Multicolor-excited cyanine dye-sensitized luminescent nanoprobe, and preparation method and application thereof

Abstract

The invention discloses a multi-color excited cyanine dye sensitization luminescence nano probe, a preparation method and an application of the multi-color excited cyanine dye sensitization luminescence nano probe. The probe is composed of a cyanine dye with a coordination group and core-shell structure rare earth nanoparticles, the coordination group is selected from one or two of sulfonate radicals or carboxylate radicals, and the cyanine dye is coordinated to the nanoparticles through ligand exchange to achieve up-conversion and down-migration luminescence enhancement. The preparation method is simple, the cyanine dye can be directly coordinated to the rare earth nanoparticles, and energy transfer is achieved. As Er < 3 + > has a very rich absorption energy level from 500-1100 nm and has different degrees of spectral overlap with emission of a series of cyanine dyes, the whole dye-sensitized system does not need Yb < 3 + > or Nd < 3 + > as an energy bridge, and an up-conversion and down-migration luminescent system for directly sensitizing Er < 3 + > by a series of multi-color excited cyanine dyes can be constructed. The probe has good repeatability and stability when being applied to temperature measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of luminescent materials, and in particular relates to a multicolor excited cyanine dye-sensitized luminescent nanoprobe, a preparation method and an application thereof. Background Art

[0002] Rare earth nanoparticles (NPs) have attracted extensive interest from scholars due to their narrow emission, non-blinking and excellent photostability. Using NPs as imaging probes can eliminate the interference of spontaneous background fluorescence of biological samples and produce images with high contrast. 3+ The ions act as sensitizers to absorb infrared radiation and transfer energy to the activator ions Er non-radiatively. 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 increase their luminescence brightness.

[0003] However, in traditional dye-sensitized systems, Yb 3+ or Nd 3+ Usually acts as a bridge for energy transfer between organic dyes and emitters, while Yb 3+ and Nd 3+ There is a strong interaction with NIR energy. Therefore, only limited NIR dyes, such as IR806, have been used for sensitization of rare earth nanoparticles due to the necessity of spectral overlap. This limitation presents a significant challenge when trying to construct a multicolor excitation dynamics sensitization system. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a multicolor excited cyanine dye-sensitized luminescent nanoprobe, a preparation method and an application thereof; the preparation method of the present invention is simple, and energy transfer is achieved by directly coordinating the cyanine dye to the rare earth nanoparticles; the cyanine dye-sensitized luminescent nanoprobe is Er 3+ Ions act as emitters, due to Er 3+ It has a very rich absorption energy level, and has different degrees of spectral overlap with the emission of a series of cyanine dyes. The entire dye-sensitized system does not require Yb 3+ or Nd 3+ As an energy bridge, a series of cyanine dyes can be constructed to directly sensitize Er 3+ The probe has good repeatability and stability when used for temperature measurement.

[0005] The technical solution of the present invention is specifically described as follows.

[0006] The cyanine dye-sensitized luminescent nanoprobe is composed of a cyanine dye with a coordination group and rare earth nanoparticles with a core-shell structure. The cyanine dye is coordinated to the rare earth nanoparticles with a core-shell structure through ligand exchange to achieve upconversion and down-migration luminescence enhancement; wherein: The coordination group is selected from one or both of sulfonate or carboxylate; The core of the rare earth nanoparticle structure is NaErF 4 , the shell is an inert shell.

[0007] In the present invention, the cyanine dye is a Cy series dye with a coordination group, which is composed of 3-7 methine groups to form a conjugated chain, and the heterocyclic rings at both ends of the conjugated chain are indole or benzindolyl.

[0008] In the present invention, the cyanine dye with a coordination group includes unsulfonated Cy dye, sulfonated Cy dye, or a Cy dye that is sulfonated and has an amino group. In a specific embodiment, it includes sulfonated Cy7.5, unsulfonated Cy5 dye, sulfonated Cy3-primary amine, sulfonated Cy5-primary amine, sulfonated Cy5.5-primary amine, and sulfonated Cy7-primary amine. The absorption wavelength of the cyanine dye is between 400-900 nm, and the emission wavelength is between 500-1000 nm.

[0009] In the present invention, the rare earth nanoparticle structure is NaErF 4 @NaLuF 4 , with a particle size between 7-16 nm, and a shell of NaLuF 4 The thickness is between 0.5-5nm; 3+ Ions act as emitters.

[0010] The present invention also provides a method for preparing the above-mentioned cyanine dye-sensitized luminescent nanoprobe, comprising the following steps: Synthesize rare earth nanoparticles with core-shell structure by layer-by-layer epitaxial growth method; The dispersion of rare earth nanoparticles and cyanine dye solution are mixed, and the cyanine dye is coordinated to the rare earth nanoparticles with core-shell structure through a ligand exchange process.

[0011] The present invention also provides an application of the above-mentioned cyanine dye-sensitized rare earth luminescent nanoprobe in constructing a multicolor excitation dynamic sensitization system, wherein a series of cyanine dyes are excited by excitation lights of different wavelengths to construct a multicolor excitation system.

[0012] Furthermore, the present invention provides an application of the above-mentioned cyanine dye-sensitized rare earth luminescent nanoprobe in temperature measurement.

[0013] In the present invention, the cyanine dye is a sulfonated Cy5 dye; when used, a light source with an excitation wavelength of 635 nm is used for excitation and irradiation.

[0014] The present invention introduces a method of directly sensitizing Er using organic dyes. 3+ A new strategy for emission without the need for an intermediate energy transfer bridge such as Yb 3+ and Nd 3+ . With Yb 3+ The difference is that Er 3+ It has a very rich absorption energy level from ultraviolet to near infrared region (500-1100 nm). 3+ The 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 to create a multicolor excitation system. To this end, a series of cyanine dyes were used as antenna molecules, including Cy3, Cy5, Cy5.5, Cy7, and Cy7.5. These dyes are closely related to Er 3+ The absorption spectra of Er have different degrees of spectral overlap, which can directly transfer energy to Er 3+ , to achieve the enhancement of up-conversion and down-migration luminescence of rare earth nanoparticles. Compared with the prior art, the beneficial effects of the present invention are: The present invention provides a series of cyanine dye-sensitized NaErF 4 The preparation method of the luminescent nanoprobe is to exchange and coordinate the cyanine dye ligand to the surface of rare earth nanoparticles to obtain dye-sensitized luminescence enhancement. Under 635 nm excitation, the laser power is 37.5 W / cm 2 Under the test conditions, Cy5-SO 3 The integrated intensities of the upconversion and downshift luminescence spectra of the sensitized 8 nm rare earth nanoparticles can be enhanced by 1942 times and 70 times respectively compared with 980 nm excitation with the same power.

[0015] In the present invention, the inert shell NaLuF is changed 4 The thickness of Er 3+ Enhancement of upconversion and down-migration luminescence.

[0016] A series of cyanine dyes can be used to treat NaErF 4 @NaLuF 4 The luminescence sensitization can achieve different degrees of up-conversion and down-migration luminescence enhancement.

[0017] Cy5-SO of the present invention 3 Cyanine dye-sensitized NaErF 4 @NaLuF 4 It can be used to measure temperature with good repeatability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1The working principle diagram of the traditional dye-sensitized luminescent nanoprobe (a), the working principle diagram of a series of cyanine dye-sensitized rare earth up-conversion and down-migration luminescent nanoprobes of the present invention (b), and the structural formula of the dye molecule (c).

[0019] Figure 2 Transmission electron micrographs (a, b) and X-ray diffraction patterns (c) of the rare earth nanoparticles and core-shell rare earth nanoparticles in Example 1, the molecular structure, absorption and emission spectra (d) of the dye in the Cy5 sensitization system, and the dye-sensitized 12 nm NaErF 4 @NaLuF 4 Upconversion and downshift emission spectra (e, f), and energy transfer mechanism diagram (g, h).

[0020] Figure 3 The NaErF particles of different sizes in Example 2 are 4 @NaLuF 4 Transmission electron micrographs (a, b) and Cy5-SO 3 Sensitized upconversion and downshift spectra (c) and comparison of the sensitization effect with the traditional IR806-sensitized Yb, Er co-doped rare earth nanoparticle system (d, e).

[0021] Figure 4 The different NaLuF of Example 3 4 Inert shell thickness of NaErF 4 @NaLuF 4 Transmission electron micrograph (a), upconversion and downshift spectra under 980 nm excitation (b, c), and Cy5-SO 3 Sensitized upconversion and downshift spectra (d, e) and kinetic decay processes (fh).

[0022] Figure 5 Absorption and emission spectra of a series of cyanine dyes in Example 4 (a, b) and their sensitized 8 nm NaErF 4 @NaLuF 4 The luminescence enhancement effect (c).

[0023] Figure 6 Cy5-SO of Example 5 3 Sensitized NaErF 4 @NaLuF 4 Application in temperature measurement. Using DSPE-modified Cy5-SO 3 Sensitized NaErF 4 @NaLuF 4Schematic diagram (a) and transmission electron micrograph (b) of the DSPE-modified Cy5-SO and its upconversion spectrum changes with temperature (c). The absolute sensitivity (d) and relative sensitivity (e) are calculated from the temperature-dependent emission intensity ratios at 525 / 541 and 525 / 408 nm, respectively. (f) 3 Sensitized NaErF 4 @NaLuF 4 Experimental and theoretical fit of the 525 / 408 nm intensity ratio as a function of temperature. (g) Repeatability test of 7 cycles at 293 K and 348 K. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 The working principle diagram of a series of cyanine dye-sensitized rare earth up-conversion and down-migration luminescent nanoprobes of the present invention ( Figure 1 b), and the structural formulas of a series of cyanine dye molecules involved in the embodiments ( Figure 1 c). Example 1

[0026] NaErF with a particle size of 12 nm 4 @NaLuF 4 Synthesis of core-shell rare earth nanoparticles.

[0027] 1 mmol (1 mL, 1 M) rare earth chloride aqueous solution (ErCl 3 :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 moisture. The mixture was then cooled to 90-110°C, and 0.1 g (2.5 mmol) of sodium hydroxide was added, degassed for 30 min, and then 0.1481 g (4 mmol) of ammonium fluoride was added, degassed for another 30 min, the solution was heated to 290°C, 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. 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). The nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 10 nm; Take 0.1 mmol (0.1 mL, 1 M) of an aqueous solution of rare earth chloride (LuCl 3: 0.1 mmol) was added into 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 for 40 min to remove moisture, then cooled to room temperature to obtain a shell precursor solution; 1.4 mL of the 10 nm core nanoparticle cyclohexane dispersion obtained in the previous step and 1.25 mL of a methanol solution in which ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) were dissolved were added, stirred under nitrogen protection, and heated at 110-120°C for 10 min to remove low-boiling solvents and part of the water; the temperature was raised to 290°C under nitrogen protection, and the reaction was maintained 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 centrifuged (12000 rpm, 10 min) to separate, the supernatant was discarded, 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, and the particle size was about 12 nm.

[0028] Cy5-SO 3 and Cy5-COO-sensitized NaErF 4 @NaLuF 4 The up-conversion and down-shift luminescence spectra of the system vary with the concentration of added dye.

[0029] Take 280 μL of NaErF 4 @NaLuF 4 The cyclohexane dispersion of core-shell rare earth nanoparticles was ultrasonically mixed with 1220 μL of chloroform solution, placed in a quartz cuvette, and mixed with 0, 2, 4, 6, … 40 μL of Cy5-SO 3 The mixture of dimethyl sulfoxide and chloroform (1:2, v / v) of Cy5-COO was mixed and stirred for 2 min. The upconversion and downshift luminescence spectra were measured on an FLS1000 fluorescence spectrometer using a 635 nm external laser as the excitation light source. The laser power was 37.5 W / cm 2 .like Figure 2 As shown, at the optimal concentration of the dye, Cy5-SO 3 The upconversion and downmigration integrated intensities of the sensitized NPs were enhanced by 117 times and 23 times, respectively, compared with those of the NPs excited at 980 nm at the same power density. The upconversion and downmigration integrated intensities of the Cy5-COO-sensitized NPs were enhanced by 29 times and 14 times, respectively, compared with those of the NPs excited at 980 nm at the same power density. Example 2

[0030] NaErF with a particle size of 8 nm 4 @NaLuF4 Synthesis of core-shell rare earth nanoparticles.

[0031] 1 mmol (1 mL, 1 M) rare earth chloride aqueous solution (ErCl 3 :1 mmol) was added to a 100 mL flask containing 10 mL oleic acid and 10 mL octadecene. The mixture was stirred under a nitrogen atmosphere, heated to 160°C, and evaporated open for 40 min to remove moisture; after cooling to 110-120°C, 0.34 g ammonium fluoride and 2.03 g sodium oleate were quickly added, dissolved at 110-120°C for 30 min, and then vacuumed for 30 min; heated to 290°C under nitrogen protection and maintained for 50 min, then cooled to room temperature; 20 mL ethanol was added to precipitate nanoparticles, and then 6 mL 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), and the nanoparticles were dispersed in 10 mL cyclohexane for storage, with a particle size of about 6 nm; Take 0.2 mmol (0.2 mL, 1 M) of an aqueous solution of a rare earth chloride (LuCl 3 : 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 for 40 min to remove moisture, then cooled to room temperature to obtain a shell precursor solution; 1 mL of the 6 nm core nanoparticle cyclohexane dispersion obtained in the previous step and 2.5 mL of a methanol solution in which ammonium fluoride (0.75 mmol) and sodium hydroxide (0.5 mmol) were dissolved were added, stirred under nitrogen protection, and heated at 110-120°C for 10 min to remove low-boiling solvents and part of the water; the temperature was raised to 290°C under nitrogen protection, and the reaction was maintained for 20 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and then 3 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 (10 mL, 1:1, v / v), and the nanoparticles were dispersed in 5 mL of cyclohexane for storage, and the particle size was about 8 nm.

[0032] NaErF with a particle size of 16 nm 4 @NaLuF 4 Synthesis of core-shell rare earth nanoparticles.

[0033] Take 0.1 mmol (0.1 mL, 1 M) of an aqueous solution of a rare earth chloride (ErCl 3: 0.1 mmol) was added into 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 for 40 min to remove moisture, then cooled to room temperature to obtain a shell precursor solution; 1 mL of the 10 nm core nanoparticle cyclohexane dispersion obtained in the previous step and 1.25 mL of a methanol solution in which ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) were dissolved were added, stirred under nitrogen protection, and heated at 110-120°C for 10 min to remove low-boiling solvents and part of the water; the temperature was raised to 290°C under nitrogen protection, and the reaction was maintained 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, 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, and the particle size was about 14 nm.

[0034] Take 0.05 mmol (0.05 mL, 1 M) of an aqueous solution of rare earth chloride (LuCl 3 : 0.05 mmol) was added to a 100 mL flask containing 3 mL oleic acid and 8 mL octadecene. The mixture was stirred under an inert atmosphere, heated to 160 °C, and evaporated open for 40 min to remove water, and then cooled to room temperature to obtain a shell precursor solution; 5 mL of the 14 nm NaErF 4 The cyclohexane dispersion of the nanoparticles and 0.625 mL of a methanol solution containing ammonium fluoride (0.1875 mmol) and sodium hydroxide (0.125 mmol) were stirred under nitrogen protection and heated at 110-120°C for 10 min to remove the low-boiling solvent and part of the water; the temperature was raised to 290°C under nitrogen protection and the reaction was maintained for 30 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and then 3 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 (10 mL, 1:1, v / v), and the nanoparticles were dispersed in 5 mL of cyclohexane for storage, and the particle size was about 16 nm.

[0035] Cy5-SO 3 Sensitized NaErF 4 @NaLuF 4 The upconversion and downshift luminescence spectra of the system and IR806-sensitized Yb, Er co-doped rare earth nanoparticles change with the added dye concentration.

[0036] Yb, Er co-doped core-shell rare earth nanoparticles NaYbF with a particle size of 12 nm 4 : Er@NaLuF 4 synthesis.

[0037] 1 mmol (1 mL, 1 M) rare earth chloride aqueous solution (YbCl 3 :0.92 mmol,ErCl 3 :0.08 mmol) was added to a 100 mL flask containing 10 mL oleic acid and 10 mL octadecene. The mixture was stirred under nitrogen atmosphere, heated to 160℃, and evaporated open for 40 min to remove water; after cooling to 110-120℃, 0.34 g ammonium fluoride and 2.03 g sodium oleate were quickly added, dissolved at 110-120℃ for 30 min, and then vacuumed for 30 min; heated to 290℃ under nitrogen protection and maintained for 50 min, then cooled to room temperature; 20 mL ethanol was added to precipitate nanoparticles, and 6 mL 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), and the nanoparticles were dispersed in 10 mL cyclohexane for storage, with a particle size of about 10 nm; Take 0.1 mmol (0.1 mL, 1 M) of an aqueous solution of rare earth chloride (LuCl 3 : 0.1 mmol) was added into 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 for 40 min to remove moisture, then cooled to room temperature to obtain a shell precursor solution; 1.4 mL of the cyclohexane dispersion of core nanoparticles obtained in the previous step and 1.25 mL of a methanol solution in which ammonium fluoride (0.375 mmol) and sodium hydroxide (0.25 mmol) were dissolved were added, stirred under nitrogen protection, and heated at 110-120°C for 10 min to remove low-boiling solvents and part of the water; the temperature was raised to 290°C under nitrogen protection, and the reaction was maintained for 20 min, then cooled to room temperature; 10 mL of ethanol was added to precipitate the nanoparticles, and then 3 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 (10 mL, 1:1, v / v), and the nanoparticles were dispersed in 10 mL of cyclohexane for storage, and the particle size was about 12 nm.

[0038] Take NaErF with different particle sizes 4 @NaLuF 4The cyclohexane dispersion of Yb and Er co-doped rare earth nanoparticles was ultrasonically mixed with the chloroform solution to keep the Er in the solution 3+ The concentration or Yb 3+ With Er 3+ The total concentration was 2.6 mM and placed in a quartz cuvette and mixed with different volumes of Cy5-SO 3 The mixture of DMSO and chloroform (1:2, v / v) of IR806 was mixed and stirred for 2 min. The up-conversion and down-shift luminescence spectra were measured on an FLS1000 fluorescence spectrometer using 635 nm and 808 nm external lasers as excitation light sources, respectively. The laser power was 37.5 W / cm 2 .like Figure 3 As shown, at the optimal concentration of the dye, Cy5-SO 3 Sensitized NaErF with different particle sizes 4 @NaLuF 4 The smallest nanoparticle, NaErF 4 @NaLuF 4 It exhibits the brightest upconversion and down-migration luminescence, and its upconversion and down-migration integrated intensities are enhanced by 1942 and 70 times respectively compared with NPs excited at 980 nm at the same power density, and the spectral integrated intensity is higher than that of traditional IR806-sensitized Yb, Er co-doped rare earth nanoparticles. Example 3

[0039] Different NaLuF 4 Inert shell thickness of NaErF 4 @NaLuF 4 Synthesis of core-shell rare earth nanoparticles.

[0040] 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 LuCl 3 The aqueous solution of 1 mL of oleic acid and 8 mL of octadecene was added to a 100 mL flask. The mixture was stirred under an inert atmosphere, heated to 160°C, and evaporated open for 40 min to remove water, and then cooled to room temperature to obtain a shell precursor solution. 1 mL of 6 nm core nanoparticles NaErF prepared in Example 2 was added. 4The cyclohexane dispersion was added with the corresponding methanol solution containing ammonium fluoride and sodium hydroxide, stirred under nitrogen protection, and heated at 110-120°C for 15, 25, 30, and 35 min. 10 mL of ethanol was added to precipitate the nanoparticles, and then 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). The nanoparticles were dispersed in 5 mL of cyclohexane and stored, and NaErF with inert shell thickness of 0.6, 2.1, 3.0, and 4.1 nm were obtained, respectively. 4 @NaLuF 4 Core-shell rare earth nanoparticles, the transmission electron microscope photo of which is shown in Figure 4 (a) shown.

[0041] Cy5-SO 3 Sensitization of different NaLuF 4 Variation of the up-conversion and down-shift spectra of the inert shell thickness with the concentration of added dye.

[0042] Take 200 μL of NaErF with different shell thicknesses 4 @NaLuF 4 The cyclohexane dispersion of core-shell rare earth nanoparticles was ultrasonically mixed with 1300 μL of chloroform solution, placed in a quartz cuvette, and incubated with different volumes of Cy5-SO 3 A mixed solution of dimethyl sulfoxide and chloroform (1:2, v / v) (1 mM) was mixed and stirred for 2 min. A 635 nm external laser was used as the excitation light source to test the up-conversion and down-shift luminescence spectra on an FLS1000 fluorescence spectrometer. The laser power was 37.5 W / cm 2 .like Figure 4 As shown, at the optimal concentration of the dye, Cy5-SO 3 The upconversion luminescence intensity of the sensitized NPs first increases and then decreases with the thickening of the inert shell. The upconversion luminescence is strongest when the shell thickness is 2.1 nm, while the downconversion luminescence intensity shows an increasing trend as the shell becomes thicker. Example 4

[0043] A series of cyanine dyes sensitized 8 nm NaErF 4 @NaLuF 4 effect.

[0044] Take 200 μL of 8 nm NaErF 4 @NaLuF 4The cyclohexane dispersion of core-shell rare earth nanoparticles was ultrasonically mixed with 1300 μL of chloroform solution, placed in a quartz cuvette, and mixed with different volumes of a series of cyanine dyes Cy3, Cy5, Cy5.5, Cy7, Cy7.5 dimethyl sulfoxide and chloroform mixed solutions (1:2, v / v) (1 mM), respectively. After stirring for 2 min, the corresponding external lasers (532, 635, 730, 808 nm) were used as excitation light sources, and the up-conversion and down-shift luminescence spectra were tested on an FLS1000 fluorescence spectrometer. The laser power was 37.5 W / cm 2 .like Figure 5 As shown in the figure, the upconversion and down-migration integrated intensities achieved different degrees of luminescence enhancement compared with NPs excited at 980 nm at the same power density, among which Cy5 had the best sensitization effect. Example 5

[0045] Cy5-SO 3 Sensitized NaErF 4 @NaLuF 4 Application in temperature measurement.

[0046] The prepared 6 nmNaErF 4 Coated with 2.1 nmNaLuF 4 The cyclohexane dispersion of rare earth nanoparticles (2 mL) was ultrasonically dispersed in 3 mL of chloroform and then mixed with 20 μL of Cy5-SO 3 The obtained Cy5-SO was mixed with dimethyl sulfoxide (10 mM) and chloroform (1:2, v / v) and stirred for 2 min. 3 -Er-NPs were mixed with 5 mL of chloroform solution containing 10 mg of 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 then taken and purified by high-speed centrifugation (15000 rpm, 15 min). 3 Sensitized NaErF 4 @NaLuF 4 , and redispersed in 1.5 mL of ethanol. 3 The purpose of modifying -Er-NPs with DSPE-PEG is to transfer them to polar solvents (ethanol phase) and expand their applicable solvent range.

[0047] The upconversion luminescence spectrum of the nanoprobe in the ethanol phase was measured on an FLS1000 fluorescence spectrometer using a 635 nm external laser as the excitation light source. The laser power was 187 W / cm2 .like Figure 6 As shown in Figure 2, the upconversion luminescence intensity gradually decreases with increasing temperature (from 293K to 348K). 2 H 11 / 2 and 2 P 3 / 2 , corresponding to Er 3+ The maximum absolute sensitivity of the nanoprobe is 3.69% / K and the maximum relative sensitivity is 1.26% / K. In addition, the nanoprobe has good stability and repeatability.

Claims

1. A cyanine dye-sensitized luminescent nanoprobe, characterized in that: The invention is composed of a cyanine dye with a coordination group and rare earth nanoparticles with a core-shell structure. The cyanine dye is coordinated to the rare earth nanoparticles with a core-shell structure through ligand exchange to achieve up-conversion and down-migration luminescence enhancement; wherein: The coordination group is selected from one or two of sulfonate and carboxylate groups; The core of the rare earth nanoparticle structure of the core-shell structure is NaErF4, and the shell is an inert shell layer.

2. The cyanine dye-sensitized luminescent nanoprobe according to claim 1, characterized in that: Cyanine dyes are Cy series dyes with coordination groups, which are composed of 3-7 methyl groups to form a conjugated chain, and the heterocyclic rings at both ends of the conjugated chain are indolyl or benzindolyl.

3. The cyanine dye-sensitized luminescent nanoprobe according to claim 1, characterized in that: The cyanine dye with a coordination group includes an unsulfonated Cy dye, a sulfonated Cy dye, or a sulfonated Cy dye having an amine group.

4. The cyanine dye-sensitized luminescent nanoprobe according to claim 1, characterized in that: The rare earth nanoparticle structure is NaErF4@NaLuF4, with a particle size between 7-16 nm and a shell NaLuF4 thickness between 0.5-5 nm. 3+ Ions act as emitters.

5. A method for preparing a cyanine dye-sensitized luminescent nanoprobe according to claim 1, characterized in that: The following steps are involved: Synthesize rare earth nanoparticles with core-shell structure by layer-by-layer epitaxial growth method; The dispersion of rare earth nanoparticles and cyanine dye solution are mixed, and the cyanine dye is coordinated to the rare earth nanoparticles with core-shell structure through a ligand exchange process.

6. A use of the cyanine dye-sensitized rare earth luminescent nanoprobe according to claim 1 in constructing a multicolor excitation dynamic sensitization system, characterized in that: A series of cyanine dyes are excited by excitation light of different wavelengths to construct a multicolor excitation system.

7. Use of the cyanine dye-sensitized rare earth luminescent nanoprobe according to claim 1 in temperature measurement.

8. The use according to claim 7, characterized in that: The cyanine dye in the cyanine dye-sensitized rare earth luminescent nanoprobe is a Cy series dye with a coordination group, which is composed of 3-7 methyl groups to form a conjugated chain, and the heterocyclic rings at both ends of the conjugated chain are indole or benzindolyl.

9. The use according to claim 8, characterized in that: The cyanine dye is a sulfonated Cy5 dye. When used, it is excited and irradiated with a light source with an excitation wavelength of 635 nm.

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