The Nanomechanics of Cellulose and Cellulose Synthesis

在这个项目中，PI将详细了解纤维素合成和纤维素微原纤维的物理性质。纤维素合成将在体外和体内用单分子敏感成像技术进行观察。此外，还将利用光学成像和操作技术对单个纤维素微原纤维的力学进行探索，以阐明其结构和动力学。这项工作将提供对单个纤维素微纤维合成和柔韧性的第一次直接观察。这项工作的具体目标是：(1)用单分子敏感成像观察体内纤维素合成的详细机制；(2)测量体外纤维素制备的单个微纤维的纳米力学；(3)观察纤维素的体外合成，测定合成过程中微纤维的动态；(4)开发一种基于拟南芥（Arabidopsis thaliana）的新型体外纤维素制备方法，拟南芥是纤维素合成遗传学最清楚和最容易操纵的植物。该项目将提供创建和验证基本生物过程及其产生的物质的物理模型所需的观察和测量。类似的模型也可以用来描述其他自然产生的纤维和由它们构建的层次结构。这项工作也将为理解纳米纤维的物理性质提供新的途径。这些方法将有助于阐明结构上有缺陷或扭曲的生物纤维和人造纤维的力学和组装。更好地了解纤维素的合成也将促进植物科学的发展。对纤维素合成的更好理解将有助于更好地控制和表征从大量植物纤维素中回收的新型材料，如纳米晶纤维素晶须。纤维素纳米晶须是高纵横比晶体纳米粒子，具有化学稳定性和碳中性；它们的物理和化学性质使它们在电子和药物输送等各种应用中都是理想的。它们的材料性质取决于它们在体内的组装，然而，天然存在的微原纤维和回收的纳米晶体之间的关系尚未很好地建立。PI将向各个层次和具有不同背景的学生介绍跨学科研究和单分子敏感生物物理技术。将通过与东北研究生教育和教授联盟（东北研究生教育和教授联盟）以及当地物理学妇女和少数民族成员支助小组共同开展的活动，从尽可能广泛的申请者中招收和留住最优秀的学生。该项目由物理系的生命系统物理学项目和分子与细胞生物科学系的细胞过程项目共同支持。

In this project the PI will develop detailed understanding of cellulose synthesis and the physical properties of cellulose microfibrils. Cellulose synthesis will be observed both in vitro and in vivo with single-molecule sensitive imaging techniques. In addition, the mechanics of individual cellulose microfibrils will be probed using optical imaging and manipulation, so as to elucidate their structure and dynamics. This work will provide the first direct observations of individual cellulose microfibril synthesis and flexibility. The specific objectives of this work are to (1) observe the detailed mechanics of cellulose-synthesis in vivo with single-molecule sensitive imaging; (2) measure the nanomechanics of individual microfibrils from an in vitro cellulose preparation; (3) observe cellulose synthesis in vitro, and measure microfibril dynamics during synthesis; and (4) develop a novel in vitro cellulose preparation based on Arabidopsis thaliana, a plant in which the genetics of cellulose synthesis is the best understood and most readily manipulated. The project will provide observations and measurements needed to create and validate physical models of a fundamental biological process and the material created by it. Similar models may be adapted to describe other naturally occurring fibers and the hierarchical structures built from them. The work will also provide new approaches for understanding the physical properties of nanoscopic fibers. These approaches will be useful in elucidating the mechanics and assembly of biological and manmade fibers that have defects or twists in their structure. Better understanding cellulose synthesis will also enhance plant science. A better understanding of cellulose synthesis will lead to better control and characterization of novel materials, such as nanocrystalline cellulose whiskers, that are recovered from bulk plant cellulose. Cellulose nanowhiskers are high-aspect ratio crystalline nanoparticles that are chemically stable and carbon neutral; their physical and chemical properties make them desirable in applications as diverse as electronics and drug delivery. Their material properties depend on their assembly in vivo, and yet the relationship between naturally occurring microfibrils and recovered nanocrystals has not been well established. The PI will introduce students at all levels and with many backgrounds to interdisciplinary research and single-molecule sensitive biophysical techniques. Recruitment and retention of the best students from the broadest possible pool of applicants will be facilitated by activities in conjunction with the Northeast Alliance for Graduate Education and the Professoriate (NEAGEP) and with a local support group for women and minority members in physics.This project is being jointly supported by the Physics of Living Systems program in the Division of Physics and the Cellular Processes Program in the Division of Molecular and Cellular Biosciences.