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Physics Colloquium: Super-Resolution Microscopy to Study Cellulose Structure at the Nanoscale
Wednesday, Nov. 20, 2019
4 p.m. - 5 p.m. Location: SLC 1.102

Dr. Jose M. Moran-Mirabal (McMaster University)

Cellulose – the major component of plant cell walls – is the most abundant biopolymer on Earth and is an attractive raw material for the production of biodegradable and renewable products, such as biocomposites, biofuels and bioplastics. Manufacturing these products often entails the chemical or biochemical depolymerization of cellulose, a process that is limited by its crystalline structure. To better understand these manufacturing processes and improve their efficiency, we require insight into the nanoscale structure of cellulose and the mechanism of its depolymerization. In this talk, I will describe the use of stochastic optical reconstruction microscopy (STORM) to study the structure of fluorescently-labelled bacterial microcrystalline cellulose (BMCC) at the nanoscale. Super-resolution imaging unveiled repeating patterns of high and low fluorophore density regions on BMCC microfibrils. Labeling cellulose with different dyes or grafting reactions produced similar patterns, which shows that the fluorescent patterns are labeling chemistry-independent and are instead encoded within the native cellulose structure. The length of the dark regions was measured and their distribution was found to correlate with the length of cellulose nanocrystals produced by short acid hydrolysis treatments. The length of the microfibril dark regions were also determined to be dependent on the concentration of dye during the grafting procedure, strongly suggesting that the observed labelling patterns are due to intervening crystalline and disordered regions of cellulose microfibrils. These experiments provide the first visualization of dislocations within crystalline cellulose microfibrils and support the fringed micellar model of cellulose structure. Understanding cellulose nanostructure has important implications on the way cellulose-based products are manufactured and can provide insights into how plant cells assemble, restructure and degrade their cell wall.

Persons with disabilities may submit a request for accommodations to participate in this event at UT Dallas' ADA website. You may also call (972) 883-5331 for assistance or send an email to [email protected]. All requests should be received no later than 2 business days prior to the event.
Contact Info:
Michael Kesden, 972-883-3598
Questions? Email me.

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