Rare earth complex polymer material with stable luminescence for organism temperature identification as well as preparation method and application of rare earth complex polymer material

Abstract

The invention discloses a rare earth complex polymer material with stable luminescence for organism temperature identification and a preparation method and application thereof, the polymer expression of the rare earth complex polymer is PEO-b-PNIPAM-P (MA-co-FMA)-CTA, and the rare earth complex polymer comprises an N-isopropylacrylamide block, a methyl acrylate and furfuryl methacrylate copolymerized block, an N-isopropylacrylamide block, a methyl acrylate and furfuryl methacrylate copolymerized block, an N-isopropylacrylamide block, a methyl acrylate and furfuryl methacrylate copolymerized block, and an N-isopropylacrylamide block, a methyl acrylate and furfuryl methacrylate copolymerized block, through a D-A cycloaddition reaction, an Eu complex with a maleimide substituted fused ring ligand is covalently bonded to a polymer, and stable luminescence of rare earth Eu in water can be realized under excitation of visible light. The rare earth complex polymer disclosed by the invention has thermosensitivity and can be used for fluorescence temperature sensing, biological imaging and temperature identification.

Description

A stable luminescent rare-earth complex polymer material for biological temperature recognition, its preparation method and application Technical Field

[0001] This invention relates to a rare earth luminescent material, specifically to a rare earth complex polymer that covalently links a rare earth complex to a polymer backbone, and also to a method for preparing the material. Background Technology

[0002] Rare earth ions (such as Eu) 3+ 、Tb 3+ 、Sm 3+ Dy 3+ Rare earth elements (REEs), due to their unique 4f electron transition characteristics, possess excellent optical properties such as high luminescence intensity, good monochromaticity, and long fluorescence lifetime, and have broad application prospects in fields such as light-emitting devices, bioimaging, optical sensing, environmental sensing, and anti-counterfeiting marking. However, the direct luminescence of rare earth ions in aqueous media is very weak. This is because after the OH vibrational groups in water molecules coordinate with rare earth ions, they consume the excited state energy through non-radiative transitions, severely quenching luminescence. In addition, rare earth ions themselves have poor water solubility, and rare earth complexes are prone to hydrolysis and coordination bond dissociation in aqueous media, leading to the shedding of rare earth ions. This not only causes luminescence quenching, but the free rare earth ions also have significant biotoxicity, severely limiting the practical application of rare earth complexes in aqueous media and biological systems.

[0003] In the existing technology, the solutions to the stability problem of rare earth complexes in water and biological media mainly include: (1) physical doping method: blending, adsorbing or embedding rare earth complexes with biocompatible polymers, but this method has the disadvantages of poor compatibility between rare earth complexes and polymers and insufficient long-term stability; (2) surface modification method: introducing hydrophilic groups (such as carboxyl, hydroxyl and amino groups) through ligands to improve water solubility, but it cannot fundamentally solve the problem of luminescence quenching caused by the dissociation of coordination bonds; (3) coordination crosslinking method: using multidentate ligands to form crosslinking structures with rare earth ions, but the synthesis process is complicated and there is still a risk of ligand exchange in biological media.

[0004] For physical doping methods, an improved approach involves copolymerizing fluorescent lanthanide monomers with matrix material monomers to avoid the aggregation of metal complexes while maintaining their photophysical properties. For example, CN 106749808 A discloses a rare-earth element-based thermosensitive complex, its preparation method, and its applications, as well as the report by Professor Feng Jiachun et al. (Poly(MMA-co-FMA) as a platform for tuning emission by clicking with luminescent lanthanide complexes J. Mater. Chem. C, 2018, 6, 10202—10206). However, for Eu, the complex described in CN106749808 A has an excitation wavelength of 275 nm, located in the ultraviolet region. The method reported by Professor Feng Jiachun cannot exist stably in water and has low biocompatibility. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a rare earth complex polymer material that responds to visible light and emits light stably in aqueous or biological media; another purpose of this invention is to provide a method for preparing the rare earth complex polymer material, and also relates to the application of the rare earth complex polymer material.

[0006] Technical solution: The rare earth complex polymer material of the present invention has the following structure:

[0007]

[0008] Where R is phenyl or naphthyl, n = 110~120, x : y : z = 0.7~6.5:1.5~3.5:1.

[0009] Preferably, n = 112~115, x : y : z = 2.4~6.5 : 1.5~3.5 : 1. This polymer can effectively protect the luminescence of rare earth ions in aqueous / biological media, while also possessing fluorescence temperature response capabilities within the physiological temperature range.

[0010] The preparation method of the aforementioned rare earth complex polymer includes the following steps:

[0011] (1) The hydroxyl group at one end of PEO undergoes an esterification reaction with 4-cyano-4-(thiobenzoylthio)valerate to form PEO-CTA. PEO-CTA undergoes a RAFT reaction with N-isopropylacrylamide and the first initiator to form the block polymer PEO-b-PNIPAM-CTA.

[0012] (2) PEO-b-PNIPAM-CTA undergoes a copolymerization reaction with methyl acrylate, furfuryl methacrylate, and a second initiator to form PEOPEO-b-PNIPAM-P(MA-co-FMA)-CTA;

[0013] (3) PEO-b-PNIPAM-P(MA-co-FMA)-CTA undergoes a cycloaddition reaction with the Eu complex to form a rare earth complex polymer. The first ligand of the Eu complex is dinadiacylmethane or diphenylacylmethane; the second ligand is 5-maleimide-1,10-phenanthroline. The structure of the Eu complex is as follows:

[0014] R = phenyl or naphthyl .

[0015] In the aforementioned steps, RAFT refers to Reversible Addition-Fragmentation Chain Transfer (RAFT). Eu complexes containing bifunctional ligands with "coordinating groups and polymerizable groups" are bonded to the polymer backbone via a Diels-Alder cycloaddition reaction, achieving stable immobilization of rare earth ions while simultaneously improving the biocompatibility of the rare earth complexes and protecting their efficient and stable luminescence in aqueous / biological media.

[0016] Preferably, in step (1), the molar ratio of PEO to 4-cyano-4-(thiobenzoylthio)pentanoic acid is 1:2~3. More preferably, the molar ratio is 1:2.4~2.6. The esterification reaction may include catalysts and coupling agents commonly used to promote esterification reactions, such as catalyst 4-dimethylaminopyridine (DMAP) and coupling agent EDC. The ratio of catalyst to PEO is 0.4~0.6, and the ratio of coupling agent to 4-cyano-4-(thiobenzoylthio)pentanoic acid is 1:1.01~1.1. The reaction is carried out at room temperature (25°C).

[0017] Preferably, in step (1), the molar ratio of PEO-CTA, N-isopropylacrylamide, and the first initiator is 1:40~220:0.2~0.4, the reaction solvent is tetrahydrofuran, the reaction is carried out under inert gas protection, and the reaction is carried out at 60~80°C for 11~13 hours. More preferably, the molar ratio of PEO-CTA, N-isopropylacrylamide, and the first initiator is 1:50~150:0.25~0.35. Most preferably, in order to improve the copolymerization yield in step (2), the molar ratio of PEO-CTA, N-isopropylacrylamide, and the first initiator is 1:80~120:0.25~0.35. The inert gas is a rare gas or nitrogen.

[0018] Preferably, in step (2), the molar ratio of PEO-b-PNIPAM-CTA, methyl acrylate, furfuryl methacrylate, and the second initiator is 1:40~120:10~60:0.3~0.6, the molar ratio of methyl acrylate to furfuryl methacrylate is 1.5~3.0:1, the reaction solvent is dioxane, the reaction is carried out under inert gas protection, and the reaction is carried out at 60~80°C for 11~13 hours. More preferably, the molar ratio of PEO-b-PNIPAM-CTA, methyl acrylate, furfuryl methacrylate, and the second initiator is 1:80~120:40~60:0.3~0.5.

[0019] Preferably, the first initiator and the second initiator are azo initiators. The azo initiator is azobisisobutyronitrile, dimethyl azobisisobutyrate, or azobisisobutyramidazole hydrochloride.

[0020] Preferably, in step (3), the mass ratio of PEO-b-PNIPAM-P(MA-co-FMA)-CTA to Eu complex is 10~20:1, the reaction solvent is dichloromethane, and the reaction is carried out at 40~60℃ for 11~13 hours under inert gas protection.

[0021] Preferably, the method for synthesizing the Eu complex is as follows:

[0022] The second ligand was synthesized by amidation of 1,10-phenanthroline-5-amine with maleic anhydride. The first ligand, europium salt, and second ligand were dissolved in a mixed solvent of ethanol and dichloromethane at a molar ratio of 1.01~1.1:1:3.01~3.1 and reacted at 40~60 °C for 1.5~2.5 hours to synthesize the Eu complex, denoted as Eu(DNPD)3MP.

[0023] Applications of the aforementioned rare earth complex polymer materials in fluorescence temperature sensing, bioimaging, or temperature recognition.

[0024] Compared with existing technologies, the beneficial effects of this invention are as follows: 1. The excitation wavelength is >400nm, located in the visible light region; by adjusting the polymer ratio and synthesis conditions, rare earth complexes are covalently linked to the polymer, and the resulting rare earth complex polymer can stably emit light in aqueous or biological media; 2. The rare earth complexes are covalently bonded to the polymer backbone, avoiding the problems of shedding and aggregation caused by physical doping, and significantly improving the structural stability of the material in biological media; 3. The polymer network effectively shields quenchers such as water molecules and biomolecules in biological media, protecting the luminescence performance of rare earth ions; 4. The introduction of the temperature-sensitive unit NIPAM in the polymer backbone improves the sensitivity of the fluorescence temperature response of rare earth ions in the physiological temperature range, meeting the application requirements of biological temperature recognition. Attached Figure Description

[0025] Figure 1 shows the excitation and fluorescence emission spectra of the rare earth complex Eu(DNPD)3MP in N,N-dimethylformamide (DMF).

[0026] Figure 2 shows the concentration of 2.5 mg / mL in an aqueous system. -1 Fluorescence spectrum of Polymer-Eu (excitation wavelength 417 nm).

[0027] Figure 3 shows the concentration of 1 mg / mL in an aqueous system. -1 Temperature-dependent transmittance curves of PEO-b-PNIPAM-P(MA-co-FMA)-CTA.

[0028] Figure 4 shows the concentration of 1 mg / mL in an aqueous system. -1 Temperature-dependent hydration particle size profile of PEO-b-PNIPAM-P(MA-co-FMA)-CTA.

[0029] Figure 5 shows the concentration of 1 mg / mL in an aqueous system. -1 Temperature-dependent transmittance curves of Polymer-Eu.

[0030] Figure 6 shows the concentration of 1 mg / mL in an aqueous system. -1 Polymer-Eu temperature-dependent hydration particle size profile.

[0031] Figure 7 shows the concentration of 1 mg / mL in an aqueous system. -1 Polymer-Eu temperature-dependent fluorescence emission spectrum.

[0032] Figure 8 shows the concentration of 1 mg / mL in an aqueous system. -1 Linear correlation plot of fluorescence emission intensity (F) versus temperature (T) of Polymer-Eu.

[0033] Figure 9 is a bar chart showing the cell viability of HeLa cells after co-incubation with different concentrations of Polymer-Eu in DMEM medium for 24 h. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0035] Example 1 Synthesis of Eu(DNPD)3MP

[0036] 1.1 Synthesis of the functional ligand 5-maleimide-1,10-phenanthroline (MP):

[0037] 1,10-Phenanthroline-5-amine (400 mg, 2.05 mmol) and maleic anhydride (1.0 g, 10.2 mmol) were heated in CH2Cl2 (20 mL) at 50 °C under reflux for 3.5 h. After cooling to room temperature, the solid was filtered and washed with CH2Cl2, then dried under vacuum to give a pale yellow solid powder (568.74 mg).

[0038] The dried, pale yellow solid powder (380 mg) and sodium acetate (2.0 g) were then added to acetic acid (20 mL), and the mixture was heated at 100 °C for 1 hour. After cooling to room temperature, the mixture was poured into ice water (100 mL) and stirred until the acetic acid was completely decomposed. The mixture was then extracted with dichloromethane, washed with water, dried over magnesium sulfate, and concentrated to 10 mL. Finally, hexane (50 mL) was added to induce precipitation of the product, yielding a solid powder (153.01 mg) of the ligand 5-maleimide-1,10-phenanthrolin (MP, 1-(1,10-phenanthrolin-5-yl)-1H-pyrrole-2,5-dione).

[0039] 1.2 Synthesis of europium rare earth complex Eu(DNPD)3MP:

[0040] Ligand dinaphthalimide (DNPD 0.973 g, 3 mmol), MP (0.275 g, 1 mmol), and sodium hydroxide (0.12 g, 3 mmol) were dissolved in 8 mL of a mixed solvent (ethanol:dichloromethane = 5:3), and then heated and stirred at 50 °C for 30 min. Europium chloride hexahydrate (0.367 g, 1 mmol) was dissolved in 4 mL of ethanol and slowly added dropwise to the stirred ligand solution, inducing the formation of a pale yellow solid precipitate. The reaction was continued at 50 °C for 2 hours and then cooled to room temperature. The product was filtered and washed with hot ethanol, and then dried in a vacuum oven at 60 °C for 24 hours to obtain a pale yellow powder, Eu(DNPD)3MP.

[0041] Example 2: Synthesis of thermosensitive polymers, the synthetic route is as follows:

[0042] 2.1 Synthesis of the macromolecular chain transfer agent PEO-CTA:

[0043]

[0044] Oligomeric poly(ethylene oxide) monomethyl ether (PEO 5.010 g, 1.0 mmol), 4-cyano-4-(thiobenzoylthio)valerate (CTBTVA 0.70 g, 2.5 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC 0.480 g, 2.5 mmol), and DMAP (0.060 g, 0.5 mmol) were dissolved in dichloromethane (20 mL), and the mixture was bubbled with high-purity nitrogen for 1 hour. Esterification was then carried out at 25 °C for 48 hours. The reaction mixture was washed three times (10 mL × 3) with saturated sodium chloride aqueous solution, and the dichloromethane layer was dried overnight with anhydrous MgSO4. The solution was then added dropwise to diethyl ether, yielding a pink precipitate. Finally, the precipitate was dried in a vacuum oven at 30 °C for 24 hours to obtain the macromolecular chain transfer agent PEO-CTA (3.56 g).

[0045] 2.2 Synthesis of the product PEO-b-PNIPAM-CTA:

[0046]

[0047] PEO-CTA (263.67 mg, 0.05 mmol), N-isopropylacrylamide (NIPAM 565.80 mg, 5.0 mmol), azobisisobutyronitrile (AIBN 2.0 mg, 0.015 mmol), and THF (4 mL) were added to a flask. The mixture was bubbled with nitrogen for 30 min, followed by vacuum. Polymerization was carried out at 70 °C for 12 hours. The mixture was then precipitated in excess n-hexane and dried to obtain a white powder or pale yellow waxy product, PEO-b-PNIPAM-CTA, which exhibited thermosensitive properties.

[0048] The amount of NIPAM added was varied, and the experiment was conducted following the same procedure as described above. The experimental parameters and results are shown in Table 1.

[0049] Table 1:

[0050] As the amount of NIPAM increases, T cp The transmittance decreased, and PEO-b-PNIPAM-CTA synthesized using PEO-CTA: NIPAM: AIBN ratios of 1:50:0.3 and 1:100:0.3 (numbers 1 and 2) was used for the next synthesis. The corresponding products are denoted as 2.2-1 and 2.2-2. (In this study, the temperature at which the transmittance decreased to 50% is defined as the cloud point temperature T.) cp, Reference: Thermorespo nsivepolymers with lower critical solution temperature: from fundamental aspects and measuring techniques to recommended turbidimetry conditions. Mater.Horiz. 2017, 4, 109−116).

[0051] 2.3 Synthesis of PEO-b-PNIPAM-bP(MA-co-FMA)-CTA:

[0052]

[0053] PEO-b-PNIPAM-CTA (601.42 mg, 0.036 mmol), methyl acrylate (MA 312.4 mg, 3.6 mmol), furfuryl methacrylate (FMA 301.4 mg, 1.8 mmol), and AIBN (2.14 mg, 0.013 mmol) were dissolved in 5 mL of 1,4-dioxane solvent. Before immersion in a preheated oil bath, the mixture was purged with argon or nitrogen for 30 min, and then stirred at 70 °C for 12 h under argon protection. After cooling to room temperature, the resulting mixture was precipitated with n-hexane and dried to obtain the waxy product PEO-b-PNIPAM-bP(MA-co-FMA)-CTA.

[0054] The addition ratios of PEO-b-PNIPAM-CTA, MA, and FMA were changed, and the experiment was conducted according to the same procedure as above. The experimental parameters and results are shown in Table 2. The molar ratios of products 2.2-1 and 2.2-2 were calculated based on the theoretical molecular weights of 10930 and 16588, respectively.

[0055] Table 2:

[0056]

[0057] The next synthesis was carried out using PEO-b-PNIPAM-bP(MA-co-FMA)-CTA synthesized in sequence 8.

[0058] 2.4 Synthesis of Rare Earth Complex-Polymer Material Polymer-Eu

[0059] PEO-b-PNIPAM-bP(MA-co-FMA)-CTA (210.13 mg) and the europium rare earth complex Eu(DNPD)3MP (14.14 mg) synthesized in Example 1 were dissolved in 10 mL of dichloromethane and then reacted at 50 °C for 12 h under argon protection. Precipitation with n-hexane yielded the pale yellow product Polymer-Eu.

[0060]

[0061] Comparative Example: The operation of this comparative example is similar to that in Section 2.4 of Example 2, except that PEO-b-PNIPAM-bP(MA-co-FMA)-CTA synthesized in serial numbers 5, 6, and 8 is used to react with the europium rare earth complex Eu(DNPD)3MP synthesized in Example 1, and the solvent is replaced with anisole and DMF. The reaction parameters and results are shown in Table 3.

[0062] Table 3:

[0063]

[0064] Test Example 3

[0065] 3.1 Excitation and fluorescence emission spectra of rare earth complex Eu(DNPD)3MP in N,N-dimethylformamide (DMF).

[0066] Weigh 0.14 mg of the rare earth complex Eu(DNPD)3MP prepared in Example 1, then dissolve it in 1 mL of DMF solvent to accurately prepare a solution with a concentration of 1×10⁻⁶. -4 A solution of M was added to a cuvette, and excitation and fluorescence emission spectra were measured. As shown in Figure 1, the maximum excitation wavelength of Eu(DNPD)3MP was 417 nm, and the maximum emission wavelength was 614 nm. By expanding the conjugated structure of the β-dicarbonyl ligand, the maximum absorption wavelength of Eu(DNPD)3MP was extended into the visible light region (Luminescence 2015; 30: 1071–1076).

[0067] 3.2 Fluorescence spectrum of Polymer-Eu in aqueous system.

[0068] Weigh 2.5 mg of Polymer-Eu prepared in Section 2.4 of Example 2, and dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 2.5 mg / mL. -1The solution was added to a cuvette, and fluorescence emission spectroscopy was performed (excitation wavelength 417 nm). As shown in Figure 2, the luminescence of Polymer-Eu was not quenched, and a strong emission peak was observed at 614 nm, indicating that the polymer can stabilize Eu. 3+ Luminescence in an aqueous medium.

[0069] 3.3 Temperature-dependent transmittance curves and turbidity point temperature of PEO-b-PNIPAM-bP(MA-co-FMA) in an aqueous system.

[0070] Weigh 1.0 mg of the product PEO-b-PNIPAM-bP(MA-co-FMA) prepared in Section 2.3 of Example 2, then dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 1 mg / mL. -1 The solution was added to a cuvette, and the transmittance was measured at a visible wavelength of 600 nm. The cloud point temperature was determined by measuring the transmittance as a function of temperature within the range of 25–50 °C (in this study, the temperature at which the transmittance decreased to 50% was defined as the cloud point temperature). As shown in Figure 3, the transmittance decreased significantly with increasing temperature within the range of 35–50 °C. When the temperature was 39 °C, the transmittance was below 50%, so the cloud point temperature of the product PEO-b-PNIPAM-bP(MA-co-FMA) was measured to be 39 °C.

[0071] 3.4 Temperature-dependent hydration particle size curves of PEO-b-PNIPAM-bP(MA-co-FMA) in an aqueous system.

[0072] Weigh 1.0 mg of the product PEO-b-PNIPAM-bP(MA-co-FMA) prepared in Section 2.3 of Example 2, then dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 1 mg / mL. -1 The solution was added to the sample cell, and the hydrated particle size was measured using a Malvern nanoparticle size analyzer. The temperature-sensitive phase separation behavior was studied by measuring the hydrated particle size as a function of temperature within the range of 25-50 °C. As shown in Figure 4, the hydrated particle size gradually increased with increasing temperature within the range of 35-41 °C. This is because PNIPAM is temperature-sensitive. At low temperatures, the amide groups of PNIPAM form hydrogen bonds with water molecules, so the product PEO-b-PNIPAM-bP(MA-co-FMA) dissolves in water and can self-assemble into micelles with a hydrated particle size of approximately 210 nm. However, as the temperature gradually increases, the hydrogen bonds are broken, causing the PNIPAM chains to dehydrate and gradually shrink, agglomerating into spherical aggregates, thus increasing the hydrated particle size and exhibiting temperature-dependent conformational change behavior.

[0073] 3.5 Temperature-dependent transmittance curves and turbidity point temperature of Polymer-Eu in an aqueous system.

[0074] Weigh 1.0 mg of the Polymer-Eu product prepared in Section 2.4 of Example 2, and dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 1 mg / mL. -1 The solution was added to a cuvette, and the transmittance was measured at a visible wavelength of 600 nm. The cloud point temperature was determined by measuring the transmittance as a function of temperature in the range of 25-50℃ (in this study, the temperature at which the transmittance decreased to 50% was defined as the cloud point temperature). As shown in Figure 5, the transmittance decreased significantly with increasing temperature in the range of 28-38℃. When the temperature was 35℃, the transmittance was less than 50%, so the cloud point temperature of the product Polymer-Eu was measured to be 35℃. Compared with the results in Figure 3, the cloud point temperature of Polymer-Eu is lower than that of PEO-b-PNIPAM-bP(MA-co-FMA), indicating that the hydrophobicity of the polymer was improved by covalently linking the rare earth complex Eu(DNPD)3MP to the polymer PEO-b-PNIPAM-bP(MA-co-FMA).

[0075] 3.6 Temperature-dependent hydration particle size curves of Polymer-Eu in aqueous systems.

[0076] Weigh 1.0 mg of the Polymer-Eu product prepared in Section 2.4 of Example 2, and dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 1 mg / mL. -1 The solution was prepared. After adding 1 mL to the sample cell, the hydrated particle size was measured using a Malvern nanoparticle size analyzer. The temperature-sensitive phase separation behavior was investigated by measuring the hydrated particle size as a function of temperature within the range of 25–50 °C. As shown in Figure 6, at 25 °C, the hydrated particle size of the micelles formed by Polymer-Eu self-assembly in aqueous medium was approximately 340 nm, which is larger than the particle size of the micelles formed by the polymer PEO-b-PNIPAM-bP(MA-co-FMA). This is due to the hydrophobicity of Eu(DNPD)3MP. Furthermore, within the temperature range of 34–39 °C, the hydrated particle size of Polymer-Eu gradually increased with increasing temperature. However, with further increases in temperature, the hydrated particle size gradually decreased. This differs from the temperature-dependent conformational change behavior of the polymer PEO-b-PNIPAM-bP(MA-co-FMA), indicating that the modification of Eu(DNPD)3MP affects the conformational change behavior of the polymer backbone.

[0077] 3.7 Temperature-dependent fluorescence emission spectra of Polymer-Eu in aqueous systems.

[0078] Weigh 1.0 mg of the Polymer-Eu product prepared in Section 2.4 of Example 2, and dissolve it in 1 mL of ultrapure water to accurately prepare a solution with a concentration of 1 mg / mL. -1 The solution was added to a cuvette, and fluorescence emission spectroscopy was performed with the excitation wavelength set to 417 nm. Its temperature-responsive fluorescence performance was studied by measuring the fluorescence emission spectra as temperature increased within the range of 24–46 °C. As shown in Figures 7 and 8, fluorescence emission decreased significantly with increasing temperature, indicating that its fluorescence has a good temperature response. The inset in Figure 8 shows a good linear correlation between fluorescence emission intensity (F) and temperature (T) within the temperature range of 26–40 °C, indicating that Polymer-Eu can be used as a suitable thermometer for temperature sensing.

[0079] 3.8 Cell survival rate after co-incubation of HeLa cells with different concentrations of Polymer-Eu for 24 h.

[0080] HeLa cells were cultured at 37 °C and under a humid atmosphere of 5% CO2 in DMEM medium containing 10% (v / v) fetal bovine serum and 1% (v / v) penicillin / streptomycin. The cytotoxicity of Polymer-Eu was investigated using the MTT assay. HeLa cells were first pre-seeded into 96-well plates and pre-cultured for 24 h. Once the cells had essentially formed a monolayer covering the bottom of the wells, concentrations of 0, 20, 40, 60, 80, 100, 120, and 140 μg / mL were added to each well. -1 Cells were cultured in DMEM medium containing Polymer-Eu, with six wells per concentration group, for 24 h. Cells were then washed with PBS and incubated at 37 °C with 0.5 mg / mL... -1 The cells were incubated in MTT medium for another 4 h. Next, the MTT medium was removed, and 200 μL of DMSO was added to each well to dissolve the formazan blue-purple crystals produced by the live cells. Finally, the 96-well plate was placed in a microplate reader and shaken at room temperature for 10 min, and the absorbance at 490 nm was recorded. The cell viability results are shown in Figure 9. It can be seen that Polymer-Eu at 80 μg / mL... -1 At concentrations of [specific concentration], cell viability is greater than 85%, and at concentrations as high as 100 μg / mL, cell viability is greater than [specific concentration]. -1 The cell viability rate was still greater than 80%, which indicates that it has good biocompatibility and is expected to be used as a novel fluorescent thermometer for temperature sensing research in living organisms.

Claims

1. A rare earth complex polymer material, characterized in that, It has the following structure: Where R is phenyl or naphthyl, n = 110~120, x : y : z = 0.7~6.5:1.5~3.5:

1.

2. The rare earth complex polymer material according to claim 1, characterized in that, n= n=112~115, x:y:z=2.4~6.5: 1.5~3.5:

1.

3. The method for preparing the rare earth complex polymer material according to claim 1 or 2, characterized in that, The process includes the following steps: (1) The hydroxyl group at one end of PEO undergoes an esterification reaction with 4-cyano-4-(thiobenzoylthio)valerate to form PEO-CTA. PEO-CTA undergoes a RAFT reaction with N-isopropylacrylamide and a first initiator to form a block polymer PEO-b-PNIPAM-CTA; (2) PEO-b-PNIPAM-CTA undergoes a copolymerization reaction with methyl acrylate, furfuryl methacrylate, and a second initiator to form PEO-b-PNIPAM-P(MA-co-FMA)-CTA; (3) PEO-b-PNIPAM-P(MA-co-FMA)-CTA undergoes a cycloaddition reaction with an Eu complex to form a rare earth complex polymer. The first ligand of the Eu complex is dinadiacylmethane or diphenylacylmethane; the second ligand is 5-maleimide-1,10-phenanthroline.

4. The preparation method according to claim 3, characterized in that, In step (1), the molar ratio of PEO to 4-cyano-4-(thiobenzoylthio)valerate is 1:2~3, the esterification catalyst is 4-dimethylaminopyridine, and the coupling agent is EDC.

5. The preparation method according to claim 3, characterized in that, In step (1), the molar ratio of PEO-CTA, N-isopropylacrylamide, and the first initiator is 1:40~220:0.2~0.4, the reaction solvent is tetrahydrofuran, the reaction is carried out under inert gas protection, and the reaction is carried out at 60~80℃ for 11~13 hours.

6. The preparation method according to claim 5, characterized in that, The molar ratio of PEO-CTA, N-isopropylacrylamide, and the first initiator is 1:80~120:0.25~0.

35.

7. The preparation method according to claim 3, characterized in that, In step (2), the molar ratio of PEO-b-PNIPAM-CTA, methyl acrylate, furfuryl methacrylate, and the second initiator is 1:40~120:10~60:0.3~0.

6. The reaction solvent is dioxane, under inert gas protection, and the reaction is carried out at 60~80℃ for 11~13 hours. The molar ratio of methyl acrylate to furfuryl methacrylate is 1.3~3.0:

1.

8. The preparation method according to claim 3, characterized in that, In step (3), the mass ratio of PEO-b-PNIPAM-P(MA-co-FMA)-CTA to Eu complex is 10~20:1, the reaction solvent is dichloromethane, and the reaction is carried out at 40~60℃ for 11~13 hours under inert gas protection.

9. The preparation method according to claim 3, characterized in that, The first initiator and the second initiator are azo initiators.

10. The application of the rare earth complex polymer material according to claim 1 or 2 in fluorescence temperature sensing, bioimaging or temperature recognition.

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