Magnesium-containing amorphous calcium phosphate stent for promoting alveolar bone repair and preparation method thereof

Abstract

The invention relates to the technical field of microspheres, in particular to a magnesium-containing amorphous calcium phosphate stent for promoting alveolar bone repair and a preparation method, and the magnesium-containing amorphous calcium phosphate stent comprises the following components: chitosan, polyacrylic acid, magnesium and amorphous calcium phosphate. The loose and porous structure on the surface of the composite scaffold is beneficial to adhesion, proliferation and growth of bone cells, the osteogenesis assisting performance of the composite scaffold is improved through amorphous calcium phosphate in the components, and meanwhile the composite scaffold overcomes the defect that traditional hydrogel cannot be subjected to minimally invasive injection. The alveolar bone filling material can be applied to the alveolar bone repairing process in the field of biomedicine, and the problems that in the prior art, an alveolar bone filling material is poor in injection performance, poor in plasticity, insufficient in stability and incapable of filling irregular-shaped defects are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of microspheres, and particularly relates to a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair and a preparation method thereof. Background Art

[0002] Dental implants are a common method for tooth repair. An artificial tooth root is implanted into the alveolar bone through a surgical operation, and then an artificial tooth is installed thereon. When performing dental implantation, only when the alveolar bone is wide enough, high enough, and strong enough can it withstand the forces of implant insertion and occlusion. Otherwise, the implantation is likely to fail. Therefore, improving the repair and reconstruction methods for alveolar bone defects has always been a popular research topic in oral clinical treatment.

[0003] The development of bone filling materials has effectively solved this common clinical problem of alveolar bone defects. Bone filling materials can solve the problem of alveolar bone defects by increasing the volume and height of the alveolar bone. Currently, common bone filling materials on the market are divided into block bone filling materials, granular bone filling materials, paste bone filling materials, and microsphere bone filling materials, etc. Among them, although block bone filling materials have good support and mechanical strength, they have poor plasticity and cannot meet the needs of filling irregular defects; while granular bone filling materials with better plasticity lack stability and cannot well withstand the soft tissue pressure at the bone grafting site. Paste bone filling materials, as a new type of bone filling material, although having good plasticity, have low compressive strength, high brittleness, and long curing time for bone cement materials; and some bone cement components are toxic. Microsphere bone filling materials can well overcome the defects of the above several materials. Microsphere materials with a certain mechanical strength and plasticity and a larger specific surface area can better act on the defect site.

[0004] Due to its excellent biological properties, hydrogel has been widely used as a matrix for cell culture, a template for tissue engineering, a carrier for drug and cell delivery, and a filling material. However, traditional block hydrogels have problems such as too large external dimensions (millimeter level and above), long cell culture cycle, the need for surgical implantation into diseased or necrotic areas, and large postoperative trauma. Therefore, researchers have developed spherical particles made of micron-level hydrogel materials as an alternative. Compared with large-sized block hydrogels, hydrogel microspheres have the following advantages: good biocompatibility: Hydrogel microspheres are usually made of biodegradable materials and have good biocompatibility and will not cause an immune response; strong controllability: The size, shape, surface properties, and composition of hydrogel microspheres can be regulated by the preparation method; versatility: Hydrogel microspheres can be used as drug carriers, tissue engineering materials, diagnostic reagents, etc.; injectability: Small-sized microspheres can be injected or inhaled by small needles and catheters, which is beneficial for the minimally invasive delivery of cells and biological products.

[0005] Chitosan is a natural-derived polysaccharide that exists in the cell walls of certain fungi, and commercial chitosan can be prepared in large quantities and economically from chitin. With the continuous expansion of application fields, in order to meet the needs of modern society, multifunctional chitosan derivatives and their corresponding modification technologies have been developed. The feasibility of preparing microspheres based on chitosan and their mechanical strength have been confirmed by researchers.

[0006] Enamel is the hardest tissue in the human body, consisting of 95 wt% inorganic hydroxyapatite (HA) and a small amount of protein-based organic matrix. Hydroxyapatite crystals provide a suitable matrix for cell growth and attachment and further initiate osteoblast and angiogenesis activities in vitro. The maturation of strengthened bone begins with an amorphous precursor: amorphous calcium phosphate (ACP) plays an important role in the biomineralization of bone, teeth, and other tissues and is a precursor to apatite minerals. The initial minerals in enamel and bone consist of a transient ACP phase, which changes over time to the final crystalline HA mineral. Compared with the relatively large hydroxyapatite, amorphous phosphate has significant advantages: the formable amorphous precursor has the ability of self-assembly and can be used for continuous biomineralization processes; compared with the crystalline phase, the amorphous phase has higher solubility, so they can effectively provide the required ions to form crystalline minerals; the smaller volume means less energy is required to form crystalline nanodomains and construct hierarchical structures. Although ACP has good biocompatibility and multiple functions in vivo, its metastability and instability limit its further application in biomedicine.

[0007] Organic additives and magnesium ions have been reported to improve the stability of amorphous calcium carbonate (ACC) during biomineralization or chemical synthesis processes. For example, polyacrylic acid (PAA) molecules with abundant carboxylic acid functional groups show the ability to improve the stability of ACC because the intercalation between carboxylate and calcium ions can inhibit the further crystallization of ACC; in addition to organic molecules, magnesium ions are also commonly present in biological acid phosphatases (hereinafter referred to as magnesium acid phosphatases), such as in human enamel. Since the hydration energy of magnesium ions (~303.9 kcal / mol) is higher than that of calcium ions (~182.0 kcal / mol), magnesium ions stabilize magnesium acid phosphatases by inhibiting further crystallization.

[0008] An ideal bone filling material needs to meet the following requirements: first, it should have good stability and biocompatibility and not cause toxicity or inflammation; second, good plasticity and supportability, capable of filling uneven defect sites without easily collapsing; in addition, as an alveolar bone filling material, it also needs sufficient degradability to prevent the material from hindering the growth of new teeth; more advanced bone filling materials should also have appropriate surface microstructure and osteoinductive properties.

[0009] Currently, commonly used bone filling materials face disadvantages such as poor plasticity, poor mechanical properties, poor stability, and inability to evenly fill irregular defects. Porous microspheres (PM) have attracted increasing attention in the medical field as bone filling materials due to their easy availability, good mechanical properties, and good bioactivity. Using chitosan as the microsphere substrate and embedding polyacrylic acid, amorphous calcium phosphate, and magnesium into the microspheres can not only ensure the good mechanical properties of the porous microspheres but also meet the requirements of related biomedical and tissue engineering.

[0010] In view of the above defects, the inventors of the present invention finally obtained the present invention through long-term research and practice. Summary of the Invention

[0011] The object of the present invention is to solve the problems that currently commonly used alveolar bone filling materials face disadvantages such as poor plasticity, poor stability, and inability to fill uneven defects, and to provide a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair and its preparation method.

[0012] To achieve the above object, the present invention discloses a preparation method of a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair, comprising the following steps:

[0013] S1, after uniformly mixing a chitosan solution and a polyacrylic acid-amorphous calcium phosphate magnesium emulsion, a composite scaffold is prepared by a microfluidic method;

[0014] S2, after preparing chitosan microspheres by a microfluidic method, the microspheres are immersed in a polyacrylic acid-amorphous calcium phosphate magnesium emulsion for 48 hours.

[0015] In the step S1, the concentration of the chitosan solution is 1%.

[0016] In the step S1, the preparation method of the polyacrylic acid-amorphous calcium phosphate magnesium emulsion is as follows: uniformly mix polyacrylic acid, calcium chloride, manganese chloride solution, and deionized water, uniformly mix disodium hydrogen phosphate and deionized water, and then uniformly mix the two mixed solutions to obtain a polyacrylic acid-amorphous calcium phosphate magnesium emulsion.

[0017] The molar ratio of polyacrylic acid, calcium, phosphate ions, and magnesium ions is 1:1:1:0 to 0.05.

[0018] The molecular weight of the polyacrylic acid is 5000.

[0019] In the step S1, the chitosan solution and the polyacrylic acid-amorphous calcium phosphate magnesium emulsion are uniformly mixed at a volume ratio of 10:10 or 10:5.

[0020] In the step S2, the microfluidic method is specifically as follows: Droplets of emulsified chitosan or a mixed solution are mixed with a solution containing a fixing agent, and through physical cross-linking, a microsphere scaffold is obtained.

[0021] The solution containing the fixing agent is an alcoholic solution of sodium hydroxide, an alcoholic solution of potassium hydroxide, an alcoholic solution of calcium chloride, an alcoholic solution of calcium nitrate, acetone or methanol. The alcoholic solution in the alcoholic solution of sodium hydroxide, the alcoholic solution of potassium hydroxide, the alcoholic solution of calcium chloride, and the alcoholic solution of calcium nitrate is any one or a combination of two of methanol and ethanol.

[0022] The solution containing the fixing agent is an alcoholic solution of sodium hydroxide, an alcoholic solution of potassium hydroxide, an alcoholic solution of calcium chloride, an alcoholic solution of calcium nitrate, and the concentration of the solution containing the fixing agent is 0.1 - 1 mol / L.

[0023] The present invention also discloses a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair prepared by the above preparation method.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention improves the mechanical properties of the magnesium-containing amorphous calcium phosphate scaffold by introducing chitosan material with good biocompatibility and degradability;

[0026] 2. The present invention improves the osteoinductive properties of the magnesium-containing amorphous calcium phosphate scaffold by introducing amorphous calcium phosphate;

[0027] 3. The present invention improves the stability of amorphous calcium phosphate by introducing the organic material polyacrylic acid and magnesium ions;

[0028] 4. The composite microsphere preparation technology of the present invention is mature, the process is simple, and the price is low;

[0029] 5. The composite microspheres of the present invention are small in volume, have better supportability and plasticity compared with other bone filling materials, and can better fill irregular bone defect sites;

[0030] 6. The composite microspheres of the present invention have a loose and porous surface structure, which is beneficial to the adsorption and proliferation of osteoblasts and the attachment and growth of bone tissue;

[0031] 7. By introducing polyacrylic acid-amorphous calcium magnesium phosphate emulsion into chitosan microspheres, the obtained composite microsphere material has improved mechanical properties compared with the bone filling materials currently used in clinics. The amorphous calcium phosphate in the microspheres improves osteogenic properties and has high biological activity. The loose and porous surface structure of the microspheres is more conducive to the adhesion, proliferation, and growth of bone cells. The introduction of polyacrylic acid and magnesium ions improves the stability of amorphous calcium phosphate. The high biological safety and low cost of chitosan enable the preparation of a new generation of microsphere bone filling materials with high safety and high osteogenic properties at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the preparation method of the composite microspheres;

[0033] Figure 2 is the scanning electron microscope image of the composite material prepared in Example 1;

[0034] Figure 3 is the scanning electron microscope image of the composite material prepared in Example 2;

[0035] Figure 4 is the scanning electron microscope image of the composite material prepared in Comparative Example 1;

[0036] Figure 5 is the scanning electron microscope image of the composite scaffold with a particle size of 100 - 300 μm prepared in Example 1;

[0037] Figure 6 is the scanning electron microscope image of the composite scaffold with a particle size of 300 - 500 μm prepared in Example 1;

[0038] Figure 7 is the scanning electron microscope image of the composite scaffold with a particle size of 500 - 700 μm prepared in Example 1;

[0039] Figure 8 is the column chart of the particle size of the composite scaffold prepared with different ratios of the outer phase to the inner phase during the preparation of Example 1;

[0040] Figure 9 is the scanning electron microscope image of the composite scaffold with different calcium-magnesium ratios prepared in Example 1;

[0041] Figure 10 is the EDS energy spectrum diagram of the composite scaffold prepared in Example 1;

[0042] Figure 11 Scanning electron microscope image of the composite scaffold obtained with different mixing ratios of the emulsion and the chitosan solution during the preparation of Example 1;

[0043] Figure 12Scanning electron microscope images of the composite scaffolds obtained with different phosphate ratios during the preparation of Example 2;

[0044] Figure 13 Fourier transform infrared spectroscopy images of three different composite scaffolds (0 mM, 3 mM, 5 mM) prepared in Example 1;

[0045] Figure 14 Bar chart of the swelling ratio of the composite scaffold prepared in Example 1;

[0046] Figure 15 Line chart of the swelling ratio of the 0 mM composite scaffold prepared in Example 1 over time;

[0047] Figure 16 Line chart of the injection force test of the 3 mM composite scaffold prepared in Example 1 under a 200 μm diameter needle;

[0048] Figure 17 Line chart of the injection force test of the 3 mM composite scaffold prepared in Example 1 under a 400 μm diameter needle;

[0049] Figure 18 Line chart of the injection force test of the 3 mM composite scaffold prepared in Example 1 under a 600 μm diameter needle. Detailed implementation manners

[0050] The following further elaborates on the above and other technical features and advantages of the present invention with reference to the accompanying drawings.

[0051] Example 1

[0052] Weigh 5.76 g of polyacrylic acid (molecular weight 5000) and dissolve it in 20 mL of deionized water to prepare a 2 M uniform polyacrylic acid mother liquor. Weigh 4.44 g of calcium chloride and dissolve it in 20 mL of deionized water to prepare a 2 M uniform calcium ion mother liquor. Weigh 10.15 g of magnesium chloride and dissolve it in 20 mL of deionized water to prepare a 0.05 M uniform magnesium ion mother liquor.

[0053] Take 1 mL of the solution from the 2 M polyacrylic acid mother liquor, 0.8 mL from the 2 M calcium ion mother liquor, and 2 mL of the solution from the 0.05 M magnesium ion mother liquor, and mix them evenly with 6 mL of deionized water to form a 10 mL uniform solution. Take 0.142 g of disodium hydrogen phosphate and dissolve it in 10 mL of water to form a 10 mL uniform solution. Then mix the above two 10 mL solutions evenly to obtain a 20 mL polyacrylic acid - amorphous calcium magnesium phosphate emulsion with a magnesium content of 5 mM.

[0054] Similarly, take 1 mL of the solution from the 2M polyacrylic acid mother liquor, take 0.9 mL / 1 mL from the 2M calcium ion mother liquor, take 1.2 mL / 0 mL of the solution from the 0.05M magnesium ion mother liquor, and mix them evenly with 6.8 mL / 8 mL of deionized water to form a 10 mL homogeneous solution. Dissolve 0.142 g of disodium hydrogen phosphate in 10 mL of water to form a 10 mL homogeneous solution. Then mix the above two 10 mL solutions evenly to obtain a 20 mL polyacrylic acid-amorphous calcium magnesium phosphate emulsion with a magnesium content of 0.3 mM / 0 mM.

[0055] Weigh 2 g of chitosan and dissolve it in 200 mL of 1% acetic acid aqueous solution to prepare a homogeneous chitosan aqueous solution; take 10 mL of the chitosan solution and mix it evenly with 10 mL of the polyacrylic acid-amorphous calcium magnesium phosphate emulsion to form a 20 mL mixed solution. Use a 5 mL syringe to extract 1 - 3 mL of the prepared mixed solution and connect it to the inner tube of the tube-in-tube microfluidic device. Use a 100 mL syringe to extract 50 - 80 mL of cyclohexane as the extrusion phase and connect it to the outer tube of the tube-in-tube microfluidic device; use a micro-injection pump to control the extrusion speeds of the two syringes respectively (the inner tube has a diameter of 60 microns and an extrusion speed of 0.03 mL / min, the outer tube has a diameter of 300 microns and an extrusion speed of 5 mL / min), and prepare a 0.6 mol NaOH ethanol solution as the solution containing the fixative to collect the extruded liquid microspheres; obtain crosslinked chitosan composite microspheres with a diameter of 300 microns; wash the crosslinked chitosan microspheres with ethanol and finally perform supercritical drying treatment to obtain three groups of magnesium-containing amorphous calcium phosphate scaffolds with magnesium contents of 0 mM / 3 mM / 5 mM respectively.

[0056] Similarly, by controlling the extrusion speeds of the two syringes to be (the inner tube has a diameter of 60 microns and an extrusion speed of 0.01 mL / min, the outer tube has a diameter of 300 microns and an extrusion speed of 2 mL / min) / (the inner tube has a diameter of 60 microns and an extrusion speed of 0.03 mL / min, the outer tube has a diameter of 300 microns and an extrusion speed of 7 mL / min) respectively, prepare a 0.6 mol / L NaOH ethanol solution as the solution containing the fixative to collect the extruded liquid microspheres, and obtain crosslinked magnesium-containing amorphous calcium phosphate scaffolds with diameters of 150 microns / 500 microns.

[0057] Example 2

[0058] Weigh 5.76 g of polyacrylic acid (molecular weight 5000) and dissolve it in 20 mL of deionized water to prepare a 2M homogeneous polyacrylic acid mother liquor. Weigh 4.44 g of calcium chloride and dissolve it in 20 mL of deionized water to prepare a 2M homogeneous calcium ion mother liquor. Weigh 8.12 g of magnesium chloride and dissolve it in 20 mL of deionized water to prepare a 2M homogeneous magnesium ion mother liquor.

[0059] Take 1 mL of the solution from the 2 M polyacrylic acid mother liquor, 0.8 mL from the 2 M calcium ion mother liquor, and 2 mL of the solution from the 0.05 M magnesium ion mother liquor, and mix them evenly with 6 mL of deionized water to form a 10 mL homogeneous solution. Dissolve 0.142 g of disodium hydrogen phosphate in 10 mL of water to form a 10 mL homogeneous solution. Then mix the above two 10 mL solutions evenly to obtain a 20 mL polyacrylic acid - amorphous calcium magnesium phosphate emulsion with a magnesium content of 5 mM.

[0060] Similarly, take 1 mL of the solution from the 2 M polyacrylic acid mother liquor, 0.8 mL from the 2 M calcium ion mother liquor, and 1.2 mL / 0 mL of the solution from the 0.05 M magnesium ion mother liquor, and mix them evenly with 6.8 mL / 8 mL of deionized water to form a 10 mL homogeneous solution. Dissolve 0.426 g / 0.71 g of disodium hydrogen phosphate in 10 mL of water to form a 10 mL homogeneous solution. Then mix the above two 10 mL solutions evenly to obtain a 20 mL polyacrylic acid - amorphous calcium magnesium phosphate emulsion with a magnesium content of 3 mM / 0 mM.

[0061] Weigh 2 g of chitosan and dissolve it in 200 mL of 1% acetic acid aqueous solution to prepare a homogeneous chitosan aqueous solution. Use a 5 mL syringe to extract 1 - 3 mL of the prepared chitosan solution and connect it to the inner tube of the tube - sleeve microfluidic device. Use a 100 mL syringe to extract 50 - 80 mL of cyclohexane as the extrusion phase and connect it to the outer tube of the tube - sleeve microfluidic device. Use a micro - injection pump to control the extrusion speeds of the two syringes respectively (the inner tube has a diameter of 60 μm and an extrusion speed of 0.03 mL / min, the outer tube has a diameter of 300 μm and an extrusion speed of 5 mL / min), and prepare a 0.6 mol NaOH ethanol solution as the solution containing the fixative to collect the extruded liquid microspheres; obtain cross - linked chitosan microspheres with a diameter of 300 μm; wash the cross - linked chitosan microspheres with ethanol and finally perform supercritical drying treatment to obtain chitosan microspheres.

[0062] Soak 0.1 - 0.5 g of the chitosan microspheres prepared above in 20 mL of the polyacrylic acid - amorphous calcium magnesium phosphate emulsion for 48 h, and after supercritical drying treatment, obtain three groups of amorphous calcium phosphate scaffolds with magnesium contents of 0 mM / 3 mM / 5 mM respectively.

[0063] Comparative Example 1

[0064] Weigh 2 g of chitosan and dissolve it in 200 mL of 1% aqueous acetic acid solution to prepare a uniform chitosan aqueous solution; use a 5 mL syringe to extract 5 - 8 mL of the prepared chitosan solution and connect it to the inner tube of the tube - sleeve microfluidic device. Use a 100 mL syringe to extract 50 - 80 mL of cyclohexane as the extrusion phase and connect it to the outer tube of the tube - sleeve microfluidic device; use a micro - injection pump to control the extrusion speeds of the two syringes respectively (the inner tube has a diameter of 60 μm and an extrusion speed of 0.03 mL / min, the outer tube has a diameter of 300 μm and an extrusion speed of 5 mL / min). Prepare a 0.6 mol NaOH ethanol solution as the solution containing the fixative to collect the extruded liquid microspheres; obtain cross - linked chitosan microspheres with a diameter of 300 μm; wash the cross - linked chitosan microspheres with ethanol and finally perform supercritical drying treatment to obtain chitosan microspheres.

[0065] Perform structural characterization tests on the obtained microspheres:

[0066] After supercritical drying the materials prepared in Example 1 and Example 2 respectively, use conductive double - sided tape to stick the materials on a metal bracket, spray gold, and then place them under a scanning electron microscope at an accelerating voltage of 5 kV to observe the structures of each material.

[0067] Result analysis: From Figure 2 It can be seen that compared with the chitosan microspheres of Comparative Example 1, nano - scale amorphous calcium phosphate particles can be observed on the microspheres prepared in Examples 1 and 2, verifying the existence of amorphous calcium phosphate. And the surface of the microspheres prepared in Example 1 presents a loose and porous structure, which is more suitable for cell adhesion, growth and proliferation compared with Example 2.

[0068] From Figure 3 , 4, it can be seen that the most suitable particle size of the composite scaffold prepared in Example 1 is 300 - 500 μm. For microspheres with a smaller particle size, the microsphere solution collapses, and for microspheres with a larger particle size, they are cylindrical and the yield is lower.

[0069] From Figure 5 It can be seen that as the concentration of magnesium ions increases, more amorphous calcium phosphate can be observed in the composite scaffold prepared in Example 1, and fewer phosphate products in the form of blocks or crystals.

[0070] From Figure 6 It can be seen that the surface of the microspheres prepared in Example 1 is loose and porous when the ratio of emulsion to chitosan solution is 10:10.

[0071] From Figure 8 It can be seen that the morphology of the microspheres prepared in Example 2 is relatively dense, and it is difficult to observe the porous structure.

[0072] From Figure 9 It can be seen that when taking the infrared spectrum of the microspheres prepared in Example 1, the characteristic peaks of amorphous phosphate groups are all shown.

[0073] From Figure 10 and Figure 11 it can be seen that the composite microspheres prepared in Example 1 have a high swelling rate and the microspheres stop swelling after swelling for a certain period of time.

[0074] From Figures 12 to 14 it can be seen that the composite microspheres prepared in Example 1 have good injectability.

[0075] The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims

1. A method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair, characterized in that: The following steps are involved: S1, mixing chitosan solution and polyacrylic acid-amorphous magnesium calcium phosphate emulsion evenly, and preparing a composite scaffold by a microfluidic method; S2, after chitosan microspheres are prepared by microfluidics, the microspheres are immersed in polyacrylic acid-amorphous magnesium calcium phosphate emulsion for 48 hours.

2. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 1, characterized in that: In the step S1, the concentration of the chitosan solution is 1%.

3. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 1, characterized in that: In step S1, the preparation method of polyacrylic acid-amorphous magnesium calcium phosphate emulsion is as follows: polyacrylic acid, calcium chloride, manganese chloride solution and deionized water are mixed evenly, disodium hydrogen phosphate and deionized water are mixed evenly, and the two mixed solutions are mixed evenly again to obtain polyacrylic acid-amorphous magnesium calcium phosphate emulsion.

4. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 3, characterized in that: The molar ratio of the polyacrylic acid, calcium, phosphate ions and magnesium ions is 1:1:1:0-0.

05.

5. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 3, characterized in that: The molecular weight of the polyacrylic acid is 5000.

6. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 1, characterized in that: In the step S1, the chitosan solution and the polyacrylic acid-amorphous magnesium calcium phosphate emulsion are uniformly mixed in a volume ratio of 10:10 or 10:

5.

7. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 1, characterized in that: In step S2, the microfluidic method is specifically as follows: emulsified chitosan or mixed solution droplets are mixed with a solution containing a fixative, and the mixture is subjected to physical cross-linking to obtain a microsphere scaffold.

8. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 7, characterized in that: The solution containing the fixative is an alcohol solution of sodium hydroxide, an alcohol solution of potassium hydroxide, an alcohol solution of calcium chloride, an alcohol solution of calcium nitrate, acetone or methanol, and the alcohol solution in the alcohol solution of sodium hydroxide, the alcohol solution of potassium hydroxide, the alcohol solution of calcium chloride and the alcohol solution of calcium nitrate is any one of methanol and ethanol or a combination of two of them.

9. The method for preparing a magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair according to claim 8, characterized in that: The solution containing the fixing agent is an alcohol solution of sodium hydroxide, an alcohol solution of potassium hydroxide, an alcohol solution of calcium chloride, or an alcohol solution of calcium nitrate. The concentration of the solution containing the fixing agent is 0.1-1 mol / L.

10. A magnesium-containing amorphous calcium phosphate scaffold for promoting alveolar bone repair, prepared by the preparation method according to any one of claims 1 to 9.

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