Hydrothermal synthesis of hydrophilic NaYF_4:Yb,Er nanoparticles with bright upconversion luminescence as biological label

摘要

A prerequisite for biomedical applications of rare-earth upconverting nanophosphors (RUNPs) is to prepare hydrophilic RUNPs with strong upconverting luminescence. Herein, we developed a simple one-pot synthesis strategy for hydrophilic NaYF_4:Yb,Er nanophosphors by hydrothermally treating water/ ethylene glycol mixture containing different rare-earth ions, BF_4~-, Na~+ and polyethylene glycol (MW=6000, abbreviated as PEG-6000). NaYF_4:Yb,Er sample consisted of irregular spherical nanoparticles with average size of ～50 nm, and it could be easily dispersed in water due to the presence of PEG-6000. Importantly, the aqueous dispersion of NaYF_4:Yb,Er nanoparticles exhibited bright upconversion luminescence and could be used for imaging HeLa cells. Therefore, these hydrophilic NaYF_4:Yb,Er nanoparticles have great potential as luminescent labeling materials for biological applications.