Tiny Particles, Big Impact

Posted on Friday, December 21st, 2018

Child in a swimming pool holding sunscreen
Nanomaterials have been added to hundreds of consumer products because of their unique properties, such as a very high surface area to volume ratio. For example, zinc oxide nanoparticles are used in sunscreen to protect from harmful UV rays.

Non-toxic, eco-friendly nanoparticles can improve health and personal care products.

Synthetic, man-made particles 1/5000th the width of a human hair (i.e., nanoparticles) are ending up down our drains and in our water sources. Nanoparticles are potentially more toxic than larger “chunks” of the same substance because they are more easily absorbed into our bodies, but the full impact that they have on our health is unknown. Nonetheless, non-toxic alternatives are needed.

University of Guelph physics professor John Dutcher and his industry partner, Mirexus Biotechnologies Inc., have discovered and developed phytoglycogen. Phytoglycogen occurs naturally as a compact nanoparticle in sweet corn. It is composed of many glucose molecules bonded together. Phytoglycogen is a promising sustainable alternative to synthetic nanoparticles because it is non-toxic and biodegradable. Now, Dutcher and his team are studying how it performs in nutraceutical and biomedical health products, as well as in personal care products compared to synthetic nanoparticles.

To accomplish this, Dutcher and his research team have studied phytoglycogen’s many different physical properties. Recently, they investigated the flow properties of colloidal dispersions of phytoglycogen nanoparticles in water. Colloidal dispersions are created when nanoparticles are evenly dispersed in a liquid. Knowing the dispersion’s flow properties is critical to knowing how the particles will perform in products such as facial moisturizers. Colloidal dispersions are “hard” when the nanoparticles are rigid or “soft” when the nanoparticles such as phytoglycogen are deformable and compressible.

By measuring the viscosity of the dispersions at different concentrations, Dutcher and his team discovered new properties of phytoglycogen. They found that the soft phytoglycogen particles can be added into water up to very high concentrations without a significant increase in viscosity, unlike other sugar-based polymers such as corn starch. At very high concentrations, the viscosity increases dramatically, forming a solid-like, glassy material consisting of compressed phytoglycogen nanoparticles. They also found evidence that phytoglycogen has a unique “hairy” surface—where long flexible chains of glucose molecules uniformly cover its surface—providing it with unique properties that can be exploited in new technologies and therapies.

“This simple colloidal dispersion provided insight into the complex behaviour of soft colloids. Our findings will motivate further research on phytoglycogen,” says Dutcher. “Having a better understanding of the flow properties of such a promising, sustainable nanoparticle will help us to optimize its use in personal care and health products.”

This work was supported by the Ontario Ministry of Agriculture, and the Natural Sciences and Engineering Research Council of Canada.

John Dutcher is a Senior Canada Research Chair in Soft Matter and Biological Physics.

Shamana H, Grossutti M, Papp-Szabo E, Miki C, Dutcher JR. Unusual polysaccharide rheology of aqueous dispersions of soft phytoglycogen nanoparticles. Soft Matter. 2018. doi: 10.1039/c8sm00815a.

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