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.
