Controllable synthesis of NH4Eu3F10 nanospheres and application in bioimaging

Abstract

Cubic phase NH₄Eu₃F₁₀ nanospheres with controllable sizes were synthesized via a modified hydrothermal route by varying the dosage of ammonium hydroxide solution. Dependence of structure and morphology on the dosage of ammonia water and reaction time were investigated by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Being unstable, NH₄Eu₃F₁₀ decomposed into EuF₃ and NH₄F during the long-time hydrothermal treatment. EDTA, as the chelation agent of Eu³⁺ and the capping ligand on the surface of as-obtained nanospheres, showed different chelating abilities depending on the dosage of ammonium hydroxide solution. Increasing the amount of ammonia not only decreased the effective concentration of Eu³⁺, but also decelerated the growth of NH₄Eu₃F₁₀ nanospheres and stabilized them by reducing the surface energy. Given the satisfactory hydrophilicity, biocompatibility, and luminescence, the as-obtained nanospheres were applied as promising agents for cell imaging by presenting high contrast.