Dispersion of chitosan nanoparticles stable over a wide pH range by adsorption of polyglycerol monostearate

We have developed stable chitosan colloids over a wide pH range without cross-linkers or gelling agents. The colloid was prepared using chitosan nanoparticle obtained from pulverization of bulk chitosan powder, followed by surface treatment using small amount of ascorbic acid (AA) and polyglycerol monostearate (PGMS) in water. Chitosan nanoparticles were well dispersed in a diluted AA solution due to the protonation of the chitosan chain on the surface. And then, the addition of PGMS led them to exhibit highly stable dispersion even in alkali conditions and 50 °C. The hydrodynamic diameter of the colloid was monitored using dynamic light scattering and the real image of the colloid was obtained using cryo-electron microscope measurement. This chitosan colloid will be useful for developing food ingredients or drug carrier templates that should be stable over a wide pH range.