Unusual Rheology of Aqueous Dispersions of Soft Phytoglycogen Nanoparticles

Phytoglycogen is a natural polysaccharide produced in the form of compact 35 nm diameter nanoparticles by some varieties of plants such as sweet corn. The highly-branched, dendrimeric structure of phytoglycogen leads to interesting and useful properties that make the particles ideal as unique additives in personal care, nutrition and biomedical formulations. One such property is the unusual rheology of aqueous dispersions of phytoglycogen nanoparticles. When added to water, the zero-shear viscosity of the dispersions remains small up to large concentrations (~20% w/w). For higher concentrations, the zero-shear viscosity increases dramatically, reaching values that exceed that of water by more than a factor of 10⁶ at the highest concentrations of 30% w/w. These very large values of the zero-shear viscosity are coupled with very small values of the yield stress (below the detection limit of the rheometer) and significant compression of the soft nanoparticles. This unusual combination of rheological properties offers new opportunities for applications of the phytoglycogen nanoparticles.