Cottrell Scholar Awards - 2015
Tailoring Bacterial Cellulose Ionogels for Diverse Chemical Tasks
Gary A. Baker, assistant professor of chemistry at the University of Missouri-Columbia, has received Cottrell Scholar funding to perfect an easy-to-produce bacterial cellulose-based material known as “ionogel.” It looks promising for use in diverse chemical tasks.
An “ionogel” is a three-dimensional transparent, flexible and porous polymer. It occurs in the form of a membrane or gel that can hold an ionic liquid—basically a molten salt composed entirely of ions, although it should be noted there are myriad different types of salts possible, making ionic liquids truly adaptable solvents.
Baker says such material promises “a wealth of potential for applications in chemical separation and extraction, drug delivery, oil cleanup, and incorporation as an electrolyte layer within batteries and fuel cells. It may also prove useful in separating gases and in optical sensing.”
What Baker brings to the search for a cheap and effective ionogel is the desire to put bacteria, tiny one-celled organisms, to work churning it out in bulk.
The intermediary material on the way to an ionogel is cellulose.
“Produced by plants and microorganisms -- certain bacteria, fungi and algae – the long-chain polysaccharide cellulose represents the most abundant natural biopolymer on the planet,” he said. Abundance is one reason why cellulose is viewed as a renewable potential replacement for non-renewable carbon-based fuels as well as plastic feedstock.
“Cellulose biosynthesized by bacteria is particularly attractive to modern materials scientists,” Baker said. Unlike plant cellulose, bacterial cellulose is highly pure and unencumbered by other components like lignin, pectin, and hemicellulose, the basic building blocks of plant cell walls, he noted.
Those plant materials basically impede the production of cellulose with an ultrafine, intricate structure of interwoven nanofibers produced by bacteria. Bacterial cellulose also shows greater “crystallinity” -- that is, its molecules are arranged in a highly ordered manner, giving it additional mechanical strength over plant cellulose, Baker said.
“Bacterial cellulose exhibits high porosity, biocompatibility, and its hydrogel can hold as much as 99% water by weight,” Baker said. “Plus, it can be grown to virtually any shape and thickness on a variety of substrates.”
And microbial cellulose is completely biocompatible and non-toxic. It’s currently being used as a foodstuff, primarily in desserts. If you’ve ever ingested nata de coco, a chewy, translucent jell produced by the fermentation of coconut water, you’ve eaten the work of Acetobacter xylinum, a bacterium with an astonishing ability to produce cellulose.
Specifically, Baker’s research is aimed at understanding the dynamics, stability, accessibility, transport properties, and local microenvironment of ionic liquids sequestered within bacterial cellulose ionogels.
“This molecular-level understanding is essential if we hope to use these materials for specific tasks,” he said.
Baker is also using his Cottrell Scholar funding to create a forward-looking response to the “pipeline problem” in STEM education. (STEM is short for Science, Technology, Engineering and Mathematics). He is developing ways to encourage greater numbers of underrepresented students to pursue science careers.