ZnO is a well-known UV absorber. At small particle sizes its absorption efficiency is substantially increased and this property, combined with transparency to visible light, has attracted growing interest in its applications in personal care products such as sunscreens. However, some recent studies suggest that ZnO nanoparticles could induce considerable toxicity to certain cells and microorganisms. Aiming to reduce cytotoxicity of ZnO nanoparticles without impairing their unique properties, this paper examines the influence of surface modifications to ZnO nanoparticles using coatings such as silica (SiO2) and Poly methyl Acrylic Acid (PMAA). It was found that both PMAA and SiO2 coatings were physically attached to the ZnO surface and their presence did not weaken UV absorption of the original nanoparticles. Uncoated ZnO and SiO2-coated ZnO exhibited similar cytotoxicity to human lymphoblastoid cells, while PMAA-coated ZnO nanoparticles had little adverse effect except at high concentrations. The type of coating was also shown to affect the generation of Reactive Oxygen Species (ROS). The correlation between cell viability and ROS level led to conclusions that enhanced oxidative stress could be one of the reasons for cytotoxicity of ZnO nanoparticles.
Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.