UV and Temperature-Sensing Based on NaGdF₄:Yb3+:Er3+@SiO₂–Eu(tta)₃

摘要

A multifunctional nanosystem was synthesized to be used as a dual sensor of UV light and temperature. NaGdF_(4):Yb~(3+):Er~(3+) upconverting nanoparticles (UCNPs) were synthesized and coated with a silica shell to which a europium(III) complex was incorporated. The synthesis of NaGdF_(4) UCNPs was performed via thermal decomposition of lanthanide ion fluoride precursors in the presence of oleic acid. To achieve sufficient water dispersibility, the surface of the hydrophobic oleate-capped UCNPs in the hexagonal phase was modified by a silica coating through a modified St?ber process through a reverse microemulsion method. An Eu(tta)_(3) (tta: thenoyltrifluoroacetonate) complex was prepared in situ at the silica shell. A dual-mode nanothermometer was obtained from a near infrared to visible upconversion fluorescence signal of Er~(3+) ions together with UV-excited downshifting emission from the Eu~(3+) complex. Measurements were recorded near the physiological temperature range (293–323 K), revealing excellent linearity (R ~(2) > 0.99) and relatively high thermal sensitivities (≥1.5%·K~(–1)). The Eu(tta)_(3) complex present in the silica shell was tested as the UV sensor because of the Eu~(3+) luminescence dependence on UV-light exposure time.