A rare earth upconversion nanofluorescent probe and its preparation method and application

Abstract

The present invention relates to the field of fluorescent probe technology, and in particular to a rare earth up-conversion nano fluorescent probe and its preparation method and application. The rare earth up-conversion nano fluorescent probe provided by the present invention is a core-shell structure, doped with Yb 3+ 、Tm 3+ and Er 3+ The NaYF4 nanoparticles are used as the core, and the NaTmF4 shell is coated on the outside of the core. The rare earth up-conversion nano-fluorescent probe provided by the present invention can respond to the 1208nm excitation wavelength under the excitation of 980nm and 1208nm excitation wavelengths. Under the excitation of 980nm excitation wavelength, the rare earth up-conversion nano-fluorescent probe is simultaneously excited by a laser with a wavelength of 1208nm. The peak value of the rare earth up-conversion nano-fluorescent probe at 539.87nm becomes stronger as the power of the 1208nm excitation wavelength increases, thereby reflecting the good linear response of the rare earth up-conversion nano-fluorescent probe to the 1208nm excitation wavelength. Therefore, it can be used to detect the power of a laser with a wavelength of 1208nm.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent probes, and in particular to a rare earth up-conversion nano fluorescent probe and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] In recent years, near-infrared (NIR) II fluorescence imaging technology (1000-1700 nm) has brought new opportunities to the field of biomedical testing. Compared to traditional short-wavelength fluorescence imaging (400-1000 nm), NIR II excitation and emission light exhibits lower scattering and absorption in biological tissues, significantly improving imaging resolution and penetration depth. 1208 nm is a typical NIR II excitation wavelength, but currently, few fluorescent probe materials responsive to 1208 nm lasers have been reported.

[0004] Currently, common fluorescent probe materials, such as organic dyes, fluorescent proteins, and quantum dots, are typically excited by ultraviolet or visible light. These materials exhibit broad and asymmetric fluorescence emission peaks, severe tailing, and overlapping spectra of various dyes. Furthermore, they experience very strong biological autofluorescence (background fluorescence) and scattered light, severely limiting their application. In contrast, upconversion nanomaterials (UCNPs) use near-infrared light as their excitation light, resulting in less photodamage, lower autofluorescence background in biological tissues, deeper penetration, multi-wavelength luminescence, near-nontoxicity, and high fluorescence intensity and stability. Summary of the Invention

[0005] In order to overcome the above problems, the present invention provides a rare earth up-conversion nano fluorescent probe and a preparation method and application thereof.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a rare earth up-conversion nano fluorescent probe, which is a core-shell structure and is doped with Yb 3+ 、Tm 3+ and Er 3+ The NaYF4 nanoparticles are the core, and the NaTmF4 shell is coated on the outside of the core.

[0008] The core is composed of rare earth ions Yb 3+ As a sensitizer, Er 3+ and Tm 3+As an activator, it is doped in the NaYF4 matrix; NaTmF4 as the shell can protect the luminescent center (rare earth ions) in the core from interference from the external environment; the NaTmF4 shell is coated to make the Tm 3+ The higher the content of Yb, the stronger the luminescence of the material, and the more obvious the test effect of the power of the 1208nm laser. This is because: under the simultaneous excitation of 980nm and 1208nm lasers, Yb 3+ Absorbing 980nm photons from the ground state 2 F 7 / 2 Transition to excited state 2 F 5 / 2 , excited state Yb 3+ Transfer energy to Er 3+ , so Er 3+ From the ground state 4 I 15 / 2 Transition to excited state 4 I 11 / 2 ; Er 3+ from 4 I 11 / 2 Through nonradiative transition to 4 I 13 / 2 energy level, or by absorbing another 980nm photon to a higher energy level, followed by a non-radiative transition to 2 H 11 / 2 and 4 S 3 / 2 Energy level; excited state of Yb 3+ Transfer energy to Tm 3+ , so that Tm 3+ From the ground state 3 H6 jumps to 3 F4 energy level, not only that, Tm 3+ Absorbing 1208nm photons, from the ground state 3 H6 transitions to the excited state 3 H5, Tm 3+ from 3 H5 undergoes a nonradiative transition to 3 F4 energy level; Tm of excited state 3+ Transfer energy to Er 3+ , so Er 3+ From the ground state 4 I 15 / 2 Jump to 4 I 9 / 2 Energy level; 3+ relaxes through nonradiative transitions to 4 I 13 / 2 Energy level; 3+ from 4 I 13 / 2 Energy level transition back 4 I15 / 2 Energy levels will emit particles; the power of 980nm and 1208nm lasers directly affects the Yb 3+ 、Tm 3+ 、Er 3+ The excitation efficiency of Er is shown in Figure 2. It can be seen that the stronger the 1208nm laser power is, the higher the 3+ exist 4 I 13 / 2 The more particles there are at the energy level, the 3+ from 4 I 13 / 2 Energy level 4 I 15 / 2 The greater the intensity of the particles emitted by the energy level transition, the greater the power of 1208nm. 3+ The higher the content, the brighter the material and the more obvious the inspection effect.

[0009] The rare earth up-conversion nano fluorescent probe emits green light at a wavelength of 530nm to 560nm under the excitation of 980nm excitation wavelength.

[0010] The second aspect of the present invention provides a method for preparing a rare earth upconversion nanofluorescent probe, comprising the following steps:

[0011] (1) adding Y salt, Yb salt, Tm salt and Er salt to a mixed solution of oleic acid, oleylamine and 1-octadecene to obtain a reaction solution containing a Y / Yb / Tm / Er-oleic acid complex precursor;

[0012] (2) NaOH and NH4F were added to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, and the core was synthesized by coprecipitation reaction. 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles;

[0013] (3) adding the Tm salt to a mixed solution of oleic acid, oleylamine, and 1-octadecene to obtain a reaction solution containing a Tm-oleic acid complex precursor;

[0014] (4) Yb-doped 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles, NaOH and NH4F are added to the reaction solution containing Tm-oleic acid complex precursor, and a co-precipitation reaction is performed to synthesize rare earth upconversion nanofluorescent probes.

[0015] The third aspect of the present invention provides the use of the rare earth up-conversion nano-fluorescent probe described in the first aspect in detecting the power of a laser with a wavelength of 1208 nm.

[0016] The rare earth upconversion nanofluorescent probe provided by the present invention can respond to an excitation wavelength of 1208 nm under both 980 nm and 1208 nm excitation wavelengths. When excited simultaneously with a 1208 nm laser under 980 nm excitation wavelength, the peak value of the rare earth upconversion nanofluorescent probe at 539.87 nm increases with increasing power of the 1208 nm excitation wavelength, demonstrating the good response of the rare earth upconversion nanofluorescent probe to the 1208 nm excitation wavelength.

[0017] The fourth aspect of the present invention provides the application of the rare earth up-conversion nano fluorescent probe described in the first aspect in the field of temperature sensing.

[0018] The rare earth up-conversion nano fluorescent probe provided by the present invention is heated (50-270° C.) under the excitation of 980 nm excitation wavelength. The fluorescence intensity of the rare earth up-conversion nano fluorescent probe decreases as the temperature rises, thereby realizing the temperature measurement function.

[0019] The fifth aspect of the present invention provides the use of the rare earth up-conversion nano fluorescent probe and carbon quantum dots described in the first aspect as a dual anti-counterfeiting material.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention relates to the field of fluorescent probe technology, and in particular to a rare earth up-conversion nano fluorescent probe and its preparation method and application. The rare earth up-conversion nano fluorescent probe provided by the present invention is a core-shell structure, doped with Yb 3+ 、Tm 3+ and Er 3+ The core is composed of NaYF4 nanoparticles and the outer shell is covered with NaTmF4. 3+ As a sensitizer, Er 3+ and Tm 3+ As an activator, it is doped in the NaYF4 matrix; NaTmF4 as the shell can protect the luminescent center (rare earth ions) in the core from interference from the external environment; the NaTmF4 shell is coated to make the Tm 3+ The higher the content of Yb, the stronger the luminescence of the material, and the more obvious the test effect of the power of the 1208nm laser. This is because: under the simultaneous excitation of 980nm and 1208nm lasers, Yb 3+ Absorbing 980nm photons from the ground state 2 F 7 / 2 Transition to excited state 2 F 5 / 2 , excited state Yb 3+ Transfer energy to Er 3+, so Er 3+ From the ground state 4 I 15 / 2 Transition to excited state 4 I 11 / 2 ; Er 3+ from 4 I 11 / 2 Through nonradiative transition to 4 I 13 / 2 energy level, or by absorbing another 980nm photon to a higher energy level, followed by a non-radiative transition to 2 H 11 / 2 and 4 S 3 / 2 Energy level; excited state of Yb 3+ Transfer energy to Tm 3+ , so that Tm 3+ From the ground state 3 H6 jumps to 3 F4 energy level, not only that, Tm 3 + Absorbing 1208nm photons, from the ground state 3 H6 transitions to the excited state 3 H5, Tm 3+ from 3 H5 undergoes a nonradiative transition to 3 F4 energy level; Tm of excited state 3+ Transfer energy to Er 3+ , so Er 3+ From the ground state 4 I 15 / 2 Jump to 4 I 9 / 2 Energy level; 3+ relaxes through nonradiative transitions to 4 I 13 / 2 Energy level; 3+ from 4 I 13 / 2 Energy level transition back 4 I 15 / 2 Energy levels will emit particles; the power of 980nm and 1208nm lasers directly affects the Yb 3+ 、Tm 3+ 、Er 3+ The excitation efficiency of Er is shown in Figure 2. It can be seen that the stronger the 1208nm laser power is, the higher the 3+ exist 4 I 13 / 2 The more particles there are at the energy level, the 3+ from 4 I 13 / 2 Energy level 4 I 15 / 2The greater the intensity of the particles emitted by the energy level transition, the greater the power of 1208nm. 3+ The higher the content, the brighter the material and the more obvious the inspection effect.

[0022] (2) The rare earth up-conversion nano-fluorescent probe provided by the present invention emits green light at a wavelength of 530nm to 560nm under excitation at a wavelength of 980nm. At the same time, the rare earth up-conversion nano-fluorescent probe provided by the present invention can respond to an excitation wavelength of 1208nm under excitation at both 980nm and 1208nm. Under excitation at a wavelength of 980nm, the rare earth up-conversion nano-fluorescent probe is simultaneously excited by a laser with a wavelength of 1208nm. The peak value of the rare earth up-conversion nano-fluorescent probe at 539.87nm becomes stronger as the power of the 1208nm excitation wavelength increases, thereby reflecting the good linear response of the rare earth up-conversion nano-fluorescent probe to the 1208nm excitation wavelength. Therefore, it can be used to detect the power of a laser with a wavelength of 1208nm.

[0023] (3) The rare earth up-conversion nanofluorescent probe provided by the present invention is heated (50-270°C) under the excitation of 980nm excitation wavelength. The fluorescence intensity of the rare earth up-conversion nanofluorescent probe decreases as the temperature rises, thereby realizing the temperature measurement function.

[0024] (4) The rare earth up-conversion nano fluorescent probe and carbon quantum dots provided by the present invention form different luminescent colors under the excitation of different excitation wavelengths, and the two can be used as dual anti-counterfeiting materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 For the kernel NaYF4:Yb 3+ / Er 3+ / Tm 3+ X-ray diffraction (XRD) pattern;

[0027] Figure 2 For the kernel NaYF4:Yb 3+ / Er 3+ / Tm 3+ Thermogravimetric (TGA) diagram;

[0028] Figure 3 It is a rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @SEM image of NaTmF4;

[0029] Figure 4 It is a rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4's Fourier infrared absorption spectrum;

[0030] Figure 5 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @X-ray diffraction pattern of NaTmF4;

[0031] Figure 6 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @Emission spectrum of NaTmF4 at 980nm excitation wavelength;

[0032] Figure 7 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 responds to 1208nm excitation wavelength under co-excitation of 980nm and 1208nm lasers;

[0033] Figure 8 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @The fluorescence spectrum of NaTmF4 changes with temperature;

[0034] Figure 9 This is a transmission electron microscope image of carbon quantum dots;

[0035] Figure 10 This is the emission spectrum of carbon quantum dots (1:64 dilution) at an excitation wavelength of 365 nm;

[0036] Figure 11 This is the emission spectrum of carbon quantum dots (1:128 dilution) at an excitation wavelength of 365 nm;

[0037] Figure 12 Figure 1 shows the luminous dolphin leaping circle pattern under the excitation of lasers of different wavelengths. Figure a is a color picture under simultaneous irradiation of 365nm laser and 980nm laser, and Figure b is a black and white picture of Figure a. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] The first typical embodiment of the present invention provides a rare earth up-conversion nano fluorescent probe, which is a core-shell structure and is doped with Yb 3+ 、Tm 3+ and Er 3+ The NaYF4 nanoparticles are the core, and the NaTmF4 shell is coated on the outside of the core.

[0041] The core is composed of rare earth ions Yb 3+ As a sensitizer, Er 3+ and Tm 3+ As an activator, it is doped in the NaYF4 matrix; NaTmF4 as the shell can protect the luminescent center (rare earth ions) in the core from interference from the external environment; the NaTmF4 shell is coated to make the Tm 3+ The higher the content of Yb, the stronger the luminescence of the material, and the more obvious the test effect of the power of the 1208nm laser. This is because: under the simultaneous excitation of 980nm and 1208nm lasers, Yb 3+ Absorbing 980nm photons from the ground state 2 F 7 / 2 Transition to excited state 2 F 5 / 2 , excited state Yb 3+ Transfer energy to Er 3+ , so Er 3+ From the ground state 4 I 15 / 2 Transition to excited state 4 I 11 / 2 ; Er 3+ from 4 I 11 / 2 Through nonradiative transition to 4 I 13 / 2 energy level, or by absorbing another 980nm photon to a higher energy level, followed by a non-radiative transition to 2 H11 / 2 and 4 S 3 / 2 Energy level; excited state of Yb 3+ Transfer energy to Tm 3+ , so that Tm 3+ From the ground state 3 H6 jumps to 3 F4 energy level, not only that, Tm 3+ Absorbing 1208nm photons, from the ground state 3 H6 transitions to the excited state 3 H5, Tm 3+ from 3 H5 undergoes a nonradiative transition to 3 F4 energy level; Tm of excited state 3+ Transfer energy to Er 3+ , so Er 3+ From the ground state 4 I 15 / 2 Jump to 4 I 9 / 2 Energy level; 3+ relaxes through nonradiative transitions to 4 I 13 / 2 Energy level; 3+ from 4 I 13 / 2 Energy level transition back 4 I 15 / 2 Energy levels will emit particles; the power of 980nm and 1208nm lasers directly affects the Yb 3+ 、Tm 3+ 、Er 3+ The excitation efficiency of Er is shown in Figure 2. It can be seen that the stronger the 1208nm laser power is, the higher the 3+ exist 4 I 13 / 2 The more particles there are at the energy level, the 3+ from 4 I 13 / 2 Energy level 4 I 15 / 2 The greater the intensity of the particles emitted by the energy level transition, the greater the power of 1208nm. 3+ The higher the content, the brighter the material and the more obvious the inspection effect.

[0042] The rare earth up-conversion nano fluorescent probe emits green light at a wavelength of 530nm to 560nm under the excitation of 980nm excitation wavelength.

[0043] In one or more embodiments, the rare earth upconversion nano fluorescent probe is in the shape of a pancake, with a thickness of 35 to 40 nm and a width of 70 nm to 80 nm. 3+ 、Tm3+ and Er 3+ The NaYF4 nanoparticles are in the shape of cakes, with a thickness of 20nm to 40nm and a width of 70nm to 80nm; the thickness of the NaTmF4 outer layer is 6 to 8nm.

[0044] In one or more embodiments, in the core, the molar ratio of Tm, Er, Yb and Y is (0.4% to 0.6%): (0.4% to 0.6%): (16% to 20%): (78% to 84%), preferably 0.5%: 0.5%: 18%: 81%.

[0045] A second typical embodiment of the present invention provides a method for preparing the rare earth upconversion nanofluorescent probe, comprising the following steps:

[0046] (1) adding Y salt, Yb salt, Tm salt and Er salt to a mixed solution of oleic acid, oleylamine and 1-octadecene to obtain a reaction solution containing a Y / Yb / Tm / Er-oleic acid complex precursor;

[0047] (2) NaOH and NH4F were added to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, and the core was synthesized by coprecipitation reaction. 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles;

[0048] (3) adding the Tm salt to a mixed solution of oleic acid, oleylamine, and 1-octadecene to obtain a reaction solution containing a Tm-oleic acid complex precursor;

[0049] (4) Yb-doped 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles, NaOH and NH4F are added to the reaction solution containing Tm-oleic acid complex precursor, and a co-precipitation reaction is performed to synthesize rare earth upconversion nanofluorescent probes.

[0050] In one or more embodiments, in step (1), the Y salt is selected from C6H9O6Y·4H2O;

[0051] The Yb salt is selected from C6H 17 O 10 Yb·4H2O;

[0052] The Tm salt is selected from C6H 11 O7Tm·4H2O;

[0053] The Er salt is selected from Er(OOCCH3)3·4H2O.

[0054] In one or more embodiments, in step (1), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is (5-8):(4-6):(14-16), preferably 6:5:15.

[0055] In one or more embodiments, in step (1), the reaction temperature is 120-140° C., preferably 130° C., and the reaction time is 30-60 min.

[0056] In one or more embodiments, in step (1), the molar ratio of Y salt, Yb salt, Tm salt and Er salt is (78% to 84%): (16% to 20%): (0.4% to 0.6%): (0.4% to 0.6%), preferably 81%: 18%: 0.5%: 0.5%.

[0057] In one or more embodiments, in step (1), the concentration of the Y salt is 0.037 to 0.04 mol / L, preferably 0.0385 mol / L.

[0058] In one or more embodiments, in step (2), NaOH and NH4F are added to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, and the core is synthesized by coprecipitation reaction, that is, the core is doped with Yb 3+ 、Tm 3+ and Er 3+ The method of preparing NaYF4 nanoparticles includes:

[0059] Dissolve NaOH and NH4F in methanol; add the methanol solution of NaOH and NH4F to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, heat the mixed solution to 65-80°C, and react for 30-40 minutes;

[0060] The mixed solution is then heated to 280-350°C under the protection of an inert gas and maintained for 1-2 hours to obtain Yb-doped 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles.

[0061] In one or more embodiments, in step (3), the Tm salt is selected from C6H 11 O7Tm·4H2O.

[0062] In one or more embodiments, in step (3), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is (5-8):(4-6):(14-16), preferably 6:5:15.

[0063] In one or more embodiments, in step (3), the concentration of the Tm salt is 0.038 to 0.057 mol / L, preferably 0.048 mol / L.

[0064] In one or more embodiments, in step (4), Yb-doped 3+ 、Tm 3+ and Er 3+ The method for synthesizing a rare earth upconversion nanofluorescent probe by adding NaYF4 nanoparticles, NaOH and NH4F to a reaction solution containing a Tm-oleic acid complex precursor and performing a coprecipitation reaction comprises:

[0065] S1, doped with Yb 3+ 、Tm 3+ and Er 3+ The NaYF4 nanoparticles were dissolved in cyclohexane and the supernatant was collected by centrifugation;

[0066] S2. Add the collected supernatant from the centrifugation to the reaction solution containing the Tm-oleic acid complex precursor, heat the mixed solution to 65-80° C., and react for 30-40 minutes;

[0067] S3, dissolving NaOH and NH4F in methanol; adding the methanol solution of NaOH and NH4F to the mixed solution heated in S2, raising the temperature of the reaction system to 65-80°C, and reacting for 30-40 minutes;

[0068] S4. The mixed solution after the reaction in S3 is heated to 280-350° C. under the protection of an inert gas and maintained at 1-2 hours to obtain a rare earth up-conversion nano fluorescent probe.

[0069] Preferably, in step S1, the centrifugal power is 4000-5000 r / min, preferably 4500 r / min, and the centrifugal time is 4-6 min, preferably 5 min.

[0070] A third typical embodiment of the present invention provides use of the rare earth up-conversion nanofluorescent probe described in the first aspect in detecting the power of a laser with a wavelength of 1208 nm.

[0071] The rare earth upconversion nanofluorescent probe provided by the present invention can respond to an excitation wavelength of 1208 nm under both 980 nm and 1208 nm excitation wavelengths. When excited simultaneously with a 1208 nm laser under 980 nm excitation wavelength, the peak value of the rare earth upconversion nanofluorescent probe at 539.87 nm increases with increasing power of the 1208 nm excitation wavelength, demonstrating the good response of the rare earth upconversion nanofluorescent probe to the 1208 nm excitation wavelength.

[0072] A fourth typical embodiment of the present invention provides application of the rare earth up-conversion nano fluorescent probe described in the first aspect in the field of temperature sensing.

[0073] In one or more embodiments, the application is visual non-contact temperature monitoring inside a material or device.

[0074] The rare earth up-conversion nano fluorescent probe provided by the present invention is heated (50-270° C.) under the excitation of 980 nm excitation wavelength. The fluorescence intensity of the rare earth up-conversion nano fluorescent probe decreases as the temperature rises, thereby realizing the temperature measurement function.

[0075] A fifth typical embodiment of the present invention provides the use of the rare earth up-conversion nano fluorescent probe and carbon quantum dots described in the first aspect as a dual anti-counterfeiting material.

[0076] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0077] Example 1

[0078] The core is doped with Yb 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles (NaYF4:Yb 3+ / Er 3+ / Tm 3+ ) preparation:

[0079] (1) Add C6H9O6Y·4H2O (0.81mmol, 81%), C6H 17 O 10 Yb·4H2O (0.18mmol, 18%), C6H 11 O7Tm·4H2O (0.05mmol, 0.5%), Er(OOCCH3)3·4H2O (0.05mmol, 0.5%), 6mL of oleic acid, 5mL of oleylamine and 15mL of 1-octadecene were added, and heated to 130°C while stirring. A light yellow transparent solution was formed in 45 minutes, and the solution was then allowed to cool naturally to room temperature to obtain a reaction solution containing a Y / Yb / Tm / Er-oleic acid complex precursor.

[0080] (2) Dissolve 2.5 mmol of NaOH and 4 mmol of NH4F in 8 mL of methanol. Add the precursor reaction solution containing the Y / Yb / Tm / Er-oleic acid complex obtained in step (1) dropwise into the methanol solution of NaOH and NH4F until the solution becomes turbid. Heat the mixed solution to 70°C for 30 min to allow the methanol to evaporate completely.

[0081] (3) The mixed solution obtained in step (2) was heated to 300° C. in a closed environment under nitrogen protection and maintained for 1 h, and then the solution was naturally cooled to room temperature.

[0082] (4) Add excess ethanol (40 mL) to the solution obtained in step (3) and centrifuge at 10000 r / min × 10 min to obtain the core NaYF4:Yb 3+ / Er 3+ / Tm 3+ , and add 10 mL of cyclohexane to dissolve the precipitate in cyclohexane, then centrifuge at a speed of 4500 r / min×5 min and collect the supernatant.

[0083] Figure 1 For the kernel NaYF4:Yb 3+ / Er 3+ / Tm 3+ The X-ray diffraction (XRD) pattern of Figure 2 The core NaYF4:Yb can be seen in 3+ / Er 3+ / Tm 3+ The XRD pattern of the prepared core NaYF4:Yb 3+ / Er 3+ / Tm 3+ The upconversion nanoparticles are phase pure and free of any impurities.

[0084] Figure 2 For the kernel NaYF4:Yb 3+ / Er 3+ / Tm 3+ Thermogravimetric (TGA) diagram, such as Figure 3 As shown, the kernel NaYF4:Yb 3+ / Er 3+ / Tm 3+ The upconversion nanoparticles showed the largest decrease at 178.9℃~539.3℃, ranging from 100.14% to 94.17%.

[0085] Example 2

[0086] Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ Preparation of @NaTmF4:

[0087] (1) Add C6H2O into a three-necked flask 11 6 mL of oleic acid, 5 mL of oleylamine and 15 mL of 1-octadecene were added to O7Tm·4H2O (1 mmol), and the mixture was heated to 130°C while stirring. A light yellow transparent solution was formed for 45 minutes, and the solution was then naturally cooled to room temperature to obtain a reaction solution containing a Tm-oleic acid complex precursor.

[0088] (2) The supernatant collected by centrifugation in step (4) of Example 1 was added dropwise to the reaction solution containing the Tm-oleic acid complex precursor, and the mixed solution was heated to 70° C. and maintained for 30 minutes to allow the cyclohexane to completely evaporate, and then the solution was naturally cooled to room temperature.

[0089] (3) Take 2.5mmol NaOH and 4mmol NH4F and dissolve them in 8mL methanol solution. Add the methanol solution of NaOH and NH4F dropwise into the solution obtained in step (2). The solution becomes turbid. Heat the mixed solution to 70℃ and keep it for 30min to completely evaporate the methanol.

[0090] (4) The mixed solution obtained in step (3) was heated to 300° C. in a closed environment under nitrogen protection and maintained for 1 h, and then the solution was naturally cooled to room temperature.

[0091] (5) Add excess ethanol (40 mL) to the solution obtained in step (4), and centrifuge at 10000 r / min × 10 min to obtain the rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4. 10 mL of cyclohexane was added to dissolve the precipitate in cyclohexane, and the mixture was centrifuged at 4500 r / min for 5 min to collect the supernatant.

[0092] Figure 3 It is a rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 scanning electron microscope image, from Figure 4 It can be seen that the rare earth up-conversion nano fluorescent probe is in a pancake shape with a thickness of 35 to 40 nm and a width of 70 nm to 80 nm.

[0093] Figure 4 It is a rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ Fourier infrared absorption spectrum of @NaTmF4, Figure 5 It can be seen that the rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ The absorption peaks of the surface functional groups of @NaTmF4 are 3402 cm -1 、2925cm -1 、2862cm -1 、1566cm -1 、1463cm -1 、1108cm -1 , 3402cm -1 The absorption peak at 2925 cm corresponds to the stretching vibration of the NH bond. -1 The absorption peak at 2862 cm corresponds to the stretching vibration of the OH bond in the hydroxyl group -OH. -1 The absorption peak at 1463 cm corresponds to the symmetrical stretching vibration absorption peak of the CH bond of methyl (-CH3) and methylene (-CH2-). -1 The absorption peak at 1108cm corresponds to the asymmetric deformation vibration of methyl (-CH3) and the shear vibration absorption peak of methylene (-CH2-). -1 The absorption peak at corresponds to the stretching vibration of the CO bond.

[0094] Figure 5 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @X-ray diffraction pattern of NaTmF4, rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ The XRD pattern of @NaTmF4 is completely consistent with the two standard cards (PDF#00-027-0814 and PDF#16-0334), indicating that the prepared rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 is pure phase and does not have any impurities.

[0095] Figure 6 Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 emission spectrum at 980nm excitation wavelength. Under the excitation of 980nm excitation wavelength, this rare earth upconversion nanofluorescent probe emits green light at a wavelength of 530nm~560nm (specifically 539.87nm).

[0096] Example 3

[0097] Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 performs dual-light response experiments. The specific steps are as follows:

[0098] The rare earth up-conversion nano fluorescent probe NaYF4:Yb prepared in Example 2 3+ / Er 3+ / Tm 3+ @NaTmF4 was added with 10 mL of cyclohexane to dissolve the precipitate in cyclohexane. The mixture was then centrifuged at 4500 rpm for 5 min and the supernatant was collected.

[0099] Take 3mL of rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 solution is placed in a 1cm×1cm standard cuvette, and the cuvette is placed in the spectrometer;

[0100] Under the combined excitation of 980nm and 1208nm excitation wavelengths, the 980nm laser power was fixed (specifically 1.5W), the 1208nm laser power was changed, and the rare earth upconversion nanofluorescent probe NaYF4:Yb was tested using a spectrometer. 3 + / Er 3+ / Tm 3+ The fluorescence spectrum of @NaTmF4 was obtained, and the curve of the fluorescence spectrum changing with the 1208nm laser power was obtained, and then the response of this material to the 1208nm laser was obtained.

[0101] The results are as follows Figure 7 As shown in the figure, the power of 1208nm laser varies from 0 to 1.4W, indicating that the rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4 has a good linear response to the 1208nm excitation wavelength when excited by both 980nm and 1208nm lasers.

[0102] Example 4

[0103] Applications of temperature sensing:

[0104] (1) Rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+The NaTmF4 material is washed and dried to obtain nanoparticle powder. An appropriate amount of the powder is placed in a solid temperature measuring device.

[0105] (2) The powder was heated by a temperature-variable device and the rare earth upconversion nanofluorescent probe NaYF4:Yb was tested by a spectrometer under 980nm laser irradiation. 3+ / Er 3+ / Tm 3+ The fluorescence spectrum of @NaTmF4 is obtained, and the curve of fluorescence spectrum changing with temperature is obtained, which can then be used to calculate the temperature of the environment in which the composite material is located. Figure 8 As shown, the excitation light source used is 980nm, the power is 1.4W, and the rare earth upconversion nanofluorescent probe NaYF4:Yb 3+ / Er 3+ / Tm 3+ @NaTmF4's fluorescence intensity decreases as the temperature (50-270°C) increases, thus achieving the temperature measurement function.

[0106] Example 5

[0107] Double anti-counterfeiting application:

[0108] (1) Preparation of carbon quantum dots (CDs):

[0109] Weigh 19.212 g of citric acid into a beaker, add 20 mL of water and stir evenly to obtain a citric acid (0.1 mol) aqueous solution, then drop 11.98 mL of ethanolamine (0.2 mol) aqueous solution into the citric acid aqueous solution and stir vigorously until the solution is clear.

[0110] The clear solution was sealed in a reactor, heated to 180° C. and maintained for 6 h, and then naturally cooled to room temperature to obtain a reddish-brown liquid.

[0111] The reddish-brown liquid was added to a dialysis bag with a molecular weight cut-off of 3500 for dialysis, with the water changed every 4 hours. The dialysis was continued for three days to remove excess small molecule products and impurities, thereby obtaining a purified CDs aqueous solution.

[0112] 0.1 mL of CDs aqueous solution was diluted by adding 6.4 mL of water, and 0.1 mL of CDs aqueous solution was diluted by adding 12.8 mL of water.

[0113] Figure 9 is a transmission electron microscope image of the carbon quantum dots prepared in this example;

[0114] Figure 10This is an emission spectrum of the carbon quantum dots (1:64 dilution) prepared in this example at an excitation wavelength of 365 nm. The peak of the carbon quantum dots (1:64 dilution) at an excitation wavelength of 365 nm is located at 570 nm, emitting yellow light.

[0115] Figure 11 This is an emission spectrum of the carbon quantum dots (1:128 dilution) prepared in this example at an excitation wavelength of 365 nm. As shown in the figure, the carbon quantum dots (1:128 dilution) have a peak at 450 nm at an excitation wavelength of 365 nm, emitting blue light.

[0116] (2) Prepare appropriate cardboard, cover it with a hollow dolphin leaping circle pattern of appropriate size, and place the rare earth upconversion nano fluorescent probe NaYF4:Yb prepared in Example 3 on the cardboard. 3+ / Er 3+ / Tm 3+ Apply the NaTmF4 cyclohexane solution to the dolphin's eyes; evenly apply the carbon quantum dots (1:64 dilution) prepared in this example to the dolphin's body; evenly apply the carbon quantum dots (1:128 dilution) prepared in this example to the hula hoop; remove the hollow dolphin jumping hoop pattern and wait for it to dry.

[0117] Using different wavelengths (365nm, 980nm) to excite, we can get Figure 12 The excitation light sources used were 365nm laser (power 4W) and 980nm laser (power 1.2W). As a result, the rare earth upconversion nanofluorescent probe and carbon quantum dots produced different luminescent colors under different excitation wavelengths, and thus the two can be used as dual anti-counterfeiting materials.

[0118] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A rare earth upconversion nanofluorescent probe, characterized in that: It is a core-shell structure, doped with Yb 3+ 、Tm 3+ and Er 3 + The NaYF4 nanoparticles are used as the core, and the NaTmF4 shell is coated on the outside of the core; In the core, the molar ratios of Tm, Er, Yb and Y are (0.4%~0.6%): (0.4%~0.6%): (16%~20%): (78%~84%).

2. The rare earth up-conversion nanofluorescent probe according to claim 1, characterized in that: The rare earth up-conversion nano fluorescent probe is in the shape of a round cake, with a thickness of 35-40 nm and a width of 70 nm-80 nm.

3. The rare earth up-conversion nano fluorescent probe according to claim 1, characterized in that: In the core, the molar ratio of Tm, Er, Yb and Y is 0.5%:0.5%:18%:81%.

4. The method for preparing the rare earth up-conversion nano fluorescent probe according to any one of claims 1 to 3, characterized in that: The steps include: (1) adding Y salt, Yb salt, Tm salt and Er salt to a mixed solution of oleic acid, oleylamine and 1-octadecene to obtain a reaction solution containing a Y / Yb / Tm / Er-oleic acid complex precursor; (2) NaOH and NH4F were added to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, and the core was synthesized by co-precipitation reaction, which was doped with Yb 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles; (3) adding Tm salt to a mixed solution of oleic acid, oleylamine and 1-octadecene to obtain a reaction solution containing a Tm-oleic acid complex precursor; (4) Doping with Yb 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles, NaOH and NH4F are added to the reaction solution containing Tm-oleic acid complex precursor, and a co-precipitation reaction is performed to synthesize rare earth upconversion nanofluorescent probes.

5. The preparation method according to claim 4, wherein In step (1), the Y salt is selected from C6H9O6Y·4H2O; the Yb salt is selected from C6H 17 O 10 Yb·4H2O; the Tm salt is selected from C6H 11 O7Tm·4H2O; the Er salt is selected from Er(OOCCH3)3·4H2O.

6. The preparation method according to claim 5, wherein In step (1), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is (5-8): (4-6): (14-16).

7. The preparation method according to claim 6, wherein In step (1), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is 6:5:

15.

8. The preparation method according to claim 4, wherein In step (1), the reaction temperature is 120-140°C, and the reaction time is 30-60 min.

9. The preparation method according to claim 8, wherein In step (1), the reaction temperature is 130°C.

10. The preparation method according to claim 4, characterized in that The molar ratio of Y salt, Yb salt, Tm salt and Er salt is (78%~84%): (16%~20%): (0.4%~0.6%): (0.4%~0.6%).

11. The preparation method according to claim 10, characterized in that The molar ratio of Y salt, Yb salt, Tm salt and Er salt is 81%:18%:0.5%:0.5%.

12. The preparation method according to claim 4, wherein In step (1), the concentration of Y salt is 0.037~0.04mol / L.

13. The preparation method according to claim 12, wherein The concentration of Y salt is 0.0385 mol / L.

14. The preparation method according to claim 4, characterized in that In step (2), NaOH and NH4F are added to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, and the core is synthesized by coprecipitation reaction, that is, Yb doped 3+ 、Tm 3+ and Er 3+ The method of preparing NaYF4 nanoparticles includes: Dissolve NaOH and NH4F in methanol; add the methanol solution of NaOH and NH4F to the reaction solution containing the Y / Yb / Tm / Er-oleic acid complex precursor, heat the mixed solution to 65-80°C, and react for 30-40 minutes; The mixed solution was then heated to 280-350 °C under the protection of inert gas and kept at this temperature for 1-2 h to obtain Yb-doped 3+ 、Tm 3+ and Er 3+ NaYF4 nanoparticles.

15. The preparation method according to claim 4, characterized in that In step (3), the Tm salt is selected from C6H 11 O7Tm·4H2O.

16. The preparation method according to claim 4, wherein In step (3), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is (5-8): (4-6): (14-16).

17. The preparation method according to claim 16, wherein In step (3), in the mixed solution of oleic acid, oleylamine and 1-octadecene, the volume ratio of oleic acid, oleylamine and 1-octadecene is 6:5:

15.

18. The preparation method according to claim 4, characterized in that In step (3), the concentration of the Tm salt is 0.038~0.057mol / L.

19. The preparation method according to claim 18, characterized in that In step (3), the concentration of Tm salt is 0.048 mol / L.

20. The preparation method according to claim 4, characterized in that In step (4), Yb 3+ 、Tm 3+ and Er 3+ The method for synthesizing a rare earth upconversion nanofluorescent probe by adding NaYF4 nanoparticles, NaOH and NH4F to a reaction solution containing a Tm-oleic acid complex precursor and performing a coprecipitation reaction comprises: S1, doped with Yb 3+ 、Tm 3+ and Er 3+ The NaYF4 nanoparticles were dissolved in cyclohexane and the supernatant was collected by centrifugation; S2. Add the collected supernatant from the centrifugation to the reaction solution containing the Tm-oleic acid complex precursor, heat the mixed solution to 65-80°C, and react for 30-40 minutes; S3, dissolving NaOH and NH4F in methanol; adding the methanol solution of NaOH and NH4F to the mixed solution heated in S2, raising the temperature of the reaction system to 65-80 °C, and reacting for 30-40 min; S4. The mixed solution after the reaction in S3 is heated to 280-350° C. under the protection of an inert gas and maintained at 1-2 h to obtain a rare earth upconversion nanofluorescent probe.

21. The preparation method according to claim 20, characterized in that In step S1, the centrifugal power is 4000-5000 r / min, and the centrifugal time is 4-6 min.

22. The preparation method according to claim 21, wherein The centrifugal power was 4500 r / min and the centrifugal time was 5 min.

23. Use of the rare earth up-conversion nanofluorescent probe according to any one of claims 1 to 3 in detecting the power of a laser with a wavelength of 1208 nm.

24. Use of the rare earth up-conversion nano fluorescent probe according to any one of claims 1 to 3 in the field of temperature sensing.

25. The use according to claim 24, characterized in that The application is visual non-contact temperature monitoring inside a material or device.

26. Use of the rare earth up-conversion nano fluorescent probe and carbon quantum dots according to any one of claims 1 to 3 as a dual anti-counterfeiting material.

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