Multicolor excitation of cyanine dye sensitized luminescent nanoprobes, methods of making and uses thereof

Abstract

The application discloses a multi-color excitation phycocyanine dye sensitized luminescent nano probe, a preparation method and application thereof; the probe is composed of phycocyanine dye with a coordination group and a core-shell structure rare earth nano particle, the coordination group is selected from one or both of sulfonate or carboxylate, the phycocyanine dye is coordinated to the nano particle through ligand exchange, and up-conversion and down-shift luminescence enhancement are realized. 3+ There are very rich absorption energy levels from 500-1100 nm, and there is a certain degree of spectral overlap with the emission of a series of phycocyanine dyes, and the whole dye sensitized system does not need Yb 3+ Or Nd 3+ As an energy bridge, a multi-color excitation series of phycocyanine dyes directly sensitized Er 3+ Up-conversion and down-shift luminescence system can be constructed, and the probe has good repeatability and stability when applied to temperature measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of luminescent materials, and particularly relates to a multi-color excitation cyanine dye sensitized luminescent nano probe, a preparation method and application thereof. BACKGROUND

[0002] Rare earth nanoparticles (NPs) have attracted extensive interest due to their narrow emission, non-flashing and excellent light stability. Using NPs as imaging probes can eliminate the interference of spontaneous background fluorescence of biological samples and produce images with high contrast. Generally, Yb 3+ ion is used as a sensitizer to absorb infrared radiation and non-radiatively transfer energy to the activator ions Er 3+ , Tm 3+ or Ho 3+ to produce visible or ultraviolet emission. However, the absorption cross section of lanthanide ions is much lower than that of organic dyes. Using organic dyes as antenna molecules can significantly improve the ability of NPs to capture photons and improve their luminescence brightness.

[0003] However, in the traditional dye sensitized system, Yb 3+ or Nd 3+ is usually used as a bridge for energy transfer between organic dyes and emitters, and Yb 3+ and Nd 3+ have a strong interaction with near-infrared energy. Therefore, due to the necessity of spectral overlap, only a limited number of NIR dyes, such as IR806, are used for sensitization of rare earth nanoparticles. When trying to build a multi-color excitation dynamic sensitization system, this limitation presents a major challenge. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a multi-color excitation cyanine dye sensitized luminescent nano probe, a preparation method and application thereof. The preparation method is simple, and energy transfer is achieved by directly coordinating cyanine dyes to rare earth nanoparticles. The cyanine dye sensitized luminescent nano probe uses Er 3+ ion as an emitter. Since Er 3+ has very rich absorption energy levels, it has different degrees of spectral overlap with a series of cyanine dyes, and the entire dye sensitized system does not need Yb 3+ or Nd 3+ as an energy bridge, a multi-color excitation series of cyanine dyes directly sensitizing Er 3+ upconversion and downshift luminescence system can be constructed. The probe has good repeatability and stability when applied to temperature measurement.

[0005] The technical solutions of the present application are described in detail as follows.

[0006] The cyanine dye sensitized luminescent nanoprobe is composed of a cyanine dye with a coordination group and a core-shell structure of rare earth nanoparticles, and the cyanine dye is coordinated to the core-shell structure of rare earth nanoparticles through ligand exchange to realize up-conversion and down-shift luminescence enhancement; wherein:

[0007] The coordination group is selected from one or both of sulfonate or carboxylate;

[0008] The core of the core-shell structure of the rare earth nanoparticles is NaErF4, and the shell is an inert shell layer.

[0009] In the present application, the cyanine dye is a Cy series dye with a coordination group, which consists of a conjugated chain of 3-7 methine groups, and the heterocyclic ring at both ends of the conjugated chain is an indole group or a benzindole group.

[0010] In the present application, the cyanine dye with a coordination group includes unsulfonated Cy dye, sulfonated Cy dye, or Cy dye with amine group after sulfonation. In specific embodiments, sulfonated Cy7.5, unsulfonated Cy5 dye, sulfonated Cy3-amine, sulfonated Cy5-amine, sulfonated Cy5.5-amine, and sulfonated Cy7-amine are included. The absorption wavelength of the cyanine dye is between 400-900 nm, and the emission wavelength is between 500-1000 nm.

[0011] In the present application, the rare earth nanoparticle structure is NaErF4@NaLuF4, the particle size is between 7-16 nm, and the thickness of the shell layer NaLuF4 is between 0.5-5 nm; Er 3+ ion as an emitter.

[0012] The present application also provides a preparation method of the above-mentioned cyanine dye sensitized luminescent nanoprobe, comprising the following steps:

[0013] The core-shell structure of the rare earth nanoparticles is synthesized by layer-by-layer epitaxial growth;

[0014] The dispersion liquid of the rare earth nanoparticles and the cyanine dye solution are mixed, and the cyanine dye is coordinated to the core-shell structure of the rare earth nanoparticles through a ligand exchange process.

[0015] The present application also provides an application of the above-mentioned cyanine dye sensitized rare earth luminescent nanoprobe in constructing a multi-color excitation dynamic sensitization system, and a series of cyanine dyes are excited by excitation light of different wavelengths to construct a multi-color excitation system.

[0016] Further, the present application provides an application of the above-mentioned cyanine dye sensitized rare earth luminescent nanoprobe in temperature measurement.

[0017] In the present application, the cyanine dye is a sulfonated Cy5 dye; in application, a light source with an excitation wavelength of 635 nm is used for excitation irradiation.

[0018] In the above, the present application introduces a new strategy for direct sensitization of Er 3+ emission without the need for an intermediate energy transfer bridge such as Yb 3+ and Nd 3+ . Unlike Yb 3+ , Er 3+ has very rich absorption energy levels from the ultraviolet to the near-infrared region (500-1100 nm), and Er 3+ rich energy levels indicate that it can act as an acceptor for organic dyes to receive energy, and a wider range of dyes can be selected for direct sensitization, creating a multi-color excitation system. For this purpose, a series of cyanine dyes are used as antenna molecules, including Cy3, Cy5, Cy5.5, Cy7 and Cy7.5. These dyes have different degrees of spectral overlap with the absorption spectrum of Er 3+ , and can directly transfer energy to Er 3+ , achieving enhancement of upconversion and downshifting luminescence of rare earth nanoparticles. Compared with the prior art, the present application has the beneficial effects of:

[0019] The present application provides a series of cyanine dye sensitized NaErF4 luminescent nanoprobe preparation methods, which obtain dye sensitized luminescence enhancement by exchanging cyanine dye ligands to the surface of rare earth nanoparticles. Under the test conditions of a laser power of 37.5 W / cm 2 , the 8 nm rare earth nanoparticles sensitized by Cy5-SO3 have upconversion and downshifting luminescence spectrum integral intensity enhancement factors of 1942 and 70, respectively, compared to the same power under 980 nm excitation.

[0020] In the present application, changing the thickness of the inert shell NaLuF4 can achieve enhancement of the upconversion and downshifting luminescence of Er 3+ .

[0021] A series of cyanine dyes can achieve luminescence sensitization of NaErF4@NaLuF4, achieving different degrees of upconversion and downshifting luminescence enhancement.

[0022] The Cy5-SO3 cyanine dye sensitized NaErF4@NaLuF4 of the present application can be used for temperature measurement and has good repeatability and stability. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1The working principle diagram of the traditional dye-sensitized luminescent nanoprobes (a), the working principle diagram of a series of the present application's cyanine dye-sensitized rare earth upconversion and downshifting luminescent nanoprobes (b), and the structural formula of the dye molecules (c).

[0024] Figure 2 The transmission electron microscope photos (a, b) and the X-ray diffraction pattern (c) of the rare earth nanoparticles and the core-shell rare earth nanoparticles in Example 1, the dye molecule structure, absorption and emission spectra (d) in the Cy5-sensitized system, and the upconversion and downshifting emission spectra (e, f) of the dye-sensitized 12 nm NaErF4@NaLuF4, and the mechanism diagram of the energy transfer (g, h).

[0025] Figure 3 The transmission electron microscope photos (a, b) of the NaErF4@NaLuF4 with different particle sizes in Example 2, and the upconversion and downshifting spectra (c) of the Cy5-SO3-sensitized system, and the comparison diagram of the sensitization effect of the traditional IR806-sensitized Yb, Er co-doped rare earth nanoparticle system (d, e).

[0026] Figure 4 The transmission electron microscope photos (a) of the NaErF4@NaLuF4 with different NaLuF4 inert shell thicknesses in Example 3, the upconversion and downshifting spectra (b, c) under the excitation of 980 nm, and the upconversion and downshifting spectra (d, e) of the Cy5-SO3-sensitized system, and the kinetic decay process (f-h).

[0027] Figure 5 The absorption and emission spectra (a, b) of a series of cyanine dyes in Example 4, and the luminescence enhancement effect (c) of the dyes in the sensitization of 8 nm NaErF4@NaLuF4.

[0028] Figure 6 The application of the Cy5-SO3-sensitized NaErF4@NaLuF4 in temperature measurement in Example 5. The schematic diagram (a) and the transmission electron microscope photo (b) of the DSPE-modified Cy5-SO3-sensitized NaErF4@NaLuF4, and the change of the upconversion spectrum (c) of the DSPE-modified Cy5-SO3-sensitized NaErF4@NaLuF4 with temperature. The absolute sensitivity (d) and the relative sensitivity (e) are respectively calculated from the emission intensity ratio at 525 / 541 and 525 / 408 nm related to temperature. (f) The experimental and theoretical fitting of the 525 / 408 nm intensity ratio of the DSPE-modified Cy5-SO3-sensitized NaErF4@NaLuF4 as a function of temperature. (g) The repeatability test of 7 cycles at 293 K and 348 K. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described in detail below in combination with the drawings and examples.

[0030] Figure 1 The working principle diagram of a series of flower cyanine dye sensitized rare earth upconversion and downshifting luminescence nanoprobes of the present application Figure 1 b), and the structural formula of a series of flower cyanine dye molecules involved in the examples Figure 1 c). Example 1

[0031] Synthesis of NaErF4@NaLuF4 core-shell rare earth nanoparticles with a particle size of 12 nm.

[0032] 1 mmol (1 mL, 1 M) of aqueous solution of rare earth chloride (ErCl3: 1 mmol) was added to a 100 mL flask containing oleic acid (6 mL) and 1-octadecene (15 mL). The mixture solution was stirred under a nitrogen atmosphere and heated to 160°C for 40 min to remove water. Then the mixture was cooled to 90-110°C, 0.1 g (2.5 mmol) of sodium hydroxide was added, degassed for 30 min, then 0.1481 g (4 mmol) of ammonium fluoride was added, degassed for another 30 min, the solution was heated to 290°C and kept for 50 min, then cooled to room temperature. 20 mL of ethanol was added to precipitate the nanoparticles, then 6 mL of cyclohexane was added, the mixture was centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, the precipitate was washed with a mixture of cyclohexane and ethanol (20 mL, 1:1, v / v), then the nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 10 nm;

[0033] A 0.1 mmol (0.1 mL, 1 M) aqueous solution of rare earth chloride (LuCl3: 0.1 mmol) was added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under inert atmosphere, heated to 160 °C, and evaporated open to remove moisture for 40 min, then cooled to room temperature to obtain a shell precursor solution; 1.4 mL of 10 nm core nanoparticles cyclohexane dispersion obtained in the previous step, and 1.25 mL of a methanol solution of dissolved ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) were added, stirred under nitrogen protection, heated at 110-120 °C for 10 min to remove low boiling point solvents and part of the water; heated to 290 °C under nitrogen protection and kept for 20 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and 3 mL of cyclohexane was added, the mixture was separated by centrifugation (12000 rpm, 10 min), the supernatant was discarded, and the precipitate was washed with a mixture of cyclohexane and ethanol (10 mL, 1:1, v / v), and the nanoparticles were dispersed in 10 mL of cyclohexane for storage, with a particle size of about 12 nm.

[0034] The upconversion and downshift luminescence spectra of Cy5-SO3 and Cy5-COO sensitized NaErF4@NaLuF4 system varied with the concentration of dye added.

[0035] 280 μL of NaErF4@NaLuF4 core-shell rare earth nanoparticles cyclohexane dispersion was ultrasonically mixed with 1220 μL of chloroform solution, placed in a quartz cuvette, mixed with 0, 2, 4, 6, … 40 μL of Cy5-SO3 and Cy5-COO dimethyl sulfoxide and chloroform mixed solution (1:2, v / v) respectively, stirred for 2 min, and then the upconversion and downshift luminescence spectra were tested on the FLS1000 fluorescence spectrometer with a 635 nm external laser as the excitation light source, and the laser power was 37.5 W / cm 2 As shown in Figure 2 , at the optimal concentration of dye, the upconversion and downshift integral intensity of Cy5-SO3 sensitized NPs were enhanced by 117 times and 23 times respectively compared with NPs excited by 980 nm at the same power density, and the upconversion and downshift integral intensity of Cy5-COO sensitized NPs were enhanced by 29 times and 14 times respectively compared with NPs excited by 980 nm at the same power density. Example 2

[0036] Synthesis of NaErF4@NaLuF4 core-shell rare earth nanoparticles with a particle size of 8 nm.

[0037] A 1 mmol (1 mL, 1 M) aqueous solution of rare earth chloride (ErCl3: 1 mmol) was added to a 100 mL flask containing 10 mL of oleic acid and 10 mL of octadecene. The mixture was stirred under a nitrogen atmosphere, heated to 160°C, and evaporated open to remove moisture for 40 min; after cooling to 110-120°C, 0.34 g of ammonium fluoride and 2.03 g of sodium oleate were quickly added, dissolved at 110-120°C for 30 min, and then vacuumed for 30 min; under nitrogen protection, the temperature was raised to 290°C and maintained for 50 min, and then cooled to room temperature; 20 mL of ethanol was added to precipitate the nanoparticles, 6 mL of cyclohexane was added, the mixture was centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, and the precipitate was washed with a mixture of cyclohexane and ethanol (20 mL, 1:1, v / v) before the nanoparticles were dispersed in 10 mL of cyclohexane for storage, with a particle size of about 6 nm;

[0038] A 0.2 mmol (0.2 mL, 1 M) aqueous solution of rare earth chloride (LuCl3: 0.2 mmol) was added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under an inert atmosphere, heated to 160°C, and evaporated open to remove moisture for 40 min; after cooling to room temperature, a shell precursor solution was obtained; 1 mL of the 6 nm core nanoparticle cyclohexane dispersion obtained in the previous step was added, and 2.5 mL of a methanol solution dissolving ammonium fluoride (0.75 mmol) and sodium hydroxide (0.5 mmol) was added, stirred under nitrogen protection, heated to 110-120°C for 10 min to remove low-boiling solvents and part of the water; under nitrogen protection, the temperature was raised to 290°C and maintained for 20 min, and then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, 3 mL of cyclohexane was added, the mixture was centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, and the precipitate was washed with a mixture of cyclohexane and ethanol (10 mL, 1:1, v / v) before the nanoparticles were dispersed in 5 mL of cyclohexane for storage, with a particle size of about 8 nm.

[0039] Synthesis of NaErF4@NaLuF4 core-shell rare earth nanoparticles with a particle size of 16 nm.

[0040] A 0.1 mmol (0.1 mL, 1 M) aqueous solution of rare earth chloride (ErCl3: 0.1 mmol) was added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under inert atmosphere, heated to 160 °C, and evaporated open to remove water for 40 min, then cooled to room temperature to obtain a shell precursor solution; 1 mL of 10 nm core nanoparticles cyclohexane dispersion obtained in the previous step, and 1.25 mL of methanol solution dissolved with ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) were added, stirred under nitrogen protection, heated at 110-120 °C for 10 min to remove low boiling point solvents and part of water; heated to 290 °C under nitrogen protection and kept for 30 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and 3 mL of cyclohexane was added, the mixture was centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, and the precipitate was washed with a mixture of cyclohexane and ethanol (10 mL, 1:1, v / v), then the nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 14 nm.

[0041] A 0.05 mmol (0.05 mL, 1 M) aqueous solution of rare earth chloride (LuCl3: 0.05 mmol) was added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under inert atmosphere, heated to 160 °C, and evaporated open to remove water for 40 min, then cooled to room temperature to obtain a shell precursor solution; 5 mL of 14 nm NaErF4nanoparticle cyclohexane dispersion obtained in the previous step, and 0.625 mL of methanol solution dissolved with ammonium fluoride (0.1875 mmol) and sodium hydroxide (0.125 mmol) were added, stirred under nitrogen protection, heated at 110-120 °C for 10 min to remove low boiling point solvents and part of water; heated to 290 °C under nitrogen protection and kept for 30 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and 3 mL of cyclohexane was added, the mixture was centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, and the precipitate was washed with a mixture of cyclohexane and ethanol (10 mL, 1:1, v / v), then the nanoparticles were dispersed in 5 mL of cyclohexane for storage, and the particle size was about 16 nm.

[0042] The upconversion and downshift luminescence spectra of Cy5-SO3sensitized NaErF4@NaLuF4system and IR806sensitized Yb, Er co-doped rare earth nanoparticles varied with the concentration of dye added.

[0043] Synthesis of Yb, Er co-doped core-shell rare earth nanoparticles NaYbF4:Er@NaLuF4 with particle size of 12 nm.

[0044] A mixture of 1 mmol (1 mL, 1 M) aqueous solution of rare earth chlorides (YbCl3: 0.92 mmol, ErCl3: 0.08 mmol) was added to a 100 mL flask containing 10 mL of oleic acid and 10 mL of octadecene. The mixture was stirred under nitrogen atmosphere, heated to 160°C, and open evaporation for 40 min to remove water; after cooling to 110-120°C, 0.34 g of ammonium fluoride and 2.03 g of sodium oleate were quickly added, and after dissolving at 110-120°C for 30 min, vacuum was applied for 30 min; under nitrogen protection, the temperature was raised to 290°C and maintained for 50 min, and then cooled to room temperature; 20 mL of ethanol was added to precipitate the nanoparticles, and 6 mL of cyclohexane was added, and the mixture was centrifuged (12000 rpm, 10 min) to separate, and the supernatant was discarded; after washing the precipitate with a mixture of cyclohexane and ethanol (20 mL, 1:1, v / v), the nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 10 nm;

[0045] A 0.1 mmol (0.1 mL, 1 M) aqueous solution of rare earth chlorides (LuCl3: 0.1 mmol) was added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under inert atmosphere, heated to 160°C, and open evaporation for 40 min to remove water; after cooling to room temperature, a shell precursor solution was obtained; 1.4 mL of the core nanoparticle cyclohexane dispersion obtained in the previous step was added, and 1.25 mL of a methanol solution dissolving ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) was added, and the mixture was stirred under nitrogen protection, heated to 110-120°C for 10 min to remove low boiling point solvents and part of the water; under nitrogen protection, the temperature was raised to 290°C and maintained for 20 min, and then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and 3 mL of cyclohexane was added, and the mixture was centrifuged (12000 rpm, 10 min) to separate, and the supernatant was discarded; after washing the precipitate with a mixture of cyclohexane and ethanol (10 mL, 1:1, v / v), the nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 12 nm.

[0046] The cyclohexane dispersions of NaErF4@NaLuF4 and Yb, Er co-doped rare earth nanoparticles with different particle sizes were mixed with chloroform solution by ultrasonic mixing, and the concentration of Er 3+ or Yb 3+ and Er 3+The total concentration of the dye was 2.6 mM, which was mixed with different volumes of Cy5-SO3and IR806in dimethyl sulfoxide and chloroform (1:2, v / v) in a quartz cuvette, respectively. After stirring for 2 min, the upconversion and downshifting luminescence spectra were measured on an FLS1000 fluorescence spectrometer with an external laser as the excitation light source at 635 nm and 808 nm, respectively. The laser power was 37.5 W / cm2. 2 As shown in Fig. 2, the upconversion and downshifting luminescence spectra of the dye-sensitized NaErF4@NaLuF4NPs were measured at the optimal concentration of the dye. The smallest NPs, i.e., 8 nm NaErF4@NaLuF4NPs, exhibited the brightest upconversion and downshifting luminescence. The upconversion and downshifting integral intensities were enhanced by 1942 and 70 times, respectively, compared with the NPs excited by 980 nm light at the same power density. The spectral integral intensity was higher than that of the traditional IR806-sensitized Yb, Er co-doped rare earth NPs. Figure 3 As shown in Fig. 2, the upconversion and downshifting luminescence spectra of the dye-sensitized NaErF4@NaLuF4NPs were measured at the optimal concentration of the dye. The smallest NPs, i.e., 8 nm NaErF4@NaLuF4NPs, exhibited the brightest upconversion and downshifting luminescence. The upconversion and downshifting integral intensities were enhanced by 1942 and 70 times, respectively, compared with the NPs excited by 980 nm light at the same power density. The spectral integral intensity was higher than that of the traditional IR806-sensitized Yb, Er co-doped rare earth NPs. Example 3

[0047] Synthesis of NaErF4@NaLuF4core-shell rare earth NPs with different inert shell thicknesses of NaLuF4.

[0048] First, 0.056 mL (0.056 mmol), 0.26 mL (0.26 mmol), 0.34 mL (0.34 mmol), and 0.60 mL (0.60 mmol) of an aqueous LuCl3solution were added to a 100 mL flask containing 3 mL of oleic acid and 8 mL of octadecene. The mixture was stirred under an inert atmosphere, heated to 160°C, and evaporated at open to remove moisture for 40 min, and then cooled to room temperature to obtain a shell precursor solution; 1 mL of the 6 nm core NPs NaErF4cyclohexane dispersion prepared in Example 2 was added, and the corresponding ammonium fluoride and sodium hydroxide dissolved in methanol solution was added, stirred under nitrogen protection, and heated at 110-120°C for 15, 25, 30, and 35 min. The NPs were precipitated by adding 10 mL of ethanol, and then 3 mL of cyclohexane was added. The mixture was centrifuged (12000 rpm, 10 min) to separate the supernatant, and the precipitate was washed with a cyclohexane and ethanol mixture (10 mL, 1:1, v / v). The NPs were dispersed in 5 mL of cyclohexane for storage, and NaErF4@NaLuF4core-shell rare earth NPs with inert shell thicknesses of 0.6, 2.1, 3.0, and 4.1 nm were obtained, respectively. The transmission electron micrographs are shown in Fig. 3 (a). Figure 4

[0049] Changes in the upconversion and downshifting spectra of Cy5-SO3-sensitized NaErF4@NaLuF4NPs with different inert shell thicknesses of NaLuF4with the addition of dye concentrations.​

[0050] Take 200 μL of different shell thickness NaErF4@NaLuF4 core-shell rare earth nanoparticles cyclohexane dispersion solution, mixed with 1300 μL chloroform solution ultrasonic, placed in a quartz cuvette, mixed with different volume of Cy5-SO3 dimethyl sulfoxide and chloroform mixed solution (1:2, v / v) (1 mM), stirred for 2 min, then use 635 nm external laser as excitation light source, test up-conversion and down-shift luminescence spectra on FLS1000 fluorescence spectrometer, laser power is 37.5 W / cm 2 . As shown in Figure 4 , under the optimal concentration of dye, the up-conversion luminescence intensity of Cy5-SO3 sensitized NPs first increases and then decreases with the thickening of inert shell, and the up-conversion luminescence is the strongest when the shell thickness is 2.1 nm, while the down-shift luminescence intensity shows a trend of increasing with the thickening of shell. Example 4

[0051] Effect of a series of cyanine dyes sensitizing 8 nm NaErF4@NaLuF4.

[0052] Take 200 μL of 8 nm NaErF4@NaLuF4 core-shell rare earth nanoparticles cyclohexane dispersion solution, mixed with 1300 μL chloroform solution ultrasonic, placed in a quartz cuvette, mixed with different volume of a series of cyanine dyes Cy3, Cy5, Cy5.5, Cy7, Cy7.5 dimethyl sulfoxide and chloroform mixed solution (1:2, v / v) (1 mM), stirred for 2 min, then use corresponding external laser (532, 635, 730, 808 nm) as excitation light source, test up-conversion and down-shift luminescence spectra on FLS1000 fluorescence spectrometer, laser power is 37.5 W / cm 2 . As shown in Figure 5 , the up-conversion and down-shift integral intensity compared with the same power density under 980 nm excitation NPs all achieved different degrees of luminescence enhancement, in which the sensitization effect of Cy5 is the best. Example 5

[0053] Application of Cy5-SO3 sensitized NaErF4@NaLuF4 in temperature measurement.

[0054] A cyclohexane dispersion (2 mL) of 6 nm NaErF4 coated with 2.1 nm NaLuF4 rare earth nanoparticles was ultrasonically dispersed in 3 mL of chloroform, and then mixed with 20 μL of a 10 mM Cy5-SO3 solution in dimethyl sulfoxide and chloroform (1:2, v / v) and stirred for 2 min. The resulting Cy5-SO3-Er-NPs were mixed with a 5 mL chloroform solution containing 10 mg DSPE-PEG in a round-bottom flask. After stirring at room temperature for 12 h, the chloroform was removed by rotary evaporation. The resulting film was hydrated with 3 mL of deionized water, and the mixture was transferred to a centrifuge tube and centrifuged at low speed (1000 rpm, 5 min). The supernatant was collected and then purified by high-speed centrifugation (15000 rpm, 15 min) of the DSPE-PEG-modified Cy5-SO3-sensitized NaErF4@NaLuF4, and redispersed in 1.5 mL of ethanol. The purpose of modifying Cy5-SO3-Er-NPs with DSPE-PEG is to transfer them to polar solvents (ethanol phase) and expand their applicable solvent range.

[0055] The upconversion emission spectrum of the nanoprobe in the ethanol phase was measured using a 635 nm external laser as the excitation source on an FLS1000 fluorescence spectrometer with a laser power of 187 W / cm². 2 .like Figure 6 As shown, its upconversion luminescence intensity gradually decreases with increasing temperature (from 293 K to 348 K). This is based on the non-thermally coupled energy level. 2 H 11 / 2 and 2 P 3 / 2 , respectively corresponding to Er 3+ The nanoprobe exhibits emission at 525 nm and 408 nm, with a maximum absolute sensitivity of 3.69 % / K and a maximum relative sensitivity of 1.26 % / K. Furthermore, this nanoprobe demonstrates good stability and repeatability.

Claims

1. Application of a fluorin dye sensitized rare earth luminescent nanoprobes in temperature measurement, characterized in that, The flower cyanine dye sensitized luminescent nanoprobes are composed of flower cyanine dye with coordination group and core-shell structure rare earth nanoparticles, and the flower cyanine dye is coordinated to the core-shell structure rare earth nanoparticles through ligand exchange to realize up-conversion and down-shift luminescence enhancement; wherein: The flower cyanine dye in the flower cyanine dye sensitized rare earth luminescent nanoprobes is Cy5, Cy5.5, Cy7 or Cy7.5; The rare earth nanoparticle structure is NaErF4@NaLuF4, the particle size is between 7-16 nm, and the thickness of the shell NaLuF4 is between 0.5-5 nm; Er 3+ ions as emitters.

2. Use according to claim 1, characterized in that, The flower cyanine dye is sulfonated Cy5 dye, and when applied, a light source with an excitation wavelength of 635 nm is used for excitation irradiation.

3. Use according to claim 1, characterized in that, The preparation method of the flower cyanine dye sensitized luminescent nanoprobes comprises the following steps: The core-shell structure rare earth nanoparticles are synthesized by a method of layer-by-layer epitaxial growth; The dispersion liquid of the rare earth nanoparticles and the flower cyanine dye solution are mixed, and the flower cyanine dye is coordinated to the core-shell structure rare earth nanoparticles through a ligand exchange process.

Images