Metal organic framework, composite scaffold and application thereof

Abstract

The invention relates to the field of bone repair, in particular to a metal organic framework, a composite scaffold and application thereof. The invention provides a metal organic framework. The metal organic framework comprises a magnesium-gallic acid metal organic framework loaded with an exosome; the concentration ratio of the exosome to the magnesium-gallic acid metal organic framework is (0.5-1): 5. The invention provides an application of an exosome functionalized GelMA hydrogel magnesium-organic metal framework (Mg-MOF) scaffold in regeneration of senescent bones. The invention further provides a preparation method of the exosome functionalized GelMA hydrogel magnesium-organic metal framework (Mg-MOF) scaffold. The exosome functionalized acellular Gel-Mg-Exo scaffold material is designed and synthesized by integrating the properties of hydrogel, a magnesium-organic metal framework and exosome, and the ability of promoting regeneration of aged bones is achieved through the multiple characteristics of anti-inflammation, anti-aging and osteogenesis promotion of the exosome functionalized acellular Gel-Mg-Exo scaffold material. In a word, the exosome functionalized nanocomposite scaffold with enhanced bone formation performance is designed, and a novel strategy and theoretical support are provided for solving the aging-related bone regeneration problem.

Description

Technical Field

[0001] The present invention relates to the field of bone repair, and particularly to metal-organic frameworks, composite scaffolds and their applications. Background Art

[0002] Bone tissue engineering (BTE) is a rapidly developing field for repairing large bone defects. BTE constructs rely on three basic components: scaffolds, seed cells, and osteoinductive factors. However, the implantation of seed cells such as BMSCs faces significant challenges, including immune rejection, potential carcinogenic risks, and weakened osteogenic differentiation ability. Therefore, cell-free regeneration, which is bone regeneration without external inoculation of stem cells, is a promising solution to these cell source problems. In fact, there have been many studies on implanting cell-free scaffolds for cell-free bone tissue. To achieve cell-free bone regeneration, cell-free scaffolds should contain effective osteoinductive factors such as BMP-2 and BMP-9. However, increased side effects have been reported during the clinical use of osteoinductive factors, such as ectopic bone formation, inflammation, bone resorption, and hematoma. Therefore, to avoid these serious side effects, there is an urgent need to find effective alternative osteoinductive factors.

[0003] In the field of regenerative medicine, exosomes, as a highly promising osteoinductive factor, are receiving extensive attention. These naturally secreted vesicles (40 - 150 nanometers in diameter) have a lipid bilayer structure and can encapsulate proteins, lipids, genetic information, and metabolites, participating in key processes such as intercellular communication, migration, bone tissue regeneration, and angiogenesis, and playing a crucial role in regulating the normal physiological functions of cells. Exosomes can regulate multiple signaling pathways, such as BMP-2, MAPK, and NF-κB, and at the same time increase the mRNA and protein expression levels of osteogenesis-related factors (such as OPN, BMP-2, ALP, and RUNX2), thereby affecting the osteogenic differentiation of recipient cells. They can also regulate the functions of inflammation-related cells, inhibit the release of inflammatory factors by macrophages, promote the release of anti-inflammatory factors, and create an anti-inflammatory microenvironment. Exosomes can regulate cell cycle-related proteins and inhibit the expression of senescence-related genes (such as P16, P21). In addition, exosomes can enhance the antioxidant capacity of cells, reduce the damage caused by oxidative stress, promote cell regeneration and repair, and restore some functions of senescent cells. In tissues and organs, exosomes help maintain tissue homeostasis and slow down the functional decline caused by aging, thus having an overall anti-aging effect. Exosomes also have the function of recruiting bone marrow mesenchymal stem cells (BMSCs). The numerous protein molecules on their surface can bind to the receptors on the cell membrane of BMSCs, activate the signal transduction pathway in BMSCs, and guide the migration of BMSCs in a specific direction. Based on these characteristics, exosomes are undoubtedly ideal osteoinductive factors in the "cell-free" tissue engineering strategy.

[0004] Magnesium ion (Mg2+ ) is the second largest cation in the human body after potassium ions. According to research, Mg at an appropriate concentration 2+ can enhance the adhesion, proliferation, and osteogenic differentiation ability of bone marrow mesenchymal stem cells (BMSCs). In addition, Mg 2+ also has a certain anti-inflammatory effect and can regulate the function of immune cells. For example, it can promote the transformation of macrophages from the pro-inflammatory M1 type to the anti-inflammatory M2 type. M2 macrophages can secrete anti-inflammatory factors such as interleukin-10 (IL-10) to reduce the inflammatory response. The research also found that insufficient intake of Mg 2+ may lead to cell senescence, while supplementing Mg 2+ can delay cell senescence. Mg 2+ participates in the regulation of the activity of various enzymes in cells, is crucial for energy metabolism and DNA repair processes, can maintain mitochondrial function, reduce the production of reactive oxygen species (ROS), and mitigate the damage of oxidative stress to cells. Mg2+ may also participate in the regulation of the cell cycle by affecting ion channels and signal transduction in cells, thereby delaying the process of cell senescence to a certain extent.

[0005] Gallic acid (GA) is a natural secondary metabolite rich in phenolic hydroxyl groups. It can effectively scavenge reactive oxygen species (ROS) and disrupt the cyclic generation of new free radicals, and can regulate the bone regeneration process through its antioxidant properties. In addition, GA plays an anti-inflammatory role by reducing the release of pro-inflammatory cytokines and chemokines.

[0006] Metal-organic frameworks (MOFs) are materials constructed by metal ion nodes and functional organic ligands through coordination bonds. With their characteristics such as structural diversity, high specific surface area, high porosity, high loading capacity, and tunable biocompatibility, they show great potential in biomedical applications. MOFs can gradually release metal ions and become ideal candidates for metal ion storage and delivery. Therefore, Mg-GA MOF can continuously and slowly release Mg 2+ and GA, and may play a role in anti-inflammation, anti-aging, and promoting osteogenesis, thereby promoting the regeneration of senescent bone. Although the application of MOFs in drug delivery has been widely studied, there is still much room for exploration in their potential application in exosome loading.

[0007] GelMA hydrogel is widely used in bone tissue engineering scaffold materials due to its many excellent properties. This hydrogel exhibits excellent biocompatibility and high cell affinity. It can simulate the natural extracellular matrix of the human body, allowing cells to adhere, grow and proliferate smoothly on it, providing an ideal environment for bone formation. In addition, GelMA hydrogel induces a low immune response and is not prone to strong immune rejection after implantation, thereby reducing damage and inflammation caused by immune response and enhancing the stability and safety of the scaffold in the body. The physical properties of GelMA hydrogel can be adjusted by different preparation methods and concentration adjustment methods to adapt it to different application requirements. GelMA hydrogel also has the ability to load bioactive factors, which can enable these factors to be released continuously and stably, prolong their action time, and improve their bioavailability. Compared with traditional direct injection methods, bioactive factors embedded in hydrogels can play a more effective role, reducing the required dosage and its potential side effects. Summary of the invention

[0008] In view of this, the present invention provides a metal organic framework, a composite scaffold and its application. The present invention provides an innovative exosome-functionalized GelMA hydrogel magnesium-organic metal framework (Mg-MOF) scaffold for use in aging bone regeneration. By integrating the unique properties of GelMA hydrogel, magnesium-organic metal framework and exosomes, an exosome-functionalized acellular Gel-Mg-Exo scaffold material was designed and synthesized, and its anti-inflammatory, anti-aging and osteogenesis properties were used to achieve the ability to promote aging bone regeneration. In short, we designed an exosome-functionalized nanocomposite scaffold with enhanced bone formation performance, providing a novel strategy and theoretical support for solving the problem of aging-related bone regeneration.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a metal-organic framework, comprising: a magnesium-gallate metal-organic framework loaded with exosomes; the concentration ratio of the exosomes to the magnesium-gallate metal-organic framework is (0.5-1):5.

[0011] In some embodiments of the present invention, in the above metal-organic framework, the concentration ratio of the exosomes to the magnesium-gallate metal-organic framework is 1:5.

[0012] In some embodiments of the present invention, the metal organic framework is the abbreviation of MOF (English name Metal organic Framework), which is a type of crystalline porous material with a periodic network structure formed by inorganic metal centers (metal ions or metal clusters) and bridging organic ligands interconnected by self-assembly.

[0013] In some embodiments of the present invention, in the above metal-organic framework, the concentration of the exosomes is 40 μg / mL.

[0014] In some embodiments of the present invention, in the above metal-organic framework, the concentration of the magnesium-gallic acid metal-organic framework is 200 μg / mL.

[0015] In some embodiments of the present invention, in the above metal-organic framework, the magnesium-gallic acid metal-organic framework is prepared by mixing a magnesium-based metal-organic framework and gallic acid; the mass ratio of the magnesium-based metal-organic framework to the gallic acid is (0.5-1):4.

[0016] In some embodiments of the present invention, in the above metal-organic framework, the mass ratio of the magnesium-based metal-organic framework to the gallic acid is 1:4.

[0017] In some embodiments of the present invention, in the above metal-organic framework, the exosomes are derived from bone marrow mesenchymal stem cells.

[0018] The present invention also provides a method for preparing a metal-organic framework, comprising the following steps:

[0019] S1: Mix the magnesium-based metal-organic framework and the gallic acid, sterilize, cool, and collect the precipitate to obtain the magnesium-gallic acid metal-organic framework;

[0020] S2: After obtaining the exosomes, mix them with the magnesium-gallic acid metal-organic framework to obtain the metal-organic framework.

[0021] In some embodiments of the present invention, in the above preparation method, the preparation method of the magnesium-gallic acid metal-organic framework comprises the following steps: Dissolve 1 g of MgCl2 in 50 mL of ultrapure water, add 4 g of gallic acid thereto, produce a large milky white precipitate and stir vigorously for 30 min; then, dropwise add 10 M potassium hydroxide aqueous solution to adjust the pH value to 8, the precipitate gradually disappears, and the milky white solution gradually turns yellowish brown; after stirring for 10 min, transfer the solution to a 100 mL autoclave and autoclave at 120 °C for 24 h; cool the solution to room temperature, centrifuge at 10000 rpm for 10 min, and discard the supernatant; wash the light gray solid precipitate three times with ultrapure water and dry it overnight in an oven at 60 °C to obtain the powder of the magnesium-gallic acid metal-organic framework.

[0022] In some embodiments of the present invention, in the above preparation method, the preparation method of the exosomes comprises the following steps: inoculating rat BMSCs (passage 3) cells in a culture dish; when the cells reach 75% confluence, collecting the cell supernatant, and removing impurities such as cell debris, dead cells, and larger vesicles by three consecutive centrifugation steps at 4°C at 300×g (10 min), 2000×g (20 min), and 10,000×g (30 min); subsequently using an ultracentrifuge to ultracentrifuge at 100,000×g for 70 min at 4°C to obtain a crude exosome extract, washing it once with PBS, and then ultracentrifuging again at 100,000×g for 70 min; the obtained precipitate contains pure exosomes.

[0023] The present invention also provides a composite scaffold, comprising: a hydrogel, and the above-mentioned metal-organic framework or the metal-organic framework obtained by the above-mentioned preparation method.

[0024] In some embodiments of the present invention, in the above composite scaffold, the concentration ratio of the metal-organic framework to the hydrogel is (0.5-1):440.

[0025] In some embodiments of the present invention, in the above composite scaffold, the concentration ratio of the metal-organic framework to the hydrogel is 1:440.

[0026] The present invention also provides a preparation method of the above composite scaffold, mixing the metal-organic framework, the hydrogel, and a photoinitiator, and after photo-crosslinking, obtaining the composite scaffold.

[0027] The present invention also provides the application of the above-mentioned metal-organic framework, the metal-organic framework obtained by the above-mentioned preparation method, the above-mentioned composite scaffold, and / or the composite scaffold obtained by the above-mentioned preparation method in the preparation of products for bone repair.

[0028] In some embodiments of the present invention, in the above application, the bone repair includes one or more of anti-inflammatory, anti-aging, and promoting bone properties.

[0029] The present invention also provides a product, comprising: the above-mentioned metal-organic framework, the metal-organic framework obtained by the above-mentioned preparation method, the above-mentioned composite scaffold, and / or the composite scaffold obtained by the above-mentioned preparation method, and an acceptable adjuvant, carrier, or system.

[0030] The present invention first synthesized Mg-GA MOF by a hydrothermal method, adsorbed the extracted exosomes through the characteristic of mutual attraction between positive and negative charges, and finally added them to a GleMA hydrogel solution to form a gel by ultraviolet light crosslinking. The GleMA hydrogel has good biocompatibility and can mimic the structure of the extracellular matrix. The MOF has a good slow-release effect and can slowly release GA and Mg 2+and exosomes, which exert anti-inflammatory, anti-aging, and osteogenic effects through these sustained-release substances, ultimately achieving the goal of promoting senescent osteogenesis. Brief Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0032] Figure 1 Showing the preparation of Gel-Mg-Exo and its mechanism of promoting senescent osteogenesis; where: A shows the preparation of Mg-GA MOF; B shows the preparation of Gel-Mg-Exo; C shows a schematic diagram demonstrating the in vivo anti-inflammatory, anti-aging, and osteogenic mechanisms of the Gel-Mg-Exo hydrogel;

[0033] Figure 2 Showing the synthesis and characterization of Gel-Mg-Exo; where: A shows the schematic diagram of the preparation of Gel-Mg-Exo; B shows the SEM and EDS images of Gel and Gel-Mg-Exo; C shows the AFM of Gel and Gel-Mg-Exo, scale bar: 1 μm; D shows the XPS spectrum; E shows the FTIR of Mg-GA, Gel, and Gel-Mg; F shows the rheological analysis of Gel and Gel-Mg-Exo hydrogels; G shows the stress-strain curves of Gel and Gel-Mg-Exo hydrogels; H shows the swelling ratio of Gel and Gel-Mg-Exo hydrogels; I shows the degradation curves of Gel and Gel-Mg-Exo hydrogels; J shows the Mg 2+ release curve of Gel-Mg-Exo; K shows the exosome release profiles of Gel-Exo and Gel-Mg-Exo.

[0034] Figure 3 Showing the macrophage phenotype regulation based on Gel-Mg-Exo; where: A shows the flow cytometry analysis of macrophage polarization; B shows the CD11b+ / CD86+ ratio; C shows the quantitative analysis of the CD11b+ / CD206+ ratio; D shows the IF staining showing the expression of F4 / 80, iNOS, and CD206, scale bar: 50 μm; E shows the quantitative analysis of the fluorescence intensity of iNOS; F shows the quantitative analysis of the fluorescence intensity of CD206; G shows Western blot; H shows the semi-quantitative analysis of iNOS protein expression; I shows the semi-quantitative analysis of CD206 protein expression;

[0035] Figure 4Evaluation of the anti-aging properties of Gel-Mg-Exo; wherein: A shows the SA-β-gal staining of BMSCs, scale bar: 200 μm; B shows the quantitative analysis of SA-β-gal staining; C shows the IF staining showing the expression of P16 and P53, scale bar: 50 μm; D shows the quantitative analysis of the fluorescence intensity of P16; E shows the quantitative analysis of the fluorescence intensity of P53; F shows the qRT-PCR analysis of p16 in BMSCs treated with hydrogel; G shows the qRT-PCR analysis of p53 in BMSCs treated with hydrogel; H shows the qRT-PCR analysis of SASP in BMSCs treated with hydrogel; I shows Western blot; J shows the semi-quantitative analysis of P16 protein expression; K shows the semi-quantitative analysis of P21 protein expression; L shows the semi-quantitative analysis of P53 protein expression;

[0036] Figure 5 Osteogenic evaluation of Gel-Mg-Exo; wherein: A shows the alizarin red and ALP staining results of BMSCs, scale bar: 200 μm; B shows the quantitative analysis of ALP staining; C shows the quantitative analysis of the calcium nodule content; D shows the IF staining showing the expression of OPN and RUNX2, scale bar: 25 μm; E shows the quantitative analysis of the fluorescence intensity of OPN; F shows the quantitative analysis of the fluorescence intensity of RUNX2; G shows the qRT-PCR analysis of ALP in BMSCs treated with hydrogel; H shows the qRT-PCR analysis of RUNX2; I shows the qRT-PCR analysis of OCN; J shows Western blot; K shows the semi-quantitative analysis of RUNX2 protein expression; L shows the semi-quantitative analysis of OPN protein expression; M shows the semi-quantitative analysis of OCN protein expression;

[0037] Figure 6 Transcriptome sequencing and immunoblot experiments were used to study the mechanism by which Gel-Mg-Exo regulates the senescence of bone marrow mesenchymal stem cells; wherein: A shows a volcano plot showing differentially expressed genes (DEGs) in the S group and the S treatment group; B shows a heat map of DEGs; C shows principal component analysis; D shows the KEGG enrichment analysis of DEGs; E shows the GSEA analysis of the AMPK and cell cycle signaling pathways; F shows the evaluation of the AMPK phosphorylation level in the AMPK signaling pathway;

[0038] Figure 7 In vivo anti-inflammatory properties in a rat cranial defect model; wherein: A shows an image depicting the key bone defect model and a schematic diagram of the experimental timeline; B shows TNF-α immunohistochemical staining of tissues; C shows IL-10 immunohistochemical staining; D shows the quantitative analysis of TNF-α immunohistochemical staining; E shows the quantitative analysis of IL-10 immunohistochemical staining; wherein: the scale bar in the upper part of Figures B and C is 1 mm, and the scale bar in the lower part is 0.2 mm;

[0039] Figure 8Demonstrating the in vivo anti - aging characteristics of the rat skull defect model; wherein: A shows the immunofluorescence double - labeling of P21 (red) and P53 (green) in the tissue at 4 weeks; B shows the scale bar at 8 weeks: 1 mm; C shows the semi - quantitative analysis of the P21 fluorescence intensity; D shows the semi - quantitative analysis of the P53 fluorescence intensity;

[0040] Figure 9 Demonstrating the in vivo osteogenic characteristics in the rat skull defect model; wherein: A shows the surface reconstruction of micro - computed tomography of the skull defect area; B shows the BV / TV measurement; C shows the evaluation of BMD in the bone defect area; D shows the hematoxylin and eosin staining of critical bone defects at 4 weeks and 8 weeks; E shows the Masson staining of critical bone defects at 4 weeks and 8 weeks, scale bars: 1 mm and 0.4 mm;

[0041] Figure 10 Demonstrating the staining analysis of in vivo osteogenic markers; wherein: A shows the immunofluorescence double - labeling of OPN (red) and OCN (green) in the tissue at 4 weeks; B shows the scale bar at 8 weeks: 1 mm; C shows the semi - quantitative analysis of the OPN fluorescence intensity; D shows the semi - quantitative analysis of the OCN fluorescence intensity;

[0042] Figure 11 Demonstrating the synthesis and characterization of Mg - GA MOF; wherein: A shows the schematic diagram of the preparation of Mg - GA; B shows Mg - GA magnified 300 times; C shows the SEM image of Mg - GA magnified 10,000 times; D shows the XRD spectrum of Mg - GA; E shows the absorption spectrum of Mg - GA; F shows the FTIR spectrum of Mg - GA; G shows the ABTS· scavenging ability; H shows the DPPH· scavenging ability; I shows the superoxide dismutase - mimicking ability of Mg - GA; J shows the cell viability at different concentrations of Mg - GA; K shows the cell - protecting ability at different concentrations of Mg - GA under H2O2 treatment;

[0043] Figure 12 Demonstrating the Transwell migration images of different groups of hydrogels recruiting BMSCs; wherein: A shows the Gel hydrogel group; B shows the Gel - Mg hydrogel group; C shows the Gel - Mg - Exo hydrogel group;

[0044] Figure 13 Demonstrating the amount of exosomes that Gel and Gel - Mg scaffolds can adsorb with the continuous addition of exosomes;

[0045] Figure 14 Demonstrating the live / dead staining images of BMSCs on different hydrogels;

[0046] Figure 15 Demonstrating the MOF material synthesized from 1.5 g of MgCl2 and 4 g of gallic acid;

[0047] Figure 16The MOF material synthesized from 0.5 MgCl2 and 4 g of gallic acid is shown;

[0048] Among them: LPS represents the simple lipopolysaccharide treatment group; G represents the simple GelMA hydrogel group; GM represents the Gel-Mg hydrogel group; GME represents the Gel-Mg-EXO hydrogel group; Y represents the young (Young) group; S represents the senescence (Senescence) group. Detailed implementation manners

[0049] The present invention discloses a metal-organic framework, a composite scaffold and their applications.

[0050] It should be understood that the expression "one or more of..." individually includes each of the objects recited after the expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0051] The terms "comprising", "having" or "containing", including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unrecited elements or steps, unless specifically stated otherwise or understood from the context otherwise.

[0052] It should be understood that as long as the present invention is still operable, the order of steps or the order of performing certain actions is not important. In addition, two or more steps or actions can be performed simultaneously.

[0053] The use of any and all examples or exemplary language in this article, such as "for example" or "including", is only intended to better illustrate the present invention and does not limit the scope of the present invention unless a claim is made. No language in this specification should be construed as indicating that any unclaimed element is essential for the practice of the present invention.

[0054] In addition, the numerical ranges and parameters used to define the present invention are approximate values. The relevant values in the specific embodiments have been presented as precisely as possible herein. However, any value inherently and inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise clearly stated, it should be understood that all ranges, amounts, values and percentages used in this disclosure are modified by "about". Herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0055] The technical solution provided by the present invention includes the following steps:

[0056] 1. Synthesis and characterization of the Gel-Mg-Exo composite scaffold

[0057] (1) Preparation of Gel-Mg-Exo composite scaffold: First, Mg-GAMOF was synthesized from MgCl2 and gallic acid by hydrothermal method; exosomes derived from BMSCs were extracted by gradient centrifugation method. Mg-GA MOF and exosomes were mixed, and due to the attraction between their positive and negative charges, the exosomes were adsorbed onto the surface of Mg-GA MOF. Finally, it was added to the GelMA solution and crosslinked into a gel by ultraviolet light.

[0058] (2) Characterization of Gel-Mg-Exo composite scaffold: ① Scanning electron microscopy (SEM) was used to observe the surface morphology of the microgel and evaluate the pore size of the scaffold; ② X-ray photoelectron spectroscopy (XPS) was further used to detect the chemical composition of the hydrogel; ③ Energy-dispersive X-ray spectroscopy (EDS) was used to detect the elemental composition of the hydrogel; ④ Atomic force microscopy (AFM) was used to evaluate the elastic modulus and surface roughness of the hydrogel and draw the force curve; ⑤ Fourier transform infrared absorption spectroscopy (FTIR) was used to detect the chemical groups of the hydrogel; ⑥ Rheological analysis and mechanical testing were used to evaluate the mechanical properties of the hydrogel; ⑦ The swelling and degradation rates of the hydrogel were calculated by the PBS immersion method. ⑧ The release of exosomes and Mg was detected by BCA protein quantification method and inductively coupled plasma mass spectrometry (ICP-MS) respectively. 2+ release.

[0059] 2. In vitro study of Gel-Mg-Exo composite scaffold

[0060] (1) Biocompatibility: Cells were co-cultured with Mg-GA MOF at different concentrations and each hydrogel. After three days of co-culture, a live / dead cell working staining solution was added and images of live / dead cells were captured using a fluorescence microscope.

[0061] (2) BMSCs recruitment: BMSCs were seeded in the upper chamber of a 24-well transwell plate and cultured in α-DMEM. The conditioned media of different hydrogels were collected and added to the lower chamber, and incubated for 12 hours. After incubation, the upper chamber was removed from the plate, the cells in the lower chamber were fixed with 4% paraformaldehyde, then stained with crystal violet, and cell observation and image capture were performed using an optical microscope.

[0062] (3) Anti-inflammatory performance: ① Flow cytometry was used to detect the polarization of macrophages after hydrogel intervention; ② Immunofluorescence staining was used to detect the M1 macrophage marker iNOS and the M2 macrophage marker CD206; ③ WB was used to detect the inflammation-related proteins iNOS and CD206.

[0063] (4) Anti-aging performance: ① Explore the senescence of cells loaded on the scaffold by β-galactosidase staining; ② Detect senescence-related markers P16 and P53 by immunofluorescence staining; ③ Detect the mRNA expression of P16, P53 and senescence-related secretory phenotypes by PCR; ④ Detect inflammation-related proteins P16, P53 and P21 by WB.

[0064] (5) Osteogenic induction performance: ① Explore the osteogenic induction of the scaffold on BMSCs by alizarin red and ALP staining; ② Detect osteogenesis-related markers OPN and RUNX2 by immunofluorescence staining; ③ Detect the mRNA expression of osteogenesis-related ALP, RUNX2 and OCN by PCR; ④ Detect osteogenesis-related proteins RUNX2, OCN and OPN by WB.

[0065] (6) Cellular transcriptomics: Collect BMSCs co-cultured with the hydrogel, extract total RNA using an RNA purification kit, and perform transcriptome sequencing and analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis is used to determine the biological functions or pathways mainly affected by differential transcripts. Further Gene Set Enrichment Analysis (GSEA) is performed to determine the upregulation or downregulation of pathways.

[0066] 3. In vivo study of Gel-Mg-Exo composite scaffold

[0067] We implanted hydrogels of different groups into a rat cranial defect model, collected cranial defect specimens at different time points (1W, 4W, and 8W), and after processing, further evaluated their anti-inflammatory, anti-aging, and osteogenic induction abilities to analyze their biological effects in vivo.

[0068] (1) Analysis of in vivo anti-inflammatory ability: Immunohistochemical staining with anti-iNOS and IL-10 antibodies was performed to detect the inflammatory environment at the cranial defect site.

[0069] (2) Analysis of in vivo anti-aging ability: IF staining of P21 and P53 was performed to detect the senescence of bone tissue.

[0070] (3) Analysis of in vivo osteogenic induction ability: H&E staining and Masson's trichrome staining were used to analyze samples at the 4th and 8th weeks after surgery to evaluate bone regeneration. IF staining of OCN and OPN was performed to evaluate the healing of bone defects in bone tissue.

[0071] In Examples 1 to 4 of the present invention, the raw materials and reagents used can be purchased from the market.

[0072] The present invention will be further described below in conjunction with examples:

[0073] Example 1

[0074] 1. Preparation of Mg-GA MOF

[0075] A biocompatible and non-toxic magnesium-based MOF was synthesized by a hydrothermal method. Briefly, 1 g of MgCl2 was dissolved in 50 mL of ultrapure water, and 4 g of gallic acid was added thereto. A large milky white precipitate was formed and stirred vigorously for 30 min. Then, 10 M aqueous potassium hydroxide solution was added dropwise to adjust the pH value to 8. The precipitate gradually disappeared, and the milky white solution gradually turned yellowish brown. After stirring for 10 min, the solution was transferred to a 100 mL autoclave and autoclaved at 120 °C for 24 h. The solution was cooled to room temperature, centrifuged at 10000 rpm for 10 min, and the supernatant was discarded. The light gray solid precipitate was washed three times with ultrapure water and dried overnight in an oven at 60 °C to obtain Mg-GA MOF powder. We detected the antioxidant properties of Mg-GA MOF at different concentrations through ABTS, DPPH scavenging and SOD mimic experiments. The results showed that the antioxidant properties of Mg-GA MOF increased with increasing concentration, but when the concentration exceeded 200 μg / mL -1 it had a certain toxic effect on cells. Therefore, we finally chose 200 μg / mL -1 as our experimental concentration.

[0076] The material synthesized from 1.5 g of MgCl2 and 4 g of gallic acid is as Figure 15 shown;

[0077] The material synthesized from 0.5 g of MgCl2 and 4 g of gallic acid is as Figure 16 shown.

[0078] 2. Extraction of exosomes

[0079] Rat BMSCs (passage 3) cells were seeded in a culture dish. When the cells reached 75% confluence, the cell supernatant was collected and cell debris, dead cells, and larger vesicles and other impurities were removed by three consecutive centrifugation steps at 4 °C at 300×g (10 min), 2000×g (20 min), and 10,000×g (30 min). Subsequently, the crude exosome extract was obtained by ultracentrifugation at 100,000×g for 70 min at 4 °C, washed once with PBS, and then ultracentrifuged again at 100,000×g for 70 min. The resulting precipitate contained pure exosomes, which were suspended in an appropriate volume of PBS and stored at -80 °C for further use.

[0080] 3. Preparation of Gel-Mg-Exo scaffold

[0081] First, to adsorb exosomes onto Mg-GA MOF, a quantified amount of exosomes was suspended in 1 mL of PBS solution and then added to Mg-GA MOF, followed by incubation overnight at 4 °C. The amount of exosomes adsorbed onto the MOF was determined by measuring the protein concentration in the PBS solution before and after the binding reaction. The final concentration of exosomes added was 40 μg mL -1 , slightly higher than the maximum adsorption capacity of Mg-GA MOF (obtained from the exosome adsorption experiment), to ensure complete adsorption of exosomes. Next, an aqueous deionized solution containing 10% GelMA and photoinitiator LAP was prepared. The Mg-ExoMOF solution after adsorbing exosomes above was directly added to the GelMA solution at a concentration of 200 μg mL -1 , and stirred overnight. Finally, the hydrogel solution was photo-crosslinked by ultraviolet light irradiation with a wavelength of 365 nm and an intensity of 6.9 mW / cm -2 to form a gel.

[0082] Example 2 Characterization of Gel-Mg-Exo Scaffold

[0083] 1. Scanning Electron Microscope (SEM)

[0084] Hydrogels of different groups were cut into appropriate sizes and fixed onto the SEM sample preparation copper plate with conductive glue. After sputtering gold on the membrane surface with an ion sputtering coater, they were placed into the scanning electron microscope. The acceleration voltage was set at 10 kv, and then observations and photographs were taken at different magnifications. The surface of the pure GelMA hydrogel scaffold was smooth and uniform, but after adding Mg-Exo, many small granular substances could be seen, which might be MOF particles.

[0085] 2. Energy Dispersive X-ray Spectrometer (EDS)

[0086] When performing scanning electron microscope observations and photographs, the micro-area component element types and contents of hydrogel samples of different components were analyzed using an energy spectrometer. The results showed that Mg MOF was successfully introduced and evenly distributed in the composite scaffold.

[0087] 3. Atomic Force Microscope (AFM) Detection

[0088] The freeze-dried hydrogel samples were cut into sizes suitable for placing on the AFM sample stage and fixed onto the special sample stage. After selecting an appropriate probe and parameter settings, they were detected by the AFM instrument. The results showed that due to the addition of MOF, the average surface roughness (Ra) of the hydrogel increased from 0.96 nm to 3.23 nm.

[0089] 4. X-ray Photoelectron Spectroscopy (XPS) Detection

[0090] The freeze-dried hydrogel samples were cut into sizes suitable for placing on the XPS sample stage, fixed on a dedicated sample stage, and detected by an XPS instrument after selecting appropriate parameter settings. The results showed that the Gel-Mg hydrogel had the characteristic peaks of both the Gel hydrogel and Mg MOF, further indicating the incorporation of Mg-GA MOF.

[0091] 5. Fourier Transform Infrared Spectroscopy (FTIR)

[0092] To accurately identify the types of functional groups on the sample surface and thus evaluate the effect of modification treatment and hydrogel bonding. Appropriate amounts of GelMA raw material, Mg-GAMOF powder, freeze-dried GelMA hydrogel, and Gel-Mg hydrogel were respectively mixed with 20 g of potassium bromide and thoroughly ground to ensure uniform mixing of the sample and potassium bromide. Subsequently, the mixture was pressed into a sheet using a tablet press device and loaded into the sample cell of an FTIR spectrometer. The scanning resolution was set at 4 cm -1 , and the scanning range was set from 500 to 4000 cm -1 . The results showed the chemical composition of the scaffolds. For the composite scaffold spectra, the characteristic absorption peaks of Gel and Mg-GAMOF were all shown, thus confirming that the Gel-Mg scaffold group contained a blend of the parent materials.

[0093] 6. Rheological Analysis

[0094] The rheological characterization of the hydrogel was evaluated using a rheometer. During the test, the sample (25 mm in diameter and 2 mm in height) was placed on the stage, and frequency and strain tests were performed using a 25-mm diameter plate device at 37 °C. Subsequently, by changing the oscillation frequency range from 0.1 to 10 HZ under the condition of a fixed shear strain value of 5%, the storage modulus and loss modulus of the hydrogel were measured. These tests can comprehensively evaluate the elastic and viscous behaviors of the hydrogel to determine its physical properties under different stress and deformation conditions. The hydrogel rheological analysis test showed that within the test frequency range of 0.1 - 10 Hz, the G′ and G″ of the gel hardly changed, indicating that the gel was intact. G′ was greater than G″, indicating a gelled state. The G′ of the Gel-Mg-Exo hydrogel was significantly higher than that of the Gel hydrogel, indicating that the addition of Mg-Exo enhanced the mechanical strength of the hydrogel.

[0095] 7. Mechanical Compression Test

[0096] Hydrogel cylinder (d = 10 mm, h = 2 mm) samples (n = 3) were prepared through a mold, and a universal mechanical tester was used at 2 mm / min -1Compression was carried out at a rate of [compression rate], and the compression stopped at 60%. The compression modulus of the hydrogel was determined by calculating the slope of the stress-strain curve passing through the origin. The compression test of the hydrogel showed that the Young's modulus of the Gel-Mg-Exo hydrogel was significantly higher than that of the Gel hydrogel.

[0097] 8. Swelling ratio test

[0098] To evaluate the swelling ratio of the hydrogel, the samples (n = 3) were freeze-dried, weighed (W0), and immersed in PBS solution (pH = 7.4) at 37 °C. They were taken out and weighed (W1) at different time intervals (1, 2, 4, 8, 12, 24, and 48 hours) respectively. And, based on Equation (1), its swelling rate was calculated.

[0099]

[0100] 9. Degradation rate test

[0101] The degradation rate of the hydrogel in PBS at pH 7.4 was evaluated to assess in vitro degradation. Briefly, at 37 °C, the freeze-dried hydrogel samples (n = 3) weighed (W0) were added to PBS (pH = 7.4). Then, PBS was removed regularly (1, 2, 3, 4, and 5 weeks), and the mass of the hydrogel (W2) was measured after drying. The degradation rate was calculated using Equation (2).

[0102]

[0103] 10. In vitro magnesium ion and exosome release

[0104] In a 50 mL centrifuge tube, the Gel-Mg-Exo hydrogel prepared from 1 mL of solution (co-loaded with 200 μg of Mg-GAMOF) was immersed in 10 mL of simulated body fluid. The tube was placed in a constant temperature shaker at 37 °C with 100 cycles per minute. At different time points (1, 3, 5, 8, 15, and 25 days), the release buffer was collected from the centrifuge tube, and the obtained supernatant was analyzed by ICP-MS to determine the concentration of elemental magnesium in each solution, and the exosome concentration was analyzed using a Micro BCA protein assay kit. The results showed that due to the microstructure of the hydrogel and Mg-GA MOF, which can play a sustained-release role on biological factors and its excellent biodegradability, Mg 2+ and exosomes can be gradually released.

[0105] Table 1

[0106]

[0107]

[0108] Table 2

[0109]

[0110] In vitro study of the Gel-Mg-Exo scaffold in Example 3

[0111] 1. Cell culture and collection of conditioned medium

[0112] Bone marrow mesenchymal stem cells (BMSCs) were extracted from the bone marrow of rats (6 weeks old, 200 g). The cells were cultured in α-DMEM medium containing 10% fetal bovine serum and 1% double antibody, placed in an incubator at 37°C with 5% CO2, and the medium was changed every 48 - 72 hours. The third-generation BMSCs were used as Y-BMSCs, and the fifteenth-generation BMSCs were used as S-BMSCs. RAW 264.7 cells were purchased from the ATCC cell bank and cultured in high-glucose DMEM medium containing 10% FBS, and the medium was changed every 3 days. Each group of hydrogels was co-incubated with BMSCs in a Transwell system. After 48 hours, the medium was collected and centrifuged at 1000 rpm for 3 min, and the obtained supernatant was collected, stored, and labeled as control medium.

[0113] 2. Cell viability and cytotoxicity assay

[0114] Cells were seeded into 24-well plates (1×10 4 cells per well) and co-cultured with different concentrations of Mg-GAMOF and each hydrogel. After three days of co-culture, cell viability was calculated using live / dead cell staining. After adding the live / dead cell working staining solution, the cells were double-stained for 15 minutes at 37°C in the dark, and images of live and dead cells were captured using a fluorescence microscope. GelMA hydrogel is an organic polymer material with good cell compatibility, and Mg-GA MOF at an appropriate concentration also has no cytotoxicity. We evaluated the biocompatibility of the composite scaffold by cell live / dead staining, and the results showed that BMSCs could survive on the composite scaffold with almost no dead cells, demonstrating that the composite scaffold also has good biocompatibility and can support cell adhesion and proliferation.

[0115] 3. Immunofluorescence analysis

[0116] Fix the cells or tissues in 4% paraformaldehyde for 20 minutes, and then incubate them in 0.2% Triton-100X for 15 minutes. Subsequently, block the samples with 5% BSA overnight. The relevant primary antibodies include anti-CD206 antibody, anti-iNOS antibody, anti-F4 / 80 antibody, anti-P16 antibody, anti-P53 antibody, anti-OPN antibody, and anti-RUNX2 antibody. Then add the relevant primary antibodies to the samples at 4°C overnight. The next day, incubate the secondary antibody, DAPI, and FITC with the samples in the dark at 37°C for 2 hours. Wash the samples three times with PBS for 5 minutes each time before each operation. Capture images with a fluorescence microscope. The results show that the Gel-Mg-Exo composite scaffold has good anti-inflammatory, anti-aging, and osteogenic properties.

[0117] Table 3

[0118]

[0119] Table 4

[0120]

[0121] Table 5

[0122]

[0123] 4. Flow cytometry

[0124] Co-culture RAW cells with each hydrogel at a concentration of 1×10 5 per well in a 12-well plate. After culturing for 3 days, harvest the cells and incubate them with the corresponding antibody or reagent working solution in the dark at room temperature for 30 minutes, and then analyze them by flow cytometry and Flowjo software. The results show that the composite scaffold can better promote the transformation of macrophages into the M2 anti-inflammatory phenotype, creating a better anti-inflammatory microenvironment for tissue osteogenesis.

[0125] 5. BMSCs migration experiment

[0126] Seed BMSCs at a density of 1×10 4 cells per well in the upper chamber of a 24-well transwell plate and culture them in α-DMEM. Add the conditioned media of different hydrogels collected to the lower chamber and incubate for 12 hours. After incubation, remove the upper chamber from the plate, fix the cells in the lower chamber with 4% paraformaldehyde, and then stain with crystal violet. Observe the cells and capture images using an optical microscope. The results show that compared with the G group and the GM group, the GME group has significantly more BMSCs migration, indicating that the composite scaffold can recruit BMSCs by releasing exosomes.

[0127] 6. Alizarin red staining

[0128] Y-BMSCs and S-BMSCs were seeded in 24-well plates at a density of 5×10 4 cells per well and co-cultured with the conditioned media of different hydrogels for 21 days. Then, alizarin red S staining kit was used for staining to observe calcium nodules. Subsequently, optical microscopy was used to observe and photograph the calcium nodules. Then the calcium nodules were dissolved in hydrochloric acid, and the absorbance was measured at 420 nm using a microplate reader. The results showed that the color intensity gradually increased from the S group to the GME group. Among them, the GME group showed the highest osteogenic differentiation efficacy in ARS analysis, but was still lower than the osteogenic differentiation performance of Y-BMSCs.

[0129] 7. ALP staining

[0130] Y-BMSCs and S-BMSCs were seeded in 24-well plates at a density of 5×10 4 cells per well and co-cultured with the conditioned media of different hydrogels for 7 days. Then, ALP staining reagent was used for staining, and optical microscopy was used to observe and photograph. Quantitative analysis was performed using an ALP activity quantification kit. The results showed that the color intensity gradually increased from the S group to the GME group. Among them, the GME group showed the highest osteogenic differentiation efficacy in ALP analysis, but was still lower than the osteogenic differentiation performance of Y-BMSCs.

[0131] 8. β-galactosidase staining

[0132] Y-BMSCs and S-BMSCs were seeded in 24-well plates at a density of 5×10 4 cells per well and co-cultured with the conditioned media of different hydrogels for 7 days. Then, β-galactosidase staining kit was used for staining, and optical microscopy was used to observe and photograph. Through the analysis of the staining results, it was found that the activity of senescence-associated β-galactosidase (SA-β-gal) gradually decreased.

[0133] 9. PCR experiment

[0134] At 7 days and 14 days after normal culture and osteogenic co-culture of Y-BMSCs and S-BMSCs with different hydrogels, qRT-PCR was performed to evaluate the expression of related genes, including osteogenic-related genes ALP, OCN, RUNX2, and COL-1, and senescence-related genes P16, P53, and senescence-associated secretory phenotype (SASP). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal reference gene. The results showed that the senescence-related mRNA expression gradually decreased, while the osteogenic-related mRNA expression gradually increased, indicating that the composite scaffold could slow down senescence and promote senescence-induced osteogenesis.

[0135] 10. Western blot

[0136] Total cellular proteins were extracted using RIPA lysis buffer containing protease inhibitor and phosphatase inhibitor, and protein concentration was determined using a BCA protein assay kit. Equal amounts of protein (10 μg) were separated on 10% gels and then transferred to polyvinylidene fluoride membranes. After blocking with 5% non-fat milk for 1 h, the membranes were incubated with anti-CD63 antibody, anti-TSG101 antibody, anti-Calnexin antibody, anti-CD206 antibody, anti-iNOS antibody, anti-P16 antibody, anti-P21 antibody, anti-P53 antibody, anti-OCN antibody, anti-OPN antibody, anti-RUNX2 antibody, anti-AMPK, anti-p-AMPK antibody, anti-GAPDH antibody, and anti-β-actin antibody, and then incubated with secondary antibodies for 1 h the next day. Protein bands were visualized using an enhanced chemiluminescence kit and analyzed using Image J software. It was found that the protein expressions related to inflammation and senescence gradually decreased, while the protein expressions related to osteogenesis gradually increased, indicating that the composite scaffold could effectively anti-inflammation, anti-aging and promote senescent osteogenesis.

[0137] Table 6

[0138]

[0139] Table 7

[0140]

[0141] Table 8

[0142]

[0143]

[0144] 11. Cellular transcriptome

[0145] S-BMSCs and S-treated-BMSCs co-cultured with Gel-Mg-Exo hydrogel were collected, and total RNA was extracted using an RNA purification kit. Transcriptome sequencing and analysis were performed by OE Biotech Co. For each pair of comparisons, genes or metabolites with false discovery rate (FDR) < 0.05 were considered significant, and the log 2-fold change (logFC) in expression under different conditions was reported. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to determine the biological functions or pathways mainly affected by the differential transcripts. Further gene set enrichment (GSEA) analysis was performed to determine the upregulation or downregulation of pathways.

[0146] Example 4 In vivo study of Gel-Mg-Exo scaffold

[0147] 1. Rat cranial defect model

[0148] Male Sprague-Dawley (SD) rats (200 - 250 g) were purchased from Zhaoyan New Drug Research Center Co., Ltd. All surgical procedures and perioperative treatments were approved by the Ethics Committee of Soochow University (SUDA 20240927 A06). The rats were anesthetized with 2% pentobarbital (2.5 mL / kg - 1), and their skulls were prepared by shaving, disinfecting, and draping. Then, a longitudinal surgical incision about 3 cm long was made along the midline of the skull. Subsequently, the soft tissues and periosteum were separated layer by layer to fully expose the sagittal suture, bilateral parietal bones, and part of the frontal and occipital bones. A circular defect with a diameter of 5 mm was created at the center of the sagittal suture using a trephine. After flushing to control bleeding, hydrogel scaffolds of different groups were implanted in situ, and no material was placed in the control group. The subcutaneous tissue and skin incisions were carefully sutured layer by layer, and the area was disinfected with iodophor. Starting from the day of surgery, penicillin was administered intramuscularly for three consecutive days as a measure to prevent infection.

[0149] 2. Sample collection

[0150] The SD rats were humanely sacrificed at 7 days, 4 weeks, and 8 weeks after surgery, respectively. Then, the cranial specimens were carefully removed from each group and fixed in 4% paraformaldehyde for 24 h.

[0151] 3. Micro-CT analysis

[0152] The cranial samples at 4 weeks and 8 weeks after surgery were scanned and processed using a Micro-CT system. The scanning parameters were set as a scanning voltage of 65 kV, a current of 385 mA, and a resolution of 7 μm. The radial, sagittal, and coronal sections of the skull were reconstructed with the assistance of CT analyzer software. Circular regions of interest were defined for morphological and histological analysis, including the evaluation of bone volume / tissue volume (BV / TV) and bone mineral density (BMD) at the cranial defect site. Further surface reconstruction of the sample models generated by the software was performed using Mimic software. The results showed that the degree of bone repair at 8 weeks after surgery was overall better than that at 4 weeks. In the blank control group, only a small amount of new bone was formed, while in the GME scaffold group, a large amount of new bone was formed, but it was still not as strong as that in the young rat group. As expected, quantitative micro-CT analysis showed that, except for the young group, the GME group had significantly higher bone volume / tissue volume (BV / TV) and mineral density (BMD), indicating that the GME group had a greater number of newly formed and densely filled trabeculae.

[0153] 4. Histological analysis

[0154] The skull samples were decalcified in an ethylenediaminetetraacetic acid solution for 4 weeks and then dehydrated using ethanol solutions of different concentrations. The samples were then immersed in pure xylene and embedded in paraffin. The samples at 7 days postoperatively were processed as described above; decalcified, embedded, sectioned, and immunohistochemically stained with antibodies against iNOS and IL-10 to detect the inflammatory environment at the skull defect site. The samples at 4 weeks and 8 weeks postoperatively were analyzed using H&E staining and Masson's trichrome staining to evaluate bone regeneration. IF staining was performed for OCN, OPN, and P21, P53. These markers were used to evaluate the senescence of bone tissue and the healing of bone defects. The results showed that the GME composite scaffold could also effectively exert anti-inflammatory and anti-aging effects in vivo, thus effectively promoting the regeneration of senescent bone.

[0155] Table 9

[0156]

[0157] Table 10

[0158]

[0159]

[0160] Table 11

[0161]

[0162] Table 12

[0163]

[0164] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A metal-organic framework, characterized in that, Comprising: Magnesium-gallic acid metal-organic framework loaded with exosomes; the concentration ratio of the exosomes to the magnesium-gallic acid metal-organic framework is (0.5 - 1):

5.

2. The metal-organic framework according to claim 1, characterized in that, The magnesium-gallic acid metal-organic framework is prepared by mixing a magnesium-based metal-organic framework and gallic acid; the mass ratio of the magnesium-based metal-organic framework to the gallic acid is (0.5 - 1):

4.

3. The metal-organic framework according to claim 1 or 2, characterized in that, The exosomes are derived from bone marrow mesenchymal stem cells.

4. The preparation method of the metal-organic framework according to claim 3, characterized in that, Comprising the following steps: S1: Mix the magnesium-based metal-organic framework and the gallic acid, sterilize, cool, and collect the precipitate to obtain the magnesium-gallic acid metal-organic framework; S2: After obtaining the exosomes, mix them with the magnesium-gallic acid metal-organic framework to obtain the metal-organic framework.

5. Composite stent, characterized in that, Comprising: A hydrogel, and the metal-organic framework according to any one of claims 1 to 3 or the metal-organic framework obtained by the preparation method according to claim 4.

6. The composite stent according to claim 5, wherein, The concentration ratio of the metal-organic framework to the hydrogel is (0.5 - 1):

440.

7. The preparation method of the composite scaffold according to claim 5 or 6, characterized in that, Mix the metal-organic framework, the hydrogel, and a photoinitiator, and after photo-crosslinking, obtain the composite scaffold.

8. Use of the metal-organic framework according to any one of claims 1 to 3, the metal-organic framework obtained by the preparation method according to claim 4, the composite scaffold according to claim 5 or 6, and / or the composite scaffold obtained by the preparation method according to claim 7 in the preparation of a product for bone repair.

9. The application according to claim 8, wherein The bone repair includes one or more of: anti-inflammatory, anti-aging, and promoting bone properties.

10. Product, characterized in that, Comprising: The metal-organic framework according to any one of claims 1 to 3, the metal-organic framework obtained by the preparation method according to claim 4, the composite scaffold according to claim 5 or 6, and / or the composite scaffold obtained by the preparation method according to claim 7, and an acceptable adjuvant, carrier, or system.

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