Monodisperse hydroxyapatite microspheres as well as preparation method and application thereof

Abstract

The invention provides a monodisperse hydroxyapatite microsphere and a preparation method and application thereof.The preparation method of the monodisperse hydroxyapatite microsphere comprises the steps that a first raw material and a microsphere template are mixed to obtain a mixed solution, the pH of the mixed solution is adjusted to 11-12, a second raw material is added to obtain a reaction solution, a hydroxyapatite precursor is obtained through a reaction, and the monodisperse hydroxyapatite microsphere is obtained. And carrying out heat treatment on the hydroxyapatite precursor to obtain the monodisperse hydroxyapatite microspheres. The preparation method provided by the invention is simple in process, and the prepared monodisperse hydroxyapatite microspheres are uniform in size and pore diameter and beneficial to large-scale application in industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of biomedical materials, and in particular to a bioceramic material, and a monodisperse hydroxyapatite microsphere, and a preparation method and application thereof. Background Art

[0002] Hydroxyapatite (HAP), as an important bioceramic material, is an important inorganic component in human body, animal bones and teeth. It has excellent biocompatibility and bioactivity, and can participate in metabolic activities in vivo to a certain extent. Microspheres prepared with hydroxyapatite as raw material have high hardness, large specific surface area, low relative density and high porosity, and are widely used in tissue engineering, drug separation, medical cosmetology, sewage treatment and other fields.

[0003] The preparation methods of hydroxyapatite microspheres include spray drying, precipitation, microemulsion, etc. The microspheres prepared by these methods have problems such as wide particle size distribution, low yield, and complex preparation process, which limits their application in large-scale production.

[0004] CN1161305A discloses a preparation method of converting natural ore into bioactive material hydroxyapatite by anion exchange reaction under hydrothermal conditions. The reaction is carried out in a sealed stainless steel reactor lined with polytetrafluoroethylene. The concentration of the exchange agent diammonium hydrogen phosphate is 0.88mol / l-6.8mol / l, the reaction temperature is 100℃-240℃, the reaction pressure is ≤40 bar, close to normal pressure, and the reaction ratio of coral reef stone to diammonium hydrogen phosphate is 1:1-1:5. The reaction conversion rate of hydroxyapatite produced by this method can reach more than 95%, the product strength can reach Mohs6.5 degrees, and the single volume can reach 15cc or more.

[0005] CN111892033A discloses a method for preparing hydroxyapatite microspheres, comprising: (1) introducing a calcium source and a phosphorus source into a solvent to form a calcium phosphate suspension; (2) adding a polymer seed into a dispersion system containing ethanol / water to form a uniformly dispersed seed suspension, wherein the solid content of the polymer seed is 5g / L to 9g / L; (3) adding the calcium phosphate suspension into the seed suspension, stirring evenly, and gradually adding an emulsifier and an initiator, wherein the emulsifier and the initiator satisfy the following ratio: W=W0(V / 3.5-4.5); (4) calcining the polymer-hydroxyapatite microspheres at high temperature to obtain porous hydroxyapatite microspheres. The porous hydroxyapatite microspheres prepared by the method have controllable particle size, uniform particle size, and controllable pore size.

[0006] CN101343054A discloses a method for preparing hydroxyapatite microspheres, comprising: a first step, adding a 0.1M-3M soluble EDTA salt solution to a 0.2M-1.5M Ca(OH)2 suspension; a second step, dropwise adding a mixed solution of a 0M-1.3M (NH4)2HPO4 solution and a 0.2M-1.5M NH4HCO3 solution to obtain a slurry; and a mixture of HCO3 － Number of moles plus 5 / 3HPO4 2－ The number of moles is equal to the Ca in the suspension 2+ molar number; the third step, adding 0.1M-1.0M H3PO4 or (NH4)2HPO4 solution to the 40℃-90℃ slurry to make the calcium-phosphorus molar ratio in the slurry be 1.66-1.7:1, and then reacting for 1-12h to obtain hydroxyapatite slurry; the fourth step, cooling, filtering, washing, drying and then grinding the hydroxyapatite slurry to obtain hydroxyapatite microspheres.

[0007] The methods for preparing hydroxyapatite in the prior art are relatively complicated or have high requirements on equipment. The prepared hydroxyapatite microspheres have the problems of wide particle size distribution and low yield, which limits their application in large-scale production.

[0008] Therefore, it is of great significance to provide a method for preparing hydroxyapatite microspheres with good dispersibility, uniform size, uniform pore size and simple process. Summary of the invention

[0009] In view of the deficiencies in the prior art, the object of the present invention is to provide a monodisperse hydroxyapatite microsphere and a preparation method and application thereof. The present invention designs the preparation process and introduces a microsphere template, so that the hydroxyapatite precursor is grown in situ on the surface or inside of the microsphere template, thereby obtaining monodisperse hydroxyapatite microspheres with an inverse structure of the microsphere template. The monodisperse hydroxyapatite microspheres prepared by the present invention have good dispersibility and high sphericity, and the size and pore size of the monodisperse hydroxyapatite microspheres are uniform. In the present invention, the size and pore size of the monodisperse hydroxyapatite microspheres are related to the size and pore size of the template, and the size and pore size of the monodisperse hydroxyapatite microspheres can be adjusted by adjusting the size and pore size of the microsphere template as needed, thereby broadening the application range of the hydroxyapatite microspheres.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing monodisperse hydroxyapatite microspheres, the preparation method comprising the following steps:

[0012] Mixing the first raw material and the microsphere template to obtain a mixed solution, adjusting the pH of the mixed solution to 11-12; mixing with the second raw material to obtain a reaction solution, reacting to obtain a hydroxyapatite precursor; heat-treating the hydroxyapatite precursor to obtain monodisperse hydroxyapatite microspheres;

[0013] The first raw material is a phosphorus source solution or a calcium source solution, and the second raw material is a phosphorus source solution or a calcium source solution; the first raw material is different from the second raw material.

[0014] The present invention designs a preparation process and introduces a microsphere template, so that a hydroxyapatite precursor is in situ grown on the surface or inside of the microsphere template, thereby obtaining monodisperse hydroxyapatite microspheres with an inverse structure of the microsphere template. In the present invention, the size and pore size of the monodisperse hydroxyapatite microspheres are associated with the size and pore size of the microsphere template, and the size and pore size of the monodisperse hydroxyapatite microspheres can be adjusted by adjusting the size and pore size of the microsphere template as needed, thereby broadening the application range of the hydroxyapatite microspheres.

[0015] In the preparation method provided by the present invention, the microsphere template is first mixed with the first raw material and then mixed with the second raw material, which is conducive to the first raw material preferentially aggregating in large quantities inside the template microspheres, and then promoting the aggregation of the second raw material inside the template microspheres by charge adsorption and other effects.

[0016] In the present invention, the method of mixing with the second raw material includes adding the second raw material into the mixed solution of the first raw material and the microsphere template in a dropwise manner.

[0017] In the present invention, the pH is adjusted to 11-12, for example, the pH can be 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9 or 12, including but not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. The method of adjusting the pH in the present invention is based on being able to adjust to the desired pH, and is not specifically limited.

[0018] Preferably, the phosphorus source solution comprises any one of NH4H2PO4 solution, (NH4)2HPO4 solution, (NH4)3PO4 solution, NaH2PO4 solution, Na2HPO4 solution, Na3PO4 solution, KH2PO4 solution, K2HPO4 solution or K3PO4 solution, or a combination of at least two thereof.Typical but non-limiting combinations include NH4H2PO4 solution and (NH4)2HPO4 solution, NH4H2PO4 solution and (NH4)3PO4 solution, NH4H2PO4 solution and NaH2PO4 solution, NH4H2PO4 solution and Na2HPO4 solution, NH4H2PO4 solution and Na3PO4 solution, NH4H2PO4 solution and KH2PO4 solution, NH4H2PO4 solution and K2HPO4 solution, NH4H2PO4 solution and K3PO4 solution, (NH4)2HPO4 solution and (NH4)3PO4 solution, (NH4)2HPO4 solution and NaH2PO4 solution, (NH4)2HPO4 solution and solution and Na2HPO4 solution, (NH4)2HPO4 solution and Na3PO4 solution, (NH4)2HPO4 solution and KH2PO4 solution, (NH4)2HPO4 solution and K2HPO4 solution, (NH4)2HPO4 solution and K3PO4 solution, (NH4)3PO4 solution and NaH2PO4 solution, (NH4)3PO4 solution and Na2HPO4 solution, (NH4)3PO4 solution and Na3PO4 solution, (NH4)3PO4 solution and KH2PO4 solution, (NH4)3PO4 solution and K2HPO4 solution, (NH4)3PO4 solution and K3PO4 solution, NaH2PO4 solution and Na 2HPO4 solution, NaH2PO4 solution and Na3PO4 solution, NaH2PO4 solution and KH2PO4 solution, NaH2PO4 solution and K2HPO4 solution, NaH2PO4 solution and K3PO4 solution, Na2HPO4 solution and Na3PO4 solution, Na2HPO4 solution and KH2PO4 solution, Na2HPO4 solution and K2HPO4 solution, Na2HPO4 solution and K3PO4 solution, Na3PO4 solution and KH2PO4 solution, Na3PO4 solution and K2HPO4 solution, Na3PO4 solution and K3PO4 solution, KH2PO4 solution and K2HPO4 solution, KH2PO4 solution and K3PO4 solution, K2HPO4 solution and K3PO4 solution, NH4H2PO4 solution and (NH4)2HPO4 solution and (NH4)3PO4 solution, (NH4)2HPO4 solution and (NH4)3PO4 solution and NaH2PO4 solution, (NH4)3PO4 solution and NaH2PO4 solution and Na2HPO4 solution, NaH2PO4 solution and Na2HPO4 solution and Na3PO4 solution, Na2HPO4 solution and Na3PO4 solution and KH2PO4 solution, Na3PO4 solution and KH2PO4 solution and K2HPO4 solution or KH2PO4 solution and K2HPO4 solution and K3PO4 solution. ,

[0019] Preferably, the calcium source solution comprises any one of CaCl2 solution, CaBr2 solution, CaI2 solution, Ca(NO3)2 solution or Ca(HCO3)2 solution, or a combination of at least two thereof. Typical but non-limiting combinations include CaCl2 solution and CaBr2 solution, CaCl2 solution and CaI2 solution, CaCl2 solution and Ca(NO3)2 solution, CaCl2 solution and Ca(HCO3)2 solution, CaBr2 solution and CaI2 solution, CaBr2 solution and Ca(NO3)2 solution, CaBr2 solution and Ca(HCO3)2 solution, CaI2 solution and Ca(NO3)2 solution, CaI2 solution and Ca(HCO3)2 solution, Ca(NO3)2 solution and Ca(HCO3)2 solution, CaCl2 solution and CaBr2 and CaI2 solution, CaBr2 solution and CaI2 solution and Ca(NO3)2 solution, or CaI2 solution and Ca(NO3)2 solution and Ca(HCO3)2 solution.

[0020] Preferably, the microsphere template comprises porous polymer microspheres and / or silica microspheres.

[0021] Preferably, the porous polymer microspheres include any one of polystyrene microspheres, polyacrylic acid microspheres, polyethylene glycol microspheres, polymethyl methacrylate microspheres or polycaprolactone microspheres, or a combination of at least two thereof. Typical but non-limiting combinations include polystyrene microspheres and polyacrylic acid microspheres, polystyrene microspheres and polyethylene glycol microspheres, polystyrene microspheres and polymethyl methacrylate microspheres, polystyrene microspheres and polycaprolactone microspheres, polyacrylic acid microspheres and polyethylene glycol microspheres, polyacrylic acid microspheres and polymethyl methacrylate microspheres, polyacrylic acid microspheres and polycaprolactone microspheres, polyethylene glycol microspheres and polymethyl methacrylate microspheres, polyethylene glycol microspheres and polycaprolactone microspheres, polymethyl methacrylate microspheres and polycaprolactone microspheres, polystyrene microspheres and polyacrylic acid microspheres and polyethylene glycol microspheres, polyacrylic acid microspheres and polyethylene glycol microspheres and polymethyl methacrylate microspheres, or polyethylene glycol microspheres and polymethyl methacrylate microspheres and polycaprolactone microspheres.

[0022] Preferably, the microsphere template is modified before use.

[0023] Preferably, the modification includes functional group modification and / or charge modification.

[0024] In the preparation method provided by the present invention, by modifying the microsphere template, the binding force between the precursor and the template microsphere can be enhanced, which is beneficial to improving the correlation between the morphology of the monodisperse hydroxyapatite microspheres and the microsphere template, so as to more accurately control the morphology, size and pore size of the monodisperse hydroxyapatite microspheres.

[0025] Preferably, the functional group modification includes any one of amino modification, thiol modification, aryl modification, carboxyl modification or hydroxyl modification, or a combination of at least two thereof. Typical but non-limiting combinations include simultaneously performing amino modification and thiol modification, amino modification and aryl modification, amino modification and carboxyl modification, amino modification and hydroxyl modification, thiol modification and aryl modification, thiol modification and carboxyl modification, thiol modification and hydroxyl modification, aryl modification and carboxyl modification, aryl modification and hydroxyl modification, carboxyl modification and hydroxyl modification on the microsphere template.

[0026] Preferably, the charge modification includes positive charge modification or negative charge modification.

[0027] In the preparation method provided by the present invention, the average particle size of the microsphere template affects the average particle size of the hydroxyapatite microspheres.

[0028] Preferably, the D of the microsphere template 50 The particle size is 30 μm-300 μm, for example, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 165 μm, 170 μm , 175μm, 180μm, 185μm, 190μm, 195μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm or 300μm, including but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 100μm-200μm.

[0029] Preferably, the coefficient of variation (CV value) of the microsphere size distribution of the microsphere template is less than 5%, for example, it can be 5%, 4%, 3%, 2% or 1%, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In the present invention, the average pore size of the microsphere template affects the surface morphology and pore structure of the hydroxyapatite microspheres.

[0031] Preferably, the average pore size of the microsphere template is For example it could be

[0032] or Including but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably

[0033]

[0034] Preferably, the molar ratio of phosphorus to calcium in the reaction solution is 1:(1.6-1.8), for example, it can be 1:1.6, 1:1.61, 1:1.62, 1:1.63, 1:1.64, 1:1.65, 1:1.66, 1:1.67, 1:1.68, 1:1.69, 1:1.7, 1:1.71, 1:1.71, 1:1.73, 1:1.74, 1:1.75, 1:1.76, 1:1.77, 1:1.78, 1:1.79 or 1:1.8, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In the preparation method provided by the present invention, the concentration of the microsphere template affects the particle size distribution (monodispersity) and pore structure of hydroxyapatite.

[0036] Preferably, the concentration of the microsphere template in the mixed solution is 2 g / L-20 g / L, for example, it can be 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L or 20 g / L, including but not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] In the present invention, the concentration of the phosphorus source or the calcium source affects the morphological structure of the microspheres. When the concentration of the calcium source or the phosphorus source is too low, during the preparation process, the content of calcium or phosphorus ions in the template microspheres is insufficient, the size of the generated microspheres is small, and they cannot grow into the inverse structure of the microsphere template. If the concentration of the calcium source or the phosphorus source is too high, during the preparation process, a large amount of free calcium source and phosphorus source exist outside the template microspheres, and a large amount of non-spherical calcium-phosphorus compound crystals are generated after high-temperature treatment, resulting in poor uniformity of the final product.

[0038] Preferably, the concentration of the phosphorus source solution is 0.03-0.125 mol / L, for example, it can be 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L, 0.12 mol / L or 0.125 mol / L, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] The concentration of the calcium source solution is 0.05-0.20 mol / L, for example, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L or 0.20 mol / L, including but not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0040] Preferably, the mixing temperature is 25°C-45°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the mixing time is 0.5h-3h, for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6, 2.7h, 2.8h, 2.9h or 3h, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the reaction method includes stirring.

[0043] Preferably, the reaction temperature is 25°C-45°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In the present invention, the reaction time of the reaction solution has an impact on the completeness and uniformity of the reaction, the sedimentation rate of the product, and the crystallization degree, particle size and morphology of the prepared monodisperse hydroxyapatite microspheres.

[0045] From the perspective of reaction completeness, a longer reaction time helps the completeness of the reaction and ensures that all raw materials are consumed. A reaction time that is too short may result in some raw materials not being fully reacted, affecting the purity and structure of the product.

[0046] From the perspective of sedimentation velocity and reaction uniformity, a reaction time that is too short may result in incomplete or uneven sedimentation, while a reaction time that is too long may lead to unnecessary side reactions or the formation of impurities.

[0047] From the perspective of the degree of crystallization of the product, a longer reaction time helps the reactants to fully react and form more complete hydroxyapatite crystals. If the reaction time is too short, the crystals of the product may be incomplete or unstable.

[0048] From the perspective of the effect on the particle size and morphology of the product, the reaction time will directly affect the particle size and morphology of the product. Longer reaction time usually promotes the growth of particles and may form larger or more regular microspheres, while shorter time may result in smaller particles or uneven shapes.

[0049] Preferably, the reaction time is 6 h-12 h, for example, it can be 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h or 12 h, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] Preferably, after the reaction is completed, the hydroxyapatite precursor is filtered and washed.

[0051] Preferably, the heat treatment comprises drying and calcining.

[0052] Preferably, the drying temperature is 80°C-150°C, for example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Preferably, the drying time is 2h-12h, for example, it can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In the preparation method provided by the present invention, the calcination temperature has an important influence on the final structure and performance of the monodisperse hydroxyapatite microspheres, including affecting the crystallinity, particle size and morphology, chemical composition stability and template removal of the monodisperse hydroxyapatite microspheres.

[0055] Specifically, from the perspective of the effect on crystallinity, a higher calcination temperature usually helps to improve the crystallinity of hydroxyapatite, allowing it to form a more regular and stable crystal structure. Too low a temperature may result in insufficient crystallization of the product, forming an amorphous or low-crystallized substance.

[0056] From the perspective of the effect on particle size and morphology, the increase in calcination temperature will promote the growth of crystals, thereby affecting the size and morphology of particles. Too high a temperature may cause particle aggregation or sintering, forming larger or uneven particles.

[0057] High temperature calcination can effectively remove the polymer template. When the calcination temperature is too low, the template may not be completely removed, which is not conducive to the solidification of the structure and affects the purity and pore structure of the product. Excessive temperature may cause instability or over-sintering of the hydroxyapatite structure, and even lead to thermal decomposition of hydroxyapatite.

[0058] Stability of chemical composition: Calcination temperature affects the chemical stability of calcium and phosphorus sources. Too high a temperature may cause the calcium or phosphorus source to decompose or lose activity, thus affecting the composition of the product.

[0059] Preferably, the calcination temperature is 350°C-800°C, for example, it can be 350°C, 375°C, 400°C, 425°C, 450°C, 475°C, 500°C, 525°C, 550°C, 575°C, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 775°C or 800°C, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] Preferably, the calcination time is 3h-12h, for example, it can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7, 7.5h, 8, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] Preferably, after the heat treatment is completed, the method further includes post-treating the monodisperse hydroxyapatite microspheres.

[0062] Preferably, the post-treatment comprises washing with deionized water.

[0063] Preferably, when the microsphere template is silicon dioxide, the monodisperse hydroxyapatite microspheres are alkali-etched before washing with deionized water.

[0064] Preferably, the alkaline etching comprises soaking in sodium hydroxide and / or potassium hydroxide solution.

[0065] Preferably, the concentration of the sodium hydroxide and / or potassium hydroxide solution is 3M-10M, for example, 3M, 3.5M, 4M, 4.5M, 5M, 5.5M, 6M, 6.5M, 7M, 7.5M, 8M, 8.5M, 9M, 9.5M or 10M, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] Preferably, the alkali etching time is 15h-30h, for example, it can be 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h or 30h, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] In a second aspect, the present invention provides a monodisperse hydroxyapatite microsphere prepared by the preparation method described in the first aspect, wherein the D 50 The particle size is 50-150μm, the CV value is less than 5%, and the average pore size is Preferably

[0068] In the present invention, the D of the monodisperse hydroxyapatite microspheres is 50 The particle size is 50-150 μm, for example, it can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm or 150 μm, including but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] In the present invention, the coefficient of variation (CV value) of the particle size distribution of monodisperse hydroxyapatite microspheres is less than 5%, for example, it can be 5%, 4%, 3%, 2% or 1%, including but not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0070] In the present invention, the average pore size of monodisperse hydroxyapatite microspheres is For example it could be or Including but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably

[0071] In a third aspect, the present invention provides an application of the monodisperse hydroxyapatite microspheres as described in the second aspect, wherein the monodisperse hydroxyapatite microspheres are applied in technical fields such as tissue engineering, drug separation, medical cosmetology, and sewage treatment.

[0072] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) The present invention designs the preparation process so that the hydroxyapatite precursor grows in situ on the surface or inside the microsphere template, thereby obtaining an inverse structure that is highly correlated with the size and morphology of the microsphere template. The size and pore size of the monodisperse hydroxyapatite microspheres can be regulated by adjusting the size and pore size of the microsphere template, thereby broadening the application range of the monodisperse hydroxyapatite microspheres.

[0075] (2) The preparation method provided by the present invention is simple in process and can realize the preparation of monodisperse hydroxyapatite microspheres through conventional solution reaction combined with subsequent heat treatment, which greatly simplifies the preparation process. In addition, the monodisperse hydroxyapatite microspheres prepared by the present invention have uniform size and pore size, which is conducive to large-scale application in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This is a microscope morphology picture of the monodisperse hydroxyapatite microspheres prepared in Example 1.

[0077] Figure 2 This is a microscope morphology image of the monodisperse hydroxyapatite microspheres prepared in Example 2.

[0078] Figure 3 This is a microscope morphology image of the monodisperse hydroxyapatite microspheres prepared in Example 3. DETAILED DESCRIPTION

[0079] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0080] Example 1

[0081] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0082] (1) Adding silica microspheres to NH4H2PO4 solution to obtain a mixed solution, mixing at 35°C for 1 hour, adjusting the pH to 11.5, dropping CaCl2 solution to obtain a reaction solution, reacting at 35°C for 9 hours, filtering and washing the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of NH4H2PO4 solution is 0.075 mol / L, the concentration of CaCl2 solution is 0.085 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.67, the concentration of silica microspheres in the mixed solution is 15 g / L, and the D of the silica microspheres is 1.5 g / L. 50 The particle size is 120μm, the CV value is less than 3%, and the average pore size is

[0083] (2) The hydroxyapatite precursor obtained in step (1) was dried at 120° C. for 6 h, and then calcined at 650° C. for 6 h, and then the calcined product was subjected to alkaline etching treatment with a 5M NaOH solution for 20 h to remove silicon dioxide. After the alkaline etching, the product was washed with deionized water until neutral to obtain monodisperse hydroxyapatite microspheres.

[0084] The D 50 The particle size is 120μm, the CV value is less than 3%, and the average pore size is

[0085] The microscopic morphology of the monodisperse hydroxyapatite microspheres obtained in this example is shown in FIG. Figure 1 shown.

[0086] Example 2

[0087] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0088] (1) Adding silica microspheres to NH4H2PO4 solution to obtain a mixed solution, mixing at 35°C for 1 hour, adjusting the pH to 11.5, dropping CaCl2 solution to obtain a reaction solution, reacting at 35°C for 9 hours, filtering and washing the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of NH4H2PO4 solution is 0.035 mol / L, the concentration of CaCl2 solution is 0.05 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.67, the concentration of silica microspheres in the mixed solution is 15 g / L, and the D of the silica microspheres is 1.5 g / L. 50 The particle size is 120μm, the CV value is less than 3%, and the average pore size is

[0089] (2) The hydroxyapatite precursor obtained in step (1) was dried at 120° C. for 6 h, and then calcined at 650° C. for 6 h, and then the calcined product was subjected to alkaline etching treatment with a 5M NaOH solution for 20 h to remove silicon dioxide. After the alkaline etching, the product was washed with deionized water until neutral to obtain monodisperse hydroxyapatite microspheres.

[0090] The D 50 The particle size is 120μm, the CV value is less than 3%, and the average pore size is

[0091] The microscopic morphology of the monodisperse hydroxyapatite microspheres obtained in this example is shown in FIG. Figure 2 shown.

[0092] Example 3

[0093] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0094] (1) Adding polystyrene microspheres to NH4H2PO4 solution to obtain a mixed solution, mixing at 35°C for 1 hour, adjusting the pH to 11.5, dropping CaCl2 solution to obtain a reaction solution, reacting at 35°C for 9 hours, filtering and washing the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of NH4H2PO4 solution is 0.075 mol / L, the concentration of CaCl2 solution is 0.085 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.67, the concentration of silica microspheres in the mixed solution is 15 g / L, and the D of the silica microspheres is 1.5 g / L. 50 The particle size is 100μm, the CV value is less than 3%, and the average pore size is

[0095] (2) The hydroxyapatite precursor obtained in step (1) was dried at 120° C. for 6 h, calcined at 650° C. for 6 h, and then washed three times with deionized water to obtain monodisperse hydroxyapatite microspheres.

[0096] The D 50 The particle size is 100μm, the CV value is less than 3%, and the average pore size is

[0097] The microscopic morphology of the monodisperse hydroxyapatite microspheres obtained in this example is shown in FIG. Figure 3 shown.

[0098] Example 4

[0099] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0100] (1) Adding polyacrylic acid microspheres to a (K)3PO4 solution to obtain a mixed solution, mixing at 45°C for 3 hours, adjusting the pH to 12, dropping a Ca(NO3)2 solution to obtain a reaction solution, reacting at 25°C for 12 hours, filtering and washing the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of the NH4H2PO4 solution is 0.125 mol / L, the concentration of the Ca(NO3)2 solution is 0.2 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.8, the concentration of the silica microspheres in the mixed solution is 20 g / L, and the D of the silica microspheres is 20 g / L. 50 The particle size is 200μm, the CV value is less than 3%, and the average pore size is

[0101] (2) The hydroxyapatite precursor obtained in step (1) was dried at 80° C. for 12 h, calcined at 350° C. for 12 h, and then washed three times with deionized water to obtain monodisperse hydroxyapatite microspheres.

[0102] The D 50 The particle size is 200μm, the CV value is less than 3%, and the average pore size is

[0103] Example 5

[0104] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0105] (1) Adding amino-modified polystyrene microspheres to (NH4)2HPO4 solution to obtain a mixed solution, mixing at 30°C for 2 hours, adjusting the pH to 11, dropping Ca(HCO3)2 solution to obtain a reaction solution, reacting at 45°C for 6 hours, filtering and washing the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of the NH4H2PO4 solution is 0.03 mol / L, the concentration of the Ca(HCO3)2 solution is 0.05 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.6, the concentration of the silica microspheres in the mixed solution is 8 g / L, and the D 50 The particle size is 60μm, the CV value is less than 5%, and the average pore size is

[0106] (2) The hydroxyapatite precursor obtained in step (1) was dried at 150° C. for 3 h, calcined at 800° C. for 3 h, and then washed twice with deionized water to obtain monodisperse hydroxyapatite microspheres.

[0107] The D 50The particle size is 60μm, the CV value is less than 5%, and the average pore size is

[0108] Example 6

[0109] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0110] (1) Add negatively charged silica to (NH4)3PO4 solution to obtain a mixed solution, mix at 40°C for 2.5 hours, adjust the pH to 11.3, dropwise add CaBr2 solution to obtain a reaction solution, react at 40°C for 7 hours, filter and wash the obtained precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of NH4H2PO4 solution is 0.1 mol / L, the concentration of CaBr2 solution is 0.16 mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.67, the concentration of silica microspheres in the mixed solution is 2 g / L, and the D of the silica microspheres is 2.5 g / L. 50 The particle size is 260μm, the CV value is less than 5%, and the average pore size is

[0111] (2) The hydroxyapatite precursor obtained in step (1) was dried at 100° C. for 10 h, and then calcined at 450° C. for 8 h, and then the calcined product was subjected to alkaline etching treatment for 15 h using a 10 M KaOH solution to remove silicon dioxide. After the alkaline etching, the product was washed with deionized water until neutral to obtain monodisperse hydroxyapatite microspheres.

[0112] The D 50 The particle size is 260μm, the CV value is less than 5%, and the average pore size is

[0113] Example 7

[0114] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is as follows:

[0115] (1) Add hydroxyl-modified silica microspheres to a (Na)2HPO4 solution to obtain a mixed solution, mix at 25°C for 0.5h, adjust the pH to 11.7, dropwise add CaI2 solution to obtain a reaction solution, react at 30°C for 10h, filter and wash the resulting precipitate with deionized water to obtain a hydroxyapatite precursor. The concentration of the NH4H2PO4 solution is 0.09mol / L, the concentration of the CaI2 solution is 0.185mol / L, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.67, the concentration of the silica microspheres in the mixed solution is 10g / L, and the D 50The particle size is 220μm, the CV value is less than 5%, and the average pore size is

[0116] (2) The hydroxyapatite precursor obtained in step (1) was dried at 130° C. for 8 h, and then calcined at 750° C. for 4 h, and then the calcined product was subjected to alkaline etching treatment for 30 h using a 3M NaOH solution to remove silicon dioxide. After the alkaline etching, the product was washed with deionized water until neutral to obtain monodisperse hydroxyapatite microspheres.

[0117] The D 50 The particle size is 220μm, the CV value is less than 5%, and the average pore size is

[0118] Example 8

[0119] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the concentration of the microsphere template in the reaction solution is 1 g / L.

[0120] The D 50 The particle size is 180μm, the CV value is less than 6%, and the average pore size is

[0121] Example 9

[0122] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the concentration of the microsphere template in the reaction solution is 30 g / L.

[0123] The D 50 The particle size is 110μm, the CV value is less than 7%, and the average pore size is

[0124] Example 10

[0125] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the concentration of the NH4H2PO4 solution in the reaction solution is 0.01 mol / L.

[0126] The D 50 The particle size is 100μm, the CV value is less than 8%, and the average pore size is

[0127] Embodiment 11

[0128] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the concentration of the NH4H2PO4 solution in the reaction solution is 0.25 mol / L.

[0129] The D 50 The particle size is 135μm, the CV value is less than 7%, and the average pore size is

[0130] Example 12

[0131] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the concentration of the CaCl2 solution in the reaction solution is 0.02 mol / L.

[0132] The D 50 The particle size is 105μm, the CV value is less than 6%, and the average pore size is

[0133] Embodiment 13

[0134] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Example 1 except that the concentration of the CaCl2 solution in the reaction solution is 0.3 mol / L.

[0135] The D 50 The particle size is 150μm, the CV value is less than 7%, and the average pore size is

[0136] Embodiment 14

[0137] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the reaction solution is reacted at 35° C. for 3 h.

[0138] The D 50 The particle size is 90μm, the CV value is less than 8%, and the average pore size is

[0139] Embodiment 15

[0140] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the reaction solution is reacted at 35° C. for 15 hours.

[0141] The D 50 The particle size is 135μm, the CV value is less than 7%, and the average pore size is

[0142] Example 16

[0143] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the calcination temperature is 200°C.

[0144] In this embodiment, the calcination temperature is too low, the template is not completely removed, and monodisperse hydroxyapatite microspheres cannot be prepared.

[0145] Embodiment 17

[0146] This embodiment provides a method for preparing monodisperse hydroxyapatite microspheres. The method for preparing monodisperse hydroxyapatite microspheres is the same as that of Embodiment 1 except that the calcination temperature is 1000°C.

[0147] The D 50 The particle size is 120μm, the CV value is less than 7%, and the average pore size is

[0148] Performance Characterization

[0149] The morphology of the monodisperse hydroxyapatite microspheres prepared in Examples 1 to 3 was tested using a microscope. The test results are as follows: Figure 1-Figure 3 shown.

[0150] The sphericity, particle size distribution coefficient of variation and average pore size of the final products obtained in the above examples and comparative examples were tested by laser particle size analyzer and scanning electron microscope. The results are shown in Table 1.

[0151] Table 1

[0152]

[0153]

[0154] The present invention designs a preparation process of hydroxyapatite and introduces a microsphere template, so that a hydroxyapatite precursor is grown in situ on the surface or inside of the microsphere template, thereby obtaining monodisperse hydroxyapatite microspheres having an inverse structure of the microsphere template. The morphology, size and pore size of the monodisperse hydroxyapatite microspheres in the present invention are highly correlated with the morphology, size and pore size of the template, and monodisperse hydroxyapatite microspheres with stable morphology, uniform size and uniform pore size can be obtained. Moreover, the size and pore size of the monodisperse hydroxyapatite microspheres can be adjusted as needed by adjusting the size and pore size of the microsphere template, thereby broadening the application range of the hydroxyapatite microspheres.

[0155] Examples 1 to 7 of the present invention all successfully prepared monodisperse hydroxyapatite microspheres, such as Figure 1-Figure 3 As shown, the monodisperse hydroxyapatite microspheres prepared by the present invention have the characteristics of good dispersibility and high sphericity, and the CV value of the monodisperse hydroxyapatite microspheres is less than 5.0% and the pore size is uniform.

[0156] According to the comparison between Example 1 and Example 8-Example 13, it can be seen that if the concentration of the microsphere template in the reaction solution is too small or too large, and the concentration of the phosphorus source or calcium source solution is too small or too large, it will affect the morphology of the prepared monodisperse hydroxyapatite microspheres. If the ion concentration relative to the phosphorus source or calcium source in the reaction solution is too high, a large amount of ions will be present in the reaction solution, which will lead to the presence of a large number of impurity crystals that are not the target microspheres after calcination. If the ion concentration relative to the phosphorus source or calcium source in the reaction solution is too small, the content of calcium ions or phosphorus ions in the template microspheres is insufficient, and the size of the resulting microspheres is too small, and they cannot grow into the inverse structure of the microsphere template.

[0157] According to the data results of Example 14-Example 17, in the reaction solution, the reaction time of the phosphorus source, calcium source and microsphere template and the temperature of subsequent calcination also affect the formation of monodisperse hydroxyapatite microspheres. Too short a reaction time will lead to incomplete crystallization of the product, insufficient deposition of the calcium source and phosphorus source inside the template microspheres, which in turn affects the uniform growth of crystals on the surface of the microspheres, resulting in poor sphericity of the microspheres and a small particle size. Prolonging the reaction time appropriately helps the growth of particles and promotes the formation of microspheres with more regular shapes. However, too long a reaction time may cause unnecessary side reactions or impurity generation, thereby affecting the surface morphology of the microspheres, and will increase production costs and reduce production efficiency. Too low a calcination temperature will lead to insufficient crystallization, and the template microspheres will not be completely removed, and non-spherical impurity particles may be formed. On the contrary, too high a calcination temperature may cause particle aggregation, affecting the particle size uniformity and structural stability of the microspheres.

[0158] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing monodisperse hydroxyapatite microspheres, characterized in that: The preparation method comprises the following steps: Mixing the first raw material and the microsphere template to obtain a mixed solution, adjusting the pH of the mixed solution to 11-12; mixing with the second raw material to obtain a reaction solution, reacting to obtain a hydroxyapatite precursor; heat-treating the hydroxyapatite precursor to obtain monodisperse hydroxyapatite microspheres; The first raw material is a phosphorus source solution or a calcium source solution, and the second raw material is a phosphorus source solution or a calcium source solution; the first raw material is different from the second raw material.

2. The preparation method according to claim 1, characterized in that The phosphorus source solution includes any one of NH4H2PO4 solution, (NH4)2HPO4 solution, (NH4)3PO4 solution, NaH2PO4 solution, Na2HPO4 solution, Na3PO4 solution, KH2PO4 solution, K2HPO4 solution or K3PO4 solution, or a combination of at least two thereof; Preferably, the calcium source solution comprises any one of CaCl2 solution, CaBr2 solution, CaI2 solution, Ca(NO3)2 solution or Ca(HCO3)2 solution, or a combination of at least two thereof.

3. The preparation method according to claim 1 or 2, characterized in that: The microsphere template includes porous polymer microspheres and / or silica microspheres; Preferably, the porous polymer microspheres include any one of polystyrene microspheres, polyacrylic acid microspheres, polyethylene glycol microspheres, polymethyl methacrylate microspheres or polycaprolactone microspheres, or a combination of at least two thereof.

4. The preparation method according to claim 3, characterized in that: The microsphere template is modified before use; Preferably, the modification method includes functional group modification and / or charge modification; Preferably, the functional group modification includes any one or a combination of at least two of amino modification, thiol modification, aromatic modification, carboxyl modification or hydroxyl modification; Preferably, the charge modification includes positive charge modification or negative charge modification.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The D of the microsphere template 50 The particle size is 30 μm-300 μm, preferably 100 μm-200 μm; Preferably, the CV value of the microsphere template is less than 5%; Preferably, the average pore size of the microsphere template is Preferably Preferably, the molar ratio of phosphorus to calcium in the reaction solution is 1:1.6-1:1.8; Preferably, the concentration of the microsphere template in the mixed solution is 2 g / L-20 g / L; Preferably, the concentration of the phosphorus source solution is 0.03-0.125 mol / L, and the concentration of the calcium source solution is 0.05-0.20 mol / L.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The mixing temperature of the first raw material and the microsphere template is 25°C-45°C; Preferably, the mixing time of the first raw material and the microsphere template is 0.5h-3h; Preferably, the reaction method includes stirring; Preferably, the reaction temperature is 25°C-45°C; Preferably, the reaction time is 6h-12h; Preferably, after the reaction is completed, the hydroxyapatite precursor is filtered and washed.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The heat treatment includes drying and calcining; Preferably, the drying temperature is 80°C-150°C; Preferably, the drying time is 2h-12h; Preferably, the calcination temperature is 350°C-800°C; Preferably, the calcination time is 3h-12h; Preferably, after the heat treatment is completed, the process further includes post-treating the monodisperse hydroxyapatite microspheres; Preferably, the post-treatment comprises washing with deionized water.

8. The preparation method according to claim 7, characterized in that: When the microsphere template is a silica microsphere, the monodisperse hydroxyapatite microsphere is alkali-etched before washing with deionized water; Preferably, the alkaline etching comprises soaking in sodium hydroxide and / or potassium hydroxide solution; Preferably, the concentration of the sodium hydroxide and / or potassium hydroxide solution is 3M-10M; Preferably, the alkali etching time is 15h-30h.

9. A monodisperse hydroxyapatite microsphere prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The monodisperse hydroxyapatite microspheres D 50 The particle size is 50-150μm, the CV value is less than 5%, and the average pore size is Preferably 10. A use of the monodisperse hydroxyapatite microspheres as claimed in claim 9, characterized in that: The monodisperse hydroxyapatite microspheres are used in technical fields such as tissue engineering, drug separation, medical cosmetology, and sewage treatment.

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