成提供了新的机会。即将进行的研究将增加我们对这些材料中发生的亚微观变化的直观理解，这些变化是对当地或全球力量的反应。因此，我们期望我们的研究能够促进用于三维控制细胞生长的新材料的创造，例如用于人造组织的创造和药物输送。在这个项目过程中获得的三维超分辨率图像将用于教育学生和公众对这类重要材料的认识。教师和K-12学生将通过参观、暑期研究和在学校的演讲直接接触到这项研究。该项目将通过国际合作加强研究和教育的基础设施。技术：细胞骨架和细胞外细丝属于大类别的半柔性聚合物，其弹性响应来自熵弹性和焓弹性贡献。在宏观尺度上，半柔性生物聚合物网络表现出独特的非线性弹性响应（应变硬化）。在许多情况下，这种非线性响应的微观起源仍然不清楚，因为缺乏亚微观数据，这些数据可以与宏观尺度联系起来，如局部网络结构、交联剂弹性或网络中的张力分布。这个项目的目标是可视化亚微观的网络结构，它对全球和局部力量的反应，以及网络中产生的力量分布。研究生和本科生将在一个跨学科的环境中接受由PI小组开发的最先进的三维扫描探针显微镜的培训。

Non-technical: Biological fibers are multifunctional materials that form a variety of structures with unique properties that have been an inspiration for material scientists for some time. Fibers that make up the cell's cytoskeleton and the extracellular matrix transmit signals between cells as well as determine the fate of cells. This strong dependence of cell response on the mechanical properties and structure of the environment opens new opportunities to control cell growth and tissue formation by well-designed biocompatible and biodegradable materials. The research that will be carried out will increase our intuitive understanding of the submicroscopic changes that take place in these materials in response to local or global forces. As a result, we expect our research to facilitate the creation of novel materials for the three-dimensional control of cell growth, for example for the creation of artificial tissue, and for drug delivery. The three-dimensional super resolution images acquired in the process of this project will be used for educating students as well as the public about this important class of materials. Teachers as well as K-12 students will have direct access to the research through visits, summer research and presentations at their schools. The project will enhance the infrastructure for research and education through international collaborations.Technical: Cytoskeletal and extracellular filaments belong to the large class of semiflexible polymers whose elastic response arises from entropic and enthalpic elastic contributions. On a macroscopic scale, networks of semiflexible biopolymers show a unique, nonlinear elastic response (strain- stiffening). The microscopic origin of this nonlinear response remains in many cases unclear because of a lack of submicroscopic data that can be linked to the macroscopic scale such as local network architecture, cross-linker elasticity or the distribution of tension in the network. The goal of this project is to visualize the submicroscopic network architecture, its response to global and local forces and the resulting force distribution in the network. Graduate and undergraduate students will be trained in an interdisciplinary environment on a state-of-the-art three-dimensional scanning probe microscope developed by the PI's group.