2. Experimental Section
2.1. Engineered nano-particles
Dispersions of nanoparticles used in this study were prepared at the laboratory of the Center of
Excellence in Nanotechnology, Asian Institute of Technology in Bangkok, Thailand. Zinc oxide
nanoparticles (nano-ZnO) were prepared from commercial ZnO nanopowder (Sigma-Aldrich, USA) by
dispersing nanoparticles in Milli-Q water through ultrasonication (300 W, 40 kHz) for 30 minutes. Particle
size distribution (Table. 1) of the nanoparticles was determined through measurements carried out on
Transmission Electron Microscopy (TEM) (JEOL JEM 2010, Japan, operated at 120 kV) images using Scion
Image processing software (Fig. 1).