A polymer-metal organic framework open nanocapsule and its preparation method and application

Abstract

The present invention discloses a polymer-metal organic framework open nanocapsule and its preparation method and application, which belongs to the field of material preparation technology. The open nanocapsule has a cavity inside with a diameter of 20 to 300 nm; a metal organic framework polymer composite shell outside with a thickness of 10 to 50 nm and an opening of 10 to 150 nm; a particle size of 100 to 500 nm; and the above-mentioned structural dimensions can be adjusted as needed. The open nanocapsule preparation method comprises: (1) mixing a dopamine compound and a metal salt in a solution; (2) adding an organic ligand to the above solution, stirring the reaction and obtaining a suspension; (3) centrifuging the above solution to obtain a precipitate for washing; (4) adding an etchant to the above precipitate dispersion, stirring the reaction, and washing the precipitate to obtain an open nanocapsule. The open nanocapsule preparation method of the present invention is simple to operate and can be used in fields such as biocatalysis and sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation, and in particular relates to a polymer-metal organic framework open nanocapsule and a preparation method and application thereof. Background Art

[0002] Open-ended nanocapsules offer the advantages of large internal storage space and a large specific surface area, and have broad application value in storage, catalysis, sensing, batteries, and drug delivery. When applied to biomedicine or analytical testing, the effective encapsulation of biomolecules and drug molecules within hollow, open-ended nanocapsules while ensuring their functionality is a critical consideration in the preparation of these materials. Ideally, these capsules should possess an appropriately sized internal cavity and stable wall material, while also exhibiting strong stability, a large specific surface area, and excellent biocompatibility. Therefore, the preparation of hollow, open-ended nanocapsules with superior performance remains a challenge and a major challenge in the current development of capsule materials.

[0003] Currently, a variety of capsule materials have been developed, but most are based on mesoporous silica and polymer resins, and the variety is limited. Metal-organic frameworks (MOFs), which have been developed in recent years, have become excellent materials for preparing open nanocapsules due to their large specific surface area, high mechanical strength, high porosity, and good structural designability. MOFs are three-dimensional porous crystalline materials composed of metal ions or metal ion clusters linked to organic ligands through coordination bonds. They have a wide range of applications in energy, adsorption, catalysis, and other fields. MOFs can be etched to produce hollow cavities under certain conditions (such as acids, bases, and chelating agents), and have great potential as nanocapsule wall materials. However, traditional etching methods use MOFs as templates, directly destroying the metal-ligand interaction in the MOF. This makes it difficult to ensure that the surface structure is not destroyed while etching to construct the hollow cavity. The etching process often causes the overall structure of the MOF to disintegrate, making it difficult to achieve the controllable preparation of hollow open nanocapsules. At the same time, the uncontrollable etching of MOFs by existing methods further leads to the inability to adjust the cavity size of the obtained hollow capsules, which is not conducive to the customized loading of biomacromolecules and drug molecules (A Versatile Competitive Coordination Strategy for Tailoring Bioactive Zeolitic Imidazolate Framework Composites. Small, 2021, 17, 2007586). This document uses typical polymers such as polystyrene, polydimethylsiloxane and polymethyl methacrylate to modify MOFs after synthesis, which can effectively enhance the chemical stability of MOFs (Enhancing MOF performance through the introduction of polymer guests. Coordination Chemistry Reviews, 2021, 427, 213525). However, in the preparation of open capsules, the MOFs-polymer obtained by this post-synthesis modification method is still in a spatially separated state, which cannot overcome the problem of collapse of the overall structure of MOFs during etching, resulting in poor overall performance of the material.

[0004] Therefore, the development of a hollow open nanocapsule that is structurally controllable, environmentally friendly, and suitable for large-scale production is of great significance in the fields of biocatalysis, medicine, and healthcare. Summary of the Invention

[0005] The purpose of the present invention is to address the existing technical deficiencies and provide a method for preparing hollow open nanocapsules and their application, which are simple to operate, low in cost, reproducible, uniform in particle size, and can be prepared on a large scale.

[0006] This invention leverages the properties of dopamine compounds, which self-polymerize under certain conditions to form polymers and readily adhere to material surfaces. Dopamine monomers are introduced during the in-situ preparation of MOFs to form a composite system of MOFs and polymers. This method utilizes in-situ modification during the synthesis process, allowing the polymer and MOFs to nest within each other, forming a stable structure. This overcomes the problem of post-synthesis modification in existing MOFs, which can lead to structural collapse. Using this composite as a template for etching, and through controlled etching conditions, hollow, open nanocapsules can be obtained, effectively encapsulating proteins and drug molecules.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A method for preparing polymer-metal organic framework open nanocapsules comprises the following steps:

[0009] (1) adding a dopamine compound solution to a metal salt solution and mixing uniformly to obtain a mixed solution containing a metal salt and a dopamine compound;

[0010] (2) adding the organic ligand solution to the mixed solution obtained in step (1), stirring and reacting to obtain a reaction suspension containing a precipitate;

[0011] (3) centrifuging the reaction suspension containing the precipitate obtained in step (2), washing and drying the precipitate to obtain a metal organic framework@polymer composite material;

[0012] (4) The metal organic framework@polymer composite material obtained in step (3) is dispersed with deionized water, an etchant solution is added to the dispersion, the mixture is stirred for reaction, the reaction solution is centrifuged, and the precipitate is washed and dried to obtain hollow open nanocapsules.

[0013] The dopamine compound described in step (1) includes but is not limited to any one of dopamine, dopa, epinephrine, norepinephrine, α-methyldopamine, 3-methacryloyldopamine, catechol, gallic acid, etc.

[0014] In the dopamine compound solution described in step (1), the concentration of the dopamine compound is 0.001 to 50 M, preferably 0.003 to 1 M.

[0015] The metal in the metal salt described in step (1) includes but is not limited to any one of zinc, copper, iron, aluminum, cobalt, nickel, zirconium, chromium, vanadium, manganese, cerium or titanium.

[0016] The salt in the metal salt described in step (1) includes but is not limited to any one of chloride, sulfate, nitrate, phosphate, acetate or formates.

[0017] The metal salt solution described in step (1) is preferably at least one of zinc nitrate solution, ferric chloride solution, zinc acetate solution, copper sulfate solution, chromium nitrate solution, cobalt nitrate solution, aluminum chloride solution and zirconium chloride solution.

[0018] The concentration of metal ions in the metal salt solution in step (1) is 0.001 to 20 M, preferably 0.001 to 0.8 M.

[0019] The dopamine compound in step (1) and the metal ions in the metal salt solution are calculated in a molar ratio of 0.05-10:4-1; more preferably in a molar ratio of 1-3:4-2.

[0020] The organic ligand described in step (2) includes but is not limited to at least one of imidazole organic ligands, aromatic carboxylic acid organic ligands, multidentate carboxylic acid organic ligands and derivatives of the above organic ligands.

[0021] The imidazole organic ligand includes but is not limited to at least one of 2-methylimidazole, 4-methylimidazole, 1-methylimidazole, benzimidazole, imidazole, and imidazole-2-carboxaldehyde.

[0022] The aromatic carboxylic acid organic ligand includes but is not limited to at least one of terephthalic acid, trimesic acid (BTC), naphthalene dicarboxylic acid and biphenyl dicarboxylic acid.

[0023] The polydentate carboxylic acid organic ligand includes but is not limited to at least one of malonic acid, succinic acid, glutaric acid, adipic acid and adipic acid.

[0024] The derivatives of the organic ligands mentioned above preferably include, but are not limited to, at least one of the halogenated derivatives, amino derivatives, hydroxylated derivatives and methylated derivatives of the organic ligands.

[0025] The organic ligand described in step (2) is preferably at least one of 2-methylimidazole, imidazole-2-carboxaldehyde, terephthalic acid, trimesic acid, biphenyldicarboxylic acid and glutaric acid.

[0026] In the organic ligand solution described in step (2), the concentration of the organic ligand is 0.001 to 50M, preferably 0.002 to 5M.

[0027] In step (2), the dopamine compound and the organic ligand are calculated in a molar ratio of 0.05-200:50-1; more preferably, in a molar ratio of 1-100:5-2.

[0028] In step (2), the organic ligand and the metal ions in the metal salt solution are calculated in a molar ratio of 1-200:50-1; more preferably, in a molar ratio of 2-100:5-2.

[0029] The stirring in step (2) is preferably magnetic stirring; the rotation speed of the magnetic stirring is preferably 200 to 800 rpm.

[0030] The stirring reaction conditions in step (2) are preferably a temperature of 0 to 150° C. and a time of 0.1 to 72 h; more preferably 4 to 150° C. and 0.5 to 24 h.

[0031] The centrifugation conditions in step (3) are preferably 5000-13000 rpm for 0.5-10 min; more preferably 8000-12000 rpm for 1-5 min.

[0032] The washing reagent used in step (3) is at least one of water, methanol, ethanol, ethylene glycol, glycerol, tert-butanol, tert-amyl alcohol, pyrrolidone, N,N-dimethylformamide (DMF), dimethylacetamide, diethylformamide, pyridine, piperidine, furan, tetrahydrofuran, dioxane, dimethyl sulfoxide, acetonitrile, toluene, n-hexane, cyclohexanone and supercritical carbon dioxide; the water is preferably deionized water;

[0033] The reagent used for washing in step (3) is more preferably at least one of deionized water, dimethyl sulfoxide, N,N-dimethylformamide (DMF), methanol, pyridine, ethanol and acetonitrile.

[0034] The number of washings in step (3) is preferably at least 1 time; more preferably 1 to 5 times; and even more preferably 2 to 3 times.

[0035] The drying described in step (3) is preferably at least one of freeze drying and high-temperature vacuum drying; the freeze drying time is preferably 5 to 48 hours; more preferably 8 to 32 hours; more preferably 12 to 24 hours; the vacuum drying time is preferably 2 to 12 hours, and the temperature is 50 to 120°C.

[0036] The concentration of the dispersion in step (4) is preferably 0.05 to 20 mg / mL; more preferably 0.5 to 5 mg / mL.

[0037] The etchant described in step (4) includes but is not limited to at least one of an acid, a base, and a chelating agent.

[0038] The acid includes but is not limited to at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, formic acid, acetic acid, and citric acid.

[0039] The alkali includes but is not limited to at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia monohydrate.

[0040] The chelating agent includes but is not limited to at least one of disodium ethylenediaminetetraacetic acid, sodium aminotriacetate, dithizone, 8-hydroxyquinoline, o-phenanthroline, potassium sodium tartrate, and ammonium citrate.

[0041] In the etchant solution described in step (4), the concentration of the etchant is preferably 0.001 to 50 M; more preferably 0.002 to 5 M.

[0042] The stirring in step (4) is preferably magnetic stirring; the rotation speed of the magnetic stirring is preferably 200 to 800 rpm.

[0043] The stirring reaction conditions in step (4) are preferably a temperature of 0 to 100° C. and a time of 0.01 to 6 h; more preferably 4 to 50° C. and 0.05 to 4 h.

[0044] The centrifugation conditions in step (4) are preferably 5000-13000 rpm for 0.5-10 min; more preferably 8000-12000 rpm for 1-5 min.

[0045] The reagent used for washing in step (4) is preferably at least one of water, methanol, ethanol, ethylene glycol, glycerol, tert-butanol, tert-amyl alcohol, pyrrolidone, N,N-dimethylformamide (DMF), dimethylacetamide, diethylformamide, pyridine, piperidine, furan, tetrahydrofuran, dioxane, dimethyl sulfoxide, acetonitrile, toluene, n-hexane, cyclohexanone and supercritical carbon dioxide; the water is preferably deionized water;

[0046] The reagent used for washing in step (4) is more preferably at least one of deionized water, dimethyl sulfoxide, N,N-dimethylformamide (DMF), methanol, pyridine, ethanol and acetonitrile.

[0047] The number of washings in step (4) is preferably at least 1 time; more preferably 1 to 5 times; and even more preferably 2 to 3 times.

[0048] The drying described in step (4) is preferably at least one of freeze drying and high-temperature vacuum drying; the freeze drying time is preferably 5 to 48 hours; more preferably 8 to 32 hours; more preferably 10 to 12 hours; the vacuum drying time is preferably 2 to 12 hours, and the temperature is 50 to 120°C.

[0049] The present invention provides a polymer-metal organic framework open nanocapsule, specifically a metal organic framework@polydopamine compound open nanocapsule, which is prepared by the above preparation method.

[0050] The MOF@polydopamine open nanocapsules have an internal cavity structure and an outer MOF@polydopamine shell. The shell has a single 10-150 nm opening. The internal cavity size of the open nanocapsules can be controlled to be between 20 and 300 nm, while the MOF@polydopamine shell thickness can be controlled to be between 10 and 50 nm, resulting in a particle size of 100 to 500 nm. The opening size and particle size of the open nanocapsules can be customized based on the size of the loaded molecules.

[0051] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0052] (1) In the present invention, dopamine compounds, organic ligands, and metal ions are self-assembled under solution conditions to form a metal organic framework@polydopamine composite material, which is further controllably etched with an etchant to obtain open nanocapsules.

[0053] (2) The dopamine compound of the present invention contains multiple phenolic hydroxyl groups and can be oxidized and self-polymerized under alkaline conditions to form a complex. Compared with typical polymers such as polystyrene used in the prior art, the dopamine compound is not only low-cost but also easier to adhere to the surface of the material, making the preparation process simpler.

[0054] (3) The open nanocapsules obtained by the present invention have a stable overall structure and controllable opening size and particle size, which is conducive to the customized loading of biomacromolecules and drug molecules. The material also has significant adsorption properties, which is conducive to the loading of substances such as biomolecules and drug molecules.

[0055] (4) The preparation method of the open nanocapsules provided by the present invention is low-cost, easy to operate, and has good stability, which is conducive to large-scale preparation. It can be used in the fields of biocatalysis, drug delivery, sewage purification, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The scanning electron micrographs of ZIF-8, ZIF-8@polydopamine, and ZIF-8@polydopamine open nanocapsules in Example 1 are shown;

[0057] Figure 2 Transmission electron microscopy images of ZIF-8, ZIF-8@polydopamine, and ZIF-8@polydopamine open nanocapsules in Example 1;

[0058] Figure 3 The X-ray diffraction spectra of ZIF-8, ZIF-8@polydopamine and ZIF-8@polydopamine open nanocapsules in Example 1;

[0059] Figure 4IR spectra of ZIF-8, ZIF-8@polydopamine and ZIF-8@polydopamine open nanocapsules in Example 1;

[0060] Figure 5 This is a scanning electron micrograph of a series of ZIF-8@polydopamine open nanocapsules controllably constructed by varying the etching time in Example 2;

[0061] Figure 6 The enzyme protein loading rates of Candida antarctica lipase (CALB) immobilized by ZIF-8@polydopamine open nanocapsules and traditional solid ZIF-8 in Example 8, as well as the relative activities of the immobilized enzymes.

[0062] Figure 7 This is a comparison chart of the adsorption rate of Congo red in sewage by MIL-100(Fe)@polydopamine methacrylamide open nanocapsules in Example 10 and traditional solid MIL-100(Fe). DETAILED DESCRIPTION

[0063] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0064] Example 1

[0065] Preparation of ZIF-8@polydopamine open nanocapsules

[0066] (1) Prepare 20 mM dopamine solution, 2.5 M 2-methylimidazole solution, 60 mM zinc nitrate solution, and 50 mM disodium ethylenediaminetetraacetic acid solution using deionized water as solvent;

[0067] (2) taking 10 mL of the dopamine solution and 10 mL of the zinc nitrate solution in step (1) and mixing them evenly to obtain a mixed solution containing dopamine and zinc nitrate;

[0068] (3) adding 20 mL of the 2-methylimidazole solution prepared in step (1) to the mixed solution obtained in step (2), stirring magnetically at 200 rpm, and reacting at 20° C. for 2 h to obtain a reaction solution containing a gray-black precipitate;

[0069] (4) The reaction solution obtained in step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with deionized water three times, and vacuum dried at 65°C for 12 h to obtain powdered ZIF-8@polydopamine nanomaterials;

[0070] (5) 5 mg of the ZIF-8@polydopamine nanomaterial obtained in step (4) was dispersed in 10 mL of deionized water, 10 mL of the 50 mM disodium ethylenediaminetetraacetic acid solution in step (1) was added to the dispersion as an etchant, and the mixture was stirred under magnetic stirring at 20°C and 200 rpm for 10 min;

[0071] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with deionized water three times, and vacuum dried at 65°C for 12 h to obtain ZIF-8@polydopamine open nanocapsules.

[0072] The scanning electron microscope images of the intermediates and final products obtained in this example are as follows Figure 1 As shown, Figure 1 a, b, and c in the figure represent ZIF-8, ZIF-8@polydopamine, and ZIF-8@polydopamine open nanocapsules, respectively. Similar to the morphology of ZIF-8, the ZIF-8@polydopamine composite nanomaterial is a dodecahedral structure with a particle size of approximately 500 nm. The ZIF-8@polydopamine open nanocapsules obtained after etching have a single open pore structure with a diameter of approximately 15 nm on their shell. Furthermore, as Figure 2 As shown in the transmission electron micrograph, Figure 2 a, b, and c in the figure represent ZIF-8, ZIF-8@polydopamine, and ZIF-8@polydopamine open nanocapsules, respectively. The internal cavity of the open nanocapsules is about 150 nm, and the thickness of the outer ZIF-8@polydopamine shell is about 150 to 200 nm. Figure 3 ) and Fourier transform infrared spectroscopy ( Figure 4 ) It can be seen that the open nanocapsules show typical ZIF-8 crystal diffraction peaks (7.4°, 12.8°, 18.1°) and dopamine (1610 cm -1 ) and 2-methylimidazole (1460cm -1 , 3138cm -1 ), indicating that the prepared ZIF-8@polydopamine open nanocapsules contain both ligand components, and the crystal structure is similar to that of ZIF-8. After etching, the original framework morphology of the metal-organic framework material can still be basically maintained.

[0073] Example 2

[0074] Controllable preparation of ZIF-8@polydopamine open-ended nanocapsules

[0075] (1) Prepare 20 mM dopamine solution, 2.5 M 2-methylimidazole solution, 60 mM zinc nitrate solution, and 50 mM disodium ethylenediaminetetraacetic acid solution using deionized water as solvent;

[0076] (2) taking 10 mL of the dopamine solution and 10 mL of the zinc nitrate solution in step (1) and mixing them evenly to obtain a mixed solution containing dopamine and zinc nitrate;

[0077] (3) adding 20 mL of the 2-methylimidazole solution prepared in step (1) to the mixed solution obtained in step (2), stirring magnetically at 200 rpm, and reacting at 20° C. for 2 h to obtain a reaction solution containing a gray-black precipitate;

[0078] (4) The reaction solution obtained in step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with deionized water three times, and vacuum dried at 65°C for 12 h to obtain powdered ZIF-8@polydopamine nanomaterials;

[0079] (5) 5 mg of the ZIF-8@polydopamine nanomaterial obtained in step (4) was dispersed in 10 mL of deionized water, 10 mL of the 50 mM disodium ethylenediaminetetraacetic acid solution in step (1) was added to the dispersion as an etchant, and the mixture was stirred under magnetic stirring at 20° C. and 200 rpm for 5 to 120 min;

[0080] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with deionized water three times, and vacuum dried at 65°C for 12 h to obtain ZIF-8@polydopamine open nanocapsules.

[0081] The scanning electron microscope image of the final product obtained in this embodiment is as follows Figure 5 As shown in the figure, the ZIF-8@polydopamine open nanocapsules obtained after etching for 5min, 10min, 20min, 30min, 60min and 120min have a single open pore structure with a diameter of about 5nm, 15nm, 25nm, 50nm, 100nm and 200nm on their shell layer, respectively. This shows that on the basis of maintaining the stability of the overall structure of the material, the controllable construction of the opening size of the open nanocapsules can be achieved by controlling the etching time.

[0082] Example 3

[0083] Preparation of ZIF-90@polydopamine open nanocapsules

[0084] (1) Prepare 20 mM dopamine solution, 160 mM imidazole-2-carboxaldehyde solution, 40 mM zinc nitrate solution, and 10 mM acetic acid solution using deionized water as solvent;

[0085] (2) taking 10 mL of the dopamine solution in step (1) and 10 mL of the zinc nitrate solution and mixing them evenly to obtain a mixed solution containing dopamine and zinc nitrate;

[0086] (3) adding 20 mL of the imidazole-2-carboxaldehyde solution prepared in step (1) to the mixed solution obtained in step (2), followed by magnetic stirring at 200 rpm and reaction at 25° C. for 24 h to obtain a reaction solution containing a precipitate;

[0087] (4) The reaction solution containing the precipitate from step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out and washed with deionized water three times, and vacuum dried at 65°C for 12 h to obtain a powdered ZIF-90@polydopamine nanomaterial;

[0088] (5) Dispersing 10 mg of the ZIF-90@polydopamine nanomaterial obtained in step (4) with 10 mL of deionized water, adding 10 mL of the 10 mM acetic acid solution in step (1) as an etchant to the dispersion, and reacting with magnetic stirring at 25°C and 200 rpm for 10 min;

[0089] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with deionized water three times, and vacuum dried at 65 °C for 12 h to obtain ZIF-90@polydopamine open nanocapsules with a particle size of ∼300 nm and an opening of ∼50 nm.

[0090] Example 4

[0091] Preparation of MIL-100(Fe)@Polydopamine Methacrylamide Open Nanocapsules

[0092] (1) Prepare 40 mM 3-methacryloyldopamine solution, 200 mM trimesic acid solution, 100 mM ferric chloride solution, and 25 mM sodium aminotriacetate solution using deionized water as solvent;

[0093] (2) taking 10 mL of the 3-methacryloyldopamine solution in step (1) and 10 mL of the ferric chloride solution and mixing them evenly to obtain a mixed solution containing 3-methacryloyldopamine and ferric chloride;

[0094] (3) adding 20 mL of the trimesic acid solution prepared in step (1) to the mixed solution obtained in step (2), and reacting with magnetic stirring at 30° C. and 400 rpm for 12 h to obtain a reaction solution containing a precipitate;

[0095] (4) The reaction solution containing the precipitate from step (3) was taken out, centrifuged at 12000 rpm for 5 min, the precipitate was taken out, washed with deionized water three times, and freeze-dried for 24 h to obtain a powdered MIL-100(Fe)@polydopamine methacrylamide nanomaterial;

[0096] (5) 8 mg of the MIL-100(Fe)@polydopamine methacrylamide nanomaterial obtained in step (4) was dispersed in 10 mL of deionized water, 10 mL of the 25 mM sodium aminotriacetate solution in step (1) was added to the resulting dispersion as an etchant, and the mixture was subjected to magnetic stirring at 30°C and 400 rpm for 20 min;

[0097] (6) The reaction solution of step (5) was taken out and centrifuged at 12000 rpm for 5 min. The precipitate was taken out and washed with deionized water three times, and freeze-dried for 24 h to obtain MIL-100(Fe)@polydopamine methacrylamide open nanocapsules with a particle size of ∼600 nm and an opening of ∼100 nm.

[0098] Example 5

[0099] Preparation of MOF-5@polyepinephrine open nanocapsules

[0100] (1) Using N,N-dimethylformamide (DMF) as solvent, a 1 M epinephrine solution, a 2 M terephthalic acid solution, a 0.8 M zinc nitrate solution, and a 0.5 M acetic acid solution were prepared respectively;

[0101] (2) taking 10 mL of the epinephrine solution in step (1) and 10 mL of the zinc nitrate solution and mixing them uniformly to obtain a mixed solution containing epinephrine and zinc nitrate;

[0102] (3) adding 20 mL of the terephthalic acid solution prepared in step (1) to the mixed solution obtained in step (2), followed by magnetic stirring at 200 rpm and reaction at 150° C. for 48 h to obtain a reaction solution containing a precipitate;

[0103] (4) The reaction solution containing the precipitate in step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out and washed with DMF three times, and vacuum dried at 65°C for 12 h to obtain powdered MOF-5@polyepinephrine nanomaterial;

[0104] (5) 50 mg of the MOF-5@polyadrenaline nanomaterial obtained in step (4) was dispersed in 10 mL of DMF, 10 mL of the 0.5 M acetic acid solution in step (1) was added to the dispersion as an etchant, and the mixture was stirred under magnetic stirring at 80° C. and 200 rpm for 2 min;

[0105] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed 3 times with deionized water and freeze-dried for 12 h to obtain MOF-5@polyepinephrine open nanocapsules with a particle size of ∼1 μm and an opening of ∼100 nm.

[0106] Example 6

[0107] Preparation of HKUST-1@polygallic acid open-ended nanocapsules

[0108] (1) Prepare 5 M gallic acid solution, 5 M trimesic acid solution, 0.5 M copper sulfate solution, and 1 M EDTA solution using methanol as solvent;

[0109] (2) taking 10 mL of the gallic acid solution in step (1) and 10 mL of the copper sulfate solution and mixing them uniformly to obtain a mixed solution containing gallic acid and copper sulfate;

[0110] (3) adding 20 mL of the trimesic acid solution prepared in step (1) to the mixed solution obtained in step (2), followed by magnetic stirring at 200 rpm and reaction at 80° C. for 24 h to obtain a reaction solution containing a precipitate;

[0111] (4) The reaction solution containing the precipitate from step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out and washed with methanol three times, and vacuum dried at 80°C for 24 h to obtain a powdered HKUST-1@polygallic acid nanomaterial;

[0112] (5) 25 mg of the HKUST-1@polygallic acid nanomaterial obtained in step (4) was dispersed in 10 mL of methanol, 10 mL of the 1 M EDTA solution in step (1) was added to the dispersion as an etchant, and the mixture was stirred under magnetic stirring at 80°C and 200 rpm for 15 min;

[0113] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with methanol three times and vacuum dried at 80°C for 24 h to obtain HKUST-1@polygallic acid open nanocapsules.

[0114] Example 7

[0115] Preparation of UIO-66@polydopamine open-ended nanocapsules

[0116] (1) Using ethanol as solvent, a 2.5 M dopamine solution, a 4 M terephthalic acid solution, a 0.5 M zirconium chloride solution, and a 2.5 M citric acid solution were prepared respectively;

[0117] (2) taking 10 mL of the dopamine solution in step (1) and 10 mL of the zirconium chloride solution and mixing them uniformly to obtain a mixed solution containing dopamine and zirconium chloride;

[0118] (3) adding 20 mL of the terephthalic acid solution prepared in step (1) to the mixed solution obtained in step (2), followed by magnetic stirring at 200 rpm and reacting at 4° C. for 10 h to obtain a reaction solution containing a precipitate;

[0119] (4) The reaction solution containing the precipitate from step (3) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out and washed with ethanol three times, and vacuum dried at 60°C for 20 h to obtain powdered UIO-66@polydopamine open nanocapsules;

[0120] (5) 8 mg of the UIO-66@polydopamine nanomaterial obtained in step (4) was dispersed in 10 mL of ethanol, 10 mL of the 2.5 M citric acid solution in step (1) was added to the dispersion as an etchant, and the mixture was stirred under magnetic stirring at 4°C and 200 rpm for 2 h;

[0121] (6) The reaction solution of step (5) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was taken out, and the precipitate was washed with ethanol three times and vacuum dried at 60°C for 20 h to obtain UIO-66@polydopamine open nanocapsules.

[0122] Example 8

[0123] Preparation of open nanocapsules loaded with lipase complex

[0124] (1) Weigh 10 mg of the ZIF-8@polydopamine open nanocapsules prepared in Example 1 and add 5 mL of 1× PBS buffer to prepare a 2 mg / mL dispersion;

[0125] (2) adding 5 mL of 2 mg / mL Candida antarctica lipase B (CALB) solution to the dispersion of step (1) and magnetically stirring at 200 rpm and 4°C for 2 h to adsorb CALB into the cavity of the open nanocapsules;

[0126] (3) The reaction solution of step (2) was taken out, centrifuged at 12000 rpm for 1 min, the precipitate was collected, washed with deionized water three times, and freeze-dried for 24 h to obtain open nanocapsules@CALB immobilized lipase;

[0127] (4) The loading amount of lipase on the open nanocapsule material and the activity of lipase before and after immobilization were determined and compared with those of traditional solid ZIF-8.

[0128] like Figure 6As shown, a is the comparison of the enzyme protein loading rate of ZIF-8@polydopamine open nanocapsules and traditional solid ZIF-8, and b is the comparison of the relative activity of ZIF-8@polydopamine open nanocapsules and traditional solid ZIF-8 after enzyme immobilization. It can be seen that the ZIF-8@polydopamine open nanocapsules obtained in this example have improved enzyme adsorption capacity compared with traditional solid ZIF-8, and the enzyme loading rate on the open nanocapsules is more than 3 times that of the original ZIF-8; at the same time, the activity recovery rate of the immobilized lipase obtained with the open nanocapsules as the carrier is about 2.8 times that of the immobilized enzyme system obtained with ZIF-8 as the carrier.

[0129] Example 9

[0130] Preparation of open nanocapsules loaded with virus-like particles

[0131] (1) Weigh 10 mg of the ZIF-90@polydopamine open nanocapsules prepared in Example 3 and add 2 mL of 1× PBS buffer to prepare a 5 mg / mL dispersion;

[0132] (2) Add 2 mL of 0.5 mg / mL African swine fever virus P22 protein nanoparticle solution to the dispersion of step (1), and stir magnetically at 200 rpm and 4°C for 12 h to allow the virus-like particles to be adsorbed in the cavity of the open nanocapsules to obtain an antigen preparation.

[0133] Example 10

[0134] Open nanocapsules adsorb and remove dye molecules from wastewater

[0135] (1) Weigh 10 mg of the MIL-100(Fe)@polydopamine methacrylamide open nanocapsules prepared in Example 4 and add 2 mL of deionized water to prepare a 5 mg / mL dispersion;

[0136] (2) Add 10 mL of 2 mg / mL Congo red solution to the dispersion of step (1), stir magnetically at 200 rpm and 25° C. for 30 min, and measure the adsorption effect of the open nanocapsules on the dye.

[0137] like Figure 7 As shown in the data, the adsorption rate of MIL-100(Fe)@polydopamine methacrylamide open nanocapsules for Congo red in the dye is about 4 times that of traditional solid MIL-100(Fe). It can be seen that MIL-100(Fe)@polydopamine methacrylamide open nanocapsules have significantly stronger adsorption capacity for dye molecules than traditional solid MIL-100(Fe). The polymer-metal organic framework open nanocapsules prepared by the present invention have good application potential in sewage treatment.

Claims

1. A method for preparing polymer-metal organic framework open nanocapsules, characterized in that: The method comprises the following preparation steps: (1) adding a dopamine compound solution to a metal salt solution and mixing uniformly to obtain a mixed solution containing a metal salt and a dopamine compound; (2) adding the organic ligand solution to the mixed solution obtained in step (1), stirring and reacting to obtain a reaction suspension containing a precipitate; (3) centrifuging the reaction suspension containing the precipitate obtained in step (2), washing and drying the precipitate to obtain a metal organic framework@polymer composite material; (4) dispersing the metal organic framework@polymer composite material obtained in step (3) with deionized water, adding an etchant solution to the dispersion, stirring the reaction, centrifuging the reaction solution, washing and drying the precipitate to obtain hollow open nanocapsules; The metal in the metal salt described in step (1) is selected from any one of zinc, copper, iron, aluminum, cobalt, nickel, zirconium, chromium, vanadium, manganese, cerium or titanium; the salt in the metal salt described in step (1) is selected from any one of chloride, sulfate, nitrate, phosphate, acetate or formate; The organic ligand in step (2) is selected from at least one of imidazole organic ligands, aromatic carboxylic acid organic ligands, multidentate carboxylic acid organic ligands and derivatives of the above organic ligands; The etching agent described in step (4) is selected from at least one of an acid and a chelating agent; the acid is selected from at least one of phosphoric acid, formic acid, acetic acid, and citric acid; the chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and sodium aminotriacetate.

2. The preparation method according to claim 1, wherein: The dopamine compound described in step (1) is selected from any one of dopamine, epinephrine, norepinephrine, α-methyldopamine, and 3-methacryloyldopamine.

3. The preparation method according to claim 2, wherein: The metal salt solution in step (1) is selected from at least one of zinc nitrate solution, ferric chloride solution, zinc acetate solution, copper sulfate solution, chromium nitrate solution, cobalt nitrate solution, aluminum chloride solution and zirconium chloride solution; The imidazole organic ligand described in step (2) is at least one selected from 2-methylimidazole, 4-methylimidazole, 1-methylimidazole, benzimidazole, imidazole, and imidazole-2-carboxaldehyde; The aromatic carboxylic acid organic ligand is selected from at least one of terephthalic acid, trimesic acid, naphthalene dicarboxylic acid and biphenyl dicarboxylic acid; The polydentate carboxylic acid organic ligand is selected from at least one of malonic acid, succinic acid, glutaric acid, adipic acid and adipic acid; The derivative of the organic ligand is at least one selected from the group consisting of a halogenated derivative, an amino derivative, a hydroxylated derivative and a methylated derivative of the organic ligand.

4. The preparation method according to claim 1, wherein: In the dopamine compound solution described in step (1), the concentration of the dopamine compound is 0.001 to 50 M; The concentration of metal ions in the metal salt solution described in step (1) is 0.001 to 20 M; The dopamine compound described in step (1) and the metal ions in the metal salt solution are calculated in a molar ratio of 0.05-10:4-1; In the organic ligand solution described in step (2), the concentration of the organic ligand is 0.001 to 50 M; In step (2), the dopamine compound and the organic ligand are calculated in a molar ratio of 0.05-200:50-1; In step (2), the organic ligand and the metal ion in the metal salt solution are calculated in a molar ratio of 1-200:50-1; The concentration of the dispersion in step (4) is 0.05 to 20 mg / mL; In the etchant solution described in step (4), the concentration of the etchant is 0.001 to 50M.

5. The preparation method according to claim 1, wherein: The washing reagents used in step (3) and step (4) are selected from at least one of water, methanol, ethanol, ethylene glycol, propylene glycol, tert-butanol, tert-amyl alcohol, pyrrolidone, N,N-dimethylformamide, dimethylacetamide, diethylformamide, pyridine, piperidine, furan, tetrahydrofuran, dioxane, dimethyl sulfoxide, acetonitrile, toluene, n-hexane, cyclohexanone and supercritical carbon dioxide.

6. The preparation method according to claim 1, wherein: The stirring in step (2) is magnetic stirring; the speed of the magnetic stirring is 200 to 800 rpm; The stirring reaction conditions in step (2) are a temperature of 0 to 150° C. and a time of 0.1 to 72 h; The stirring in step (4) is magnetic stirring; the speed of the magnetic stirring is 200 to 800 rpm; The stirring reaction conditions in step (4) are a temperature of 0 to 100° C. and a time of 0.01 to 6 h.

7. The preparation method according to claim 1, wherein: The centrifugation condition in step (3) is 5000-13000 rpm for 0.5-10 min; The number of washing steps in step (3) is at least 1; The drying in step (3) is at least one of freeze drying and high temperature vacuum drying; the freeze drying time is 5 to 48 hours; the vacuum drying time is 2 to 12 hours, and the temperature is 50 to 120°C; The centrifugation condition in step (4) is 5000-13000 rpm for 0.5-10 min; The number of washing steps in step (4) is at least 1; The drying in step (4) is at least one of freeze drying and high-temperature vacuum drying; the freeze drying time is 5 to 48 hours; the vacuum drying time is 2 to 12 hours, and the temperature is 50 to 120°C.

8. A polymer-metal organic framework open nanocapsule, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.

9. The polymer-metal organic framework open nanocapsule according to claim 7, characterized in that: The capsule has a cavity structure inside and a metal-organic framework @ polydopamine complex shell outside; there is a single 10-150nm open pore structure on the shell, the size of the cavity inside the open nanocapsule is 20-300nm, the thickness of the outer metal-organic framework @ polydopamine complex shell is 10-50nm, and the particle size is 100-500nm.

10. Use of the polymer-metal organic framework open nanocapsule material according to claim 8 or 9 in biocatalysis, drug delivery, and sewage purification.

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