Preparation method of biphase calcium phosphate hollow microspheres

Abstract

The invention belongs to the field of medical materials. The preparation method comprises the following steps: S1, preparing a K2HPO4 solution with the pH (Potential of Hydrogen) of 8 to 12 and the concentration of 0.25 M or a K2HPO4 solution with the pH of 7 to 12 and the concentration of 0.1 M; s2, Li-Ca-B glass microspheres are prepared, the Li-Ca-B glass microspheres and the phosphate solution in the step S1 are mixed, the mixture is heated to react for 2-4 days, and calcium-deficient hydroxyapatite hollow microspheres are obtained; s3, washing and drying the calcium-deficient hydroxyapatite hollow microspheres; and S4, calcining the dried calcium-deficient hydroxyapatite hollow microspheres to obtain the biphase calcium phosphate hollow microspheres. According to the preparation method disclosed by the invention, the biphase calcium phosphate hollow microspheres with different proportions of HA / beta-TCP can be prepared, the dynamic balance of material performance is realized, and meanwhile, the prepared biphase calcium phosphate hollow microspheres have gradient pores and can promote the repair of bone tissues.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical materials, and particularly relates to a preparation method of biphasic calcium phosphate hollow microspheres. BACKGROUND

[0002] Biphasic calcium phosphate (BCP) is a composite biomaterial composed of two different calcium phosphate phases (usually hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP)). Hydroxyapatite (HA) has a calcium to phosphorus ratio (Ca / P) of 1.67, a structure highly similar to human bone mineral, excellent biocompatibility and bone conductivity, but extremely slow degradation (more than 5 years for complete degradation in vivo). Beta-tricalcium phosphate (β-TCP) has a Ca / P ratio of 1.5, a faster degradation rate (6-24 months), but lower mechanical strength, and is prone to losing support too early.

[0003] Currently, the methods for preparing biphasic calcium phosphate microspheres include sintering, hydrothermal synthesis, and template method. The sintering method converts HA and β-TCP precursors into a biphasic structure by adjusting the sintering temperature and time, but high temperature (>800℃) easily leads to grain coarsening, and the porosity is limited (<50%). The hydrothermal method synthesizes nanoscale biphasic microspheres by adding a morphology control agent in a high-pressure hydrothermal environment, avoiding damage to drug activity at high temperature, but the dense shell hinders drug release. The template method uses calcium carbonate microspheres as templates to generate a multi-shell HA / β-TCP hollow structure through ion exchange reaction, achieving phased control of the degradation rate, but template residues (such as CaO >2wt.%) will reduce biocompatibility. Traditional microspheres are mainly closed or small pores (<50μm), which will hinder cell infiltration (such as bone volume fraction of only 12.3% when the pore size is <100μm), and the ratio of HA to β-TCP will affect the degradation rate, and different application fields or implantation sites have different requirements for the degradation rate. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method of biphasic calcium phosphate hollow microspheres. The present application can prepare biphasic calcium phosphate hollow microspheres with different ratios of hydroxyapatite (HA) to beta-tricalcium phosphate (β-TCP) by adjusting the phosphate concentration and pH value, so that the biphasic calcium phosphate hollow microspheres have different degradation rates to meet different application scenarios.

[0005] The technical solution adopted by the present application to solve the above problems is as follows:

[0006] A preparation method of biphasic calcium phosphate hollow microspheres, comprising the following steps:

[0007] S1. preparing a K2HPO4 solution with a pH of 8-12 and a concentration of 0.25M or a K2HPO4 solution with a pH of 7-12 and a concentration of 0.1M;

[0008] S2. Preparing Li-Ca-B glass microspheres, mixing the obtained Li-Ca-B glass microspheres with the phosphate solution obtained in step S1, controlling the temperature to be 37℃, and reacting for 2-4 days under stirring to obtain calcium-deficient hydroxyapatite hollow microspheres;

[0009] S3. Washing the calcium-deficient hydroxyapatite hollow microspheres obtained in step S2, and drying after washing;

[0010] S4. Calcining the calcium-deficient hydroxyapatite hollow microspheres obtained in step S3 to obtain biphasic calcium phosphate hollow microspheres.

[0011] Through the above technical solution, with the dissolution of the Li-Ca-B glass microspheres, the Ca+ released from the Li-Ca-B glass microspheres reacts with the phosphate anions transported by the reaction layer in the aqueous solution, and the calcium phosphate layer grows from the surface to the inside to form calcium-deficient hydroxyapatite hollow microspheres. Then, the calcium-deficient hydroxyapatite hollow microspheres are calcined and heated to their decomposition to obtain calcium phosphate hollow microspheres. By adjusting the concentration and pH value of the phosphate solution, the types of phosphate anions in the solution can be controlled to obtain calcium-deficient hydroxyapatite hollow microspheres with different calcium-phosphorus ratios Ca / P, thereby preparing biphasic calcium phosphate hollow microspheres with a hydroxyapatite (HA) / β-tricalcium phosphate (β-TCP) ratio of 20:80 to 50:50. In the preparation process, the reaction of Li-Ca-B glass microspheres with a phosphate solution with a concentration of 0.25M or 0.1M is relatively mild, and finally biphasic calcium phosphate hollow microspheres with a relatively loose porous pore structure and a relatively fast degradation rate can be obtained. Using a too high concentration of the phosphate solution or increasing the reaction temperature of the Li-Ca-B glass microspheres and the phosphate solution will cause the hollow pore diameter of the final product biphasic calcium phosphate hollow microspheres to decrease sharply, and the shell structure to be sparse; on the contrary, if a too low concentration of the phosphate solution or a reduced reaction temperature is used, the hollow pore diameter of the biphasic calcium phosphate hollow microspheres will increase, and the outermost layer of the shell will be too dense, which are all not conducive to the growth of tissue cells. The biphasic calcium phosphate hollow microspheres prepared by the preparation method of the present application not only have a multi-level pore structure to promote vascularization and cell infiltration, but also can be prepared in different proportions to have different degradation rates to meet different application scenarios.

[0012] Further, the composition of the Li-Ca-B glass microspheres is CaO: 15wt%, Li2O: 11wt%, and B2O3: 74wt%.

[0013] Further, the mixing mass-volume ratio of the Li-Ca-B glass microspheres and the phosphate solution is 1g of Li-Ca-B glass microspheres to 200mL of phosphate solution.

[0014] Through the technical scheme, the reaction of the Li-Ca-B glass microspheres and the phosphate solution is more rapid and sufficient at a ratio of 1 g of the Li-Ca-B glass microspheres to 200 mL of the phosphate solution, and the formation of the hollow porous microsphere structure of the biphasic calcium phosphate hollow microsphere is promoted.

[0015] Further, the stirring speed in step S2 is 50-100 r / min.

[0016] Further, the washing in step S3 is performed with deionized water and anhydrous ethanol in sequence.

[0017] Preferably, the washing in step S3 is performed with deionized water for three times and then with anhydrous ethanol for three times.

[0018] Further, the drying treatment comprises first drying and second drying; the temperature of the first drying is 25℃, and the time is ≥12 h; the temperature of the second drying is 90℃, and the time is ≥12 h.

[0019] Through the technical scheme, the first drying can prevent the washed calcium-deficient hydroxyapatite hollow microspheres from being prone to agglomeration, and the second drying can make the residual liquid after washing be fully volatilized.

[0020] Further, the proportion of hydroxyapatite (HA) to β-tricalcium phosphate (β-TCP) in the biphasic calcium phosphate hollow microspheres obtained in step S4 is 20:80 to 50:50.

[0021] Further, the calcination temperature is 800℃, and the calcination time is 5 h. The calcination can make the biphasic calcium phosphate hollow microspheres be fully decomposed and converted into different phase proportions of HA / β-TCP hollow microspheres.

[0022] Through the technical scheme, 800℃ can ensure that the carbonated hydroxyapatite (CDHA) is converted into biphasic calcium phosphate, and lower than 800℃ cannot make the carbonated hydroxyapatite (CDHA) be converted, and higher than 800℃ can make the outermost shell layer of the biphasic calcium phosphate hollow microspheres be very dense and almost have no pore structure, which is not conducive to the growth of tissue cells. The calcination for 5 hours can retain the hollow structure of the biphasic calcium phosphate hollow microspheres while increasing the degradation rate of the biphasic calcium phosphate hollow microspheres, and as the shell structure is gradually opened, the dissolved Ca and P and the more porous internal structure are more conducive to the growth of cells.

[0023] Further, the particle size of the Li-Ca-B glass particles is 150-250 μm.

[0024] Further, the preparation method of the Li-Ca-B glass microspheres comprises the following steps:

[0025] A1. Heating CaCO3, LiCO3, H3BO3 to a molten state;

[0026] A2. Quenching the mixture in a molten state obtained in step A1 between stainless steel plates to obtain a Li-Ca-B glass;

[0027] A3. Crushing the Li-Ca-B glass and sieving to obtain Li-Ca-B glass particles;

[0028] A4. Passing the Li-Ca-B glass particles through a vertical furnace spheroidizing device to obtain Li-Ca-B glass microspheres.

[0029] Further, the heating temperature of the CaCO3, LiCO3, H3BO3 is 1200℃, and the heating time is 45 min.

[0030] Further, the sieving mesh number of the Li-Ca-B glass is 60 mesh and 100 mesh. The Li-Ca-B glass is first sieved through a 60 mesh sieve, and then sieved through a 100 mesh sieve.

[0031] Through the above technical solution, the Li-Ca-B glass particles with a particle size of less than 250μm can be obtained after sieving through a 60 mesh sieve, and the Li-Ca-B glass particles that cannot pass through the sieve are retained after sieving through a 100 mesh sieve, so that the Li-Ca-B glass particles with a particle size of 150-250μm can be obtained.

[0032] Further, the temperature of the vertical furnace spheroidizing device is 1200℃.

[0033] Through the above technical solution, the Li-Ca-B glass microspheres with a particle size of 150-250μm can be prepared, and the loss rate of the Li-Ca-B glass microspheres is less than 10%.

[0034] The present application has the following beneficial effects:

[0035] The preparation method of the present application can prepare the bi-phase calcium phosphate hollow microspheres with a HA / β-TCP ratio of 20:80 to 50:50, realizing the dynamic balance of material performance. The bi-phase calcium phosphate microspheres with different HA / β-TCP ratios have different degradation rates, which can meet different application scenarios. Hydroxyapatite (HA) as a scaffold can maintain structural integrity and promote bone cell attachment and mineralization. β-tricalcium phosphate (β-TCP) can accelerate the degradation of calcium and phosphorus ions to promote osteogenesis and provide space for the growth of new bone tissue.

[0036] The bi-phase calcium phosphate hollow microspheres prepared by the present application have gradient porosity, from the relatively dense outer shell to the relatively loose and porous inner shell, and the center part is a large hole. With the degradation process, different pore structures are gradually exposed, which is beneficial to the growth of cell tissue and promotes vascularization and infiltration.

[0037] The Li-Ca-B glass microspheres prepared by the vertical furnace spheroidization device can reduce the loss rate of the Li-Ca-B glass microspheres, and the loss rate is less than 10%, and can increase the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the XRD analysis of the biphasic calcium phosphate (BCP) microspheres prepared from Li2O-CaO-B2O3 glass in (A) 0.25 M phosphate solution and (B) 0.1 M phosphate solution.

[0039] Figure 2 is the Ca / P ratio calculated from the quantitative XRD and ICP-OES analysis.

[0040] Figure 3 is the SEM image of the biphasic calcium phosphate (BCP) hollow microspheres prepared in part of 0.25 M phosphate solution.

[0041] Figure 4 is the SEM image of the biphasic calcium phosphate (BCP) hollow microspheres prepared in part of 0.1 M phosphate solution.

[0042] Figure 5 is the comparison of the biphasic calcium phosphate (BCP) hollow spheres before and after immersion in SBF solution.

[0043] Figure 6 (A1) is the optical image of the H&E stained section of the rat skull defect after implanting the biphasic calcium phosphate (BCP) hollow microspheres of Example 6 for 8 weeks.

[0044] Figure 6 (A2) is the optical image of the H&E stained section of the rat skull defect after implanting the carbonated hydroxyapatite (CDHA) hollow microspheres of Comparative Example 2 for 8 weeks.

[0045] Figure 6 (B1) is the optical image of the H&E stained section of the rat skull defect after implanting the biphasic calcium phosphate (BCP) hollow microspheres of Example 2 for 8 weeks.

[0046] Figure 6 (B2) is the optical image of the H&E stained section of the rat skull defect after implanting the biphasic calcium phosphate (BCP) hollow microspheres of Comparative Example 1 for 8 weeks.

[0047] REFERENCE NUMERALS:

[0048] 1, host bone; 2, new bone. DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and technical advantages of the present application clearer, specific examples will be described in detail below, but the protection scope of the present application is not limited to the following specific examples, the described examples are only some of the examples of the present application, but not all the examples, and are not a limitation of the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0050] Unless otherwise defined, all the professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific examples, and are not intended to limit the protection scope of the present application.

[0051] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0052] In the quantitative test in the following examples, three repeated experiments were set, and the data were the average value or average value ± standard deviation of the three repeated experiments.

[0053] Example 1

[0054] Preparation of Li-Ca-B glass microspheres:

[0055] 26.77 g of CaCO3, 26.29 g of Li2CO3, 132.10 g of H3BO3 were heated to 1200℃ in a platinum crucible for 45 min; the obtained molten mixture was quenched on a stainless steel plate to obtain Li-Ca-B glass with a composition of CaO: 15wt%, Li2O: 11wt%, B2O3: 74wt%; the Li-Ca-B glass was crushed, first passed through a 60 mesh screen to obtain Li-Ca-B glass particles with a particle size of less than 250 μm, then passed through a 100 mesh screen while retaining the Li-Ca-B glass particles that did not pass through the 100 mesh screen to obtain Li-Ca-B glass particles with a particle size of 150-250 μm; the temperature of the vertical furnace spheroidizing device was adjusted to 1200℃, the glass particles were placed in the vibrator above the vertical furnace spheroidizing device, and the Li-Ca-B glass particles were uniformly leaked out by vibration, so that the Li-Ca-B glass particles passed through the center of the heating pipe of the vertical furnace spheroidizing device, to obtain Li-Ca-B glass microspheres with a particle size of 150-250 μm.

[0056] Preparation of double-phase calcium phosphate hollow microspheres:

[0057] A K2HPO4 solution with a concentration of 0.25 M was prepared, and a 0.1 M HCl solution was added to adjust the pH to 8. The Li-Ca-B glass microspheres prepared above were mixed with the phosphate solution, 200 mL of the phosphate solution was used for every 1 g of the Li-Ca-B glass microspheres, the temperature was controlled at 37°C, and the reaction was carried out at 60 r / min for 2 days to obtain calcium-deficient hydroxyapatite hollow microspheres. The calcium-deficient hydroxyapatite hollow microspheres were washed with deionized water, the mass-volume ratio of the calcium-deficient hydroxyapatite hollow microspheres to the deionized water was 1:50 mL, and the washing was repeated three times. After the washing, the liquid was poured out after the solid settled at the bottom. The calcium-deficient hydroxyapatite hollow microspheres were washed with anhydrous ethanol, the mass-volume ratio of the calcium-deficient hydroxyapatite hollow microspheres to the deionized water was 1:30 mL, and the washing was repeated three times. After the washing, the first drying was carried out at a temperature of 25°C for 12 h. The second drying was carried out at a temperature of 90°C for 12 h. After the drying, the calcium-deficient hydroxyapatite hollow microspheres were calcined at a temperature of 800°C for 5 h to obtain biphasic calcium phosphate hollow microspheres.

[0058] Example 2

[0059] The difference from Example 1 is that a K2HPO4 solution with a concentration of 0.25 M was prepared, and a 0.1 M HCl solution or a 0.1 M KOH solution was added to adjust the pH to 9 because the initial pH value of the K2HPO4 solution fluctuated around 9.

[0060] Example 3

[0061] The difference from Example 1 is that a K2HPO4 solution with a concentration of 0.25 M was prepared, and a 0.1 M KOH solution was added to adjust the pH to 10.

[0062] Example 4

[0063] The difference from Example 1 is that a K2HPO4 solution with a concentration of 0.25 M was prepared, and a 0.1 M KOH solution was added to adjust the pH to 12.

[0064] Example 5

[0065] The difference from Example 1 is that a K2HPO4 solution with a concentration of 0.1 M was prepared, and a 0.1 M HCl solution was added to adjust the pH to 7.

[0066] Example 6

[0067] The difference from Example 1 is that a K2HPO4 solution with a concentration of 0.1 M was prepared, and a 0.1 M KOH solution was added to adjust the pH to 12.

[0068] Comparative Example 1

[0069] The difference from Example 2 is that the calcium-deficient hydroxyapatite hollow microspheres are not calcined.

[0070] Comparative Example 2

[0071] The difference from Example 6 is that the calcium-deficient hydroxyapatite hollow microspheres are not calcined.

[0072] The specific components and preparation conditions of the examples and comparative examples are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Experimental detection

[0077] The biphasic calcium phosphate hollow microspheres are characterized by quantitative X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), and H&E staining section optical images, and the results are shown in Figures 1 to 6 , Tables 2-3.

[0078] The experimental method of the H&E staining section optical image is as follows: 3-month-old male SD rats are selected. Using sterile instruments and sterile techniques, four 4.6 mm diameter defects are made on the skull. 10 mg of the microspheres of Example 2, Example 6, and Comparative Examples 1-2 are respectively implanted in the four defects, and only one kind of microspheres is implanted in each defect. After 8 weeks, the rats are sacrificed by inhaling CO2, and the skull defect site and surrounding bone and soft tissue are collected to observe the formation of new bone and the residual microspheres, wherein the formation of new bone is indicated by the percentage of new bone to the defect after 8 weeks, and the experiment is repeated 6 times.

[0079] The calcium-phosphorus ratio Ca / P and the HA / β-TCP ratio of some biphasic calcium phosphate hollow microspheres are shown in Table 2.

[0080] Table 2

[0081]

[0082] As shown in Figure 1 , X-ray diffraction analysis shows that the calcined calcium-deficient hydroxyapatite hollow microspheres have been converted into a mixture of crystalline hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), and the proportion of HA increases with the increase of the pH value of the phosphate solution. From the relative fractions of HA (Ca / P = 1.67) and β-TCP (Ca / P = 1.50), the quantitative XRD data Figure 1 , 2) shows that the average Ca / P ratio of the biphasic calcium phosphate hollow microspheres generated in the phosphate solution with a higher pH value increases. The quantitative analysis shown in Figure 2 Table 2 shows that the Ca / P ratio is consistent with the result of the solution in which the biphasic calcium phosphate hollow microspheres are dissolved in acid, which is determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0083] The surface area and average pore size of the biphasic calcium phosphate hollow microspheres are shown in Table 3.

[0084] Table 3

[0085] Example 1 Example 4 Example 5 Example 6 Surface area (m 2 / g) 1.4±0.3 0.6±0.1 3.6±0.1 6.6±0.2 Average pore size (nm) 7.9±0.5 6.9±0.2 6.8±0.6 6.2±0.3

[0086] Table 3 shows the surface area and average pore size of the biphasic calcium phosphate hollow microspheres, and the quantitative analysis shown in Figure 3 and Figure 4 shows the micro-morphology of the BCP hollow microspheres prepared in the 0.25M and 0.1M phosphate solutions, which shows that the biphasic calcium phosphate hollow microspheres prepared by the present application have a hollow structure, and the shell layer of the microspheres has a gradient pore, the outer surface of the shell is relatively dense, and the inner surface of the shell is gradually loose and porous. With the increase of the pH value, the outer surface and the inner surface of the shell gradually become dense. For the biphasic calcium phosphate hollow microspheres prepared in the 0.25M phosphate solution, the ratio of the inner diameter to the outer diameter is 30% to 40%. For the biphasic calcium phosphate hollow microspheres prepared in the 0.1M phosphate solution, the ratio of the inner diameter to the outer diameter is 45% to 55%. According to the research, bone cells like to grow in pores of 50 to 500 μm, and the overall size of the biphasic calcium phosphate hollow microspheres prepared by the present application is 150 to 250 μm, and the size of the hollow part can be calculated as 45 to 137 μm, which is very suitable for the growth of bone cells.

[0087] As shown in Figure 5 , the biphasic calcium phosphate hollow microspheres are soaked in a simulated human plasma ion solution (SBF), and after the immersion, the surface of the biphasic calcium phosphate hollow microspheres is covered with smaller particles (<100 nm), and some of the smaller particles form clusters. This is because the calcium ions and phosphate ions released from the biphasic calcium phosphate hollow microspheres are re-deposited on the surface of the biphasic calcium phosphate hollow microspheres in the form of nano-hydroxyapatite particles, and the formation of apatite is a standard for evaluating the in-vitro biological activity of implant materials, which shows that the biphasic calcium phosphate hollow microspheres of the present application have excellent ability to promote bone tissue regeneration.

[0088] The area fraction of new bone formation and the residual microspheres after the rat skull defects are implanted with different microspheres for 8 weeks are shown in Table 4.

[0089] Table 4

[0090] Example 2 Example 6 Comparative Example 1 Comparative Example 2 HA / β-TCP 30 / 70 56 / 44 / / Ca / P 1.55 1.59 1.55 1.59 New bone (%) 33±7 20±9 17±4 17±5 Residual microspheres (%) 23±4 29±3 31±6 32±6

[0091] By comparing the test results of Example 2, Example 6 and Comparative Examples 1-2, it can be seen that the new bone formation is: Comparative Example 1 = Comparative Example 2 < Example 6 < Example 2, which indicates that the biphasic calcium phosphate hollow microspheres prepared in the present application can better promote the generation of new bone than ordinary hydroxyapatite carbonate (CDHA), and the promoting effect of Example 2 is better than that of Example 6. At the same time, the residual microsphere fraction is: Example 2 < Example 6 < Comparative Example 1 = Comparative Example 2, which indicates that the residual microsphere fraction of the biphasic calcium phosphate hollow microspheres prepared in the present application is lower than that of ordinary hydroxyapatite carbonate (CDHA), which proves that the biphasic calcium phosphate hollow microspheres prepared in the present application have a faster degradation rate, and the improvement of the degradation rate can further promote the generation of new bone. The above-mentioned situation is consistent with the H&E staining section optical images of Figure 6 , combined with Figure 6 , the two sides of the section are the original host bone (1), the middle part is defective, and obvious new bone (2) can be seen growing in the defective part, and Figure 6 the effect of (B1) is better than that of Figure 6 (A1), Figure 6 (A2) and Figure 6 (B2).

[0092] Combined with Figure 6 (A1), after implanting the biphasic calcium phosphate hollow microspheres of Example 6, the new bone growth is limited to the periphery of the defects (the edge and bottom of the defects), and the connective tissue fills most of these defects. Combined with Figure 6 (B1), after implanting the biphasic calcium phosphate hollow microspheres of Example 2, the increasing content of β-TCP can further promote the generation of new bone by the degradation and release of calcium ions and phosphorus ions. The inner hole of the biphasic calcium phosphate hollow microspheres is exposed with degradation, and cells can enter the hollow structure with degradation, which is more conducive to cell growth, and the larger specific surface area and porosity can also promote cell tissue growth.

[0093] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0094] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0095] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed in the present application.

Claims

1. A method for preparing biphasic calcium phosphate hollow microspheres, characterized by, The method comprises the following steps: S1. preparing a K2HPO4 solution with a pH of 8-12 and a concentration of 0.25 M or a K2HPO4 solution with a pH of 7-12 and a concentration of 0.1 M; S2. preparing Li-Ca-B glass microspheres, mixing the obtained Li-Ca-B glass microspheres with the phosphate solution obtained in step S1, controlling the temperature to be 37℃, and reacting for 2-4 days under stirring to obtain calcium-deficient hydroxyapatite hollow microspheres; S3. washing the calcium-deficient hydroxyapatite hollow microspheres obtained in step S2, and then performing drying treatment; S4. calcining the calcium-deficient hydroxyapatite hollow microspheres obtained in step S3 to obtain biphasic calcium phosphate hollow microspheres.

2. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The Li-Ca-B glass microspheres have a composition of CaO: 15 wt%, Li2O: 11 wt%, and B2O3: 74 wt%.

3. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The mixing mass-volume ratio of the Li-Ca-B glass microspheres and the phosphate solution is 1 g of Li-Ca-B glass microspheres to 200 mL of phosphate solution.

4. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The calcium-deficient hydroxyapatite hollow microspheres in step S3 are sequentially washed with deionized water and anhydrous ethanol.

5. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The biphasic calcium phosphate hollow microspheres obtained in step S4 have a hydroxyapatite (HA) / β-tricalcium phosphate (β-TCP) ratio of 20:80 to 50:

50.

6. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The drying treatment comprises first drying and second drying; the first drying is performed at a temperature of 25℃ for ≥12 h; and the second drying is performed at a temperature of 90℃ for ≥12 h.

7. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The calcination is performed at a temperature of 800℃ for 5 h.

8. The method of producing biphasic calcium phosphate hollow microspheres according to claim 1, characterized by, The Li-Ca-B glass particles have a particle size of 150-250 μm.

9. The production method of the biphasic calcium phosphate hollow microspheres according to claims 1 to 8, characterized by, The method for preparing the Li-Ca-B glass microspheres comprises the following steps: A1. heating CaCO3, LiCO3, and H3BO3 to a molten state; A2. quenching the molten mixture obtained in step A1 between stainless steel plates to obtain Li-Ca-B glass; A3. crushing the Li-Ca-B glass, sieving, and obtaining Li-Ca-B glass particles; A4. passing the Li-Ca-B glass particles through a vertical furnace spheroidization device to obtain Li-Ca-B glass microspheres.

10. The method of producing biphasic calcium phosphate hollow microspheres according to claim 9, characterized by, The vertical furnace spheroidization device has a temperature of 1200℃.

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