Monodisperse Upconversion NaYF₄ Nanocrystals: Syntheses and Bioapplications

A facile strategy using cheap and readily available precursors has been successfully developed for the synthesis of rare-earth doped hexagonal phase NaYF₄ nanocrystals with uniform shape and small particle size as well as strong photoluminescence. Due to their optical properties and good biocompatibility, these multicolor nanocrystals were successfully used as a bio-tag for cancer cell imaging. This novel synthetic method should also be capable of extension to the synthesis of other fluoride nanocrystals such as YF₃ and LaF₃.