Fluoroapatite material with both up-conversion fluorescence and photothermal conversion and preparation method of fluorapatite material

Abstract

The invention belongs to the field of luminescent materials and biomedical materials, and provides a fluorapatite material with both upconversion fluorescence and photothermal conversion and a preparation method thereof. The preparation method comprises the following steps: (1) dissolving a Ca < 2 + > source, an Ln13 < + > source and an Ln23 < + > source in deionized water to obtain a solution A; dissolving a PO4 < 3-> source, an F <-> source and a MoO4 < 2-> source in deionized water to obtain a solution B; (2) dropwise adding the solution B into the solution A, and stirring for 1-2 hours after dropwise adding to obtain a reaction precursor solution; (3) carrying out hydrothermal reaction on the reaction precursor solution; (4) carrying out thermal activation treatment on the obtained hydrothermal product; and (5) dispersing the obtained activated powder in an aqueous solution of Fe < 3 + >, and carrying out hydrothermal reaction, washing and drying to obtain the Fe < 3 + >-doped porous carbon material. According to the invention, the upconversion fluorescent material can be endowed with good photothermal conversion performance on the basis of no need of compounding a photothermal conversion agent, and the preparation method of the material with both upconversion fluorescence and photothermal conversion performance is simplified.

Description

Technical Field

[0001] The invention belongs to the field of luminescent materials and biomedical materials, and relates to a fluoroapatite material having both up-conversion fluorescence and photothermal conversion and a preparation method thereof. Background Art

[0002] Hydroxyapatite (HAp) crystals are the main inorganic components in human bone and tooth tissues. They have good biocompatibility with cells and tissues and can be used as biomaterials. The hydroxyl groups in hydroxyapatite can undergo ion exchange reactions with fluoride ions, so that the hydroxyl groups in hydroxyapatite are replaced by fluoride ions to obtain fluoroapatite (FAp). The fluoride ions in fluoroapatite have smaller phonon energy and better antibacterial ability, and can be used as rare earth ion-doped apatite biomaterials with good fluorescence properties. Incorporating specific rare earth elements into apatite crystals can give apatite materials upconversion fluorescence properties, and incorporating molybdate into apatite crystals can further increase the upconversion fluorescence intensity of apatite. At present, the excitation light of materials such as hydroxyapatite or fluoroapatite with upconversion fluorescence properties is near-infrared light. Compared with visible light and ultraviolet light, near-infrared light has better tissue penetration ability. Therefore, this type of material has been proven to have good in vivo tracing properties.

[0003] Photothermal conversion materials can absorb excitation light of a specific wavelength and generate heat through photothermal conversion. Photothermal therapy has been applied to antibacterial and anti-tumor applications in the field of biomaterials. Biomaterials with both upconversion fluorescence and photothermal conversion capabilities can simultaneously achieve the dual functions of in vivo material tracing and photothermal therapy. However, direct use of upconversion materials for photothermal conversion often has poor photothermal conversion performance (see Zhao, X., Suo, H., Zhang, Z., Guo, C. (2019). Upconverting CeO2: Yb 3+ / Tm 3+ hollow nanospheres for photo-thermal sterilization and deep-tissue imaging in the first biological window. Ceramics International , 45(17), 21910-21916). To achieve a higher photothermal conversion efficiency, it is usually necessary to compound photothermal conversion agents such as dopamine and carbon materials outside the upconversion material, but the preparation process of the material is complicated (see Zhu, X., Feng, W., Chang, J., Tan, YW, Li, J., Chen, M., Sun, Y., Li, F. (2016). Temperature-feedback upconversion nanocomposite for accurate photothermaltherapy at facile temperature. Nature communications , 7 (1), 1-10. ,Gu, M., Zhang, L., Hao, L., Wang, K., Yang, W., Liu, Z., Lei, Z., Zhang, Y., Li, W., Jiang, L., Li, X. (2023). Upconversion Nanoplatform Enables MultimodalImaging and Combinatorial Immunotherapy for Synergistic Tumor Treatment andMonitoring. ACS Applied Materials&Interfaces , 15 (18), 21766-21780). Summary of the invention

[0004] In view of the poor photothermal conversion performance of existing upconversion materials, it is necessary to compound dopamine, carbon materials and other photothermal conversion agents outside the upconversion materials to effectively enhance the photothermal conversion performance of the materials, which leads to problems such as complicated material preparation process. The present invention provides a fluoroapatite material having both upconversion fluorescence and photothermal conversion and a preparation method thereof, so as to give the upconversion fluorescent material good photothermal conversion performance without the need for compounding photothermal conversion agents, thereby simplifying the preparation method of the material having both upconversion fluorescence and photothermal conversion performance.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion, comprising the following steps: (1) Ca 2+ Source, Ln1 3+ Source, Ln2 3+ The source was dissolved in deionized water to obtain solution A; in solution A, Ln1 3+、Ln2 3+ With Ca 2+ The molar ratio is (5~20): (0.05~2): (78~94.95); Ln1 3+ With Ln2 3+ For different rare earth ions; PO4 3- Source, F - Source and MoO4 2- The source is dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo is (80-92):(8-20), and the ratio of the sum of the molar amounts of P and Mo to the molar amount of F is 3:1;

[0007] (2) adding solution B dropwise to solution A at 20-80°C with stirring, controlling the pH value of the resulting mixed solution to be between 9 and 10 during the addition, and continuing to stir for 1-2 hours after the addition is completed to obtain a reaction precursor solution; controlling the ratio of the sum of the molar amounts of Ca, Ln1 and Ln2 to the sum of the molar amounts of P and Mo in the reaction precursor solution to be 5:3;

[0008] (3) subjecting the reaction precursor solution to a hydrothermal reaction at 120-200 °C, collecting the precipitate obtained by the reaction, washing it, and drying it to obtain a hydrothermal product;

[0009] (4) subjecting the hydrothermal product to thermal activation treatment in an air atmosphere at 600-1000°C to obtain an activated powder;

[0010] (5) Disperse the activated powder fully in Fe 3+ A hydrothermal reaction is carried out in an aqueous solution at 120-200°C, and the precipitate obtained by the reaction is collected, washed, and dried to obtain a fluoroapatite material having both upconversion fluorescence and photothermal conversion.

[0011] In the technical solution of the above preparation method, the Ln1 3+ Yb 3+ , the Ln2 3+ For Ho 3+ , Er 3+ 、Tm 3+ 、Nd 3+ 、Dy 3 + , Pr 3+ 、Eu 3+ , Tb 3+ 、Sm 3+ 、Ce 3+ At least one of .

[0012] In the technical scheme of the above preparation method, the Ca in solution A 2+The concentration of PO4 in solution B is 10~2000 mmol / L, preferably 15~160 mmol / L. 3- The concentration is 5~500 mmol / L, preferably 9~110 mmol / L.

[0013] In step (5) of the technical solution of the above preparation method, Fe 3+ Fe in aqueous solution 3+ The concentration of Fe is preferably 0.1~10mmol / L, and the activated powder and Fe 3+ The mass ratio of the aqueous solution is 1:(10~100).

[0014] In step (3) of the technical solution of the above preparation method, the hydrothermal reaction time is preferably controlled to be 4 to 24 hours.

[0015] In step (5) of the technical solution of the above preparation method, the time of the hydrothermal reaction is preferably controlled to be 1 to 24 hours.

[0016] In step (4) of the technical solution of the above preparation method, the time of the thermal activation treatment is preferably controlled to be 1 to 4 hours.

[0017] In the technical scheme of the above preparation method, Ca 2+ Source: Ca 2+ Water-soluble salts, such as Ca 2+ The source can be calcium nitrate, calcium chloride or calcium acetate; Ln1 3+ Source is Ln1 3+ Water-soluble salts, such as Ln1 3+ The source can be Ln1 3+ nitrate, hydrochloride, acetate or sulfate; Ln2 3+ Source is Ln2 3+ Water-soluble salts, such as Ln2 3+ The source can be Ln2 3+ nitrate, hydrochloride, acetate or sulfate; PO4 3- The source is trisodium phosphate, diammonium phosphate or diammonium phosphate; F - The source is sodium fluoride or ammonium fluoride; MoO4 2- The source is ammonium molybdate or ammonium heptamolybdate.

[0018] In the technical scheme of the above preparation method, Fe 3+ The aqueous solution is Fe 3+ The water-soluble salt of Fe is dissolved in water. 3+ The water-soluble salt may be ferric nitrate, ferric chloride, ferric acetate or ferric sulfate.

[0019] The present invention also provides a fluoroapatite material having both upconversion fluorescence and photothermal conversion prepared by the above method, wherein the multi-ion doped fluoroapatite material is obtained by first replacing part of the lattice calcium ions and phosphate groups in the fluoroapatite with rare earth ions and molybdate ions, and then replacing part of the calcium ions and / or rare earth ions on the surface of the obtained material with iron ions. The multi-ion doped fluoroapatite material can emit fluorescence visible to the human eye under the excitation of near-infrared light with a wavelength of 980 nm, and at the same time has excellent photothermal energy conversion performance imparted by iron ions.

[0020] Compared with the prior art, the technical solution provided by the present invention produces the following beneficial technical effects:

[0021] 1. The present invention provides a method for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion. The method first prepares fluoroapatite co-doped with rare earth ions and molybdate ions, then heat-treats the fluoroapatite to obtain an activated powder having upconversion fluorescence, and then disperses the activated powder in Fe 3+ The aqueous solution of Fe 3+ It is obtained by replacing part of the calcium ions and / or rare earth ions on the surface of the activated powder. The method of the present invention mainly enhances the non-radiative energy transfer of the material by introducing iron ions on the surface of the multi-ion-doped fluoroapatite material with strong up-conversion fluorescence, and gives the material good photothermal conversion performance on the basis of strong up-conversion fluorescence performance. Compared with the prior art method of strengthening the photothermal conversion performance of the up-conversion material by compounding photothermal conversion agents such as dopamine and carbon materials outside the up-conversion material, the method of the present invention is based on a simple hydrothermal synthesis technology, that is, it realizes the preparation of materials with both strong up-conversion fluorescence and photothermal conversion functions, and has the characteristics of low production cost, economy, environmental protection, and convenience for industrial production.

[0022] 2. Fluorapatite materials and rare earth-doped fluoroapatite materials have good osteogenic biological activity, are similar to the chemical properties of autologous bone minerals, can promote the repair of bone tissue, and have important application prospects in the medical field. The present invention endows the fluoroapatite material with strong upconversion fluorescence performance and excellent photothermal conversion performance. The material prepared by the present invention has a high upconversion emission efficiency under the excitation of near-infrared light with a wavelength of 980 nm. Under the excitation of near-infrared light, the material located in the deep tissue can be efficiently excited and traced, thereby avoiding the problem of shallow tissue penetration depth and tissue damage caused by ultraviolet and visible light excitation. At the same time, the photothermal conversion performance of the material enables it to realize photothermal therapy on the basis of in vivo tissue repair and material tracing. The above characteristics can effectively expand the application of existing fluoroapatite materials and rare earth-doped fluoroapatite materials in basic biomedical research, in vivo tracing of biomaterials, tissue repair, and photothermal therapy.

[0023] 3. The present invention has experimentally confirmed that, compared with the existing doped hydroxyapatite powder with upconversion fluorescence performance, the photothermal conversion performance of the fluoroapatite material with both upconversion fluorescence and photothermal conversion prepared by the method of the present invention has been significantly improved. When irradiated with near-infrared light of a wavelength of 980 nm for 25 s at the same power, the heating temperature of the fluoroapatite material with both upconversion fluorescence and photothermal conversion of the present invention can reach 70°C, while the heating temperature of the existing doped hydroxyapatite powder with upconversion fluorescence performance is only about 15°C. The photothermal conversion efficiency of the fluoroapatite material with both upconversion fluorescence and photothermal conversion prepared by the method of the present invention is significantly higher.

[0024] 4. The present invention has been verified through experiments that the fluoroapatite material with both upconversion fluorescence and photothermal conversion prepared by the method of the present invention was placed under the pig skin, excited with near-infrared light with a wavelength of 980 nm and observed under a two-photon microscope. The results show that under the excitation of near-infrared light, the fluoroapatite material with both upconversion fluorescence and photothermal conversion of the present invention can still emit strong green upconversion fluorescence in the tissue, and is not interfered by the autofluorescence of the tissue, and can distinguish the material from the autologous tissue in vivo. The upconversion fluorescence performance of the fluoroapatite material with both upconversion fluorescence and photothermal conversion can meet the intensity requirements for fluorescent tracing of the material in vivo in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope image of FYEM / Fe.

[0026] Figure 2 This is the XPS spectrum of FYEM / Fe, where (a) is the overall XPS spectrum and (b) is the Fe 2p spectrum.

[0027] Figure 3 It is the XRD spectrum of FYEM / Fe and FYEM, among which ICDD: 15-0876 is the XRD spectrum of the standard card of fluoroapatite, and ICDD: 29-0351 is the XRD spectrum of the standard card of calcium molybdate.

[0028] Figure 4 It is the UV-visible-near-infrared diffuse reflectance absorption spectra of FYEM / Fe and FYEM.

[0029] Figure 5 It is the up-conversion fluorescence emission spectra of FYEM / Fe and FYEM.

[0030] Figure 6 Figure (a) is a bright field photograph of powdered FYEM / Fe placed under 6 mm thick pig skin under a stereo microscope. Figure 6Figure (b) is a dark field photograph taken under a stereo microscope using near-infrared light with a wavelength of 980 nm for excitation.

[0031] Figure 7 It is the temperature rise curve of FYTM / Fe, FYEM / Fe, FYEM and FYH / Fe drawn by the readings of infrared thermal imager under the excitation of near-infrared light with a wavelength of 980 nm. DETAILED DESCRIPTION

[0032] The following examples further illustrate the fluoroapatite material with both upconversion fluorescence and photothermal conversion and the preparation method thereof. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. The technical personnel in the relevant field make some non-essential improvements and adjustments to the present invention according to the above invention content for specific implementation, which still falls within the scope of protection of the present invention.

[0033] Example 1

[0034] In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows:

[0035] (1) Calcium nitrate, ytterbium nitrate and thulium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ 、Tm 3+ With Ca 2+ The molar ratio is 20: 0.1: 79.9, and the concentration of calcium nitrate is 15.98 mmol / L.

[0036] Diammonium hydrogen phosphate, sodium fluoride and ammonium heptamolybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 92: 8, the molar ratio of the sum of the molar amounts of P and Mo (P+Mo) to F was 3: 1; the concentration of diammonium hydrogen phosphate was 11.04 mmol / L.

[0037] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Tm (Ca+Yb+Tm) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0038] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0039] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 900°C for 2 h to obtain an activated powder with upconversion fluorescence, which is denoted as FYTM.

[0040] (5) FYTM was added to an aqueous solution of ferric nitrate with a concentration of 2 mmol / L, and the mass ratio of FYTM to the aqueous solution of ferric nitrate was controlled to be 1:50. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 180 °C for 6 h to replace some calcium ions and / or rare earth ions on the surface of FYTM with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Tm / Mo / Fe (FYTM / Fe for short) with both upconversion fluorescence and photothermal conversion.

[0041] Comparative Example 1

[0042] In this comparative example, a multi-ion doped fluoroapatite material with up-conversion fluorescence performance is prepared by the following steps:

[0043] (1) Dissolve calcium nitrate, ytterbium nitrate and thulium nitrate in deionized water to obtain solution A; in solution A, Ln1 3+ 、Ln2 3+ With Ca 2+ The molar ratio is 20: 0.1: 79.9, and the concentration of calcium nitrate is 15.98 mmol / L.

[0044] Diammonium hydrogen phosphate, sodium fluoride and ammonium heptamolybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 92: 8, and the ratio of the molar sum of P and Mo (P+Mo) to the molar amount of F was 3: 1; the concentration of diammonium hydrogen phosphate was 11.04 mmol / L.

[0045] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Tm (Ca+Yb+Tm) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0046] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0047] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 900° C. for 2 h to obtain an activated powder with upconversion fluorescence, denoted as FYTM. The FYTM is a multi-ion-doped fluoroapatite material with upconversion fluorescence performance.

[0048] Example 2

[0049] In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows:

[0050] (1) Calcium nitrate, ytterbium nitrate and erbium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ , Er 3+ With Ca 2+ The molar ratio is 10:0.5:89.5, and the concentration of calcium nitrate is 17.9 mmol / L.

[0051] Diammonium hydrogen phosphate, sodium fluoride and ammonium heptamolybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 85:15, and the ratio of the molar sum of P and Mo (P+Mo) to the molar amount of F was 3:1; the concentration of diammonium hydrogen phosphate was 10.2 mmol / L.

[0052] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the obtained mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Er (Ca+Yb+Er) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0053] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0054] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 900°C for 2 h to obtain an activated powder with upconversion fluorescence, which is denoted as FYEM.

[0055] (5) FYEM was added to an aqueous solution of ferric nitrate with a concentration of 2 mmol / L, and the mass ratio of FYEM to the aqueous solution of ferric nitrate was controlled to be 1:50. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 180 °C for 6 h to replace some calcium ions and / or rare earth ions on the surface of FYEM with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Er / Mo / Fe (abbreviated as FYEM / Fe) with both upconversion fluorescence and photothermal conversion.

[0056] The scanning electron microscope (SEM) image of FYEM / Fe prepared in this example is as follows: Figure 1 As shown by Figure 1 It can be seen that the microstructure of FYEM / Fe prepared in this embodiment is a nanorod and nanosphere-like structure.

[0057] The FYEM / Fe prepared in this example was subjected to X-ray photoelectron spectroscopy (XPS) analysis, and the results were as follows: Figure 2 As shown, (a) is the XPS total spectrum, and (b) is the Fe 2p spectrum. Figure 2 It can be seen that the doped Yb +3, Er +3, Mo +6 and Fe +3 were detected in FYEM / Fe, indicating that Yb 3+ , Er 3+ 、MoO4 2- was successfully incorporated into fluorapatite, and Fe 3+ The FYEM / Fe prepared in this embodiment was subjected to ICP-MS analysis, and the relative atomic content of each element in FYEM / Fe was measured as shown in Table 1. As can be seen from Table 1, the atomic content of iron in the FYEM / Fe prepared in this embodiment is 6.24%.

[0058] Table 1 Relative atomic content of each element in FYEM / Fe

[0059] element Relative atomic content (%) Ca 12.33 Yb 3.30 Er 0.13 Fe 6.24 P 11.92 Mo 2.70 O 58.50

[0060] Comparative Example 2

[0061] In this comparative example, a multi-ion doped fluoroapatite material with up-conversion fluorescence performance is prepared by the following steps:

[0062] (1) Calcium nitrate, ytterbium nitrate and erbium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ , Er 3+ With Ca 2+ The molar ratio is 10:0.5:89.5, and the concentration of calcium nitrate is 17.9 mmol / L.

[0063] Diammonium hydrogen phosphate, sodium fluoride and ammonium heptamolybdate are dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo is 85:15, and the ratio of the molar sum of P and Mo (P+Mo) to the molar ratio of F is 3:1; the concentration of diammonium hydrogen phosphate is 10.2 mol / L.

[0064] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the obtained mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Er (Ca+Yb+Er) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0065] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0066] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 900° C. for 2 h to obtain an activated powder with upconversion fluorescence, denoted as FYEM. The FYEM is a multi-ion-doped fluoroapatite material with upconversion fluorescence performance.

[0067] Comparative Example 3 In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows: (1) Calcium nitrate, ytterbium nitrate and holmium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ 、Ho 3+ With Ca 2+ The molar ratio is 10:0.1:89.9, and the concentration of calcium nitrate is 17.18 mmol / L.

[0068] Diammonium hydrogen phosphate and sodium fluoride were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to F was 3:1; and the concentration of diammonium hydrogen phosphate was 10.2 mmol / L.

[0069] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Ho (Ca+Yb+Ho) to the molar amount of P in the reaction precursor solution was 5:3.

[0070] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0071] (4) The hydrothermal product was activated in an air atmosphere at 900 °C for 2 h to obtain a thermally activated powder, denoted as FYH.

[0072] (5) FYH was added to an aqueous solution of ferric nitrate with a concentration of 2 mmol / L, and the mass ratio of FYH to the aqueous solution of ferric nitrate was controlled to be 1:50. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 180 °C for 6 h to replace some calcium ions and / or rare earth ions on the surface of FYH with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Ho / Fe (FYH / Fe for short) with both upconversion fluorescence and photothermal conversion.

[0073] X-ray diffraction (XRD) analysis was performed on the FYEM / Fe prepared in Example 2 and the FYEM prepared in Comparative Example 2. The results are as follows: Figure 3 As shown. Figure 3 It can be seen that the diffraction peaks of FYEM / Fe prepared in Example 2 and FYEM prepared in Comparative Example 2 are basically consistent with the standard card of fluoroapatite (FAp) (ICDD: 15-0876), and a certain degree of CaMoO4 (ICDD: 29-0351) impurity phase appears, indicating that the rare earth ion Yb is doped 3+ , Er 3+ and Fe 3+ The FAp crystal structure was not significantly changed, while the addition of MoO4 2- This will lead to the appearance of CaMoO4 impurity phase in FAp crystals.

[0074] UV-Vis-NIR DRS analysis was performed on the FYEM / Fe prepared in Example 2 and the FYEM prepared in Comparative Example 2 to investigate the change in absorbance of the co-doped materials in the UV-Vis-NIR region. The results are as follows: Figure 4 As shown. Figure 4 It can be seen that compared with the FYEM prepared in Comparative Example 2, the absorbance value of FYEM / Fe prepared in Example 2 in the visible light region is significantly higher, which indicates that after the incorporation of iron ions, the high-energy-level electrons of the lanthanide ions can interact with the energy levels of the iron ions through non-radiative energy transfer.

[0075] The FYEM / Fe prepared in Example 2 and the FYEM prepared in Comparative Example 2 were excited by near-infrared light with a wavelength of 980 nm, and the upconversion fluorescence emission spectra of each sample were tested to investigate the changes in the upconversion fluorescence properties of the co-doped materials. The results are shown in FIG. Figure 5 As shown. Figure 5 It can be seen that under the excitation of near-infrared light with a wavelength of 980 nm, the up-conversion fluorescence intensity of FYEM / Fe prepared in Example 2 in the visible light region is weakened compared to FYEM prepared in Comparative Example 2, and the fluorescence intensity in the green light region decreases by about 90%, which is mainly due to the introduction of iron ions to enhance non-radiative energy transfer. The powdered FYEM / Fe prepared in Example 2 was placed under 6 mm thick pig skin, and near-infrared light with a wavelength of 980 nm was used to excite from above the pig skin and observed under a stereo microscope to investigate the in vivo fluorescence tracing performance of FYEM / Fe prepared in Example 2. The results are shown in FIG. Figure 6 As shown in the figure, (a) is a bright field photo of powdered FYEM / Fe padded under 6 mm thick pig skin under a stereo microscope, and (b) is a dark field photo of near-infrared light with a wavelength of 980 nm under a stereo microscope. Figure 6 It can be seen that under the excitation of near-infrared light with a wavelength of 980 nm, the FYEM / Fe prepared in Example 2 can still emit strong green upconversion fluorescence in the tissue, and is not interfered by the tissue autofluorescence, so that the FYEM / Fe material and the tissue can be distinguished in vivo. In summary, although the upconversion fluorescence intensity of the obtained FYEM / Fe in the visible light region is weakened after the introduction of iron ions, its upconversion fluorescence performance can still meet the requirements of fluorescent tracing of materials in vivo in practical applications.

[0076] The FYTM / Fe prepared in Example 1, the FYEM / Fe prepared in Example 2, the FYEM prepared in Comparative Example 2, and the FYH / Fe prepared in Comparative Example 3 were irradiated with near-infrared light of 980 nm for 25 s at the same power, and the infrared thermal imaging images of each sample were tested to examine the changes in the photothermal properties of the materials after co-doping. The results are shown in FIG. Figure 7 As shown. Figure 7 It can be seen that under the excitation of near-infrared light with a wavelength of 980 nm, the temperature rise of FYEM / Fe prepared in Example 2 is greater than that of FYEM prepared in Comparative Example 2. This is because part of the upconversion fluorescence energy is transferred to the Fe on the surface of FYEM / Fe. 3+, photothermal conversion occurs during the non-radiative energy transfer process and generates heat; at the same time, the temperature rise of FYEM / Fe prepared in Example 2 is higher than that of FYTM / Fe prepared in Example 1, and the temperature rise of FYTM / Fe and FYEM / Fe is higher than that of FYH / Fe prepared in Comparative Example 3, that is, the photothermal conversion efficiency of FYTM / Fe prepared in Example 1 and FYEM / Fe prepared in Example 2 are significantly higher than that of FYH / Fe prepared in Comparative Example 3. This is because the upconversion fluorescence intensity of FYEM is better than that of FYTM, and the upconversion fluorescence intensity of FYTM is better than that of FYH / Fe without molybdate doping, which shows that the photothermal conversion performance of the material is positively correlated with the intensity of the upconversion fluorescence of the material. The stronger the upconversion fluorescence intensity of the material, the stronger its photothermal conversion performance after the hydrothermal reaction with iron ions.

[0077] Example 3

[0078] In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows:

[0079] (1) Calcium nitrate, ytterbium nitrate and holmium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ 、Ho 3+ With Ca 2+ The molar ratio is 10:0.1:89.9, and the concentration of calcium nitrate is 17.18 mmol / L.

[0080] Diammonium hydrogen phosphate, sodium fluoride and ammonium heptamolybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 80:20, the ratio of the molar sum of P and Mo (P+Mo) to the molar ratio of F was 3:1; the concentration of diammonium hydrogen phosphate was 9.6 mmol / L.

[0081] (2) Solution B was added dropwise to solution A at 25 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Ho (Ca+Yb+Ho) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0082] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 180° C. for 6 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0083] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 900°C for 2 h to obtain an activated powder with upconversion fluorescence, which is denoted as FYHM.

[0084] (5) FYHM was added to an aqueous solution of ferric nitrate with a concentration of 0.1 mmol / L, and the mass ratio of FYHM to the aqueous solution of ferric nitrate was controlled to be 1:100. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 180 °C for 6 h to replace some calcium ions and / or rare earth ions on the surface of FYHM with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Ho / Mo / Fe (abbreviated as FYHM / Fe) with both upconversion fluorescence and photothermal conversion.

[0085] Example 4

[0086] In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows:

[0087] (1) Calcium nitrate, ytterbium nitrate and praseodymium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ , Pr 3+ With Ca 2+ The molar ratio is 5: 0.05: 94.95, and the concentration of calcium nitrate is 18.99 mmol / L.

[0088] Diammonium hydrogen phosphate, ammonium fluoride and ammonium molybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 80:20, and the ratio of the molar sum of P and Mo (P+Mo) to the molar amount of F was 3:1; the concentration of diammonium hydrogen phosphate was 9.6 mmol / L.

[0089] (2) Solution B was added dropwise to solution A at 20 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to be 10 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 2 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Pr (Ca+Yb+Pr) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0090] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 120° C. for 24 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0091] (4) The hydrothermal product obtained in step (3) is thermally activated in an air atmosphere at 1000°C for 1 h to obtain an activated powder with upconversion fluorescence, which is denoted as FYPM.

[0092] (5) FYPM was added to an aqueous solution of ferric nitrate with a concentration of 10 mmol / L, and the mass ratio of FYPM to the aqueous solution of ferric nitrate was controlled to be 1:10. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 120 °C for 24 h to replace some calcium ions and / or rare earth ions on the surface of FYPM with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Pr / Mo / Fe (FYPM / Fe for short) with both upconversion fluorescence and photothermal conversion.

[0093] Example 5

[0094] In this embodiment, the steps for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion are as follows:

[0095] (1) Calcium nitrate, ytterbium nitrate and europium nitrate are dissolved in deionized water to obtain solution A. In solution A, Yb 3+ 、Eu 3+ With Ca 2+ The molar ratio is 20: 2: 78, and the concentration of calcium nitrate is 156 mmol / L.

[0096] Trisodium phosphate, sodium fluoride and ammonium heptamolybdate were dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo was 90:10, and the ratio of the molar sum of P and Mo (P+Mo) to the molar ratio of F was 3:1; the concentration of trisodium phosphate was 108mmol / L.

[0097] (2) Solution B was added dropwise to solution A at 80 °C with stirring. During the addition, the pH value of the resulting mixed solution was controlled to 9 by adding sodium hydroxide solution. After the addition was completed, stirring was continued for 1 h to obtain a reaction precursor solution. The amount of solution B added was controlled so that the ratio of the sum of the molar amounts of Ca, Yb and Eu (Ca+Yb+Eu) to the sum of the molar amounts of P and Mo (P+Mo) in the reaction precursor solution was 5:3.

[0098] (3) The reaction precursor solution obtained in step (2) was subjected to a hydrothermal reaction at 200° C. for 4 h, and the precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a hydrothermal product.

[0099] (4) The hydrothermal product was thermally activated at 600 °C in air atmosphere for 4 h to obtain an activated powder with upconversion fluorescence, denoted as FYUM.

[0100] (5) FYUM was added to an aqueous solution of ferric nitrate with a concentration of 0.1 mmol / L, and the mass ratio of FYUM to the aqueous solution of ferric nitrate was controlled to be 1:50. The mixture was stirred thoroughly and subjected to a hydrothermal reaction at 200 °C for 1 h to replace some calcium ions and / or rare earth ions on the surface of FYUM with iron ions. The precipitate obtained by the reaction was collected by filtration, washed three times with deionized water and anhydrous ethanol respectively, and freeze-dried to obtain a fluoroapatite material FAp:Yb / Eu / Mo / Fe (FYUM / Fe for short) with both upconversion fluorescence and photothermal conversion.

Claims

1. A method for preparing a fluoroapatite material having both upconversion fluorescence and photothermal conversion, characterized in that: The following steps are involved: (1) Ca 2+ Source, Ln1 3+ Source, Ln2 3+ The source was dissolved in deionized water to obtain solution A; in solution A, Ln1 3+ 、Ln2 3+ With Ca 2+ The molar ratio is (5~20): (0.05~2): (78~94.95); Ln1 3+ With Ln2 3+ For different rare earth ions; PO4 3- Source, F - Source and MoO4 2- The source is dissolved in deionized water to obtain solution B; in solution B, the molar ratio of P to Mo is (80-92):(8-20), and the ratio of the sum of the molar amounts of P and Mo to the molar amount of F is 3:1; (2) adding solution B dropwise to solution A at 20-80°C with stirring, controlling the pH value of the resulting mixed solution to be between 9 and 10 during the addition, and continuing to stir for 1-2 hours after the addition is completed to obtain a reaction precursor solution; controlling the ratio of the sum of the molar amounts of Ca, Ln1 and Ln2 to the sum of the molar amounts of P and Mo in the reaction precursor solution to be 5:3; (3) subjecting the reaction precursor solution to a hydrothermal reaction at 120-200 °C, collecting the precipitate obtained by the reaction, washing it, and drying it to obtain a hydrothermal product; (4) subjecting the hydrothermal product to thermal activation treatment in an air atmosphere at 600-1000°C to obtain an activated powder; (5) Disperse the activated powder fully in Fe 3+ The product is prepared by hydrothermal reaction at 120-200°C in an aqueous solution, collecting the precipitate obtained by the reaction, washing it, and drying it.

2. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to claim 1, characterized in that: Ln1 3+ Yb 3+ , Ln2 3+ For Ho 3+ , Er 3+ 、Tm 3+ 、Nd 3+ 、Dy 3+ , Pr 3+ 、Eu 3+ , Tb 3+ 、Sm 3+ 、Ce 3+ At least one of .

3. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to claim 1, characterized in that: Ca in solution A 2+ The concentration of PO4 in solution B is 10~2000 mmol / L. 3- The concentration is 5~500 mmol / L.

4. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to claim 1, characterized in that: In step (5), Fe 3+ Fe in aqueous solution 3+ The concentration of Fe is 0.1~10 mmol / L, controlling the activation powder and Fe 3+ The mass ratio of the aqueous solution is 1:(10~100).

5. The method for preparing the fluoroapatite material having both up-conversion fluorescence and photothermal conversion according to any one of claims 1 to 4, characterized in that: The time of the hydrothermal reaction in step (3) is controlled to be 4 to 24 h.

6. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to any one of claims 1 to 4, characterized in that: The time of the hydrothermal reaction in step (5) is controlled to be 1 to 24 h.

7. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to any one of claims 1 to 4, characterized in that: In step (4), the time of thermal activation treatment is controlled to be 1 to 4 h.

8. The method for preparing the fluoroapatite material having both upconversion fluorescence and photothermal conversion according to any one of claims 1 to 4, characterized in that: Ca 2+ Source: Ca 2+ Water-soluble salt, Ln1 3+ Source is Ln1 3+ Water-soluble salt, Ln2 3+ Source is Ln2 3+ Water-soluble salt, PO4 3- The source is trisodium phosphate, diammonium hydrogen phosphate or diammonium phosphate, and the F - The source is sodium fluoride or ammonium fluoride, MoO4 2- The source is ammonium molybdate or ammonium heptamolybdate.

9. Fluorapatite material having both upconversion fluorescence and photothermal conversion prepared by the method according to any one of claims 1 to 4.

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