CN112111275B

CN112111275B - Temperature measurement method based on rare earth luminescent life temperature probe

Info

Publication number: CN112111275B
Application number: CN202010870391.8A
Authority: CN
Inventors: 李富友; 冯玮; 顾昱飏; 孔梦涯
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2020-08-26
Filing date: 2020-08-26
Publication date: 2022-01-14
Anticipated expiration: 2040-08-26
Also published as: CN112111275A

Abstract

The invention discloses a temperature measurement method of an internally quenched rare earth luminescence lifetime temperature probe which realizes temperature detection based on the change of fluorescence lifetime. The center of the present invention is a nano-core doped with rare earth trivalent ions Yb ³⁺ and B ³⁺ , and the periphery is an inert shell, wherein there is a phonon-assisted energy transfer process between Yb ³⁺ and B ³⁺ rare earth ions. Phonons participate in the energy transfer process to realize that the lifetime of rare earth ions changes with temperature. The inert shell can protect the lifetime of the luminescent core from changing with environmental changes (except temperature). The luminescent wavelength is in the 700-1700nm region. , and can improve water solubility by modifying ligands on the surface. The luminescence lifetime temperature probe of the present invention can realize the near-infrared luminescence lifetime temperature probe of accurate temperature measurement in different complex environments (including living bodies), and has the advantages of internal quenching temperature sensitivity, near-infrared band luminescence, nano-scale, accurate and quantifiable, It has the advantages of good stability and dispersion.

Description

Temperature measurement method based on rare earth luminescent life temperature probe

Technical Field

The invention relates to the field of luminescent nanoprobes and application, in particular to a temperature measurement method based on a rare earth luminescent life temperature probe.

Background

The life activities in nature are always accompanied by temperature changes, and the tolerance degree of different organisms to the temperature is greatly different in the evolution process of the organisms. For example, psychrophiles can survive below-15 ℃ while thermophiles can survive at temperatures as high as 110 ℃. For mammals, metabolism and nerve signal transmission are always accompanied by temperature changes, cells are a tiny unit for temperature regulation, and the role of a plurality of cells is converged to show macroscopic temperature of a living body. Finally, the temperature change in a certain range can be resisted outwards, and the normal body temperature in a certain range can be maintained inwards. The mechanism of organism temperature regulation and life action can be researched by accurately measuring the temperature change of cells; by accurately measuring the temperature of a minute region of a living body, it is possible to study a local physiological change of the living body and to guide the progress of a temperature-dependent operation. Therefore, it is important for our understanding of the temperature of the micro-area of the living body to accurately measure the temperature of the micro-area.

The technology of the nano material for fluorescence imaging provides a new development direction for rapidly determining the temperature of organisms. The nano-scale probe can be used for temperature detection at the cell level, and the fluorescence imaging technology comprises the use of fluorescence intensity and fluorescence lifetime as detection signals, wherein the nano temperature measurement probe based on the change of the fluorescence intensity is very abundant in variety. The luminescent property of the rare earth ions is closely related to the temperature, and the rare earth ions have the advantages that the luminescent wavelength is not easily interfered by the outside, the near infrared band is absorbed and scattered by biological tissues little, and the luminescent band is rich, so that a plurality of temperature probes made of rare earth materials are developed. In order to reduce the interference of the outside on the fluorescence signal and improve the detection accuracy of the fluorescence intensity as the temperature detection signal, a dual-wavelength contrast temperature probe is further developed to eliminate the influence of the material concentration and the like. However, because the fluorescent signals of different wave bands are absorbed and scattered by tissues to different degrees, the attenuation degrees of the fluorescent signals of different wave bands of the contrast temperature probe are different under different complex environments, and therefore the accurate reading of the intensity of the fluorescent signals is influenced.

At present, research and development of a luminescent probe based on luminescence life as a temperature detection signal are few, research and development personnel use a nano gold cluster as a temperature measurement probe, the fluorescence life of the gold cluster is greatly influenced by external environments except temperature, the temperature of the environment where the gold cluster is located cannot be accurately reflected, the service life of the gold cluster is in a nanosecond level, and the requirements on exciting light and a detector are high.

Therefore, those skilled in the art have made an effort to develop an internal quenching type rare earth temperature probe and a temperature measuring method capable of accurately detecting a change in luminescence lifetime of a temperature in a complex environment.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the technical problem to be solved by the present invention is how to quickly measure the temperature of a living body without being affected by environmental changes (other than temperature).

In order to achieve the purpose, the invention provides an internal quenching type rare earth temperature nano probe for realizing temperature detection based on the change of luminescence life and a temperature measuring method. The nanometer probe consists of two layers of an inner core and a shell, wherein the inner core is a luminous center doped with two rare earth ions capable of mutually transferring energy, and the shell is an inert shell for protecting the inner core to emit light. The luminescence wavelength is in the near infrared region and enables accurate temperature detection in complex environments (including oil and water phases).

The object of the invention can be achieved by the following measures:

a temperature measurement method based on a rare earth luminescent life temperature probe comprises the following steps:

s1, providing a rare earth luminescent life temperature probe with the center doped with rare earth trivalent ion Yb³⁺And B³⁺The periphery of the nano inner core is an inert shell layer;

s2, establishing a functional relation between the luminous life temperature probe and the temperature, wherein the functional formula is ln (L) ═ b + aT;

wherein L represents fluorescence lifetime, T represents temperature, and a and b are constants;

s3, testing the service life of the luminous service life temperature probe in the object to be tested, substituting the tested service life into the function expression, and calculating the temperature of the object to be tested;

wherein the lifetime temperature probe Yb³⁺And B³⁺Yb exists between rare earth ions³⁺To B³⁺Or in the presence of B³⁺To Yb³ ⁺The phonons of (1) assist the energy transfer process.

In particular, in Yb³⁺And B³⁺An energy transfer process exists between the two, and the energy process is involved by phonons, such as Yb³⁺Transfer energy to B³⁺The process of (a) involves the participation of one or more phonons, so that the higher the temperature, the faster the energy transfer rate. And vice versa. It is characterized by a temperature-sensitive characteristic of an internal quenching type and is irrelevant to other environments except temperature.

Further, B is³⁺Can be selected from Nd³⁺、Ho³⁺、Tm³⁺Or Er³⁺。

Further, the nano-core may be selected from rare earth fluorides, complex salts of rare earth fluorides, rare earth oxides, rare earth oxyfluorides, rare earth oxysulfides, rare earth hydroxides, rare earth carbonates, rare earth oxalates, or rare earth vanadates;

the inert shell layer is selected from CaF₂、NaYF₄Or NaLuF₄。

Preferably, the nano-core has a particle size in the range of not more than 2 μm and is selected from the group consisting of the rare earth fluorides Yb xB-xF₃Double salt of rare earth fluoride NxYbxB-xF₃+ ax, rare earth oxide YbxB-xOx, rare earth oxyfluoride YbxB-xOxFy, rare earth oxysulfide YbxB-xOxSy, rare earth hydroxide YbxB-x (OH) x, rare earth carbonate Yb xB-x (CO)₃) x, rare earth oxalate YbxB-x (C)₂O₄) x or rare earth vanadate YbxB-xVO₄(ii) a B can be selected from rare earth elements Nd, Ho, Tm and Er, and N is selected from one or more of alkali metals Li, Na, K, Ca and Ba; x and y are integers or non-integers conforming to the chemical composition.

The luminescence wavelength of the nano-core is in the near infrared region (700-1700nm), and the specific luminescence wavelength is related to the doped rare earth ion species. When doped with rare earth ions B³⁺Is Nd³⁺When the wavelength of the light is 800-³⁺Is Tm³⁺When the wavelength of light emission is 800nm and 1600nm, when B is³⁺Is Yb³⁺Corresponds to 970-³⁺Is Ho³⁺Corresponding to 1100 + 1300nm and Er³⁺Corresponding to 1550 nm. And are doped with different rare earth ionsThe temperature-sensitive effect is that the luminous life of the luminous band is linearly related to the temperature.

In one practical manner, the Yb³⁺And B³⁺The doping molar ratio of (A) is 0.001:1 to 1:0.001, preferably 0.001:1 to 1:1, preferably 1:20 to 1:1, more preferably 1:9 to 1: 3.

In one embodiment, the thickness of the inert shell is 0.001-10 nm, preferably 0.001-5 nm, preferably 0.01-5 nm, and more preferably 0.1-2 nm.

In one possible implementation, the nanocore further comprises: rare earth inert ions for the regulation of Yb³⁺And B³⁺Preferably, the rare earth inert ion is Y³⁺Or Lu³⁺。

In one practical way, the luminescent lifetime temperature probe is doped with Nd (TFA) in the center₃、Yb(TFA)₃And Na (TFA), and an inert shell CaF surrounding the compound₂The general formula of the structure is NaYbF₄:Nd@CaF₂。

It is worth noting that when the doping amount of Nd is x₁The mol and Yb doping amount is x₂When mol, x₁+x₂1 mol. I.e. the doping molar ratio is x₁:x₂The general formula of the writing material name is shown as NaYbF₄:x₁% Nd or NaNdF₄:x₂% Yb, when the nanokernel is coated with inert shell CaF₂The general structural formula of the material name is shown as NaYbF₄:x₁％Nd@CaF₂Or NaNdF₄:x₂％Yb@CaF₂。

In a preferred material, the general structural formula is NaYbF₄:x₁％Nd@CaF₂The law is reflected in that the higher the Nd doping amount is, the weaker the material emits light, and the higher the temperature-dependent change speed of the luminous life of Yb is, which is related to a phonon-assisted energy transfer mechanism. Phonons participate in the process of Yb transferring energy to Nd, and phonons do not participate in the process of Nd transferring energy to Yb, and the temperature is not related. Therefore, the doping amount of Nd is increased, the probability of Yb transferring to Nd is increased, and the process of phonon participation accounts for the total energy transfer processThe temperature sensitivity is up to 2%/K in 95% Nd-doped materials, and the material is the highest material in the currently reported neodymium ion-based nanometer temperature measurement probe. Meanwhile, as shown in fig. 1, the inert shell layer wrapped by the outer layer can isolate the temperature-sensitive center from the external environment, so that external solvent molecules or other substances cannot interfere the temperature-sensitive center to perform temperature response. In addition, after the surface of the nanoparticle is modified with the polymer, the nanoparticle can be modified from oil solubility to water solubility, so that temperature detection in a living body can be realized.

In a practical manner, the temperature sensitivity is between 0.01% and 2%/K, preferably between 0.8% and 2%/K.

The sensitivity can be regulated and controlled according to the composition of the material core, the thickness of the shell layer and the like.

In one practical manner, the method for preparing the luminescence lifetime temperature probe in step S1 is as follows:

s11, nano-core NaYbF₄Preparation of Nd

Taking Nd (TFA)₃、Yb(TFA)₃Adding sodium trifluoroacetate into a reaction vessel containing oleic acid, oleylamine and octadecene, reacting for 40-60 minutes at 110-300 ℃, and performing post-treatment to obtain NaYbF₄Nd solid is dispersed in solvent and stored;

in which Yb (TFA)₃And Nd (TFA)₃The molar ratio of (a) is 0.001:1 to 1:0.001, preferably 0.001:1 to 1:1, preferably 1:20 to 1:1, more preferably 1:9 to 1: 3.

S12 preparation of luminescent life temperature probe

NaYbF₄Nd and calcium trifluoroacetate are added into a reaction vessel containing oleic acid and oleylamine, react for 40-60 minutes at the temperature of 110-300 ℃, and are subjected to post-treatment to obtain NaYbF₄:Nd@CaF₂Solid, and dispersed in solvent for storage;

wherein the nanoinner core NaYbF₄The molar ratio of Nd to calcium trifluoroacetate is 1: 0.1-1: 100, 1: 1-1: 10, and preferably 1: 2-1: 6.

In one practical manner, the functional relationship ln (l) b + aT between the emission lifetime temperature probe and the temperature in step S2 is established as follows:

s21, dispersing a life temperature probe in an aqueous solution with the concentration of 0.001-10 mmol/mL, and adding the solution into a quartz cuvette; the concentration of the lifetime temperature probe is preferably 0.001 to 1mmol/mL, more preferably 0.02 to 1 mmol/mL;

s22, controlling the temperature of the solution in the cuvette to be 0.1-100 ℃, and keeping N temperature points with the temperature interval of 0.1-10 ℃ for 2-20 minutes;

wherein N is 3 to 100;

s23, exciting the life temperature probe at each temperature point and collecting a fluorescence attenuation curve, wherein the formula I is I₀e^-t/τ+ C, fitting to obtain the luminescence lifetime of the lifetime temperature probe aT N temperature points, and fitting to obtain ln (L) ═ b + aT

Wherein I represents the fluorescence intensity at time t, I₀Representing the initial fluorescence intensity, t is the time corresponding to each fluorescence intensity information, tau represents the luminescence lifetime, and C is a constant;

l represents the fluorescence lifetime, T represents the temperature, and a and b are constants.

The spectrometer collects the fluorescence attenuation curve and then passes the formula I ═ I₀e^-t/τ+ C fitting gives the luminescence lifetime. The luminescence lifetime at each temperature state can be obtained by collecting the fluorescence decay curve once at each temperature. 0.1-100 ℃, and the temperature is selected according to the freezing point and the boiling point of the solvent of the dispersion probe solvent or the temperature range required by the test. Under different solvent conditions, there is a certain difference in the temperature range that can be set. Especially when the lifetime probe is in the form of a solid, the temperature may be as high as the melting point of the material. Keeping for 2-20 minutes, preferably 5-20 minutes, and achieving sufficient heat transfer and stable temperature.

The temperature measuring method of the rare earth luminescent life temperature probe provided by the invention can be used for measuring the temperature of a solid device, the temperature of a solution or the temperature in a living body.

Technical effects

The near-infrared rare earth luminescence life temperature probe provided by the invention has the characteristic that luminescence life change is taken as a detection signal, can further avoid detection errors caused by environment, detection conditions and the like, and realizes temperature detection with higher accuracy.

The near-infrared internal quenching type rare earth luminescence life temperature probe provided by the invention is externally wrapped with an inert shell layer, so that a luminescence center is protected from being influenced by the outside, and the luminescence life is only related to the temperature. And the water solubility can be easily improved on the surface of the external material, so that the probe can obtain an accurate temperature detection result in a complex water phase environment.

The rare earth luminescent life temperature probe provided by the invention can improve water solubility through modification of a surface hydrophilic polymer, so that temperature detection in a complex water phase environment based on luminescent life is realized. Because the outer layer of the temperature probe is protected by the inert shell layer, the luminous life can be kept unchanged under different environments, and an accurate temperature detection result is provided. Furthermore, the light-emitting wavelength is in the near infrared region, so that the penetration depth of the fluorescence of the material in the tissue is high, and an accurate living body temperature detection result can be realized.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.

Drawings

FIG. 1 is a schematic diagram of the structural mechanism of the rare earth luminescence lifetime temperature probe of the present invention;

FIG. 2 is NaYbF in example 3₄Transmission electron microscopic imaging picture of 75% Nd luminous probe;

FIG. 3 is NaYbF in example 3₄:75％Nd@CaF₂(1:6) transmission electron microscopy imaging photograph of the luminescent probe;

FIG. 4 shows NaYbF with different molar doping ratios in example 5₄:75％Nd@CaF₂(1:6) fluorescence intensity map of the luminescent probe;

FIG. 5 shows NaYbF with different molar doping ratios in example 6₄:75％Nd@CaF₂(1:6) rate of change of luminescence lifetime with temperature;

FIG. 6 is NaYbF in example 7₄:75％Nd@CaF₂(1:2) transmission electron microscopic imaging photograph of the luminescent probe;

FIG. 7 shows NaYbF in example 8₄:75％Nd@CaF₂(1:4) transmission electron microscopy imaging of the luminescent probe;

FIG. 8 is a plot of NaYbF at different molar core-shell ratios for example 9₄:75％Nd@CaF₂The rate of change of luminescence lifetime with temperature;

FIG. 9 is a fluorescence attenuation spectrum of the rhodamine dye in different solvents in the comparative example;

FIG. 10 shows NaYbF in example 10₄:75％Nd@CaF₂(1:6) a graph of luminescence lifetime of the luminescence probe versus temperature;

FIG. 11 shows NaYbF in example 12₄:75％Nd@CaF₂-luminescence lifetime versus temperature of PAAPEG (1:6) in water, fetal bovine serum and rabbit whole blood environments;

FIG. 12 shows NaYbF in example 13₄:Nd@CaF₂-fluorescence imaging of PAAPEG (1:6) material accumulated in the mouse liver, with the dashed box indicating the location of the liver;

FIG. 13 is a scattergram of liver temperature and epidermal temperature during anesthesia and during recovery in the mouse of this example 13.

Detailed Description

The technical contents of the preferred embodiments of the present invention will be more clearly and easily understood by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

The surface modification method and the ligand of the internal quenching type rare earth luminescent life temperature probe provided by the invention are selected as follows: while the oleic acid ligand on the surface of the temperature probe is retained, amphiphilic polymers such as phospholipid polyethylene glycol amino and phospholipid polyethylene glycol methoxy are selected, and the polymers are wound on the surface of the temperature probe through hydrophobic interaction and covalent binding, so that the material is dispersed in the aqueous solution. Polyacrylic acid can be further modified through covalent connection on the basis, so that the surface of the material is converted from positive charge to negative charge. When the oleic acid ligand on the surface of the probe is removed by an acid washing method or a ligand exchange method, the surface of the probe can be positively or negatively charged by the entanglement of long polymer chains. The choice of polymer is not limited at this time, and the longer the polymer chain, the more stable the material exists in the aqueous solution, and the better the dispersibility.

In a preferred material, the structure is NaYbF₄75％Nd@CaF₂The core-shell ratio is 1: 6. The surface oleic acid ligand of the temperature probe is exchanged by a ligand exchange method and then dispersed in N, N-dimethylformamide, then polyacrylic acid polymer is added to be stirred and wound on the surface of the temperature probe with the ligand removed, and then the methoxy polyethylene glycol amino polymer is further modified by a covalent method. The water-soluble temperature probe obtained by the ligand modification method can be stably dispersed in an aqueous solution, and the service life of the water-soluble temperature probe is kept consistent before and after water, fetal calf serum and coverslips.

The hydrophilic temperature probe can be injected into the body of the small animal through veins, and after entering the liver of the small mouse, the hydrophilic temperature probe can acquire the fluorescence signal of the liver through a camera to measure the liver temperature of the small mouse at different anesthesia depths.

EXAMPLE 1 Life temperature Probe NaYbF₄:95％Nd@CaF₂(1:6) Synthesis

1-1) Nano-core NaYbF₄Synthesis of 95% Nd

1mmol of lanthanide rare earth trifluoroacetate (containing 0.95mmol of Nd (TFA))₃And 0.05 mmoleYb (TFA)₃) And 1mmol trifluoroacetic acid sodium salt was added to a three-necked flask containing 10mmol oleic acid, 10mmol oleylamine and 20mmol octadecene. The system was pumped to near vacuum with an oil pump, and the temperature was raised to 110 ℃ with vigorous stirring, and the solid powder was completely dissolved in about 20 minutes. Then fully diffusing nitrogen to the whole system, pumping the system to be close to a vacuum state by using an oil pump, repeating the operation for three times, fully removing air in the system, and then protecting the reaction system by using nitrogen. Then the temperature is quickly raised to 300 ℃, the reaction solution is turbid to be clear, the heater is closed after 30 minutes, the temperature of the system is gradually restored to the room temperature, and then the reaction body is heatedThe resulting mixture was transferred to a centrifuge tube, 20mL of absolute ethanol was added thereto, and the mixture was thoroughly mixed and centrifuged at 14000rpm for 10 minutes to separate the mixture. Collecting the precipitated solid, namely the nano-core NaYbF ₄95% Nd, washed three times with ethanol and dispersed in 10mL cyclohexane solution.

1-2) Life temperature Probe NaYbF₄:95％Nd@CaF₂(1:6) Synthesis

2.5mL, 0.1mmol/mL of the NaYbF synthesized in step 1-1)₄A95% Nd cyclohexane solution and 1.5mmol of calcium trifluoroacetate salt were charged into a three-necked flask containing 20mmol of oleic acid and 20mmol of oleylamine. After the reaction system was filled with nitrogen, the temperature was raised to 110 ℃. After the ethylene solution was completely volatilized while stirring, the system was pumped to a state close to vacuum with an oil pump, and after about 10 minutes, the solid powder was completely dissolved. And (3) fully diffusing nitrogen into the whole system, pumping the system to be in a state close to vacuum by using an oil pump, repeating the operation for three times, fully removing air in the system, and then protecting the reaction system by using nitrogen. Then, the temperature was rapidly raised to 300 ℃ and the reaction was maintained for 45 minutes, and then the heater was turned off to naturally return the reaction solution to room temperature. Then, the reaction system was transferred to a centrifuge tube, 20mL of anhydrous ethanol was added thereto, and after thorough mixing, the mixture was centrifuged at 14000rpm for 10 minutes to be separated. Collecting the precipitated solid as lifetime temperature probe NaYbF₄:95％Nd@CaF₂(1:6), washed three times with ethanol, and dispersed in 10mL of cyclohexane solution.

EXAMPLE 2 Life temperature Probe NaYbF₄:90％Nd@CaF₂(1:6) Synthesis

The procedure of this example is essentially the same as example 1, except that 1mmol of the lanthanide rare earth trifluoroacetate in step 1-1) contains 0.90mmol of Nd (TFA)₃And 0.10mmol Yb (TFA)₃(ii) a Finally obtaining NaYbF₄:90％Nd@CaF₂(1:6) and dispersed in 10mL of a cyclohexane solution.

EXAMPLE 3 Life temperature Probe NaYbF₄:75％Nd@CaF₂(1:6) Synthesis

The method of this embodiment is substantially the same as embodiment 1, except that step 1-1) Middle 1mmol of lanthanide rare earth trifluoroacetate salt containing 0.75mmol of Nd (TFA)₃And 0.25 mmoleYb (TFA)₃(ii) a Finally obtaining NaYbF₄:75％Nd@CaF₂(1:6) and dispersed in 10mL of a cyclohexane solution.

In addition, FIG. 2 shows the nanokernel NaYbF in this embodiment₄A transmission electron microscopic image of 75% Nd, the size of the material is 5nm, the dispersibility of the material is good, and the particle size is uniform.

FIG. 3 shows a lifetime temperature probe NaYbF in this example₄:75％Nd@CaF₂(1:6) transmission electron microscopic image, the size of the material is 11.3nm, the dispersibility of the material is good, and the particle size is uniform.

EXAMPLE 4 Life temperature Probe NaYbF₄:50％Nd@CaF₂(1:6) Synthesis

The procedure of this example is essentially the same as example 1, except that in step 1-1) 1mmol of the lanthanide rare earth trifluoroacetate salt contains 0.75mmol of Nd (TFA)₃And 0.25mmol Yb (TFA)₃(ii) a Finally obtaining NaYbF₄:50％Nd@CaF₂(1:6) and dispersed in 10mL of a cyclohexane solution.

EXAMPLE 5 Life temperature probes of different molar doping ratios, NaYbF₄:Nd@CaF₂(1:6) light intensity comparison

1mL, 0.025mmoL (2.5 mL, 0.1mmoL/mL lanthanide rare earth trifluoroacetate dispersed in 10mL cyclohexane solution) of NaYbF from example 1 was taken₄:95％Nd@CaF₂(1:6) cyclohexane solution, NaYbF in example 2₄:90％Nd@CaF₂(1:6) cyclohexane solution, NaYbF in example 3₄:75％Nd@CaF₂(1:6) cyclohexane solution, NaYbF in example 4₄:50％Nd@CaF₂(1:6) adding the cyclohexane solution into four quartz cuvettes, respectively exciting by using laser with the wavelength of 785nm, and collecting the fluorescence with the wavelength of 800-1100nm by using a fiber spectrometer. The instrument used was a self-contained time gated spectrum with chopper frequency 1000Hz, phase 138 °, integration time 2 s.

As shown in fig. 4, where the higher the Nd doping amount, the weaker the material emitted light. Even if the doping amount of Yb is less than 5%, the detector can still detect a strong fluorescence signal.

Example 6 comparison of the rate of change of the luminescence lifetime with temperature for lifetime temperature probes of different molar doping ratios (NaYbF4: Nd @ CaF2)

The rare earth temperature probe prepared by the invention has uniform size, takes the change of the luminescence life as a temperature detection signal, and has the characteristics of internal quenching temperature sensitivity, near-infrared band luminescence, nano-size level, precision, quantifiability, good stable dispersibility and the like.

1mL of 0.025mmol/mL of the NaYbF4: 95% Nd @ CaF2(1:6) cyclohexane solution in example 1, the NaYbF4: 90% Nd @ CaF2(1:6) cyclohexane solution in example 2, the NaYbF4: 75% Nd @ CaF2(1:6) cyclohexane solution in example 3, and the NaYbF in example 4 were taken₄:50％Nd@CaF₂(1:6) adding the cyclohexane solution into four quartz cuvettes, setting the materials to be excited by light emission at 785nm by using an opo laser, and then collecting a fluorescence attenuation curve with the wavelength of 1000nm by using a transient time resolution spectrometer. The cuvette is placed on a sample rack in the spectrometer, the sample rack is connected with a water bath temperature controller, the temperature of the water bath controller is set, the temperature of the solution in the cuvette is changed to 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃ and 35 ℃, each temperature is stable for 20 minutes, and the actual reading temperature is displayed by a temperature probe connected with the sample rack. Fitting the fluorescence attenuation curves under different temperature conditions by using a single exponential function to obtain the corresponding luminescence life of the 1000nm wavelength material under different temperature conditions, and finally calculating the change rate of the life of the material with different doping ratios along with the temperature.

As shown in fig. 5, in which the higher the Nd doping amount, the higher the rate of change of the material life with temperature. Specifically, the temperature measurement sensitivity of the 95% Nd-doped nano material is as high as 2%/DEG C.

The fluorescence attenuation curve of the life probe at different temperatures acquired by a spectrometer is expressed by the formula I ═ I₀e^-t/τFitting to obtain the luminous life under the corresponding temperature state. Briefly, since the process follows a single exponential decay, the fluorescence intensity is I₀The time corresponding to/e is considered to be the luminescence lifetime of the material. The material is correspondingly different under different temperature conditionsLuminescence lifetime, and thus a luminescence lifetime-temperature working curve can be obtained. The operating curve can be fitted by ln (L) b + aT (a, b are slope and intercept respectively, L is the emission lifetime function, T denotes temperature). The rate of change is calculated on the basis of the operating curve. In short, the slope a is the rate of change. Specifically, when the lowest temperature of the test is T₁At a time, the luminous lifetime is τ₁When the maximum temperature tested is T₂At a time, the luminous lifetime is τ₂The rate of change of the light emission lifetime with temperature is (T)₂-T₁)/(τ₁-τ₂). As can be seen from the results, the rate of change gradually increased as the doping of Nd increased. The corresponding relative sensitivity is calculated as Sr | δ τ/δ T |, 1/τ, where Sr stands for sensitivity and | δ τ/δ T | is the rate of change of lifetime with temperature. It is clear that we can easily calculate this sensitivity using Origin software.

NaYbF₄:75％Nd@CaF₂(1:6) the luminescence life of the cyclohexane solution at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ was 570.5 μ s, 537.3 μ s, 515.8 μ s, 484.5 μ s, 448.9 μ s, 416.2 μ s.

NaYbF₄:95％Nd@CaF₂(1:6) the luminescence lifetime of the cyclohexane solution at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ was 111.9. mu.s, 100.6. mu.s, 91.5. mu.s, 82.1. mu.s, 76.2. mu.s, 69.5. mu.s.

NaYbF₄:90％Nd@CaF₂(1:6) the luminescence life of the cyclohexane solution was 194.9. mu.s, 181.9. mu.s, 168.2. mu.s, 157.2. mu.s, 144.9. mu.s, 135.2. mu.s at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃.

NaYbF₄:50％Nd@CaF₂(1:6) the emission life of the cyclohexane solution at 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ was 1161. mu.s, 1134. mu.s, 1094. mu.s, 1070. mu.s, 1035. mu.s, and 993.9. mu.s.

Combining examples 5 and 6, it can be seen that the higher the Nd doping amount, the lower the fluorescence intensity and the higher the temperature measurement sensitivity. In order to enable the detector to collect enough photons for fitting the fluorescence decay curve while maintaining comparable thermometric sensitivity, we consider both fluorescence intensity and sensitivity factors. A superior doping ratio lifetime probe NaYbF4: 75% Nd was obtained. In addition, the doping ratio can be further adjusted by doping non-luminous rare earth ions, such as yttrium (Y) and lutetium (Lu) ions, so that a better doping ratio is obtained. Obviously, the luminous intensity or the temperature measurement sensitivity are considered preferentially, or the luminous intensity or the temperature measurement sensitivity is balanced and compromised, and the luminous intensity or the temperature measurement sensitivity is different under different temperature measurement requirements, and the actual requirements need to be met.

EXAMPLE 7 Life temperature Probe NaYbF₄:75％Nd@CaF₂(1:2) Synthesis

The preparation was carried out in substantially the same manner as in step 1-2) of example 1, except that the nanocore NaYbF₄75 percent of Nd and calcium trifluoroacetate salt have a molar ratio of 1: 2; finally obtaining NaYbF₄:75％Nd@CaF₂(1:2) and dispersed in 10mL of a cyclohexane solution.

FIG. 6 shows NaYbF in the present embodiment₄:75％Nd@CaF₂(1:2) transmission electron microscopic imaging photo of the luminescent probe, the size of the material is 8nm, the dispersibility of the material is good, and the particle size is uniform.

EXAMPLE 8 Life temperature Probe NaYbF₄:Nd75％@CaF₂(1:4) Synthesis

The preparation was carried out in substantially the same manner as in step 1-2) of example 1, except that the nanocore NaYbF₄75 percent of Nd and calcium trifluoroacetate salt have a molar ratio of 1: 4; finally obtaining NaYbF₄:75％Nd@CaF₂(1:4) and dispersed in 10mL of a cyclohexane solution.

FIG. 7 shows NaYbF in the present example₄:75％Nd@CaF₂(1:4) Transmission electron microscopic imaging photo of the luminescent probe, the size of the material is 10nm, the dispersibility of the material is good, and the particle size is uniform.

Example 9 Life temperature probes of different core-Shell ratios, NaYbF₄:75％Nd@CaF₂Comparison of the rate of change of the luminous Life with temperature (1:2,1:4)

1mL of 0.025mmoL of NaYbF of example 7 was taken₄:75％Nd@CaF₂(1:2) cyclohexane solution, NaYbF in example 8₄:75％Nd@CaF₂(1:4)Cyclohexane solution, NaYbF in example 3₄:75％Nd@CaF₂(1:6) adding the cyclohexane solution into four quartz cuvettes, respectively exciting by using laser with the wavelength of 785nm, and then collecting the fluorescence attenuation curve with the wavelength of 1000nm by using a transient time-resolved spectrometer. The cuvette is placed on a sample holder in the spectrometer, the sample holder is connected with a water bath temperature controller, the temperature of the water bath controller is set, the temperature of the solution in the cuvette is changed to 5-50 ℃, each temperature is stabilized for 20 minutes every 5 ℃ at intervals, and the actual reading temperature is displayed by a temperature probe connected with the sample holder.

The fitting method described in embodiment 6 is adopted, and a single exponential function is used to fit the fluorescence attenuation curves under different temperature conditions, so as to obtain the corresponding luminescence lives of the 1000nm wavelength materials under different temperature conditions, and finally, the change rates of the lives of the materials with different doping ratios along with the temperature are calculated.

As shown in fig. 8, where the greater the shell thickness, the greater the rate of change of material life with temperature. Accordingly, the greater the lifetime change, the higher the material temperature sensing sensitivity. The core-shell ratio is 1:2 and 1:4 in sequence, and the thicker the shell layer is, the higher the temperature-sensitive accuracy is.

Comparative example

Dyes capable of temperature detection based on lifetime change have been reported to be mainly quantum dots and small molecule dyes, but both of these probes are susceptible to external environments such as solvents. In this case, for example, rhodamine dye is dispersed in deionized water, PBS buffer solution and rabbit whole blood, and fluorescence attenuation spectra are measured by a fluorescence spectrometer. The excitation wavelength is 510nm, and the fluorescence attenuation at the wavelength band of 575nm is tested. As is apparent from FIG. 9, the fluorescence decay rate of rhodamine dye in different solvents changes significantly.

EXAMPLE 10 Life temperature Probe NaYbF₄:75％Nd@CaF₂(1:6) relationship between luminescence lifetime and temperature

Taking 1mL of 0.025mmoL NaYbF₄:Nd@CaF₂(1:6) adding cyclohexane solution into a quartz cuvette, setting the light-emitting excitation material at 785nm by using an opo laser, and then collecting the fluorescence attenuation at 1000nm by using a transient time-resolved spectrometerCurve line. The cell is placed on the sample frame in the spectrum appearance, and the water bath temperature controller is connected to the sample frame, sets up the temperature of water bath controller, changes the temperature of solution in the cell, and every temperature is stable for 20 minutes, and the temperature that actually reads out uses the temperature probe that the sample frame links to show as the standard. And fitting the fluorescence attenuation curves under different temperature conditions by using a single exponential function to obtain the corresponding luminescence lives of the 1000nm wavelength materials under different temperature conditions. The fitting procedure was as in example 6.

As shown in fig. 10, as the temperature increases, the lifetime of the luminescence probe gradually decreases.

Example 11NaYbF₄:Nd@CaF₂Preparation of-PAAPEG (1:6)

Exchange of temperature Probe NaYbF by ligand exchange₄:Nd@CaF₂The surface oleic acid ligand is dispersed in N, N-Dimethylformamide (DMF), then polyacrylic acid (PAA) is added into the solution, after 12 hours of uniform mixing, the upper layer solution is removed by centrifugation. The solid was dispersed in DMF and then 1:1 solid of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was added and after 2 hours of thorough reaction, the upper solution was removed by centrifugation. And dispersing the solid in DMF, adding methoxypolyethylene glycol aminopolymer (PEG), stirring, and centrifuging to remove supernatant to obtain solid precipitate, namely the temperature probe with the surface wound with PAA and PEG and ligand removed.

EXAMPLE 12 Life temperature Probe NaYbF₄:75％Nd@CaF₂(1:6) relationship between luminescence lifetime and temperature in different aqueous environments

Respectively taking 1mLNaYbF₄:95％Nd@CaF₂PAAPEG (1:6) was dispersed in an aqueous solution, 20% fetal bovine serum solution and 20% fetal bovine serum solution +2mm pork piece coverage (in quartz cuvettes) at a concentration of 0.025 mmoL. The material was excited at 785nm light output with an opo laser setting, and then a 1000nm wavelength fluorescence decay curve was collected with a transient time-resolved spectrometer. The cell is placed on the sample holder in the spectrometer, the sample holder is connected with the water bath temperature controller, the temperature of the water bath temperature controller is set, the temperature of the solution in the cell is changed, and each temperature is stable by 2At 0 minute, the actual temperature reading is based on the temperature probe attached to the sample holder. And fitting the fluorescence attenuation curves under different temperature conditions by using a single exponential function to obtain the corresponding luminescence lives of the 1000nm wavelength materials under different temperature conditions.

FIG. 11 shows NaYbF in this example₄:Nd@CaF₂-the luminescence lifetime of PAAPEG (1:6) in water, fetal bovine serum and rabbit whole blood environments, respectively, as a function of temperature, with the relation: wherein, ln (L) 6.493-0.01385TL is the luminous life of the nano material, and the unit is mus; t is the corresponding temperature in degrees Celsius. The light emitting life of the temperature probe is consistent in different environments and different temperatures, and the trend of the temperature probe along with the temperature change is also consistent.

The luminous process of the temperature probe accords with first-order reaction kinetics, excitation and emission wavelengths are in a near infrared region, the fluorescence lifetime is in microsecond level, and the luminous lifetime and temperature change are in a linear relation.

EXAMPLE 13 Life temperature Probe NaYbF₄:Nd@CaF₂(1:6) use of liver temperature for detecting core temperature change during anesthesia of mouse

Tail vein injection of 300. mu.L, 0.025mmol/mL NaYbF₄:Nd@CaF₂PAAPEG (1:6) in 6-week-old male nude mice. After a nude mouse is anesthetized by the anesthesia machine, the gas used by the anesthesia machine is the mixed gas of isoflurane and oxygen, the nude mouse is placed under an imaging device to prepare for imaging tracking, the anesthesia is maintained by isoflurane gas in the period, and the mouse is prevented from hypothermia by the constant temperature cushion. The temperature of the epidermis of the liver of the mouse was tracked by an infrared thermal imager while the lifetime of the liver of the mouse was imaged by an ICCD camera. After 1 hour of anesthesia, the level of anesthetic gas was gradually decreased until the anesthetic gas was turned off, and the mice were followed for liver luminescence lifetime imaging and thermal imaging, as shown in fig. 12-13.

Wherein the liver temperature is calculated from the luminescence lifetime of the temperature probe, and the relation is as follows: wherein, ln (L) 6.493-0.01385TL is the luminous life of the nano material, and the unit is mus; t is the corresponding temperature in degrees Celsius.

Example 12 has demonstrated that NaYbF₄:Nd@CaF₂PAAPEG (1:6) temperature probeThe lifetime-temperature function is invariant in environments of varying complexity, so we can use the in vitro established function of the operating curve ln (l) 6.493-0.01385T. The calculated luminescence lifetime is substituted into this functional relation, and the temperature in the mouse liver obtained by using the luminescence lifetime as a detection signal can be obtained.

The skin temperature was measured by an infrared thermal imager. The change trend of the liver core temperature is consistent with the epidermis temperature, and the liver temperature is higher than the epidermis temperature.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims

1. a temperature measurement method based on rare earth luminescence lifetime temperature probe, is characterized in that, comprises the steps:

S1. Provide a rare earth luminescence lifetime temperature probe, the center of the rare earth luminescence lifetime temperature probe is a nano-core doped with rare earth trivalent ions Yb ³⁺ and B ³⁺ , the Yb ³⁺ and B ³⁺ doping The hetero molar ratio is 0.001:1 to 1:0.001, the periphery is an inert shell layer, and the thickness of the inert shell layer is 0.001 to 10 nm; the center of the luminescence lifetime temperature probe is doped with Nd(TFA) ₃ , Yb(TFA) ) ₃ and Na(TFA), the periphery is an inert shell CaF ₂ , and the general structural formula is NaYbF ₄ :Nd@CaF ₂ ;

S2, establish the functional relationship between the rare earth luminescence lifetime temperature probe and the temperature, the functional formula is ln(L)=b+aT;

where L represents the fluorescence lifetime, T represents the temperature, and a and b are constants;

S3, testing the fluorescence lifetime of the rare earth luminescence lifetime temperature probe in the object to be tested, and bringing the measured fluorescence lifetime into the functional formula to calculate the temperature of the object to be tested;

Wherein, there is a phonon-assisted energy transfer process from Yb ³⁺ to B ³⁺ or simultaneously from B ³⁺ to Yb ³⁺ between Yb ³⁺ and B ³⁺ rare earth ions of the rare earth luminescence lifetime temperature probe;

Wherein, the B ³⁺ is selected from Nd ³⁺ .

2 . The temperature measurement method according to claim 1 , wherein the doping molar ratio of the Yb ³⁺ and B ³⁺ is 1:20˜1:1, and the thickness of the inert shell layer is 0.01˜1. 3 . 5nm.

3 . The temperature measurement method according to claim 1 , wherein the nano-core further comprises rare earth inert ions, the rare earth inert ions are used to adjust the concentrations of Yb ³⁺ and B ³⁺ , and the rare earth inert ions are used to adjust the concentrations of Yb 3+ and B 3+ . is Y ³⁺ or Lu ³⁺ .

4. The temperature measuring method according to claim 1, wherein the nano-core can be selected from rare earth fluorides, double salts of rare earth fluorides, rare earth oxides, rare earth oxyfluorides, rare earth oxysulfides, rare earth Hydroxides, rare earth carbonates, rare earth oxalates or rare earth vibrates, the inert shell is selected from CaF ₂ .

5 . The temperature measurement method according to claim 1 , wherein the temperature measurement sensitivity of the rare earth luminescence lifetime temperature probe measured by the temperature measurement method is 0.01% to 2%/K. 6 .

6. The temperature measurement method according to any one of claims 1-4, wherein the preparation method of the luminescence lifetime temperature probe in step S1 is as follows:

S11. Preparation of nano-core NaYbF ₄ : Nd

Take Nd(TFA) ₃ , Yb(TFA) ₃ and trifluoroacetic acid sodium salt and add them to a reaction vessel containing oleic acid, oleylamine and octadecene, react at 110～300° C. for 40～60 minutes, and obtain NaYbF ₄ after post-processing : Nd solid, and dispersed in solvent for storage,

Wherein, the molar ratio of Yb(TFA) ₃ and Nd(TFA) ₃ is 0.001:1 to 1:0.001;

S12. Preparation of Luminescence Lifetime Temperature Probe

NaYbF ₄ : Nd and calcium trifluoroacetic acid salt were added to the reaction vessel containing oleic acid and oleylamine, reacted at 110～300 ℃ for 40～60 minutes, and after post-processing NaYbF ₄ :Nd@CaF ₂ solid was obtained, which was dispersed in the solvent store;

Wherein, the molar ratio of NaYbF ₄ :Nd and calcium trifluoroacetate is 1:0.1-1:100.

7. The temperature measurement method according to any one of claims 1-4, wherein in step S2, the method for establishing the functional relationship between the luminescence lifetime temperature probe and temperature ln(L)=b+aT is as follows:

S21. The lifetime temperature probe is dispersed in an aqueous solution with a concentration of 0.001-10 mmol/mL, and added to a quartz cuvette, and the concentration of the lifetime temperature probe is 0.001-1 mmol/mL;

S22, control the temperature of the solution in the cuvette, respectively at 0.1-100 °C, take N temperature points with a temperature interval of 0.1-10 °C, and keep it for 2-20 minutes, wherein N is 3-100;

S23. At each temperature point, the lifetime temperature probe is excited and the fluorescence decay curve is collected. According to the formula I=I ₀ e ^-t/τ +C, the luminescence lifetime of the lifetime temperature probe at N temperature points is obtained by fitting , the fitting obtains ln(L)=b+aT,

Among them, I represents the fluorescence intensity at time t, I ₀ represents the initial fluorescence intensity, t is the time corresponding to each fluorescence intensity information, τ represents the luminescence lifetime, and C is a constant.

8 . The temperature measurement method according to claim 7 , wherein the concentration of the lifetime temperature probe in S21 is 0.02-1 mmol/mL. 9 .