A composite gel containing calcium hydroxylapatite microspheres with core-shell structure, a preparation method and applications thereof

Abstract

The present application relates to the technical field of biomedical materials, in particular to a composite gel containing core-shell structure calcium hydroxyapatite microspheres, a preparation method and application thereof. The composite gel comprises a gel carrier and microspheres dispersed in the gel carrier, the microspheres comprise a core and a shell layer coated on the outside of the core, the core is a biodegradable polymer, and the shell layer is calcium hydroxyapatite. After the core-shell structure calcium hydroxyapatite microsphere composite gel of the present application is implanted, calcium hydroxyapatite first contacts human tissues and is degraded into calcium ions and phosphate ions, stimulates collagen production and carries out tissue remodeling; then the biodegradable polymer is also metabolically degraded; and the degradation rate of calcium hydroxyapatite can control the exposure rate of the polymer microspheres, so that a long-term plumping filling effect is achieved; the gel has suitable viscoelasticity, can uniformly suspend the composite microspheres, and after injection into the human body, the microspheres are also uniformly dispersed in the gel.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a composite gel containing core-shell structured hydroxyapatite calcium microspheres, its preparation method, and its applications. Background Technology

[0002] Due to injuries and aging, the human body may experience loosening and loss of local soft tissues, sometimes even leading to loss of soft tissue function. Clinically, treatment can involve reinforcing local soft tissues by injecting tissue-enhancing materials into the areas requiring filling, restoring the tissue to its original shape and function.

[0003] Hydroxyapatite calcium, also known as hydroxyapatite, is a natural component of the human body and has good biocompatibility, making it a highly efficient material for soft tissue filling. However, hydroxyapatite calcium has extremely low solubility under physiological conditions, especially dense hydroxyapatite calcium, which exhibits an even lower biodegradation rate. When existing dense hydroxyapatite calcium injection microspheres are injected into the body, a large number of these microspheres gradually crystallize and harden at the injection site, forming new solid tissue. This results in a stiff injection site and a hard lump that is difficult to remove. Forcibly removing the hardened tissue can damage nerves and blood vessels, causing deformities and depressions at the removal site.

[0004] Therefore, optimizing and improving the structure and preparation method of hydroxyapatite calcium injection microspheres to obtain hydroxyapatite calcium microspheres that do not aggregate and harden after implantation, have good dispersibility and stability, slow degradation, can maintain a long-term filling effect, are resistant to high-temperature sterilization, and are easy to inject is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the primary objective of this invention is to provide a composite gel containing core-shell structured hydroxyapatite calcium microspheres. By coating the biodegradable polymer microspheres with hydroxyapatite calcium, after implantation, the hydroxyapatite calcium, acting as the shell, first contacts human tissue and degrades into calcium ions and phosphate ions, stimulating only collagen production and achieving tissue remodeling. The exposed biodegradable polymer microspheres are also metabolically degraded, preventing them from becoming undegradable and unremovable lumps. Furthermore, the exposure rate of the polymer microspheres can be controlled based on the degradation rate of the hydroxyapatite calcium shell, achieving a long-lasting, full-filling effect without the need for repeated injections. Due to the high molecular weight... The polymer microspheres have poor heat resistance and are prone to deformation during high-temperature sterilization. With the protection of the hydroxyapatite calcium shell, the microspheres will not soften or deform, which helps to reduce friction during injection. It can also be squeezed out with finer needles, reducing injection pain and allowing for better control of injection force and volume. Choosing a suitable gel carrier not only maintains appropriate viscoelasticity before and after sterilization to keep the microspheres in suspension, but also allows the composite gel to be pre-filled before use and injected directly, which is more conducive to clinical use and thus effectively improves the efficiency of clinical use. It also ensures that the composite gel can be stably stored at room temperature without the need for special storage and transportation.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned composite gel containing core-shell structured hydroxyapatite calcium microspheres.

[0007] Another object of the present invention is to provide an application of the above-mentioned composite gel containing core-shell structured hydroxyapatite calcium microspheres in soft tissue filling.

[0008] In a first aspect, the present invention provides a composite gel containing core-shell structured calcium hydroxyapatite microspheres. The composite gel includes a gel carrier and microspheres dispersed in the gel carrier. The microspheres include a core and a shell covering the core. The core is a biodegradable polymer, and the shell is calcium hydroxyapatite. The particle size of the microspheres is 15 μm to 150 μm.

[0009] In one optional embodiment, the mass ratio of the polymer to the calcium hydroxyapatite is 1:0.1 to 0.3.

[0010] In one alternative embodiment, the biodegradable polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone.

[0011] In one optional embodiment, the gel carrier comprises a gel matrix, solvent, thickener, humectant, and anesthetic in a mass ratio of 0–3:30–99.5:0.5–5:0–60:0–1. The thickener and solvent can form a gel. The thickener has the functions of binding, suspending, thickening, emulsifying, and slow-release. When mixed with the solvent, it can achieve the application effect.

[0012] In one optional embodiment, the volume ratio of the microspheres to the gel carrier is 1-5:6-9. In the composite gel, the microspheres are the final filling component. The density of core-shell structured microspheres prepared in different proportions will be different. The present invention calculates the mass based on the volume ratio and then mixes them.

[0013] In one optional embodiment, the solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution.

[0014] In one optional embodiment, the gel matrix is ​​at least one of sodium hyaluronate, carbomer, alginate, collagen, and chitosan.

[0015] In one alternative embodiment, the thickener is at least one selected from gelatin, soluble starch, and cellulose derivatives.

[0016] In one alternative embodiment, the moisturizer is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol.

[0017] In one optional embodiment, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

[0018] In one optional embodiment, the sodium hyaluronate comprises low molecular weight sodium hyaluronate with a molecular weight of 30W to 100W, medium molecular weight sodium hyaluronate with a molecular weight of 120W to 180W, and high molecular weight sodium hyaluronate with a molecular weight of 200W to 250W, wherein the mass ratio of the low molecular weight sodium hyaluronate to the medium molecular weight sodium hyaluronate and the high molecular weight sodium hyaluronate is 0.5 to 3: 0.5 to 5: 1 to 10.

[0019] In one alternative embodiment, the cellulose derivative includes at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose.

[0020] Secondly, the present invention provides a method for preparing a composite gel containing core-shell structured microspheres, comprising the following steps:

[0021] S1. Prepare hydroxyapatite calcium and biodegradable polymer spheres separately. Add the hydroxyapatite calcium, the biodegradable polymer spheres and polyethylene glycol to a mixed solvent of water and alcohol, mix, so that the hydroxyapatite calcium coats the surface of the biodegradable polymer spheres, and obtain core-shell structured hydroxyapatite calcium microspheres.

[0022] S2. Prepare a gel carrier by adding the core-shell structured hydroxyapatite calcium microspheres obtained in step S1 to the gel carrier and mixing them thoroughly.

[0023] In one optional embodiment, the mass percentage of polyethylene glycol in the mixing system of step S1 is 4% to 5%.

[0024] In one optional implementation, the mixing time in step S1 is 2h to 4h.

[0025] In one alternative embodiment, the mass ratio of the biodegradable polymer spheres to the calcium hydroxyapatite is 1:0.1 to 0.3.

[0026] In one optional embodiment, the method for preparing the hydroxyapatite calcium includes: adding citric acid, a calcium source, and a phosphorus source to a mixed solvent of water and ethanol, adjusting the pH of the system to 9-11 to allow the reaction to occur, and the resulting precipitate is hydroxyapatite calcium.

[0027] In one optional embodiment, the method for preparing the biodegradable polymer spheres includes: preparing an aqueous stabilizer solution and a polymer solution respectively; adding the polymer solution to the aqueous stabilizer solution while it is being continuously stirred; continuing to stir for a first time; and then heating the mixture to evaporate the solvent to obtain polymer spheres.

[0028] In one optional embodiment, the preparation method of the gel carrier includes: adding a thickener to a humectant in at least three portions, mixing to obtain a first mixture; mixing a gel matrix with a solvent to obtain a second mixture; adding the first mixture to the second mixture, mixing to obtain a third mixture; adding an anesthetic to the third mixture, mixing to obtain a fourth mixture, which is the gel carrier.

[0029] In one optional embodiment, the mass percentage of citric acid in the preparation system of calcium hydroxyapatite is 2% to 3%. Citric acid can maintain the stability of the system, reduce the formation of impurities such as calcium oxide, and facilitate the formation of uniform and well-dispersed calcium hydroxyapatite.

[0030] In one alternative embodiment, the volume ratio of water to ethanol in the mixed solvent is 3:1-2, and citric acid, calcium source, and phosphorus source are more easily dissolved in the mixed solvent of water and ethanol.

[0031] And / or, the mass ratio of the calcium source to the phosphorus source is 5-10:3-4.

[0032] In one optional embodiment, the calcium source is at least one of calcium nitrate and calcium chloride.

[0033] In one optional embodiment, the phosphorus source is at least one of diammonium hydrogen phosphate, sodium phosphate, and disodium hydrogen phosphate.

[0034] In one optional embodiment, the stabilizer aqueous solution contains 0.7% to 5% by mass of the stabilizer.

[0035] In one optional embodiment, the stabilizer is at least one of polyvinyl alcohol (PVA) and polyacrylic acid; preferably PVA. Because PVA water molecules have both hydrophilic and lipophilic structures, they adsorb onto the surface of polymer particles to form a protective film, reduce interfacial tension, and increase the viscosity of the system (medium). Therefore, the PVA aqueous solution is used as a stabilizer in the emulsion polymerization process, synergistically improving the stability of the emulsion polymerization system. The particle size of the microspheres is controlled by adjusting the mass percentage of the PVA aqueous solution, further controlling the uniformity of particle size distribution and the spheroidization effect. Microspheres can be prepared using different organic solvents and polymers during the preparation process; the choice of solvent affects the raw material content of the polymer microspheres and subsequent solvent residue issues; the choice of polymer affects the surface morphology and particle size of the microspheres; in the preparation of polylactic acid microspheres, this invention uses polylactic acid as the polymer and chloroform as the solvent, resulting in microspheres with good structure and high encapsulation efficiency.

[0036] In one optional embodiment, the polymer solution contains 8% to 15% by mass of polymer.

[0037] In one alternative embodiment, the polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone.

[0038] In one optional embodiment, the solvent of the polymer solution is at least one of chloroform and dichloroform.

[0039] In one optional implementation, the first time is 1 hour to 3 hours.

[0040] In one optional embodiment, the mass ratio of the gel matrix to the solvent, the thickener, the humectant, and the anesthetic is 0–3:30–99.5:0.5–5:0–60:0–1.

[0041] In one optional embodiment, the volume ratio of the core-shell structured hydroxyapatite calcium microspheres to the gel carrier is 1–5:6–9.

[0042] In one optional embodiment, when preparing the first mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 5 min to 60 min.

[0043] In one optional embodiment, when preparing the second mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 0.5h to 4h.

[0044] In one optional embodiment, when preparing the third mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 3 min to 30 min.

[0045] In one optional embodiment, when preparing the fourth mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 10 min to 30 min.

[0046] In one optional embodiment, the mixing in step S2 is performed by maintaining a stirring temperature of 20°C to 65°C and a stirring time of 5 min to 40 min.

[0047] In one optional embodiment, the solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution.

[0048] In one optional embodiment, the gel matrix is ​​at least one of sodium hyaluronate, carbomer, alginate, collagen, and chitosan; the sodium hyaluronate includes low molecular weight sodium hyaluronate with a molecular weight of 30W to 100W, medium molecular weight sodium hyaluronate with a molecular weight of 120W to 180W, and high molecular weight sodium hyaluronate with a molecular weight of 200W to 250W, wherein the mass ratio of the low molecular weight sodium hyaluronate to the medium molecular weight sodium hyaluronate and the high molecular weight sodium hyaluronate is 0.5 to 3: 0.5 to 5: 1 to 10.

[0049] In one optional embodiment, the thickener is at least one of gelatin, soluble starch, and cellulose derivatives; the cellulose derivatives include at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose.

[0050] In one alternative embodiment, the moisturizer is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol.

[0051] In one optional embodiment, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

[0052] Thirdly, the present invention provides the application of the above-mentioned composite gel containing core-shell structured microspheres in soft tissue filling.

[0053] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0054] 1. The present invention provides a composite gel containing core-shell structured hydroxyapatite calcium microspheres. The composite gel includes a gel carrier and microspheres dispersed in the gel carrier. Each microsphere includes a core and a shell covering the core. The core is a biodegradable polymer, and the shell is hydroxyapatite calcium. The present invention encapsulates hydroxyapatite calcium on the outside of biodegradable polymer microspheres. After implantation, the hydroxyapatite calcium, acting as the shell, first contacts human tissue and degrades into calcium ions and phosphate ions, stimulating only collagen production and achieving tissue remodeling. Meanwhile, the gradually exposed polymer microspheres are also metabolically degraded, preventing them from becoming undegradable and unremovable lumps. Furthermore, the exposure rate of the polymer microspheres can be controlled based on the degradation rate of the hydroxyapatite calcium shell, achieving a long-term, full-filling effect without the need for repeated injections. However, due to the poor heat resistance of the biodegradable polymer, it is prone to deformation during high-temperature sterilization. With the protection of the hydroxyapatite calcium shell, the microspheres will not soften or deform, which helps reduce friction during injection. It also allows for extrusion with finer needles, reducing injection pain and better controlling injection force and volume. Choosing a suitable gel carrier ensures that the microspheres remain suspended before and after sterilization, allowing the composite gel to be pre-filled before use and injected directly, which is more conducive to clinical use and improves the efficiency of clinical use. It also ensures that the composite gel can be stably stored at room temperature without special storage and transportation.

[0055] The gel of the present invention has suitable viscoelasticity, which can make the microspheres uniformly suspended. After being injected into the human body, the microspheres are still uniformly dispersed in the gel, making it difficult for the microspheres to aggregate and clump. After the gel carrier is degraded and absorbed, the hydroxyapatite calcium as the shell is also degraded to expose the core polylactic acid microspheres, thereby reducing the formation of solid tissues.

[0056] The present invention forms a dense shell on the outside of the polymer, which can reduce the aggregation of biodegradable polymers and obtain microspheres with smooth surfaces that are easy to inject and do not easily clump together.

[0057] The control of microsphere size mainly considers the migration and injectability of microspheres in vivo. The core-shell structured hydroxyapatite calcium microspheres of this invention have a particle size of 15μm to 150μm. The microspheres are suspended in a gel carrier and pre-filled into a syringe. The finer the needle used for injection, the less painful the injection. When the microspheres are smaller than 15μm, they are prone to agglomeration and are easily phagocytosed by cells and eliminated through the lymphatic system after implantation, making it difficult to play a role. When the microspheres are larger than 150μm, the microspheres are too large to pass through the injection needle, which can easily cause needle blockage.

[0058] 2. The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided by this invention utilizes sodium carboxymethyl cellulose, which has strong adhesion, ensuring good tissue integration after injection. The addition of a humectant provides lubrication, reducing friction during injection and allowing for better control of injection force and volume with finer needles, thus alleviating injection pain. The addition of a thickener overcomes the poor adhesion of tissue filler materials, ensuring strong positional stability after injection and preventing migration. The gel is prepared at room temperature, allowing for stable storage without special storage or transportation. Furthermore, the gel is pre-filled before use, facilitating direct injection and improving clinical efficiency.

[0059] 3. The method for preparing a composite gel containing core-shell structured hydroxyapatite calcium microspheres provided by the present invention involves adding hydroxyapatite calcium, biodegradable polymer spheres, and polyethylene glycol to a mixed solvent of water and alcohol, mixing them, so that the hydroxyapatite calcium coats the surface of the biodegradable polymer spheres, thereby obtaining core-shell structured hydroxyapatite calcium microspheres; adding the above-prepared core-shell structured hydroxyapatite calcium microspheres to a gel carrier, and mixing thoroughly. The present invention uses a sol-gel polymerization method to uniformly coat hydroxyapatite calcium onto a biodegradable polymer, resulting in a relatively uniform and smooth surface, and uniform dispersion in the carrier gel for soft tissue filling.

[0060] Hydroxyapatite calcium is uniformly deposited layer by layer under the action of polyethylene glycol to form completely encapsulated and dense microspheres; polyethylene glycol can solve the agglomeration problem in the preparation process of hydroxyapatite calcium, modify the surface of hydroxyapatite calcium, and maintain its shape. Attached Figure Description

[0061] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0062] Figure 1 This is a SEM image of the core-shell structured hydroxyapatite calcium microspheres prepared in Example 1 of this invention.

[0063] Figure 2 This is a high-magnification SEM image of the core-shell structured hydroxyapatite calcium microspheres prepared in Example 1 of this invention.

[0064] Figure 3 This shows the aggregation of hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 1 of this invention.

[0065] Figure 4 This shows the aggregation of hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 2 of this invention.

[0066] Figure 5 This shows the aggregation of hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 3 of this invention.

[0067] Figure 6 This shows the aggregation of hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 4 of this invention.

[0068] Figure 7 This shows the aggregation of hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 5 of this invention.

[0069] Figure 8 This is a microscopic image of the aggregated hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 1 of this invention.

[0070] Figure 9 This is a microscopic image of the aggregated hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 2 of the present invention.

[0071] Figure 10 This is a microscopic image of the aggregated hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 3 of the present invention.

[0072] Figure 11 This is a microscopic image of the aggregated hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 4 of the present invention.

[0073] Figure 12 This is a microscopic image of the aggregated hydroxyapatite calcium microspheres with a core-shell structure prepared in Example 5 of the present invention.

[0074] Figure 13 These are sample images of gels 1-3 prepared according to the present invention and control gel 1.

[0075] Figure 14 These are microscopic images of Gel No. 1 after sterilization according to the present invention.

[0076] Figure 15 These are microscopic images of Gel No. 2 after sterilization according to the present invention.

[0077] Figure 16 These are microscopic images of Gel No. 3 after sterilization according to the present invention.

[0078] Figure 17 These are microscopic images of the comparative gel No. 1 after sterilization according to the present invention.

[0079] Figure 18 This is a schematic diagram of the gel injection points of the present invention.

[0080] Figure 19 The filling effect of gels 1-3 of this invention and comparative gels 1-2 after 1 week of injection is shown.

[0081] Figure 20 The filling effect of gels 1-3 of this invention and comparative gels 1-2 one month after injection is shown. Detailed Implementation

[0082] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0083] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0084] Existing injectable composite microspheres have a porous structure and rough surface, resulting in weak mechanical strength, rapid degradation, and an inability to maintain a long-term filling effect. Furthermore, after high-temperature sterilization, the microspheres are prone to deformation, making subsequent injections more difficult.

[0085] Therefore, this invention provides a composite gel containing core-shell structured hydroxyapatite calcium microspheres. The composite gel includes a gel carrier and microspheres dispersed within the gel carrier. Each microsphere includes a core and a shell covering the core. The core is a biodegradable polymer, and the shell is hydroxyapatite calcium. This invention encapsulates hydroxyapatite calcium on the outside of biodegradable polymer microspheres. After implantation, the hydroxyapatite calcium, acting as the shell, first contacts human tissue and degrades into calcium and phosphate ions, stimulating collagen production and achieving tissue remodeling. Meanwhile, the gradually exposed polymer microspheres are also metabolically degraded, preventing them from becoming undegradable and removable lumps. Furthermore, the exposure rate of the polymer microspheres can be controlled based on the degradation rate of the hydroxyapatite calcium shell, achieving a long-lasting, full-filling effect without the need for repeated injections. However, due to the poor heat resistance of biodegradable polymers, they are prone to deformation during high-temperature sterilization. With the protection of the hydroxyapatite calcium shell, the microspheres will not soften or deform, which helps reduce friction during injection and allows for extrusion with finer needles, reducing injection pain and allowing for better control of injection force and volume. Choosing a suitable gel carrier ensures that the microspheres remain suspended both before and after sterilization, allowing the composite gel to be pre-filled before use and injected directly, which is more beneficial for clinical use and improves efficiency. It also ensures that the composite gel can be stably stored at room temperature without special storage or transportation. The gel in this application has suitable viscoelasticity, allowing the microspheres to be uniformly suspended. After injection into the human body, the microspheres remain uniformly dispersed in the gel, preventing clumping. After the gel carrier is degraded and absorbed, the hydroxyapatite calcium shell is also degraded, exposing the core polylactic acid microspheres, thus reducing the formation of solid tissue. The core-shell structured hydroxyapatite calcium microspheres prepared in this application are dense spheres, preventing deformation of the composite microspheres after high-temperature sterilization, which would make subsequent injection difficult.

[0086] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0087] In the following examples and comparative examples of the present invention, the molecular weight of polyvinyl alcohol was 20,000-140,000 and it was purchased from Adamas; the average molecular weight of polyacrylic acid was 450,000 and it was purchased from Adamas; the molecular weight of polylactic acid was 60,000 and it was purchased from Adamas; the molecular weight of poly-L-lactic acid was 10,000 and it was purchased from Adamas; and the molecular weight of polycaprolactone was 150,000 and it was purchased from Sigma.

[0088] In the following examples and comparative examples, % represents the mass percentage content.

[0089] Example 1

[0090] The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in this embodiment includes the following steps:

[0091] (1) Preparation of polylactic acid microspheres:

[0092] Prepare 1L of 0.7% polyvinyl alcohol aqueous solution in a container and stir it with an electric stirrer; weigh 11g of polylactic acid and dissolve it in 100mL of chloroform in another container. While stirring, add the polylactic acid chloroform solution to the polyvinyl alcohol aqueous solution. After stirring for 2 hours, heat the solution in a water bath to evaporate the chloroform. After evaporation, wash, filter and dry to obtain polylactic acid microspheres.

[0093] (2) Preparation of hydroxyapatite calcium microspheres with core-shell structure:

[0094] Prepare a 750 mL mixed solution of 2.5% citric acid monohydrate in water and ethanol (volume ratio of water to ethanol is 3:1) in a container, then add 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate. Stir to dissolve, then add ammonia water to adjust the pH of the solution to 10. React for 1 h to form 4.25 g of hydroxyapatite calcium precipitate. Then add 30 g of polyethylene glycol (mass percentage of 4%). After the polyethylene glycol dissolves, add 15 g of polylactic acid microspheres from step (1). After reacting for 3 h, hydroxyapatite calcium is deposited on the surface of polylactic acid microspheres. Finally, wash, filter, and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm. Figure 1 and Figure 2 This is a SEM image of the core-shell structured hydroxyapatite calcium microspheres prepared according to an embodiment of the present invention. As can be seen from the image, the surface structure is dense and non-porous.

[0095] (3) Preparation of gel carrier:

[0096] a. Preparation of PBS buffer: Weigh 138g of sodium dihydrogen phosphate and dissolve it in water, then bring the volume to 1L to obtain a sodium dihydrogen phosphate solution; weigh 142g of disodium hydrogen phosphate and dissolve it in water, then bring the volume to 1L to obtain a disodium hydrogen phosphate solution; mix 390mL of sodium dihydrogen phosphate solution and 610mL of disodium hydrogen phosphate solution evenly to obtain 1L of PBS buffer with a pH of 7.0;

[0097] b. Mix 120g of glycerol and 8.5g of sodium carboxymethyl cellulose and stir at 25°C for 15 minutes using an electric mixer to obtain the first mixture;

[0098] c. Weigh 68.5g of PBS buffer, and add 0.25g of low molecular weight sodium hyaluronate (80W), 0.25g of medium molecular weight sodium hyaluronate (120W), and 0.5g of high molecular weight sodium hyaluronate (220W) in sequence. Stir at 25°C for 3 hours using an electric stirrer to obtain the second mixture.

[0099] d. Add the first mixture to the second mixture and stir at 25°C for 10 minutes to obtain the third mixture;

[0100] e. Weigh 2g of lidocaine hydrochloride and add it to the third mixture. Stir with an electric mixer at 25°C for 15 minutes and let stand for 4 hours to obtain a gel. The contents of each component are: sodium hyaluronate 0.5%, PBS buffer 34.25%, sodium carboxymethyl cellulose 4.25%, glycerol 60%, and lidocaine hydrochloride 1%.

[0101] (4) Preparation of composite gel containing core-shell structured hydroxyapatite calcium microspheres:

[0102] The core-shell structured hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3) and stirred at 25°C for 20 min to obtain a composite gel containing core-shell structured hydroxyapatite calcium microspheres, denoted as Gel No. 1; wherein the volume ratio of core-shell structured hydroxyapatite calcium microspheres to gel carrier was 5:5.

[0103] Example 2

[0104] The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in this embodiment includes the following steps:

[0105] (1) Polylactic acid microspheres were prepared using the same method as in Example 1.

[0106] (2) Preparation of hydroxyapatite calcium microspheres with core-shell structure:

[0107] Prepare a 750 mL mixed solution of 2.5% citric acid monohydrate in water and ethanol (volume ratio of water to ethanol is 2:1) in a container, then add 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate. Stir to dissolve, then add ammonia water to adjust the pH of the solution to 10. React for 1 h to form 4.25 g of hydroxyapatite calcium precipitate. Then add 30 g of polyethylene glycol (mass percentage of 4%). After the polyethylene glycol dissolves, add 25 g of polylactic acid microspheres from step (1). After reacting for 3 h, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, wash, filter, and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0108] (3) Preparation of gel carrier:

[0109] a. Preparation of glucose solution: Weigh 25g of glucose, add it to water and dissolve it, then make up to 500mL.

[0110] b. Mix 10g of butanediol and 6g of gelatin, and stir at 65°C for 60 minutes using an electric mixer to obtain the first mixture;

[0111] c. Weigh 177.8g of glucose solution, add 6g of collagen, and stir at 20°C for 4 hours using an electric mixer to obtain the second mixture;

[0112] d. Mix the first mixture with the second mixture and stir at 20°C for 25 minutes to obtain the third mixture;

[0113] e. Weigh 0.2g of ropivacaine hydrochloride and add it to the third mixture. Stir with an electric mixer at 45°C for 10 minutes and let stand for 4 hours to obtain a gel. The contents of each component are: collagen 3%, glucose 88.9%, gelatin 3%, butylene glycol 5%, and ropivacaine hydrochloride 0.1%.

[0114] (4) Preparation of composite gel containing core-shell structured hydroxyapatite calcium microspheres:

[0115] The core-shell structured hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3) and stirred at 50°C for 5 min to obtain a composite gel containing core-shell structured hydroxyapatite calcium microspheres, denoted as Gel No. 2; wherein the volume ratio of core-shell structured hydroxyapatite calcium microspheres to gel carrier was 2:8.

[0116] Example 3

[0117] The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in this embodiment includes the following steps:

[0118] (1) Polylactic acid microspheres were prepared using the same method as in Example 1.

[0119] (2) Preparation of hydroxyapatite calcium microspheres with core-shell structure:

[0120] Prepare a 750 mL mixed solution of 2.5% citric acid monohydrate in water and ethanol (volume ratio of water to ethanol is 3:2) in a container, then add 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate. Stir to dissolve, then add ammonia water to adjust the pH of the solution to 10. React for 1 h to form 4.25 g of hydroxyapatite calcium precipitate. Then add 30 g of polyethylene glycol (mass percentage of 4%). After the polyethylene glycol dissolves, add 42.5 g of polylactic acid microspheres from step (2). After reacting for 3 h, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, wash, filter and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0121] (3) Preparation of gel carrier:

[0122] a. Preparation of sodium chloride solution: Weigh 4.5g of sodium chloride, add it to water and dissolve it, then make up to 500mL.

[0123] b. Mix 60g of sorbitol and 1g of soluble starch, and stir at 50°C for 60 minutes using an electric mixer to obtain the first mixture;

[0124] c. Weigh 136g of sodium chloride solution, add 2g of carbomer, and stir at 50°C for 0.5h using an electric stirrer to obtain the second mixture;

[0125] d. Mix the first mixture with the second mixture and disperse them in a high-speed disperser at 20°C for 5 minutes to obtain the third mixture;

[0126] e. Weigh 1g of tetracaine hydrochloride and add it to the third mixture. Stir with an electric mixer at 20°C for 30 minutes and let stand for 4 hours to obtain a gel. The contents of each component are: carbomer 1%, sodium chloride solution 68%, soluble starch 0.5%, sorbitol 30%, and tetracaine hydrochloride 0.5%.

[0127] (4) Preparation of composite gel containing core-shell structured hydroxyapatite calcium microspheres:

[0128] The core-shell structured hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3) and stirred at 30°C for 40 min to obtain a composite gel containing core-shell structured hydroxyapatite calcium microspheres, denoted as Gel No. 3; wherein the volume ratio of core-shell structured hydroxyapatite calcium microspheres to gel carrier was 2:8.

[0129] Example 4

[0130] The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in this embodiment includes the following steps:

[0131] (1) Preparation of poly-L-lactic acid microspheres:

[0132] Prepare 1L of 3% polyacrylic acid aqueous solution in a container and stir it with an electric stirrer; weigh 8g of poly-L-lactic acid and dissolve it in 100mL of chloroform in another container. While stirring, add the poly-L-lactic acid chloroform solution to the polyacrylic acid aqueous solution and stir for 1 hour. Then, heat the solution in a water bath to evaporate the chloroform. After evaporation, wash, filter and dry to obtain poly-L-lactic acid microspheres.

[0133] (2) Preparation of hydroxyapatite calcium microspheres with core-shell structure:

[0134] Prepare a 750 mL mixed solution of 2% citric acid monohydrate in water and ethanol (volume ratio of water to ethanol is 3:1) in a container, then add 5 g of calcium chloride and 3.86 g of disodium hydrogen phosphate. Stir to dissolve, then add sodium hydroxide to adjust the pH of the solution to 9. React for 1 h to form 5 g of hydroxyapatite calcium precipitate. Then add 34 g of polyethylene glycol (mass percentage of 4.5%). After the polyethylene glycol dissolves, add 35 g of poly(L-lactic acid) microspheres from step (1). After reacting for 3 h, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, wash, filter and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0135] (3) Preparation of gel carrier:

[0136] Weigh 196g of water for injection, add 4g of methylcellulose, stir at 20℃ for 60min using an electric mixer, and let stand for 4h to obtain a gel. The contents of each component are: water for injection 98% and methylcellulose 2%.

[0137] (4) Preparation of composite gel containing core-shell structured hydroxyapatite calcium microspheres:

[0138] The core-shell structured hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3), and stirred at 25°C for 20 min to obtain a composite gel containing core-shell structured hydroxyapatite calcium microspheres, denoted as Gel No. 4; wherein the volume ratio of core-shell structured hydroxyapatite calcium microspheres to gel carrier was 1:9.

[0139] Example 5

[0140] The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in this embodiment includes the following steps:

[0141] (1) Preparation of polycaprolactone microspheres:

[0142] Prepare a 1L 5% polyvinyl alcohol aqueous solution in a container and stir it with an electric stirrer; in another container, weigh 15g of polycaprolactone and dissolve it in 100mL of chloroform. While stirring, add the polycaprolactone chloroform solution to the polyvinyl alcohol aqueous solution. After stirring for 2 hours, heat the solution in a water bath to evaporate the chloroform. After evaporation, wash, filter, and dry to obtain polycaprolactone microspheres.

[0143] (2) Preparation of hydroxyapatite calcium microspheres with core-shell structure:

[0144] Prepare a 750 mL solution of 3% citric acid monohydrate in water and ethanol (volume ratio of water to ethanol is 3:1) in a container. Then add 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate ((NH4)2HPO4). Stir to dissolve and then add ammonia water to adjust the pH of the solution to 11. React for 1 h to form 4.25 g of hydroxyapatite calcium precipitate. Then add 30 g of polyethylene glycol (mass percentage of 4%). After the polyethylene glycol dissolves, add 20 g of polycaprolactone microspheres from step (1). After reacting for 3 h, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, wash, filter and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0145] (3) Preparation of gel carrier:

[0146] a. Preparation of PBS buffer: Weigh 138g of sodium dihydrogen phosphate and dissolve it in water, then bring the volume to 1L to obtain a sodium dihydrogen phosphate solution; weigh 142g of disodium hydrogen phosphate and dissolve it in water, then bring the volume to 1L to obtain a disodium hydrogen phosphate solution; mix 390mL of sodium dihydrogen phosphate solution and 610mL of disodium hydrogen phosphate solution evenly to obtain 1L of PBS buffer with a pH of 7.0;

[0147] b. Mix 52g of propylene glycol and 8g of oxidized cellulose, and stir at 35°C for 5 minutes using an electric mixer to obtain the first mixture;

[0148] c. Weigh 140g of PBS buffer and mix it with the first mixture. Use an electric stirrer to stir at 20°C for 30 minutes and let it stand for 4 hours to obtain a gel. The contents of each component are: PBS buffer 70%, oxidized cellulose 4%, and propylene glycol 26%.

[0149] (4) Preparation of composite gel containing core-shell structured hydroxyapatite calcium microspheres:

[0150] The core-shell structured hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3), and stirred at 25°C for 20 min to obtain a composite gel containing core-shell structured hydroxyapatite calcium microspheres, denoted as Gel No. 5; wherein the volume ratio of core-shell structured hydroxyapatite calcium microspheres to gel carrier was 2:8.

[0151] Comparative Example 1

[0152] This comparative example provides a composite gel containing polylactic acid microspheres, and its preparation method is as follows:

[0153] The polylactic acid microspheres prepared in Example 1 were added to the carrier gel prepared in Example 1 and stirred at 25°C for 20 min to obtain a composite gel containing polylactic acid microspheres, which was designated as control gel 1; wherein the volume ratio of polylactic acid microspheres to gel carrier was 5:6.

[0154] Comparative Example 2

[0155] This comparative example provides a composite gel containing hydroxyapatite calcium microspheres, and its preparation method is as follows:

[0156] The purchased hydroxyapatite calcium was mixed in the gel carrier prepared in step (3) of Example 1 at a volume ratio of 5:6 between microspheres and gel carrier, and was designated as control gel 2.

[0157] Experimental Example 1

[0158] The core-shell structured hydroxyapatite calcium microspheres prepared in Examples 1 to 5 were immersed in freshly prepared TRIS-HCl buffer solution with pH = 7.4 at a mass ratio of 1:20 for degradation at a degradation temperature of 37°C. The aggregation of microspheres was observed after 6 months.

[0159] Figures 3-7 The images show the agglomeration of the core-shell structured hydroxyapatite calcium microspheres prepared in Examples 1 to 5. It can be seen that the microspheres are all in a dispersed state and are in powder form, with no obvious agglomeration. Figure 3 A few needle-like crystals were observed.

[0160] Figures 8-12 The images show the agglomeration of hydroxyapatite calcium microspheres with core-shell structure prepared in Examples 1 to 5. It can be seen that the microspheres are relatively uniformly dispersed and there are no obvious agglomerations.

[0161] Experimental Example 2

[0162] Sample images of gels 1-3 prepared in this invention and control gel 1 are shown below. Figure 13 As shown in the figure, it can be seen that compared to gels 1, gel 1 is more difficult to maintain its shape and appears more cloudy than gels 1-3.

[0163] Gels 1-3 and control gel 1 were separately placed into high-temperature and high-pressure resistant glass bottles, then sterilized in a 121℃ autoclave for 30 minutes. Their morphology was then observed under a microscope. Figures 14-17 As shown. Figures 14-16 These are microscopic images of gels 1-3 after sterilization. As can be seen from the images, the microspheres are evenly distributed and all maintain a basically spherical shape. Figure 17 Comparing the microscopic images of Gel No. 1 after sterilization, it can be seen that about 80% of the microspheres cannot maintain their spherical shape, and the distribution of microspheres is extremely uneven, making subsequent injections more difficult.

[0164] The sterilized gel was filled into 1mL syringes. Each syringe was equipped with 18G and 22G needles. The extrusion force generated by the gel was expelled through the injection needles of the 18G and 22G needles at a speed of 30mm / min. The results are shown in the table below.

[0165] Table 1. Measurement results of the extrusion force of gels 1-5 and control gel 1.

[0166]

[0167] As can be seen from the table above, the finer the needle size, the greater the extrusion force. For 18G injection needles, the extrusion force of gels 1-5 after sterilization is 6.1-11 G / N, and the gels in the syringe can be smoothly extruded. Compared with sterilized gels 1-5, the extrusion force of control gel 1 after sterilization is greater, and it will cause needle tip blockage when using a 22G needle. This may be due to the deformation of microspheres after sterilization, resulting in irregular shapes that increase particle size and uneven distribution in the gel, leading to needle blockage. Compared with gels 1-2, the extrusion force of gels 3-5 is smaller, which may be due to the larger volume of the core-shell structured hydroxyapatite calcium microspheres prepared in Examples 3-5 compared to the gel (gel 1). In addition, the content of thickener in the gel substrate is also an important factor affecting the extrusion force of the gel. Too little thickener will affect the uniform suspension of microspheres in the gel, while too much will increase the extrusion force of the gel (gel 2). When using an 18G injection needle, there is not much difference in the pushing force between gels 1-2 and gels 3-5. When using a finer 22G injection needle, the pushing force is greater for gel 1 than gel 2, and greater for gel 3 than gel 4 than gel 5. This is because finer injection needles are more sensitive to the viscoelasticity of the gel during the pushing process. The difference in gel viscoelasticity is due to the use of different gel carrier ratios to suspend microspheres of different volumes. The more microspheres added, the greater the viscoelasticity of the gel carrier needs to be, and the greater the viscoelasticity, the greater the pushing force required.

[0168] Experimental Example 3

[0169] The control gel No. 2 was sterilized according to the sterilization requirements in Experiment Example 2, placed into a high-temperature and high-pressure resistant glass bottle, and sterilized in a high-pressure steam sterilizer at 121°C for 30 minutes. At the same time, the sterilized gels No. 1-3 from Experiment Example 2 and the control gel No. 1 were injected subcutaneously into the tissues on both sides of the spine on the back of rabbits under aseptic conditions. Figure 18 The diagram shows the injection points. An 18G injection needle was used, and the injection volume was 0.3 mL. The filling effect of the injection site was observed 24 hours, 1 week, and 1 month after injection.

[0170] Observation 24 hours after injection: No redness, swelling, ecchymosis or allergic reaction were observed at injection sites 1-3; slight erythema was observed at injection sites of contrast gel 1 and contrast gel 2, which was relieved after applying ice.

[0171] Observation after 1 week of injection Figure 19 As shown, the filling effect of injection point 1 of the contrast gel was not obvious because it was difficult to maintain a fixed shape after injection; the injection point of contrast gel 2 showed redness and swelling, and a hardened clump of microspheres could be found by light touch; injection points 1-3 showed no redness, swelling, bruising, or allergic reactions and had obvious filling effects.

[0172] Observation one month after injection Figure 20 As shown, no filler was observed at injection point 1 of the gel, with slight redness and swelling, and the microspheres degraded or shifted, failing to achieve the filling effect at the injection point; at injection point 2 of the gel, the hardened lumps shifted, causing redness and ecchymosis, failing to achieve the filling effect at the injection point; injection points 1-3 showed no displacement, the microspheres degraded slowly, and there was a significant filling effect.

[0173] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite gel containing core-shell structured hydroxyapatite calcium microspheres, characterized in that, The composite gel includes a gel carrier and microspheres dispersed in the gel carrier. Each microsphere includes a core and a shell covering the core. The core is a biodegradable polymer, and the shell is calcium hydroxyapatite. The particle size of the microspheres is 15 μm to 150 μm. The method for preparing the composite gel containing core-shell structured microspheres includes the following steps: S1. Prepare hydroxyapatite calcium and biodegradable polymer spheres separately. Add the hydroxyapatite calcium, the biodegradable polymer spheres and polyethylene glycol to a mixed solvent of water and alcohol, mix, so that the hydroxyapatite calcium coats the surface of the biodegradable polymer spheres, and obtain core-shell structured hydroxyapatite calcium microspheres. S2. Prepare a gel carrier by adding the core-shell structured hydroxyapatite calcium microspheres obtained in step S1 to the gel carrier and mixing them thoroughly.

2. The composite gel containing core-shell structured hydroxyapatite calcium microspheres according to claim 1, characterized in that, The mass ratio of the polymer to the calcium hydroxyapatite is 1:0.1 to 0.3; And / or, the biodegradable polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone.

3. The composite gel containing core-shell structured hydroxyapatite calcium microspheres according to claim 1, characterized in that, The gel carrier comprises a gel matrix, solvent, thickener, humectant, and anesthetic in a mass ratio of 0–3:30–99.5:0.5–5:0–60:0–1. And / or, the volume ratio of the microspheres to the gel carrier is 1-5:6-9.

4. The composite gel containing core-shell structured hydroxyapatite calcium microspheres according to claim 3, characterized in that, The solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution; And / or, the gel matrix is ​​at least one of sodium hyaluronate, carbomer, alginate, collagen, and chitosan; And / or, the thickener is at least one of gelatin, soluble starch, and cellulose derivatives; And / or, the moisturizer is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol; And / or, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

5. The composite gel containing core-shell structured hydroxyapatite calcium microspheres according to claim 4, characterized in that, The sodium hyaluronate includes low molecular weight sodium hyaluronate with a molecular weight of 30W to 100W, medium molecular weight sodium hyaluronate with a molecular weight of 120W to 180W, and high molecular weight sodium hyaluronate with a molecular weight of 200W to 250W. The mass ratio of the low molecular weight sodium hyaluronate to the medium molecular weight sodium hyaluronate and the high molecular weight sodium hyaluronate is 0.5 to 3: 0.5 to 5: 1 to 10. And / or, the cellulose derivative includes at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose.

6. A method for preparing a composite gel containing core-shell structured microspheres, characterized in that, Includes the following steps: S1. Prepare hydroxyapatite calcium and biodegradable polymer spheres separately. Add the hydroxyapatite calcium, the biodegradable polymer spheres and polyethylene glycol to a mixed solvent of water and alcohol, mix, so that the hydroxyapatite calcium coats the surface of the biodegradable polymer spheres, and obtain core-shell structured hydroxyapatite calcium microspheres. S2. Prepare a gel carrier by adding the core-shell structured hydroxyapatite calcium microspheres obtained in step S1 to the gel carrier and mixing them thoroughly.

7. The method for preparing the composite gel containing core-shell structured microspheres according to claim 6, characterized in that, In the mixing system of step S1, the mass percentage of polyethylene glycol is 4% to 5%; and / or, The mixing time in step S1 is 2h-4h; and / or, The mass ratio of the biodegradable polymer spheres to the calcium hydroxyapatite is 1:0.1–0.3; and / or, The method for preparing the hydroxyapatite calcium includes: adding citric acid, a calcium source, and a phosphorus source to a mixed solvent of water and ethanol, adjusting the pH of the system to 9-11 to allow the reaction to occur, and the resulting precipitate is hydroxyapatite calcium; and / or, The method for preparing the biodegradable polymer spheres includes: preparing an aqueous stabilizer solution and a polymer solution respectively; adding the polymer solution to the aqueous stabilizer solution while it is being continuously stirred; continuing stirring for a first time; and then heating the mixture to evaporate the solvent to obtain polymer spheres; and / or, The preparation method of the gel carrier includes: adding a thickener to a humectant and mixing to obtain a first mixture; mixing a gel matrix with a solvent to obtain a second mixture; adding the first mixture to the second mixture and mixing to obtain a third mixture; adding an anesthetic to the third mixture and mixing to obtain a fourth mixture, which is the gel carrier.

8. The method for preparing the composite gel containing core-shell structured microspheres according to claim 7, characterized in that, In the preparation system of calcium hydroxyapatite, the mass percentage of citric acid is 2% to 3%. And / or, in the mixed solvent, the volume ratio of water to ethanol is 3:1-2; And / or, the mass ratio of the calcium source to the phosphorus source is 5-10:3-4; And / or, the calcium source is at least one of calcium nitrate and calcium chloride; And / or, the phosphorus source is at least one of diammonium hydrogen phosphate, sodium phosphate, and disodium hydrogen phosphate; And / or, the stabilizer in the aqueous solution contains 0.7% to 5% by mass; And / or, the stabilizer is at least one of polyvinyl alcohol and polyacrylic acid; And / or, the polymer solution contains 8% to 15% by mass of polymer; And / or, the polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone; And / or, the solvent of the polymer solution is at least one of chloroform and dichloroform; And / or, the first time is 1 hour to 3 hours; And / or, the mass ratio of the gel matrix to the solvent, the thickener, the humectant, and the anesthetic is 0–3:30–99.5:0.5–5:0–60:0–1; And / or, the volume ratio of the core-shell structured hydroxyapatite calcium microspheres to the gel carrier is 1-5:6-9; And / or, when preparing the first mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 5 min to 60 min; And / or, when preparing the second mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 0.5h to 4h; And / or, when preparing the third mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 3 min to 30 min; And / or, when preparing the fourth mixture, the stirring temperature is maintained at 20°C to 65°C, and the stirring time is 10 min to 30 min; And / or, the mixing in step S2 is performed with the stirring temperature maintained at 20℃~65℃ and the stirring time at 5min~40min.

9. The method for preparing the composite gel containing core-shell structured microspheres according to claim 7, characterized in that, The solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution; And / or, the gel matrix is ​​at least one of sodium hyaluronate, carbomer, alginate, collagen, and chitosan; the sodium hyaluronate includes low molecular weight sodium hyaluronate with a molecular weight of 30W to 100W, medium molecular weight sodium hyaluronate with a molecular weight of 120W to 180W, and high molecular weight sodium hyaluronate with a molecular weight of 200W to 250W, wherein the mass ratio of the low molecular weight sodium hyaluronate to the medium molecular weight sodium hyaluronate and the high molecular weight sodium hyaluronate is 0.5 to 3: 0.5 to 5: 1 to 10; And / or, the thickener is at least one of gelatin, soluble starch, and cellulose derivatives; the cellulose derivatives include at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose. And / or, the moisturizer is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol; And / or, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

10. The application of the composite gel containing core-shell structured hydroxyapatite calcium microspheres as described in any one of claims 1 to 5, or the composite gel containing core-shell structured microspheres prepared by the preparation method described in any one of claims 6 to 9, in soft tissue filling.

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