Colloidal behaviors of ZnO nanoparticles in various aqueous media

We have evaluated the particle sizes, zeta potentials and hydrodynamic radii of zinc oxide (ZnO) nanoparticles in various aqueous conditions such as deionized water, phosphate buffered saline and Minimum Essential Media Eagle. In order to study the size and surface chemistry effect in colloidal behaviors, different size of 20 and 70 nm ZnO nanoparticles were selected and their surface was modified with either citrate or L-serine. It was revealed that surface modification did not strongly affect the particle size or morphology but altered the surface charge and chemistry. In various aqueous media, although the surface charge of ZnO nanoparticles are slightly affected by the existence of electrolyte, the overall particle sizes and morphologies are determined to be preserved, suggesting that their properties as nanoparticles are not significantly changed in physiological conditions.