Today’s breakthrough bone regeneration techniques rely on scaffolding, which provides a support system where new tissue can grow. Douglas M. Fox, PhD, an associate professor of chemistry at American University, has developed a simple, scalable method to improve the performance of cellulose nanocrystals so they could be used in these treatments—as well as in transportation, infrastructure, and energy applications.
“When we cultivated cells on the cellulose nanocrystal-based scaffolds, preliminary results showed remarkable potential of the scaffolds for both their mechanical properties and the biological response,” said Martin Chiang, team leader for the Biomaterials for Oral Health Project at the National Institute of Standards and Technology (NIST). “This suggests that scaffolds with appropriate cellulose nanocrystal concentrations are a promising approach for bone regeneration.”
Cellulose nanocrystals represent the molecular matter of all plant life. According to researchers, they can be blended with plastics and other synthetics. They also are as strong as steel, tough as glass, lightweight, and environmentally friendly. For example, plastics are currently reinforced with fillers made of steel, carbon, Kevlar, or glass. Cellulose nanocrystals, though, would perform just as well. Plus, they are better for the environment.
“If there comes a time that they’re used widely in manufacturing, cellulose nanocrystals will lessen the weight of materials, which will reduce energy,” said Fox, who has submitted a patent for his work.
Cellulose gives stems, leaves, and other organic material their strength. At the nanolevel, cellulose fibers can be broken down into tiny crystals smaller than 10 millionths of a meter. Researchers can prepare crystals of different sizes and strengths by deriving cellulose from natural sources such as wood, tunicate (ocean-dwelling sea cucumbers), and certain kinds of bacteria.
The challenge lies in finding the right amount of nanoparticle-matrix interaction that yields the strongest yet lightest property. Fox solved this issue by altering the surface chemistry of nanocrystals via ion exchange. This reduces water absorption, as cellulose composites lose their strength if the absorb water; it increases the temperature at which the nanocrystals decompose; reduces clumping; and improves re-dispersal after the crystals dry.
Experimenting with Fox’s modified nanocrystals, NIST’s researchers were able to disperse nanocrystals in scaffolds for dental regenerative purposes. Additional projects are investigating their use in replacing glass-reinforced plastic in airplanes, cars, and wind turbines. Plus, Fox is working with Vireo Advisors and NIST to characterize the health and safety of cellulose nanocrystals and nanofibers.
“As we continue to show these nanomaterials are safe, and make it easier to disperse them into a variety of materials, we get closer to utilizing nature’s chemically resistant, strong, and most abundant polymer in everyday products,” Fox said.
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