Core-shell structure up-conversion nano-composite, preparation method and application

Abstract

The invention discloses an up-conversion nano-composite with a core-shell structure, a preparation method and application, and belongs to the technical field of biomedical bimodal nano-probes. According to the nanocomposite, up-conversion nanoparticles (UCNPs) serve as a core, metal-organic frameworks (MOFs) serve as a shell layer, horse radish peroxidase (HRP) is loaded on the shell layer, and UCNP (at) MOF / HRP is formed. Subsequent biological functional modification, such as coupling of an antibody, an antigen, nucleic acid and other substances, can be carried by an activating group or a metal coordination bond carried by a shell ligand of the upconversion nanocomposite MOF with the core-shell structure, so that the functions of specific recognition, targeted capture, specific loading and the like are realized.

Description

Technical Field

[0001] This invention belongs to the field of biomedical bimodal nanoprobe technology, specifically relating to a core-shell upconversion nanocomposite and its preparation method, as well as its application in the preparation of bimodal nanoprobes. Background Technology

[0002] Nanomaterials, due to their small size, large surface area, functionalizability, and unique physicochemical properties, have shown broad application prospects in the field of in vitro diagnostics (IVD). With the development of nanotechnology, significant progress has been made in the research of nanoprobes in early disease detection, precision diagnosis, and multiplexing.

[0003] Upconversion nanoparticles (UCNPs) have shown significant application potential in the field of fluorescence detection for in vitro diagnostics due to their unique fluorescence emission properties. UCNPs can convert low-energy near-infrared (NIR) light into high-energy visible or ultraviolet light, and their emission wavelength can be adjusted by doping with different types and proportions of rare-earth ions. The optimization of UCNP applications in in vitro diagnostics is reflected in three main aspects: the near-infrared excitation light of UCNPs is located in the optical window region of the biological sample, effectively avoiding interference from the autofluorescence of the sample matrix; the fluorescence emission wavelength of UCNPs has a large Stokes shift compared to the excitation wavelength, reducing background noise and improving the signal-to-noise ratio; and UCNPs exhibit long-term stability, maintaining stable emission under prolonged light and chemical environments, and are not prone to photobleaching. Therefore, UCNPs have enormous application potential for the direct detection of biomarkers in complex biological samples.

[0004] To further enhance the advantages of core-shell nanoparticles (UCNPs) in the detection field, an inert and biocompatible outer shell is typically coated onto their surface. The resulting core-shell nanocomposite reduces the biotoxicity of UCNPs, enhances biocompatibility and stability, and ensures good dispersibility of the nanoparticles in aqueous solutions, preventing aggregation. The outer shell reduces non-radiative energy transfer between UCNPs and their surrounding environment, preventing photon quenching on the UCNP surface and thus improving upconversion efficiency. Furthermore, the outer shell provides a good platform for the biofunctionalization of the nanocomposite surface, such as linking antibodies, nucleic acids, and small molecules, thereby achieving functions such as specific recognition, targeted capture, and specific loading, laying the foundation for the preparation of nanocomposite probes with different functions.

[0005] Currently, researchers mostly choose silica to coat UCNPs. Silica coating not only protects the optical integrity of the nanoparticles but also effectively reduces surface quenching effects. However, silica coating of UCNPs has the following drawbacks: the silica shell coating often uses a "water-in-oil reverse microemulsion" method, which can easily result in coreless silica particles and multiple UCNPs being co-encapsulated within a single silica shell; it is difficult to precisely control the thickness of the silica shell on the UCNPs; the surface of silica has a large number of active hydroxyl groups, limiting its biofunctionalization. Additional chemical treatment steps are usually required to introduce functional groups, such as amino (CN112125312A) and carboxyl (CN102091331A) modifications, for subsequent antibody and nucleic acid modifications.

[0006] The advent of metal-organic frameworks (MOFs) has attracted significant attention from researchers. MOF materials are nanomaterials with intramolecular pores, formed by the self-assembly of organic ligands and metal ions through coordination bonds. Compared to silica materials, MOFs exhibit superior structural diversity and tunability. By changing the type of metal center or organic ligand, the pore size, shape, and chemical properties of the material can be precisely controlled, enabling designs tailored to different applications. Given the diversity of organic ligands in MOFs, specific chemical properties and active groups can be directly endowed to MOFs through functionalized ligands, following subsequent biofunctionalization. Furthermore, compared to mesoporous silica, MOFs possess advantages such as high porosity and uniform pore size, and their specific surface area is 10 times higher than that of mesoporous silica, enabling efficient loading of target small molecules.

[0007] Based on the above background, the present invention prepares a core-shell structured upconversion nanocomposite, wherein the composite has an upconversion nanoparticle (UCNP) core and a Zr-MOF (UIO-66-NH2) shell, and uses the MOF shell to load horseradish peroxidase (HRP) to obtain a detection probe with both fluorescence and catalytic colorimetric modes. Summary of the Invention

[0008] One object of this invention is to provide an upconversion nanocomposite with a core-shell structure, wherein the composite has an upconversion nanoparticle (UCNP) core, a Zr-MOF (UIO-66-NH2) shell, and the shell is loaded with horseradish peroxidase (HRP), forming a UCNP@MOF / HRP detection probe with both fluorescence and catalytic colorimetric modes. Another object of this invention is to provide a method for preparing the aforementioned core-shell upconversion nanocomposite. A further object of this invention is to provide the application of the nanocomposite in the preparation of detection probes.

[0009] In a first aspect, the present invention provides a core-shell structured upconversion nanocomposite, characterized in that the nanocomposite has an upconversion nanoparticle (UCNPs) as the core and a metal-organic framework (MOFs) as the shell, and the shell is loaded with horseradish peroxidase (HRP) to form UCNP@MOF / HRP.

[0010] The upconversion nanoparticles are composed of rare earth ions doped into nanocrystals NaYF4, Y2O3 or NaGdF4, and the rare earth ions include sensitizing ions and activating ions.

[0011] The sensitizing ion is selected from Nd. 3+ Yb 3+ One or a combination of two of them, with a molar content of sensitizing ions ranging from 0.01% to 60%.

[0012] In a preferred embodiment of the present invention, the sensitizing ion is Yb. 3+ .

[0013] The activating ions are selected from Pr 3+ 、Nd 3+ 、Sm 3+ 、Tb 3+ Ho 3+ Er 3+ Tm 3+ One or more combinations of the active ions, with a molar content of 0.01-20%.

[0014] In a preferred embodiment of the present invention, the activating ion is selected from Er 3+ Tm 3+ Ho 3+ One of them.

[0015] In the most preferred embodiment of the present invention, the upconversion nanoparticles are NaYF4:Yb / Tm, the amount of Yb is 20-25% of the molar amount of NaYF4, and the amount of Tm is 0.3-0.6% of the molar amount of NaYF4.

[0016] More preferably, the upconversion nanoparticles are PEG-phosphate ligand-stabilized upconversion nanoparticles, specifically, the PEG-phosphate ester is PEG(1000)-phosphate ester.

[0017] The metal-organic framework described in this invention is a porous material formed by the coordination of metal nodes with multidentate organic ligands.

[0018] The metal nodes are selected from Zn²⁺, Cu²⁺, Fe³⁺, Al³⁺, and Zr. 4 One or more of the ⁺, with a molar content of 0.01-60% for metal nodes.

[0019] The multidentate organic ligand is selected from one or more of terephthalic acid, dimethyl terephthalate, and 2-imidazolium carboxylic acid, and the molar content of the organic ligand is 0.01-40%.

[0020] In a specific embodiment of the present invention, the metal-organic framework is Zr-MOF, specifically UIO-66-NH2.

[0021] The mass of horseradish peroxidase loaded in the metal-organic framework shell is 2-4% of the mass of the nanocomposite.

[0022] Secondly, the present invention provides a method for preparing a core-shell structured upconversion nanocomposite, characterized in that the method comprises the following steps: (1) Preparation of UCNPs Rare earth raw materials were dissolved in deionized water, and a certain amount of high-temperature solvent was added. The water was evaporated to dryness. The reaction was carried out at 150-170℃ for 1-1.5h under an argon atmosphere to obtain a transparent yellow solution, which was then cooled to room temperature. The solution was added dropwise to a methanol solution containing NH4F and NaOH, and the methanol solvent was evaporated to dryness. The temperature was raised to 290-320℃ under a nitrogen atmosphere and kept at that temperature for 1-2h, then cooled to room temperature. The solution was precipitated with ethanol, centrifuged, washed, and the upconversion nanoparticles were obtained and stored in cyclohexane for later use. (2) Preparation of PEG-phosphate ligand-stabilized UCNPs The above-prepared upconversion nanoparticles were dispersed in anhydrous ethanol containing PEG-phosphate ligands, slowly heated to 60-70℃, reacted for 8-10 h, cooled to room temperature, and centrifuged to obtain PEG-phosphate ligand-stabilized upconversion nanoparticles. (3) Preparation of UCNP@UIO-66-NH2 The PEG-phosphate ligand-stabilized UCNPs prepared above were dispersed in DMF, and ZrOCl2•8H2O solution was added dropwise. The reaction was carried out at 60-65℃ for 30-40 min, followed by the dropwise addition of BDC-NH2 solution. The reaction was carried out at 100-120℃ for 1-1.5 h to grow a thin UIO-66-NH2 shell on the surface of UCNPs. The UIO-66-NH2 growth method was repeated to obtain the ideal shell thickness, thus preparing UCNP@UIO-66-NH2, which was then dispersed in DMF for later use.

[0023] (4) Preparation of UCNP@MOF / HRP The UCNP@UIO-66-NH2 dispersion prepared above was mixed with an equal volume of Tris HCl buffer, and HRP was added to a final concentration of 1.0-1.5 mg / mL. The mixture was incubated at room temperature for 24 hours, centrifuged, washed, and dispersed in Tris HCl buffer for later use.

[0024] Preferably, the high-temperature solvent in step (1) is one or a combination of two or more of oleic acid, octadecene, oleylamine, tri-n-octylphosphine oxide, and trioctylphosphine.

[0025] In a specific embodiment of the present invention, the high-temperature solvent is a combination of oleic acid and octadecene.

[0026] Preferably, the rare earth raw materials mentioned in step (1) are selected from one or more combinations of YCl3, YbCl3, TmCl3, and ErCl3.

[0027] In a specific embodiment of the present invention, the rare earth raw material is selected from a combination of YCl3, YbCl3 and TmCl3, wherein the molar ratio of YCl3, YbCl3 and TmCl3 is (1.6-1.8):(0.4-0.5):(0.007-0.008).

[0028] Preferably, in step (2), the PEG-phosphate ester is PEG(1000)-phosphate ester, and the mass ratio of the upconversion nanoparticles to PEG(1000)-phosphate ester is (30-40mg):1g.

[0029] In step (3), the molar concentrations of the ZrOCl2•8H2O solution and the BDC-NH2 solution are 5-6 mM, preferably freshly prepared solutions.

[0030] Thirdly, the present invention provides an application of a core-shell upconversion nanocomposite in the preparation of a dual-modal nanodetection probe.

[0031] Fourthly, the present invention provides an application of a core-shell upconversion nanocomposite in the preparation of photodynamic therapy drugs.

[0032] This invention prepares a core-shell nanocomposite with the above-mentioned conversion nanoparticles (UCNP) as the core and Zr-MOF (UIO-66-NH2) as the shell. By loading horseradish peroxidase (HRP) onto the MOF shell, a detection probe UCNP@MOF / HRP with both fluorescence and catalytic colorimetric modes is prepared.

[0033] During the preparation process, a "layer-by-layer self-assembly" method was employed, with repeated additions of the metal center raw material ZrOCl2•8H2O and the organic ligand raw material BDC-NH2 solution to precisely control the thickness of the MOF shell. Furthermore, the MOF shell on the surface of the nanocomposite provided by this invention carries amino groups provided by the organic ligand, which can be used for subsequent direct modification with antibodies; the phosphate-modified nucleic acid chains can be stably and specifically bound to the UIO-66-NH2 surface via Zr-OP bonds.

[0034] Lanthanide-doped upconversion nanoparticles (UCNPs) are a special class of optical materials that can absorb near-infrared light and convert it into tunable short-wavelength emitted light from the ultraviolet to near-infrared region. When the core-shell structured upconversion nanocomposite UCNP@MOF / HRP prepared in this invention is coupled with an antibody, it serves as a dual-modal detection probe, and its working principle is as follows: When the core-shell upconversion nanocomposite UCNP@MOF / HRP prepared in this invention is coupled to a certain nucleic acid chain, it serves as a dual-modal detection probe, and its working principle is as follows: Attached Figure Description Figure 1 Flowchart of nanocomposite probe preparation.

[0035] Figure 2 Characterization of the core-shell structure of UCNP@UIO-66-NH2; (A) OA-encapsulated UCNPs; (B) PEG-phosphate modified UCNPs; (C) TEM and particle size distribution of UCNP@UIO-66-NH2 (UIO-66-NH2 shell is indicated by red arrows) and (D) Elemental mapping analysis of UCNP@UIO-66-NH2.

[0036] Figure 3 Evaluation of HRP loading efficiency by UCNPs@UIO-66-NH2; (A) UV-Vis absorption standard curves of HRP at different concentrations; (B) UV-Vis absorption spectrum of the supernatant after loading HRP onto the nanoprobe.

[0037] Figure 4 Zeta potential diagram of antibody modified on the surface of UCNP@UIO-66-NH2 / HRP nanoprobe. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The compound names corresponding to the English abbreviations involved in this invention are as follows: Example 1: Preparation of UCNP@MOF nanocomposite probes (1) Preparation of UCNPs (NaYF4:Yb / Tm) YCl3•6H2O (482 mg, M=303), YbCl3•6H2O (155 mg, M=387), and TmCl3•6H2O (2.8 mg, M=383) were dissolved in 2 mL of deionized water and added to a mixture of oleic acid (15 mL) and 1-octadecene (30 mL). The solution was stirred at room temperature under argon atmosphere for 1 hour to remove oxygen. The solution was then slowly heated to 120 °C to remove water and reacted at 156 °C for about 1 hour until a homogeneous, transparent yellow solution was obtained. After cooling the solution to room temperature under argon atmosphere, 10 mL of a methanol solution containing NH4F (296 mg) and NaOH (200 mg) was added dropwise. The mixture was then heated to 70 °C and held for 20 minutes to evaporate the methanol. Subsequently, the solution was heated to 290 °C and reacted for 2 hours before being cooled to room temperature. Add 20 mL of anhydrous ethanol to the above reaction solution, shake thoroughly, and centrifuge at 9000 rpm for 10 minutes. Collect the centrifuged product, i.e., UCNPs. After repeated washing with cyclohexane and ethanol, redisperse the final product in 20 mL of cyclohexane, freeze-dry, and prepare for further use.

[0041] (2) Preparation of PEG-phosphate ligand-stabilized UCNPs The synthesized 30 mg UCNPs powder was dispersed in 2 mL of anhydrous ethanol containing 1 g of PEG(1000)-phosphate ligand. The solution was slowly heated to 70 °C and reacted for 8 hours. The reaction solution was then cooled to room temperature and centrifuged at 7000 rpm for 15 minutes to obtain PEG-phosphate ligand-stabilized UCNPs. The reaction product was washed twice with cyclohexane (2 mL) and then four times with anhydrous ethanol (2 mL) to remove free PEG(1000)-phosphate ligand from the reaction system. Finally, the final product was redispersed in 2 mL of N,N-dimethylformamide (DMF) for subsequent coating with the UIO-66-NH2 shell.

[0042] (3) Synthesis of UCNP@UIO-66-NH2 This experiment employed a "layer-by-layer self-assembly" method to coat UCNPs with a UIO-66-NH2 shell. The specific steps were as follows: 2 mL of the PEG(1000)-phosphate ligand-stabilized UCNPs dispersion was added to 8 mL of DMF, followed by dropwise addition of 5 mL of freshly prepared ZrOCl2•8H2O solution (5 mM). The reaction was carried out at 60°C with stirring for 40 minutes to allow for efficient adsorption of Zr on the UCNPs surface. 4+Ions. Subsequently, 5 mL of freshly prepared BDC-NH2 solution (5 mM) was added dropwise to the solution, which was then heated to 120 °C and reacted for 1 hour. A thin UIO-66-NH2 shell was grown on the surface of UCNPs. The intermediate product was collected by centrifugation at 9000 rpm for 10 minutes. To further increase the thickness of the MOF shell, the above method for growing the UIO-66-NH2 shell can be repeated until the desired shell thickness is obtained. Finally, the final product was washed six times alternately with ethanol and deionized water and redispersed in 10 mL of DMF for short-term stable storage.

[0043] like Figure 2 As shown, characterization of the UCNP@MOF nanocomposite probe obtained in this embodiment reveals that the oleic acid-encapsulated UCNPs (NaYF4:Yb / Tm) exhibit a distinct hexagonal phase structure. A layer-by-layer self-assembly method was used to form MOF shells of varying thicknesses. After repeating the above method three times, the thickness of the encapsulated MOF shell was approximately 10.7 nm. Elemental mapping showed that Y, F, Tm, and Zr were uniformly distributed on the nanoparticles, indicating the successful synthesis of the nanoprobe with NaYF4:Yb / Tm as the core and UIO-66-NH2 as the shell.

[0044] Example 2: Loading HRP with UCNP@UIO-66-NH2 The 1 mL UCNP@UIO-66-NH2 dispersion was mixed thoroughly with an equal volume of Tris HCl buffer, and HRP was added to a final concentration of 1.0 mg / mL. The mixture was then incubated on a shaker at room temperature for 24 hours (250 rpm). After the reaction, the constructed probe was collected by centrifugation at 9000 rpm for 15 minutes. Finally, the collected product was washed three times with Tris HCl buffer to remove free HRP, and the supernatant after each wash was collected and dispersed in 2 mL of Tris HCl buffer for later use. The collected solution was incubated with the HRP substrate tetramethylbenzidine (TMB) and H2O2 for 15 minutes, and a stop solution was added. The product turned yellow, and its UV-Vis absorption spectrum was measured. The loading efficiency of HRP was calculated by comparing it with the absorbance standard curves at 450 nm for different concentrations of HRP.

[0045] like Figure 3 As shown, by measuring the absorbance of HRP in the supernatant after loading in this embodiment, and substituting it into the linear equation of HRP absorbance at different concentrations, it was calculated that 1 mg of nanoprobe loaded approximately 24 μg of HRP.

[0046] Example 3: Modification of UCNP@UIO-66-NH2 / HRP nanoprobe antibody Disperse UCNP@UIO-66-NH2 / HRP in 100 μL of MES buffer, add 1.5 μL of NHS solution, and mix well for 1 min using a shaker. Then add 1.5 μL of EDC solution and incubate at 37°C on a shaker for 30 min. Centrifuge and redisperse in 200 μL of HEPES buffer. Add 100 μg of fluorescent antibody to the above solution and incubate at 37°C on a shaker for 120 min. Then add 30 μL of blocking buffer, sonicate for 1 min, and continue incubating for 60–120 min. After the reaction, centrifuge at 9000 rpm for 15 min to collect the constructed probe. Finally, wash the collected product three times with HEPES buffer to remove free antibody, centrifuge to remove the supernatant, and resuspend in 500 μL of fluorescent antibody protection buffer.

[0047] like Figure 4 As shown, by measuring the Zeta potential of the UCNP@UIO-66-NH2 / HRP nanoprobe before and after antibody modification in this embodiment, it is proved that the antibody was successfully modified on the surface of the UCNP@UIO-66-NH2 / HRP nanoprobe.

[0048] Example 4: Modification of nucleic acid chains by UCNP@UIO-66-NH2 / HRP nanoprobes UCNP@MOF / HRP was dispersed in water. An aqueous solution containing 2 nmol of phosphate-modified nucleic acid chains was added to the dispersion of the nanoparticles, and the mixture was incubated on a shaker at room temperature for 8–14 hours (250 rpm). During this period, NaCl solution was added to the reaction solution in three portions to a final concentration of 0.5 M. After the reaction was completed, the UCNP@UIO-66-NH2 core-shell complex modified with nucleic acid chains was collected by centrifugation at 9000 rpm for 15 minutes. Subsequently, the collected product was washed three times with Tris HCl buffer (20 mM pH 7.4) to remove free nucleic acid chains, and finally dispersed in 1 mL of Tris HCl buffer for later use.

[0049] By measuring the Zeta potential of the UCNP@UIO-66-NH2 / HRP nanoprobe before and after modification of the nucleic acid chain in this embodiment, it was found that the Zeta potential of the nanocomposite changed significantly after successful modification to the MOF surface via Zr-OP bonds, due to the negative charge of the nucleic acid backbone. The value decreased from 6.7 mV to -5.8 mV, proving that the nucleic acid chain was successfully modified on the surface of the UCNP@UIO-66-NH2 / HRP nanoprobe.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A core-shell structured upconversion nanocomposite, characterized in that, The nanocomposite takes upconversion nanoparticles (UCNPs) as a core, metal-organic frameworks (MOFs) as a shell layer, and the shell layer loads horseradish peroxidase (HRP), forming UCNP@MOF / HRP.

2. The core-shell structure upconversion nanocomplex according to claim 1, wherein, The upconversion nanoparticles are composed of rare earth ions doped in nanocrystals NaYF4, Y2O3 or NaGdF4; the rare earth ions include sensitized ions and activated ions. the sensitizing ions are selected from the group consisting of Nd 3+ , Yb 3+ , alone or in combination, the molar content of the sensitizing ions being between 0.01 and 60%; The activating ion is selected from one or more of Pr 3+ , Nd 3+ , Sm 3+ , Tb 3+ , Ho 3+ , Er 3+ , Tm 3+ in combination, and the molar content of the activating ion is 0.01-20%.

3. The core-shell structure upconversion nanocomplex according to claim 2, wherein, The upconversion nanoparticles are NaYF4:Yb / Tm, the amount of Yb is 20-25% of the molar amount of NaYF4, and the amount of Tm is 0.3-0.6% of the molar amount of NaYF4.

4. The core-shell structure upconversion nanocomposite of claim 1, wherein, The metal-organic framework is a porous material formed by coordination of metal nodes and polydentate organic ligands; the metal nodes are selected from one or more of Zn²⁺, Cu²⁺, Fe³⁺, Al³⁺, Zr 4 ⁺, the molar content of the metal nodes is 0.01-60%; the polydentate organic ligands are selected from one or more of terephthalic acid, dimethyl terephthalate, 2-imidazole carboxylic acid, and the molar content of the organic ligands is 0.01-40%.

5. The core-shell structure upconversion nanocomposite of claim 4, wherein, The metal-organic framework is Zr-MOF, specifically UIO-66-NH2, and the mass of the horseradish peroxidase loaded on the metal-organic framework shell layer is 2-4% of the mass of the nanocomposite.

6. A method of preparing the core-shell structured up-conversion nanocomposite of claim 1, characterized in that, The method comprises the following steps: (1) Preparation of UCNPs Dissolve rare earth raw materials in deionized water, add a certain amount of high-temperature solvent, and evaporate the water; react at 150-170℃ for 1-1.5h under argon atmosphere, obtain a transparent yellow solution, cool to room temperature; dropwise add to a methanol solution containing NH4F and NaOH, evaporate the methanol solvent; heat to 290-320℃ under nitrogen atmosphere and keep for 1-2h, cool to room temperature; ethanol precipitation, centrifugation, washing, obtain upconversion nanoparticles, save in cyclohexane for standby; (2) Preparation of PEG-phosphate ligand stabilized UCNPs Disperse the above-prepared upconversion nanoparticles in anhydrous ethanol containing PEG-phosphate ligand, slowly heat to 60-70℃, react for 8-10h, cool to room temperature, centrifuge, obtain PEG-phosphate ligand stabilized upconversion nanoparticles; (3) Preparation of UCNP@UIO-66-NH2 Disperse the above-prepared PEG-phosphate ligand stabilized UCNPs into DMF, dropwise add ZrOCl2·8H2O solution, react at 60-65℃ for 30-40min, then dropwise add BDC-NH2 solution, heat to 100-120℃ and react for 1-1.5h, grow a thin UIO-66-NH2 shell on the surface of UCNPs, repeat the above UIO-66-NH2 growth method to obtain the desired shell thickness, prepare UCNP@UIO-66-NH2, disperse in DMF for standby; (4) Preparation of UCNP@MOF / HRP Mix the above-prepared UCNP@UIO-66-NH2 dispersion with an equal volume of Tris HCl buffer, add HRP to a final concentration of 1.0-1.5mg / mL, incubate at room temperature for 24h, centrifuge, wash, and disperse in Tris HCl buffer for standby.

7. The production method according to claim 6, characterized by, The high-temperature solvent in step (1) is one or a combination of two or more of oleic acid, octadecene, oleylamine, tri-n-octylphosphine oxide, and tri-octylphosphine; the rare earth raw materials are selected from one or a combination of two or more of YCl3, YbCl3, TmCl3, and ErCl3.

8. The preparation method according to claim 6, characterized in that, The PEG-phosphate in the step (2) is PEG(1000)-phosphate, and the mass ratio of the upconversion nanoparticles to PEG(1000)-phosphate is (30-40 mg):1 g; the molar concentration of the ZrOCl2·8H2O solution and the BDC-NH2 solution in the step (3) is 5-6 mM.

9. Use of the core-shell structure upconversion nanocomposite according to any of claims 1-5 in the preparation of a bimodal nanodetection probe.

10. Use of the core-shell structure upconversion nanocomposite according to any of claims 1-5 in the preparation of a photodynamic therapy drug.

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