Europium-doped NaGd(WO₄)₂ nanophosphors: synthesis, luminescence and their coating with fluorescein for pH sensing

Abstract

Uniform Eu-doped NaGd(WO4)2 nanophosphors having spherical shape have been synthesized for the first time by using a wet chemistry method based on a homogeneous precipitation process at low temperature (120ºC) in ethylene glycol/water mixtures. The obtained nanoparticles crystallized into the tetragonal structure and presented polycrystalline character. The europium content in such phosphors has been optimized through the analysis of the luminescence dynamics (lifetime measurements).By coating the Eu 3+ -doped wolframate based nanoparticles with fluorescein through a layer-by-layer (LbL) approach, a wide range (4-10) ratiometric pH-sensitive sensor has been developed, which uses the pH insensitive emission of Eu 3+ as reference.2

Molecular Bottom-Up Approaches for the Synthesis of Inorganic and Hybrid Nanostructures

“…Ionic liquid are good alternatives, as they can either act as precursors (for example, the ionic liquid 1-butyl-2-methylimidazolium tetrafluoroborate) (BMIMBF 4 also releases slowly fluoride anions when heating), and solvents [91,92]. In other cases, metal complexes can be formed, as it occurs for calcium citrate complexes, which also slowly release Ca 2+ into the solution at elevated temperature [93], and rare earth-citrate complexes [94,95], used as precursors for the synthesis of uniform rare earth-based NPs.…”

Porous Particle‐Based Inkjet Printing of Flexible Fluorescent Films: Enhanced Sensing Performance and Advanced Encryption

“…High concentration (10 −4 m) of the ink was used to facilitate the encryption process here. [42] When irradiated under UV light, green "SNNU" appeared due to different fluorescence of the two fluorophores (Figure 5c) www.advmattechnol.de "SNNU" appeared ( Figure 5d). When exposed in diethylamine vapor, orange red "SNNU" emerged because of interaction between fluorescein and diethylamine (Figure 5b).…”

“…When exposed in diethylamine vapor, orange red "SNNU" emerged because of interaction between fluorescein and diethylamine (Figure 5b). [42] When irradiated under UV light, green "SNNU" appeared due to different fluorescence of the two fluorophores (Figure 5c) www.advmattechnol.de "SNNU" appeared ( Figure 5d). All the three states (Figure 5b,c) could recover back to the primary state (Figure 5a) under certain condition (marked in Figure 5).…”

Upconversion Luminescence Sensitized pH-Nanoprobes

“…The NIR light falls within the biological transparency window (700–1300 nm) and its deep-penetration and low auto-fluorescence give low photostability in comparison to UV and visible light. Most of the optical pH-sensors are investigated to perform within this window [ 30 , 31 , 32 , 33 , 34 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ]. A list of the UC materials speculating pH-sensing is given in Table 2 .…”