Composite gel containing calcium hydroxyapatite microspheres having a core-shell structure, preparation method therefor, and use thereof

Abstract

The present application relates to the technical field of biomedical materials, and in particular, to a composite gel containing calcium hydroxyapatite microspheres having a core-shell structure, a preparation method therefor, and a use thereof. The composite gel comprises a gel carrier and microspheres dispersed in the gel carrier, the microspheres each comprise a core and a shell layer covering the core, the core is a biodegradable polymer, and the shell layer is calcium hydroxyapatite. After the composite gel containing calcium hydroxyapatite microspheres having a core-shell structure of the present application is implanted, calcium hydroxyapatite first comes into contact with human tissue and is degraded into calcium ions and phosphate ions, to stimulate collagen production for tissue remodeling; subsequently, the biodegradable polymer is also metabolically degraded; in addition, the degradation rate of calcium hydroxyapatite can control the exposure rate of the polymer microspheres, to achieve a long-term full filling effect. The gel has suitable viscoelasticity, so that the composite microspheres are uniformly suspended, and after being injected into a human body, the microspheres are still evenly dispersed in the gel.

Description

Composite gel containing core-shell structured calcium hydroxyapatite microspheres, preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on September 21, 2023, with application number 202311228107.7 and invention name “A composite gel containing core-shell structured hydroxyapatite calcium microspheres, preparation method and application thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of biomedical materials, and in particular to a composite gel containing core-shell structured calcium hydroxyapatite microspheres, a preparation method and applications thereof. Background Art

[0004] Due to injury and aging, the human body can experience local soft tissue laxity and loss, sometimes even leading to loss of soft tissue function. Clinically, local soft tissue augmentation can be used to treat this problem. Tissue augmentation materials are injected into the area in need of augmentation, restoring the tissue to its original shape and function.

[0005] Calcium hydroxyapatite, also known as hydroxyapatite, is an inherent component of the human body with excellent biocompatibility, making it a highly effective material for soft tissue filling. However, the solubility of calcium hydroxyapatite under physiological conditions is extremely low, and dense calcium hydroxyapatite, in particular, exhibits an even lower biodegradation rate. Existing dense calcium hydroxyapatite injectable microspheres, after injection into the body, gradually crystallize and harden in large quantities at the injection site, forming new solid tissue. This causes the injection site to become stiff and the lump difficult to remove. Forcible removal of the lump can damage nerves and blood vessels, resulting in deformities and depressions at the removal site.

[0006] Therefore, how to optimize and improve the structure of hydroxyapatite calcium injection microspheres and their preparation method to obtain hydroxyapatite calcium microspheres that will not aggregate and harden after implantation, have good microsphere dispersibility and stability, degrade slowly, maintain a long-term filling effect, and are resistant to high-temperature sterilization and easy to inject, is a technical problem that needs to be solved urgently in this field.

[0007] Summary of the Invention

[0008] In view of this, the primary purpose of the present application is to provide a composite gel containing core-shell structured hydroxyapatite calcium microspheres, wherein hydroxyapatite calcium is coated on the outside of biodegradable polymer microspheres. After implantation, the hydroxyapatite calcium as the shell first contacts human tissue and degrades into calcium ions and phosphate ions, thereby stimulating only the production of collagen and achieving tissue remodeling. At this time, the exposed biodegradable polymer microspheres can also be metabolically degraded and will not become hard lumps that cannot be degraded or removed. In addition, the exposure rate of the high-molecular polymer microspheres can be controlled according to the degradation rate of the hydroxyapatite calcium shell, so that a long-term plumping filling effect can be achieved without repeated injections. injection; since high molecular polymer microspheres have poor heat resistance and are easily deformed during high-temperature sterilization, with the protection of the calcium hydroxyapatite shell, the microspheres will not soften and deform, which is beneficial to reduce the friction during injection, and can also be extruded with a finer injection needle, reducing injection pain and better controlling the injection force and injection volume; selecting a suitable gel carrier can not only maintain appropriate viscoelasticity before and after sterilization to maintain the suspended state of the microspheres, but also make the composite gel filled in a pre-filled state before use, and can be directly injected when used, which is more conducive to clinical use, thereby effectively improving the efficiency of clinical use, and can also ensure that the composite gel can be stably stored in a room temperature environment without the need for special storage and transportation.

[0009] Another object of the present application is to provide a method for preparing the composite gel containing the core-shell structured calcium hydroxyapatite microspheres.

[0010] Another object of the present application is to provide an application of the composite gel containing core-shell structured calcium hydroxyapatite microspheres in soft tissue filling.

[0011] In the first aspect, the present application provides a composite gel containing core-shell structured hydroxyapatite calcium microspheres, wherein the composite gel includes a gel carrier and microspheres dispersed in the gel carrier, wherein the microspheres include a core and a shell layer coated on the outside of the core, wherein the core is a biodegradable polymer and the shell layer is hydroxyapatite calcium; the particle size of the microspheres is 15 μm to 150 μm.

[0012] In an optional embodiment, the mass ratio of the polymer to the calcium hydroxyapatite is 1:0.1-0.3.

[0013] In an optional embodiment, the biodegradable polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone.

[0014] In an optional embodiment, the gel carrier includes a gel matrix, a solvent, a thickener, a moisturizer, and an anesthetic in a mass ratio of 0-3:30-99.5:0.5-5:0-60:0-1. The thickener and the solvent can form a gel. The thickener has the functions of adhesion, suspending, thickening, emulsification, and sustained release, and can achieve the application effect when mixed with the solvent.

[0015] In an optional embodiment, the volume ratio of the microspheres to the gel carrier is 1-5:6-9. In the composite gel, it is the microsphere part that ultimately plays a filling effect. The density of the core-shell structure microspheres prepared in different ratios will be different. This application calculates the mass based on the volume ratio and then mixes them.

[0016] In an optional embodiment, the solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution.

[0017] In an optional embodiment, the gel matrix is ​​at least one of sodium hyaluronate, carbomer, alginate, collagen, and chitosan.

[0018] In an optional embodiment, the thickener is at least one of gelatin, soluble starch, and cellulose derivatives.

[0019] In an optional embodiment, the moisturizing agent is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol.

[0020] In an optional embodiment, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

[0021] In an optional embodiment, 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, and 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 0.5-3:0.5-5:1-10.

[0022] In an optional embodiment, the cellulose derivative includes at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose.

[0023] In a second aspect, the present application provides a method for preparing a composite gel containing core-shell structured microspheres, comprising the following steps:

[0024] S1. hydroxyapatite calcium and biodegradable polymer spheres are prepared separately, and the hydroxyapatite calcium, the biodegradable polymer spheres and polyethylene glycol are added to a mixed solvent of water and alcohol, and mixed so that the hydroxyapatite calcium is coated on the surface of the biodegradable polymer spheres to obtain core-shell structured hydroxyapatite calcium microspheres;

[0025] S2. Prepare a gel carrier, add the core-shell structured calcium hydroxyapatite microspheres prepared in step S1 into the gel carrier, and mix well.

[0026] In an optional embodiment, in the mixing system of step S1, the mass percentage of polyethylene glycol is 4% to 5%.

[0027] In an optional embodiment, the mixing time in step S1 is 2 hours to 4 hours.

[0028] In an optional embodiment, the mass ratio of the biodegradable polymer spheres to the calcium hydroxyapatite is 1:0.1-0.3.

[0029] In an optional embodiment, the preparation method of calcium hydroxyapatite includes: adding citric acid, a calcium source and a phosphorus source to a mixed solvent of water and ethanol, adjusting the pH value of the system to 9-11 for reaction, and the resulting precipitate is calcium hydroxyapatite.

[0030] In an optional embodiment, the method for preparing the biodegradable polymer spheres includes: separately preparing a stabilizer aqueous solution and a polymer solution, adding the polymer solution to the stabilizer aqueous solution under continuous stirring, continuing stirring for a first time, and then heating the mixed system to evaporate the solvent to obtain polymer spheres.

[0031] In an optional embodiment, the preparation method of the gel carrier includes: adding a thickener to a moisturizer in at least three times, mixing, and obtaining a first mixture; mixing a gel matrix with a solvent to obtain a second mixture; adding the first mixture to the second mixture, mixing, and obtaining a third mixture; adding an anesthetic to the third mixture, mixing, and obtaining a fourth mixture, which is the gel carrier.

[0032] In an optional embodiment, in the preparation system of calcium hydroxyapatite, the mass percentage of citric acid is 2% to 3%. Citric acid can maintain the stability of the system, reduce the formation of impurities such as calcium oxide, and is conducive to the formation of uniform and well-dispersed calcium hydroxyapatite.

[0033] In an optional 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.

[0034] And / or, the mass ratio of the calcium source to the phosphorus source is 5-10:3-4.

[0035] In an optional embodiment, the calcium source is at least one of calcium nitrate and calcium chloride.

[0036] In an optional embodiment, the phosphorus source is at least one of diammonium hydrogen phosphate, sodium phosphate, and disodium hydrogen phosphate.

[0037] In an optional embodiment, the mass percentage of the stabilizer in the stabilizer aqueous solution is 0.7% to 5%.

[0038] In an optional embodiment, the stabilizer is at least one of polyvinyl alcohol and polyacrylic acid; preferably polyvinyl alcohol, because the water molecules of polyvinyl alcohol have hydrophilic and lipophilic structures, they are adsorbed on the surface of polymer particles to form a protective film, reduce interfacial tension and increase the viscosity of the system (medium). Therefore, the polyvinyl alcohol aqueous solution is used as a stabilizer in the emulsion polymerization process, and cooperates with the polymer to improve the stability of the emulsion polymerization system. The particle size of the microspheres is controlled by adjusting the mass percentage of the polyvinyl alcohol aqueous solution, and the uniformity of the particle size distribution and the ball-forming effect are further controlled. Microspheres can be prepared using different organic solvents and polymers during the preparation process; the choice of solvent will affect the raw material content of the polymer microspheres, as well as the subsequent solvent residue problem; the choice of polymer will affect the surface morphology and particle size of the microspheres; when preparing polylactic acid microspheres, the present application uses polylactic acid as the polymer and chloroform as the solvent, and the obtained microspheres have a good structure and a high encapsulation rate.

[0039] In an optional embodiment, the mass percentage of the polymer in the polymer solution is 8% to 15%.

[0040] In an optional embodiment, the polymer is at least one of polylactic acid, poly-L-lactic acid, and polycaprolactone.

[0041] In an optional embodiment, the solvent of the polymer solution is at least one of chloroform and dichloromethane.

[0042] In an optional implementation, the first time is 1 hour to 3 hours.

[0043] In an optional embodiment, the mass ratio of the gel matrix to the solvent, the thickener, the moisturizer, and the anesthetic is 0-3:30-99.5:0.5-5:0-60:0-1.

[0044] In an optional embodiment, the volume ratio of the core-shell structured calcium hydroxyapatite microspheres to the gel carrier is 1-5:6-9.

[0045] In an 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.

[0046] In an optional embodiment, when preparing the second mixture, the stirring temperature is maintained at 20° C. to 65° C., and the stirring time is 0.5 h to 4 h.

[0047] In an 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.

[0048] In an 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.

[0049] In an optional embodiment, the mixing in step S2 is performed by maintaining the stirring temperature at 20° C. to 65° C. and the stirring time at 5 min to 40 min.

[0050] In an optional embodiment, the solvent is at least one of water for injection, PBS buffer, glucose, and sodium chloride aqueous solution.

[0051] In an 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, and 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.

[0052] In an optional embodiment, the thickener is at least one of gelatin, soluble starch, and a cellulose derivative; the cellulose derivative includes at least one of sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, and oxidized cellulose.

[0053] In an optional embodiment, the moisturizing agent is at least one of glycerin, propylene glycol, butylene glycol, and sorbitol.

[0054] In an optional embodiment, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

[0055] In a third aspect, the present application provides the use of the composite gel containing core-shell structured microspheres in soft tissue filling.

[0056] Compared with the existing technology, the technical solution of this application has the following advantages:

[0057] 1. The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided by the present application comprises a gel carrier and microspheres dispersed in the gel carrier, the microspheres comprising a core and a shell coating the outside of the core, the core being a biodegradable polymer, and the shell being hydroxyapatite calcium. The present application wraps hydroxyapatite calcium on the outside of biodegradable polymer microspheres. After implantation, the hydroxyapatite calcium serving as the shell first comes into contact with human tissue and degrades into the form of calcium ions and phosphate ions, stimulating only collagen production to achieve tissue remodeling. At this time, the gradually exposed polymer microspheres are also metabolically degraded and will not become lumps that cannot be degraded or removed. Moreover, the exposure rate of the high-molecular polymer microspheres can be controlled according to the degradation rate of the hydroxyapatite calcium shell, so that it can achieve a long-term, full-filling effect without the need for repeated injections. Due to the poor heat resistance of biodegradable polymers, they are easily deformed during high-temperature sterilization. With the protection of the calcium hydroxyapatite shell, the microspheres will not soften and deform, which is beneficial to reducing the friction during injection. They can also be extruded with a finer-gauge injection needle, reducing injection pain and better controlling the injection force and injection volume. Choosing a suitable gel carrier can not only maintain appropriate viscoelasticity before and after sterilization to maintain the suspended state of the microspheres, but also make the composite gel filled in a pre-filled state before use and directly injected when used, which is more conducive to clinical use, thereby effectively improving the efficiency of clinical use, and can also ensure that the composite gel can be stably stored in a room temperature environment without the need for special storage and transportation.

[0058] The gel of the present application has suitable viscoelasticity, which allows the microspheres to be evenly suspended. After injection into the human body, the microspheres are still evenly 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 serving as the shell is also degraded, exposing the core polylactic acid microspheres, thereby reducing the formation of solid tissue.

[0059] The present application forms a dense shell layer on the outside of the polymer, which can reduce the agglomeration of the biodegradable polymer and obtain microspheres with a smooth surface, good injection properties, and low agglomeration.

[0060] The control of microsphere size mainly considers the migration and injectability of the microspheres in the body. The particle size of the core-shell structured hydroxyapatite calcium microspheres of the present application is 15μm to 150μm. The microspheres are suspended in a gel carrier and pre-filled in a syringe. The thinner the needle used for injection, the less painful the injection. When the microspheres are smaller than 15μm, the microspheres are prone to agglomeration and are easily phagocytosed by cells and eliminated through the lymphatic system after implantation in the body, 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, and needle clogging is likely to occur.

[0061] 2. The composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in the present application uses sodium carboxymethyl cellulose with strong adhesion, so that the gel can better fit the tissue after injection; the addition of a moisturizer can exert its lubricating properties, reduce the friction during injection, and can be extruded with a finer-gauge injection needle, better control the injection force and injection volume, and reduce the pain of injection; the addition of a thickener solves the disadvantage of poor adhesion of tissue filling materials, so that the material has strong positional stability after being injected into the tissue and will not wander or shift; the gel of the present application is prepared at room temperature, so it can be stably stored in a room temperature environment and does not require special storage and transportation; in addition, the gel prepared in the present application is filled in a pre-filled state before use and can be directly injected when used, which is more conducive to clinical use, thereby effectively improving the efficiency of clinical use.

[0062] 3. The preparation method of the composite gel containing core-shell structured hydroxyapatite calcium microspheres provided in the present application is as follows: hydroxyapatite calcium, biodegradable polymer spheres, and polyethylene glycol are added to a mixed solvent of water and alcohol, and the mixture is mixed so that the hydroxyapatite calcium is coated on the surface of the biodegradable polymer spheres to obtain core-shell structured hydroxyapatite calcium microspheres; the core-shell structured hydroxyapatite calcium microspheres prepared above are added to a gel carrier and mixed evenly. The present application adopts a sol-gel polymerization method to uniformly coat the hydroxyapatite calcium on the biodegradable polymer, and the surface is relatively uniform and smooth, and the hydroxyapatite calcium is evenly dispersed in the carrier gel for soft tissue filling;

[0063] Under the action of polyethylene glycol, calcium hydroxyapatite is uniformly deposited layer by layer to form completely encapsulated and dense microspheres; polyethylene glycol can solve the agglomeration problem in the preparation process of calcium hydroxyapatite, modify the surface of calcium hydroxyapatite, and maintain its shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0065] FIG1 is an SEM image of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 1 of the present application.

[0066] FIG2 is a high-magnification SEM image of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 1 of the present application.

[0067] FIG3 shows the agglomeration of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 1 of the present application.

[0068] FIG4 shows the agglomeration of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 2 of the present application.

[0069] FIG5 shows the agglomeration of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 3 of the present application.

[0070] FIG6 shows the agglomeration of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 4 of the present application.

[0071] FIG7 shows the agglomeration of calcium hydroxyapatite microspheres having a core-shell structure prepared in Example 5 of the present application.

[0072] FIG8 is a microscopic image of agglomeration of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 1 of the present application.

[0073] FIG9 is a microscopic image of agglomeration of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 2 of the present application.

[0074] FIG10 is a microscopic image of agglomeration of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 3 of the present application.

[0075] FIG11 is a microscopic image of agglomerates of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 4 of the present application.

[0076] FIG12 is a microscopic image of agglomeration of calcium hydroxyapatite microspheres containing a core-shell structure prepared in Example 5 of the present application.

[0077] FIG13 is a sample diagram of gels No. 1 to No. 3 prepared in the present application and comparative gel No. 1.

[0078] FIG14 is a microscopic image of the sterilized gel No. 1 of the present application.

[0079] FIG15 is a microscopic image of the sterilized gel No. 2 of the present application.

[0080] FIG16 is a microscopic image of the sterilized gel No. 3 of the present application.

[0081] FIG17 is a microscopic image of the comparative gel No. 1 of the present application after sterilization.

[0082] FIG18 is a schematic diagram of the gel injection point of the present application.

[0083] FIG19 shows the filling effects of the present application's gel No. 1-3 and the comparative gel No. 1-2 one week after injection.

[0084] FIG20 shows the filling effects of the present application's gel No. 1-3 and the comparative gel No. 1-2 one month after injection. DETAILED DESCRIPTION

[0085] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0086] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0087] The surface of existing injectable composite microspheres is a porous structure with a rough surface, weak mechanical strength, rapid degradation, and inability to maintain a long-term filling effect; and after high-temperature sterilization, the microspheres are easily deformed, making subsequent injection more difficult.

[0088] To this end, the present application provides a composite gel containing core-shell structured hydroxyapatite calcium microspheres, the composite gel comprising a gel carrier and microspheres dispersed in the gel carrier, the microspheres comprising a core and a shell coating the outside of the core, the core being a biodegradable polymer, and the shell being hydroxyapatite calcium. The present application wraps hydroxyapatite calcium on the outside of biodegradable polymer microspheres, and after implantation, the hydroxyapatite calcium serving as the shell first comes into contact with human tissue and degrades into the form of calcium ions and phosphate ions, stimulating only collagen production to achieve tissue remodeling; at this time, the gradually exposed polymer microspheres are also metabolically degraded and will not become lumps that cannot be degraded or removed, and the exposure rate of the high-molecular polymer microspheres can be controlled according to the degradation rate of the hydroxyapatite calcium shell, so that it can achieve a long-term, full-filling effect without the need for repeated injections; since the heat resistance of biodegradable polymers is poor, they are easily deformed during high-temperature sterilization. With the protection of the hydroxyapatite calcium shell, the microspheres will not soften and deform, which is beneficial to reducing the friction during injection, and can also be extruded with a finer-gauge injection needle, reducing the pain of injection and better controlling the injection force and injection volume; selecting a suitable gel carrier can not only maintain the appropriate viscoelasticity before and after sterilization to maintain the suspended state of the microspheres, so that the composite gel is filled into a pre-filled state before use and injected directly when used, which is more conducive to clinical use, thereby effectively improving the efficiency of clinical use, and can also ensure that the composite gel can be stably stored in a room temperature environment without the need for special storage and transportation. The gel of the present application has appropriate viscoelasticity, which can make the microspheres evenly suspended. After being injected into the human body, the microspheres are still evenly 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 tissue. The core-shell structured hydroxyapatite calcium microspheres prepared in the present application are dense spheres, which avoid the composite microspheres from being easily deformed after high-temperature sterilization, making subsequent injection more difficult.

[0089] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0090] In the following examples and comparative examples of the present application, the molecular weight of polyvinyl alcohol is 20,000-140,000, purchased from Adamas; the average molecular weight of polyacrylic acid is 450,000, purchased from Adamas; the molecular weight of polylactic acid is 60,000, purchased from Adamas; the molecular weight of poly-L-lactic acid is 10,000, purchased from Adamas; and the molecular weight of polycaprolactone is 150,000, purchased from Sigma.

[0091] % in the following examples and comparative examples represents mass percentage.

[0092] Example 1

[0093] The composite gel containing core-shell calcium hydroxyapatite microspheres provided in this embodiment comprises the following steps:

[0094] (1) Preparation of polylactic acid microspheres:

[0095] Prepare 1L of 0.7% polyvinyl alcohol aqueous solution in a container and stir it with an electric stirrer; weigh 11g of polylactic acid in another container and dissolve it in 100mL of chloroform. While stirring, add the chloroform solution of polylactic acid to the polyvinyl alcohol aqueous solution. After stirring for 2 hours, heat the solution in a water bath to volatilize the chloroform in the solution. After volatilization, wash, filter, and dry to obtain polylactic acid microspheres.

[0096] (2) Preparation of calcium hydroxyapatite microspheres with core-shell structure:

[0097] Prepare 750mL of a mixed solution of 2.5% monohydrated citric acid in water and ethanol (the volume ratio of water to ethanol is 3:1) in a container, then add 9.98g of calcium nitrate tetrahydrate and 3.34g of diammonium hydrogen phosphate, stir to dissolve, add ammonia water to adjust the solution pH to 10, react for 1 hour, and form 4.25g of hydroxyapatite calcium precipitate, then add 30g of polyethylene glycol (mass percentage is 4%), after the polyethylene glycol is dissolved, add 15g of polylactic acid microspheres from step (1), react for 3 hours, and hydroxyapatite calcium is deposited on the surface of the polylactic acid microspheres. Finally, wash, filter, and dry to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15μm-150μm. Figures 1 and 2 are SEM images of the core-shell structured hydroxyapatite calcium microspheres prepared in the examples of the present application. It can be seen from the figures that the surface structure is dense and non-porous.

[0098] (3) Preparation of gel carrier:

[0099] a. PBS buffer preparation: Weigh 138 g of sodium dihydrogen phosphate and dissolve it in water, then dilute to 1 L to obtain a sodium dihydrogen phosphate solution; weigh 142 g of disodium hydrogen phosphate and dissolve it in water, then dilute to 1 L to obtain a disodium hydrogen phosphate solution; mix 390 mL of the sodium dihydrogen phosphate solution and 610 mL of the disodium hydrogen phosphate solution to obtain 1 L of PBS buffer with a pH of 7.0;

[0100] b. Mix 120 g of glycerol and 8.5 g of sodium carboxymethyl cellulose, and stir at 25° C. for 15 min using an electric stirrer to obtain a first mixture;

[0101] c. Weigh 68.5 g of PBS buffer, add 0.25 g of low molecular weight sodium hyaluronate (molecular weight 80W), 0.25 g of medium molecular weight sodium hyaluronate (molecular weight 120W), and 0.5 g of high molecular weight sodium hyaluronate (molecular weight 220W) in sequence, and stir at 25° C. for 3 h using an electric stirrer to obtain a second mixture;

[0102] d. Add the first mixture to the second mixture and stir at 25° C. for 10 min to obtain a third mixture;

[0103] e. Weigh 2 g of lidocaine hydrochloride and add it to the third mixture. Stir with an electric stirrer at 25°C for 15 minutes. Let it stand for 4 hours to obtain a gel. The contents of the components are as follows: 0.5% sodium hyaluronate, 34.25% PBS buffer, 4.25% sodium carboxymethyl cellulose, 60% glycerol, and 1% lidocaine hydrochloride.

[0104] (4) Preparation of composite gel containing core-shell structured calcium hydroxyapatite microspheres:

[0105] The core-shell 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 hydroxyapatite calcium microspheres, which was recorded as gel No. 1; wherein the volume ratio of the core-shell hydroxyapatite calcium microspheres to the gel carrier was 5:5.

[0106] Example 2

[0107] The composite gel containing core-shell calcium hydroxyapatite microspheres provided in this embodiment comprises the following steps:

[0108] (1) Polylactic acid microspheres were prepared using the same method as in Example 1.

[0109] (2) Preparation of calcium hydroxyapatite microspheres with core-shell structure:

[0110] A mixed solution of 750 mL of 2.5% citric acid monohydrate in water and ethanol (the volume ratio of water to ethanol is 2:1) is prepared in a container, and then 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate are added. After stirring to dissolve, ammonia water is added to adjust the pH of the solution to 10. The mixture is reacted for 1 hour to form 4.25 g of hydroxyapatite calcium precipitate. Then 30 g of polyethylene glycol (4% by mass) is added. After the polyethylene glycol is dissolved, 25 g of the polylactic acid microspheres of step (1) are added. After reacting for 3 hours, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, the microspheres are washed, filtered, and dried to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0111] (3) Preparation of gel carrier:

[0112] a. Preparation of glucose solution: weigh 25g of glucose and dissolve it in water, then dilute to 500mL;

[0113] b. Mix 10 g of butanediol and 6 g of gelatin, use an electric stirrer, and stir at 65° C. for 60 min to obtain a first mixture;

[0114] c. Weigh 177.8 g of glucose solution, add 6 g of collagen, and stir using an electric stirrer at 20° C. for 4 h to obtain a second mixture;

[0115] d. mixing the first mixture and the second mixture, and stirring at 20° C. for 25 min to obtain a third mixture;

[0116] e. Weigh 0.2 g of ropivacaine hydrochloride and add it to the third mixture. Use an electric stirrer to stir at 45° C. for 10 minutes. Let it stand for 4 hours to obtain a gel. The contents of each component are: 3% collagen, 88.9% glucose, 3% gelatin, 5% butylene glycol, and 0.1% ropivacaine hydrochloride.

[0117] (4) Preparation of composite gel containing core-shell structured calcium hydroxyapatite microspheres:

[0118] The core-shell hydroxyapatite calcium microspheres prepared in step (2) were added to the carrier gel prepared in step (3), and stirred at 50° C. for 5 minutes to obtain a composite gel containing core-shell hydroxyapatite calcium microspheres, which was recorded as gel No. 2; wherein the volume ratio of the core-shell hydroxyapatite calcium microspheres to the gel carrier was 2:8.

[0119] Example 3

[0120] The composite gel containing core-shell calcium hydroxyapatite microspheres provided in this embodiment comprises the following steps:

[0121] (1) Polylactic acid microspheres were prepared using the same method as in Example 1.

[0122] (2) Preparation of calcium hydroxyapatite microspheres with core-shell structure:

[0123] A mixed solution of 750 mL of 2.5% citric acid monohydrate in water and ethanol (the volume ratio of water to ethanol is 3:2) is prepared in a container, and then 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate are added. After stirring to dissolve, ammonia water is added to adjust the pH of the solution to 10. The mixture is reacted for 1 hour to form 4.25 g of hydroxyapatite calcium precipitate. Then 30 g of polyethylene glycol (4% by mass) is added. After the polyethylene glycol is dissolved, 42.5 g of polylactic acid microspheres from step (2) are added. After reacting for 3 hours, hydroxyapatite calcium is deposited on the surface of the microspheres. Finally, the microspheres are washed, filtered, and dried to obtain hydroxyapatite calcium microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0124] (3) Preparation of gel carrier:

[0125] a. Preparation of sodium chloride solution: Weigh 4.5g of sodium chloride and dissolve it in water, then dilute to 500mL.

[0126] b. Mix 60 g of sorbitol and 1 g of soluble starch, use an electric stirrer, and stir at 50° C. for 60 min to obtain a first mixture;

[0127] c. Weigh 136 g of sodium chloride solution, add 2 g of carbomer, and stir at 50° C. for 0.5 h using an electric stirrer to obtain a second mixture;

[0128] d. Mix the first mixture and the second mixture, and disperse them in a high-speed disperser at 20° C. for 5 minutes to obtain a third mixture;

[0129] e. Weigh 1 g of tetracaine hydrochloride and add it to the third 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 the components are: carbomer 1%, sodium chloride solution 68%, soluble starch 0.5%, sorbitol 30%, and tetracaine hydrochloride 0.5%.

[0130] (4) Preparation of composite gel containing core-shell structured calcium hydroxyapatite microspheres:

[0131] The core-shell 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 hydroxyapatite calcium microspheres, which was recorded as gel No. 3; wherein the volume ratio of the core-shell hydroxyapatite calcium microspheres to the gel carrier was 2:8.

[0132] Example 4

[0133] The composite gel containing core-shell calcium hydroxyapatite microspheres provided in this embodiment comprises the following steps:

[0134] (1) Preparation of poly (L-lactic acid) microspheres:

[0135] 1 L of a 3% polyacrylic acid aqueous solution was prepared in a container and stirred using an electric stirrer. In another container, 8 g of poly (L-lactic acid) was weighed and dissolved in 100 mL of chloroform. While stirring, the chloroform solution of poly (L-lactic acid) was added to the polyacrylic acid aqueous solution. After stirring for 1 hour, the chloroform in the solution was heated in a water bath to evaporate the chloroform. After evaporation, the solution was washed, filtered, and dried to obtain poly (L-lactic acid) microspheres.

[0136] (2) Preparation of core-shell calcium hydroxyapatite microspheres:

[0137] A mixed solution of 750 mL of 2% monohydrated citric acid in water and ethanol (the volume ratio of water to ethanol is 3:1) is prepared in a container, and then 5 g of calcium chloride and 3.86 g of disodium hydrogen phosphate are added. After stirring to dissolve, sodium hydroxide is added to adjust the pH of the solution to 9. The reaction is carried out for 1 hour to form 5 g of calcium hydroxyapatite precipitate. Then 34 g of polyethylene glycol (4.5% by mass) is added. After the polyethylene glycol is dissolved, 35 g of poly (L-lactic acid) microspheres prepared in step (1) are added. After reacting for 3 hours, calcium hydroxyapatite is deposited on the surface of the microspheres. Finally, the microspheres are washed, filtered, and dried to obtain calcium hydroxyapatite microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0138] (3) Preparation of gel carrier:

[0139] Weigh 196 g of water for injection, add 4 g of methyl cellulose, use an electric stirrer, stir at 20° C. for 60 min, and let it stand for 4 h to obtain a gel. The content of each component is: 98% water for injection and 2% methyl cellulose.

[0140] (4) Preparation of composite gel containing core-shell structured calcium hydroxyapatite microspheres:

[0141] The core-shell 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 hydroxyapatite calcium microspheres, which was recorded as gel No. 4; wherein the volume ratio of the core-shell hydroxyapatite calcium microspheres to the gel carrier was 1:9.

[0142] Example 5

[0143] The composite gel containing core-shell calcium hydroxyapatite microspheres provided in this embodiment comprises the following steps:

[0144] (1) Preparation of polycaprolactone microspheres:

[0145] Prepare 1L of 5% polyvinyl alcohol aqueous solution in a container and stir with an electric stirrer; weigh 15g of polycaprolactone in another container and dissolve it in 100mL of chloroform. While stirring, add the chloroform solution of polycaprolactone to the polyvinyl alcohol aqueous solution. After stirring for 2 hours, heat in a water bath to volatilize the chloroform in the solution. After volatilization, wash, filter, and dry to obtain polycaprolactone microspheres.

[0146] (2) Preparation of calcium hydroxyapatite microspheres with core-shell structure:

[0147] A mixed solution of 750 mL of 3% monohydrated citric acid in water and ethanol (the volume ratio of water to ethanol is 3:1) is prepared in a container, and then 9.98 g of calcium nitrate tetrahydrate and 3.34 g of diammonium hydrogen phosphate ((NH4)2HPO4) are added. After stirring to dissolve, ammonia water is added to adjust the pH of the solution to 11. The solution is reacted for 1 hour to form 4.25 g of calcium hydroxyapatite precipitate. Then, 30 g of polyethylene glycol (4% by mass) is added. After the polyethylene glycol is dissolved, 20 g of polycaprolactone microspheres prepared in step (1) are added. After reacting for 3 hours, calcium hydroxyapatite is deposited on the surface of the microspheres. Finally, the microspheres are washed, filtered, and dried to obtain calcium hydroxyapatite microspheres with a core-shell structure and a particle size of 15 μm-150 μm.

[0148] (3) Preparation of gel carrier:

[0149] a. PBS buffer preparation: Weigh 138 g of sodium dihydrogen phosphate and dissolve it in water, then dilute to 1 L to obtain a sodium dihydrogen phosphate solution; weigh 142 g of disodium hydrogen phosphate and dissolve it in water, then dilute to 1 L to obtain a disodium hydrogen phosphate solution; mix 390 mL of the sodium dihydrogen phosphate solution and 610 mL of the disodium hydrogen phosphate solution to obtain 1 L of PBS buffer with a pH of 7.0;

[0150] b. Mix 52 g of propylene glycol and 8 g of oxidized cellulose, and stir at 35° C. for 5 min using an electric stirrer to obtain a first mixture;

[0151] c. Weigh 140 g of PBS buffer solution and mix it with the first mixture. Use an electric stirrer to stir at 20° C. for 30 minutes. Let it stand for 4 hours to obtain a gel. The content of each component is: 70% PBS buffer solution, 4% oxidized cellulose, and 26% propylene glycol.

[0152] (4) Preparation of composite gel containing core-shell structured calcium hydroxyapatite microspheres:

[0153] The core-shell 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 hydroxyapatite calcium microspheres, which was recorded as gel No. 5; wherein the volume ratio of the core-shell hydroxyapatite calcium microspheres to the gel carrier was 2:8.

[0154] Comparative Example 1

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

[0156] 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 comparative gel No. 1. The volume ratio of the polylactic acid microspheres to the gel carrier was 5:6.

[0157] Comparative Example 2

[0158] This comparative example provides a composite gel containing calcium hydroxyapatite microspheres, and its preparation method is as follows:

[0159] The purchased calcium hydroxyapatite was mixed with the gel carrier prepared in step (3) of Example 1 at a volume ratio of 5:6 between microspheres and gel carrier, and recorded as comparative gel No. 2.

[0160] Experimental Example 1

[0161] The core-shell calcium hydroxyapatite microspheres prepared in Examples 1 to 5 were immersed in a newly prepared TRIS-HCl buffer solution with a mass ratio of 1:20 at pH 7.4 for degradation at a degradation temperature of 37° C. The agglomeration of the microspheres was observed after 6 months.

[0162] Figures 3 to 7 show the agglomeration of the core-shell calcium hydroxyapatite microspheres prepared in Examples 1 to 5. It can be seen that the microspheres are all in a dispersed state and in powder form without obvious agglomeration. Only a few needle-shaped crystals are observed in Figure 3.

[0163] FIG8 to FIG12 are microscopic images of the agglomeration of calcium hydroxyapatite microspheres with a core-shell structure prepared in Examples 1 to 5. It can be seen that the microspheres are dispersed relatively evenly without obvious agglomeration.

[0164] Experimental Example 2

[0165] Sample images of gels No. 1 to No. 3 prepared in the present application and comparative gel No. 1 are shown in FIG13 . From the figure, it can be seen that comparative gel No. 1 is more difficult to maintain a fixed shape and its appearance looks more turbid than gels No. 1 to No. 3.

[0166] Gels 1-3 and Comparative Gel 1 were placed in high-temperature and autoclavable glass bottles and sterilized in an autoclave at 121°C for 30 minutes. Their morphologies were then observed under a microscope, as shown in Figures 14-17. Figures 14-16 show microscopic images of Gels 1-3 after sterilization. As can be seen, the microspheres are evenly distributed and largely maintain their spherical shape. Figure 17 shows a microscopic image of Comparative Gel 1 after sterilization, showing that approximately 80% of the microspheres failed to maintain their spherical shape and that their distribution was extremely uneven, making subsequent injection difficult.

[0167] The sterilized gel was filled into 1 mL syringes, each equipped with an 18G and a 22G needle. The pushing force generated by squeezing the prepared gel through the 18G and 22G needles at a speed of 30 mm / min was shown in the table below.

[0168] Table 1 Pushing force measurement results of gels No. 1-5 and comparative gel No. 1

[0169] As can be seen from the above table, the thinner the needle size, the greater the pushing force; for an 18G injection needle, the pushing force of the sterilized samples of gels No. 1 to 5 is 6.1-11G / N, and the gel in the syringe can be squeezed out smoothly; compared with the sterilized gels No. 1 to 5, the sterilized comparative gel No. 1 has a larger pushing force, and will cause needle tip clogging when using a 22G needle. This may be due to the deformation of the microspheres after sterilization, and the irregular shape causes the particle size to increase, resulting in uneven distribution in the gel, leading to needle clogging; compared with gels No. 1-2, the pushing force of gels No. 3-5 is smaller, which may be due to the larger volume of the core-shell structured hydroxyapatite calcium microspheres prepared in Example 3-5 and the gel (Gel No. 1); in addition, the content of the thickener in the gel matrix is ​​also an important factor affecting the pushing force of the gel. Too little thickener will affect the uniform suspension of the microspheres in the gel, and too much will increase the pushing force of the gel (Gel No. 2). When using an 18G injection needle, there is not much difference in pushing force between gels No. 1-2 and gels No. 3-5. When using a thinner 22G injection needle, the pushing force of No. 1 is greater than that of No. 2, and the pushing force of No. 3 is greater than that of No. 4 and greater than that of No. 5. This is because thinner 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 is required, and the greater the viscoelasticity, the greater the pushing force required.

[0170] Experimental Example 3

[0171] Comparative Gel No. 2 was placed into a high-temperature and high-pressure resistant glass bottle according to the sterilization requirements of Experimental Example 2 and sterilized in a high-pressure steam sterilizer at 121°C for 30 minutes. At the same time, Gels No. 1-3 and Comparative Gel No. 1 sterilized in Experimental Example 2 were injected into the subcutaneous tissue on both sides of the rabbit's spine under sterile conditions. Figure 18 is a schematic diagram of the injection point. 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.

[0172] Observation 24 hours after injection showed no redness, swelling, ecchymosis, etc. at the injection sites of gels 1-3, and no allergic reaction; there were slight erythema at the injection sites of contrast gels 1 and 2, which was relieved after ice compress.

[0173] Observations one week after injection are shown in Figure 19. Comparative gel No. 1 injection site had no obvious filling effect because it was difficult to maintain a fixed shape after injection; comparative gel No. 2 injection site had redness and swelling, and a light touch revealed a hardened agglomeration of microspheres at the injection site; injection sites No. 1-3 had no redness, swelling, bruises, etc., and no allergic reactions, indicating a significant filling effect.

[0174] Observations one month after injection are shown in Figure 20. In contrast, no filler was observed at the injection site of gel No. 1, but there was slight redness and swelling, and the microspheres were degraded or shifted, and the filling effect on the injection site was not achieved. In contrast, the hardened agglomerates at the injection site of gel No. 2 were shifted, causing redness, swelling and bruises, and the filling effect on the injection site was not achieved. There was no displacement at injection sites 1-3, the microspheres degraded slowly, and there was a significant filling effect.

[0175] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A composite gel containing core-shell structured calcium hydroxyapatite microspheres, characterized in that: The composite gel comprises a gel carrier and microspheres dispersed in the gel carrier, wherein the microspheres comprise a core and a shell layer coated outside the core, the core is a biodegradable polymer, and the shell layer is calcium hydroxyapatite; the particle size of the microspheres is 15 μm to 150 μm.

2. The composite gel containing core-shell structured calcium hydroxyapatite microspheres according to claim 1, characterized in that: The mass ratio of the polymer to the calcium hydroxyapatite is 1:0.1-0.3; 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 calcium hydroxyapatite microspheres according to claim 1, characterized in that: The gel carrier comprises a gel matrix, a solvent, a thickener, a moisturizer, and an 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 calcium hydroxyapatite 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 moisturizing agent is at least one of glycerol, 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 calcium hydroxyapatite 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, and 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: The steps include: S1, preparing calcium hydroxyapatite and biodegradable polymer spheres respectively, adding the calcium hydroxyapatite, the biodegradable polymer spheres and polyethylene glycol into a mixed solvent of water and alcohol, and mixing them so that the calcium hydroxyapatite is coated on the surface of the biodegradable polymer spheres to obtain core-shell structured calcium hydroxyapatite microspheres; S2, preparing a gel carrier, adding the core-shell structured calcium hydroxyapatite microspheres obtained in step S1 into the gel carrier, and mixing well.

7. The method for preparing the composite gel containing core-shell structure microspheres according to claim 6, characterized in that: In the mixed 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 sphere to the calcium hydroxyapatite is 1:0.1-0.3; and / or, The preparation method of calcium hydroxyapatite comprises: adding citric acid, a calcium source and a phosphorus source to a mixed solvent of water and ethanol, adjusting the pH value of the system to 9-11 to react, and the resulting precipitate is calcium hydroxyapatite; and / or, The method for preparing the biodegradable polymer sphere comprises: preparing a stabilizer aqueous solution and a polymer solution respectively, adding the polymer solution to the stabilizer aqueous solution which is being continuously stirred, continuing stirring for a first time, and then heating the mixed system to volatilize the solvent to obtain the polymer sphere; and / or, The preparation method of the gel carrier includes: adding a thickener to a moisturizer, mixing, and obtaining a first mixture; mixing a gel matrix with a solvent, obtaining a second mixture; adding the first mixture to the second mixture, mixing, and obtaining a third mixture; adding an anesthetic to the third mixture, mixing, and obtaining a fourth mixture, which is the gel carrier.

8. The method for preparing the composite gel containing core-shell structure 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 mass percentage of the stabilizer in the stabilizer aqueous solution is 0.7% to 5%; And / or, the stabilizer is at least one of polyvinyl alcohol and polyacrylic acid; And / or, the mass percentage of the polymer in the polymer solution is 8% to 15%; 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 dichloromethane; And / or, the first time is 1h to 3h; and / or, the mass ratio of the gel matrix to the solvent, the thickener, the moisturizer, 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 calcium hydroxyapatite 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 5min to 60min; and / or, when preparing the second mixture, the stirring temperature is maintained at 20° C. to 65° C., and the stirring time is 0.5 h to 4 h; 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 at a stirring temperature of 20° C. to 65° C. and a stirring time of 5 min to 40 min.

9. The method for preparing the composite gel containing core-shell structure 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, and 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 sodium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, oxidized cellulose, One less; And / or, the moisturizing agent is at least one of glycerol, propylene glycol, butylene glycol, and sorbitol; And / or, the anesthetic is at least one of lidocaine hydrochloride, tetracaine hydrochloride, and ropivacaine hydrochloride.

10. Use of the composite gel containing core-shell calcium hydroxyapatite microspheres according to any one of claims 1 to 5 or the composite gel containing core-shell microspheres prepared by the preparation method according to any one of claims 6 to 9 in soft tissue filling.

Images