Synthesis of ZnO Nanoparticles with Tunable Emission Colors and Their Cell Labeling Applications

ZnO nanoparticles have been studied for potential cell labeling applications over the past several years. However, little progress has been made because of the limited emission color and poor water stability of ZnO nanoparticles. In this work, ZnO nanoparticles with various emission colors, including blue, green, yellow, and orange, were synthesized through an ethanol-based precipitation method. The emission color of the ZnO nanoparticles could be tuned by adjusting the pH value of the precipitation solution. The as-prepared ZnO nanoparticles were then encapsulated with silica to form ZnO@silica core shell nanoparticles, to improve the water stability of the ZnO nanoparticles. The visible emissions of the ZnO nanoparticles were yell retained after they had been coated with silica shells. The resultant ZnO@silica core shell nanoparticles exhibited low cytotoxity and were promising in cell labeling applications.