Structure and hydration of phytoglycogen nanoparticles: Nature's dendrimer
July 31-August 4, 2017
Nature offers amazing examples of nanostructured molecules and materials. I will focus on phytoglycogen, a highly-branched polymer of glucose produced in the form of dense, monodisperse nanoparticles by some varieties of plants such as sweet corn. The particles are chemically simple, but have a special dendrimeric or tree-like structure that produces interesting and unusual properties such as extraordinary water retention, and low viscosity and exceptional stability in water. These properties point to a wide variety of potential applications from cosmetics to drug delivery, yet these applications need to be enabled by a deeper understanding of the unique structure of the particles and their interaction with water. To achieve this, we have used a wide range of techniques. Neutron scattering has revealed that the nanoparticles have uniform size and density and are highly hydrated, with each nanoparticle containing about 250% of its mass in water . Surface-sensitive infrared absorption measurements on phytoglycogen films show that the high degree of branching in phytoglycogen leads to a well ordered “network” structure of the hydration water within the particles . Rheology measurements have revealed weak interactions between the particles, allowing loading of the particles into water up to 20% w/w before significant increases in viscosity are observed, showing that this is an interesting model system for studying soft colloid physics . Taken together, these studies provide new insights that are key to fully understanding and exploiting these materials in new technologies and therapies.
 J.D. Nickels, J. Atkinson, E. Papp-Szabo, C. Stanley, S.O. Diallo, S. Perticaroli, B. Baylis, P. Mahon, G.
Ehlers, J. Katsaras and J.R. Dutcher. Structure and Hydration of Highly-Branched, Monodisperse
Phytoglycogen Nanoparticles, Biomacromolecules 17, 735-743 (2016).
 M. Grossutti and J.R. Dutcher. Correlation Between Chain Architecture and Hydration Water Structure in
Polysaccharides, Biomacromolecules 17, 1198-1204 (2016).
 H. Shamana, E. Papp-Szabo, J. Atkinson, C. Miki and J.R. Dutcher. Phytoglycogen Nanoparticles in Water: A Model Soft Colloid System, in preparation.
John R. Dutcher, Michael Grossutti, John Atkinson, Hurmiz Shamana, Jonathan Nickels, and John Katsaras, "Structure and hydration of phytoglycogen nanoparticles: Nature's dendrimer" in "Association in Solution IV", Ulf Olsson, Lund University, Sweden Norman Wagner, University of Delaware, USA Anand Yethiraj, Memorial University of Newfoundland, Canada Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/assoc_solution_iv/17
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