Abstract
Monodisperse, water-dispersible lanthanide (Ln(3+))-doped BaYF5 nanocrystals (NCs) are synthesized through a fast, facile and environmentally-friendly microwave-assisted modified polyol process with polyethyleneimine as the surfactant. The TEM images illustrate the sphere-like and flower-like morphologies of the obtained NCs. Intense multicolor down conversion (DC) luminescence is also achieved in Ce3+/Ln(3+) (Ln = Tb, Dy) doped BaYF5 NCs. Then, upon excitation at 980 nm, upconversion (UC) luminescent properties of BaYF5:Yb3+/Ln(3+) (Ln = Er, Tm, Ho) NCs and energy transfer between Yb3+ and Ln(3+) are systematically surveyed. Furthermore, a layer of SiO2 is coated on the surface of the NCs and the methyl thiazolyl tetrazolium (MTT) assays are performed to test the cytotoxicity of BaYF5:Ln(3+) NCs. Due to the X-ray absorption property of Ba element, a proof-of-concept CT imaging with BaYF5:Ln(3+) NCs is conducted. These results indicate that the obtained NCs have great potential as optical/CT bioprobe. (C) 2015 Elsevier B.V. All rights reserved.