Novel optical thermometer through upconversion emission of Ho3+ sensitized by Nd3+

Cr3+-Doped InTaO4 phosphor for multi-mode temperature sensing with high sensitivity in a physiological temperature range

“…20 Among the optical thermometers based on the single emission center, the temperature sensing method based on the thermally coupled energy levels of trivalent rareearth (Re 3+ ) ions is the most studied and applied. 2,12,13,[21][22][23][24] For example, Zhu et al realized real-time monitoring of microscopic temperature in photothermal therapy with an Er 3+doped nanophosphor by utilizing the thermally coupled energy levels of 2 H 11/2 and 4 S 3/2 of Er 3+ . 25 Balabhadra et al reported a novel Nd 3+ -doped Gd 2 O 3 phosphor that exhibited high-performance thermometry with an optimal relative sensitivity of 1.75% K −1 at 288 K. 13 In principle, the relative sensitivity (S r ) value obtained from such optical thermometry involving thermally coupled energy levels (TCELs) of Re 3+ is proportional to the energy difference ΔE between the two coupled levels.…”

Ratiometric upconversion luminescence nanoprobes from construction to sensing, imaging, and phototherapeutics

“…120 Due to Hg 2+ -responsive ruthenium complex N719, Hg 2+ induces regular changes in the absorption spectra (absorbance is abbreviated as A) and UCL spectra, showing both ratiometric colorimetric (A 485nm /A 541nm ) and ratiometric UCL (U 541nm /U 801nm , λ ex : 980 nm) modes for naked-eye visual detection of Hg 2+ . In addition, previous studies of ratiometric UCL nanoprobe systems usually involve investigation studies of UCL lifetime, 32,36,39,47,58,60,65,72,80,86,87,93,109,116,132,134,148,161 and NIR laser pump power-dependent UCL spectral properties. 39,44,47,50,57,58,64,73 Auxiliary methods are widely used to further investigate the UCL emission behaviors of upconverting luminescence components in nanoprobe systems, aiming to yield high UCL quantum yield, bright, long-term stable, photostable, and long-lifetime UCL for sensing.…”

“…To construct ratiometric UCL nanoprobes, the ratio of dual-UCL peak intensities (UCL 1 , UCL 2 ) at respective wavelengths is used as signal output (UCL 1 /UCL 2 ) to establish a well-plotted (typically linear) func-Scheme 3 Schematic diagram of this present review focusing on the construction of UCL ratiometric nanoprobes for sensing, imaging and phototherapeutics applications. 36 LiYF 4 :20Yb 3+ /1Ho 3+ micro-octahedrons, 39 NaGdF 4 :Yb 3+ /Er 3+ microcrystals, 40 NaYF 4 :Er 3+ /Yb 3+ microspheres, 45 NaYF 4 :Er 3+ microcrystals, 54 NaY(Lu)F 4 :Yb 3+ /Mn 2+ nanocrystals, 87 etc. (c) Core@shell structural systems Lanthanide-doped Bi 2 SiO 5 @SiO 2 , 37 Bi 2 SiO 5 :Yb 3+ /Tm 3+ @SiO 2 , 38 Yb/Er@Yb/Nd, 41 Yb 3+ -sensitized Tm 3+doped GdVO 4 @SiO 2 , 68 NaYF 4 :Yb 3+ /Tm 3+ @NaYF 4 :Yb 3+ /Nd 3+ , 79 TPAMC-UCNPs@PEG, 102 UCNPs-Cy787 dyes@PC, 110 Ce 3+ -doped LiYF 4 :Yb 3+ /Ho 3+ @LiYF 4 , 126 UCNPs@PDA, 155 etc.…”

“…As summarized in Table 1, previous studies have largely reported various types of ratiometric UCL nanoprobes for temperature sensing. [168][169][170][171][172][173][174][175][176]193,194 Most of the nanoprobe systems consist of lanthanide-doped UCNPs, other upconverting luminescent inorganic materials, 29,36,40,43,45,47,48,54,[56][57][58][59][60][61]65,[73][74][75][76] and the derivatives with functional modifications, including the core@shell, 37,38,41,68,72,78,79 hollow/porous, 38 complexes, 46,49,51 hybrid, 32,52 mixture, 33,35 assembly, 34,55 or engineering structures.…”

“…This review systematically summarizes various types of ratiometric UCL nanoprobes, referring to the primary structures and compositions of the nanoprobe systems, dual-signal ratiometric modes, sensing mechanisms, and application performances. For convenient mastering, previous studies on ratiometric UCL nanoprobes are appropriately classified and regularly arranged based on specific targets and characters, including temperature (Table 1), 28–84 pH (Table 2), 85–99 inorganic anions, cations, free radicals (Table 3), 100–126 gases, small common molecules, biological small molecules and biomacromolecules (Table 4). 127–162 For a better understanding of construction strategies, the following sections provide principle construction methods and ratiometric dual-signal modes of ratiometric UCL nanoprobes by discussing the state-of-the-art related studies.…”