Preparation process of flaky amorphous hydroxyapatite

Abstract

The invention relates to a preparation process of flaky amorphous hydroxyapatite, and belongs to the technical field of hydroxyapatite preparation. The precipitation and crystallization processes are regulated and controlled by adding tannic acid, so that low-energy-consumption and high-biological-activity synthesis at room temperature is realized. The tannic acid is used as a retardant to guide hydroxyapatite to grow along a specific direction to form a sheet structure, so that the specific surface area, the surface activity and the permeability of the material are remarkably improved. Calcium stearate is added in the production of hydroxyapatite, so that the dispersity and the stability of the material are further improved. After baicalein is added, hydroxyapatite has a remarkable inhibition effect on escherichia coli, staphylococcus aureus and other harmful bacteria, and the advantages of the hydroxyapatite serving as an oral care product are further enhanced. Compared with a traditional preparation method, hydroxyapatite is generated under the room temperature condition, and the method has the advantages of being energy-saving and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of hydroxyapatite preparation, and relates to a preparation process of flaky amorphous hydroxyapatite. Background Art

[0002] As the main inorganic component of human bones and teeth, hydroxyapatite has great application potential in biomedicine, oral care and other fields due to its excellent biocompatibility and bioactivity. In the field of toothpaste, hydroxyapatite, as an important additive, can adhere to the surface of teeth and fill the tiny gaps and cracks in the enamel. It can effectively enhance the hardness of teeth, clean the surface of teeth, promote tooth remineralization and inhibit bacterial growth, thereby improving oral health.

[0003] However, the morphology of hydroxyapatite has a significant impact on its performance and application effect. Traditional hydroxyapatite morphologies include rods, spheres, etc. Although the application of hydroxyapatite with these morphologies in toothpaste has achieved certain results, there are still some shortcomings. For example, the adhesion and permeability of rod-shaped and spherical hydroxyapatite on the tooth surface are relatively poor, making it difficult to fully cover the tooth surface and penetrate into the tooth gaps, thus affecting its cleaning, antibacterial and remineralization effects. Therefore, it is of great significance to develop a hydroxyapatite with a functionalized morphology. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation process of flaky amorphous hydroxyapatite.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0007] S1-1: Add a calcium source to 60-80°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add phosphate to an equal mass of deionized water to prepare a phosphate solution with a concentration of 0.03M;

[0008] S1-2: adding the phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 600 to 800 r / min, adjusting the pH of the solution to 10 to 11 using ethylenediamine, and ultrasonicating for 30 minutes to obtain solution A;

[0009] S1-3: adding 0.5-1.5 mM tannic acid solution to solution A, ultrasonicating at 50-60°C for 1.5 h, then adding 1 wt% calcium stearate, stirring at room temperature for 10-14 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 12-16 h to obtain powder B;

[0010] S1-4: Add 3 to 5 parts by weight of Baicalin to 100 parts by weight of 60°C ethanol solution, ultrasonicate for 30 minutes, then add 5 to 15 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 2 to 4 hours, wash with deionized water and ethanol, and then place in a 60°C vacuum drying oven to dry for 12 to 16 hours to obtain the hydroxyapatite.

[0011] As a preferred technical solution of the present invention, the calcium source in S1-1 includes one or a combination of two or more of calcium carbonate, calcium chloride or calcium sulfate.

[0012] As a preferred technical solution of the present invention, the phosphate in S1-1 is a water-soluble phosphate.

[0013] As a preferred technical solution of the present invention, the phosphate in S1-1 includes one or a combination of two or more of diammonium dihydrogen phosphate, diammonium hydrogen phosphate, potassium salt or sodium salt of phosphate.

[0014] As a preferred technical solution of the present invention, the dropping speed of the phosphate solution in S1-2 is 0.4 to 0.6 mL / min.

[0015] As a preferred technical solution of the present invention, the amount of tannic acid solution added in S1-3 is 5-15% of the mass of solution A.

[0016] As a preferred technical solution of the present invention, the ultrasonic power in S1-3 is 6 to 8 kW.

[0017] As a preferred technical solution of the present invention, the mass fraction of the ethanol solution in S1-4 is 60-80%.

[0018] As a preferred technical solution of the present invention, the stirring speed in S1-4 is 500-700 r / min.

[0019] The invention discloses an application of flaky amorphous hydroxyapatite, wherein the hydroxyapatite can be applied to the fields of oral care and restoration.

[0020] Tannic acid is added to the preparation of hydroxyapatite. Tannic acid can regulate its microstructure by affecting the precipitation and crystallization process of hydroxyapatite. Tannic acid can form a stable complex with calcium ions. This complexation helps to control the precipitation process of hydroxyapatite in an alkaline environment. Due to the presence of tannic acid, the crystal growth mode of hydroxyapatite is modulated. Tannic acid, as a retarder, can be adsorbed on the growth surface of hydroxyapatite crystals, guiding the crystals to grow in a specific direction, and prompting hydroxyapatite to form a lamellar structure during precipitation. Tannic acid, as a natural organic compound, has good biocompatibility and bioactivity. When tannic acid is combined with hydroxyapatite, it can further improve the biocompatibility of hydroxyapatite, making it more suitable for use as an oral care ingredient. The addition of calcium stearate can reduce the surface tension of the reaction system and improve the dispersibility and stability of hydroxyapatite.

[0021] The traditional hydroxyapatite synthesis method is often carried out under high temperature conditions, which not only increases energy consumption, but also may affect the biological activity of the material. The preparation method of the present invention can obtain hydroxyapatite by stirring at room temperature for 10 to 14 hours. The hydroxyapatite prepared by the present invention is an amorphous flaky structure with low crystallinity, but this low-temperature synthesis method helps to maintain the biological activity of the material and can effectively reduce energy consumption.

[0022] Compared with rod-shaped and spherical hydroxyapatite structures, lamellar amorphous hydroxyapatite has unique advantages in the field of toothpaste. First, the lamellar structure gives hydroxyapatite a larger specific surface area and higher surface activity, which can contact and function more effectively with the tooth surface. This structure not only improves the adhesion of hydroxyapatite on the tooth surface, but also enhances its permeability, allowing it to penetrate deep into the teeth and remove hidden dirt and bacteria. Secondly, the amorphous structure makes lamellar hydroxyapatite more easily dissolved and recrystallized in the oral environment, thereby reacting with the minerals on the tooth surface and promoting the remineralization process of the teeth. This reaction can repair damaged enamel and enhance the hardness and wear resistance of the teeth. In addition, lamellar amorphous hydroxyapatite also has excellent biocompatibility and stability, and will not cause irritation or damage to teeth and gums. At the same time, its tiny particle size makes toothpaste more delicate and tastes better. From the perspective of morphology, lamellar amorphous hydroxyapatite is superior to traditional rod-shaped and spherical hydroxyapatite in the field of toothpaste. Its unique flaky structure and amorphous properties give the toothpaste better cleaning effects, remineralization capabilities and biocompatibility, thereby better maintaining oral health.

[0023] The lamellar amorphous structure of hydroxyapatite has a large specific surface area and surface defects. Baicalein has strong polarity and can form non-covalent forces such as hydrogen bonds and electrostatic interactions with the surface of hydroxyapatite. Baicalein can stably adhere to the surface of hydroxyapatite or embed into its structure. When baicalein is stably attached to the surface of hydroxyapatite or embedded in its structure, its stability is significantly improved, reducing the activity loss of baicalein due to degradation or hydrolysis. After adding baicalein, the advantages of hydroxyapatite as an oral care product are further enhanced. Baicalein is the main active ingredient in the root of Scutellaria baicalensis, a flavonoid compound, which has a significant inhibitory effect on the growth of harmful bacteria such as Escherichia coli and Staphylococcus aureus. The lamellar amorphous structure of hydroxyapatite can increase the contact area and opportunity between baicalein and bacterial cells. Baicalein uses the ATP synthase on the cell surface as a molecular target and connects to the inhibitor binding site of this enzyme, thereby inhibiting the synthesis of ATP synthase, making it impossible for bacteria to produce energy for their own growth and metabolism, and then causing the bacteria to die.

[0024] Beneficial effects of the present invention:

[0025] The present invention adds tannic acid to the preparation of hydroxyapatite. Tannic acid guides hydroxyapatite to form a flaky amorphous structure by regulating the precipitation and crystallization process, which significantly enhances the specific surface area, surface activity and permeability of the material, making it more suitable as an oral care ingredient. At the same time, the addition of calcium stearate improves the dispersibility and stability of the material. The addition of baicalein further enhances the antibacterial properties and effectively inhibits the growth of harmful bacteria. This flaky amorphous structure further promotes the antibacterial effect of baicalein. Compared with the traditional method, the present invention not only reduces energy consumption, but also maintains the biological activity of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0027] Figure 1 This is a scanning electron microscope image of hydroxyapatite obtained in Example 1. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0029] In the embodiments of the present invention and the comparative examples:

[0030] Calcium carbonate: purchased from Shanghai Bolin Biotechnology Co., Ltd.;

[0031] Calcium sulfate: purchased from Shanghai Bolin Biotechnology Co., Ltd.;

[0032] Calcium chloride: purchased from Nantong Badi Chemical Co., Ltd.;

[0033] Ammonium dihydrogen phosphate: purchased from Shanghai Guanghua Technology Co., Ltd.;

[0034] Diammonium hydrogen phosphate: purchased from Jinan Yuanshang New Materials Co., Ltd.

[0035] Sodium dihydrogen phosphate: purchased from Shanghai Dingfen Chemical Technology Co., Ltd.;

[0036] Potassium hydrogen phosphate: purchased from Shanghai Yanze Chemical Co., Ltd.

[0037] Sodium phosphate: purchased from Jiangsu Bosite Chemical Technology Co., Ltd.;

[0038] Ethylenediamine: purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0039] Tannic acid: purchased from Wufeng Chicheng Biotechnology Co., Ltd.;

[0040] Calcium stearate: purchased from Nanjing Jinling Chemical Plant Co., Ltd.;

[0041] Anhydrous ethanol: purchased from Changshu Hongsheng Fine Chemical Co., Ltd.;

[0042] Baicalin: purchased from Nanjing Bingcheng Biotechnology Co., Ltd.

[0043] Example 1

[0044] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0045] S1-1: Add calcium carbonate to 70°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add ammonium dihydrogen phosphate to an equal mass of deionized water to prepare an ammonium dihydrogen phosphate solution with a concentration of 0.03M;

[0046] S1-2: Add the ammonium dihydrogen phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 700 r / min, wherein the dropping speed of the ammonium dihydrogen phosphate solution is 0.5 mL / min, adjust the pH of the solution to 10.5 using ethylenediamine, and perform ultrasound for 30 min to obtain solution A;

[0047] S1-3: 1 mM tannic acid solution was added to solution A, wherein the amount of tannic acid solution added was 10% of the mass of solution A, and ultrasonicated at 55°C for 1.5 h with an ultrasonic power of 7 kW, followed by adding 1 wt% calcium stearate, stirring at room temperature for 12 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 14 h to obtain powder B;

[0048] S1-4: Add 4 parts by weight of Baicalin to 100 parts by weight of 60°C 70% ethanol solution, ultrasonicate for 30 minutes, then add 10 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 3 hours at a stirring speed of 600 r / min, wash with deionized water and ethanol, and then dry in a 60°C vacuum drying oven for 14 hours to obtain the hydroxyapatite.

[0049] Example 2

[0050] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0051] S1-1: Add calcium chloride to 60°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add diammonium hydrogen phosphate to an equal mass of deionized water to prepare a diammonium hydrogen phosphate solution with a concentration of 0.03M;

[0052] S1-2: Add the diammonium hydrogen phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 600 r / min, wherein the diammonium hydrogen phosphate solution is added at a dropping speed of 0.4 mL / min, and the pH of the solution is adjusted to 10 using ethylenediamine, and ultrasonicated for 30 min to obtain solution A;

[0053] S1-3: adding 0.5 mM tannic acid solution to solution A, wherein the amount of tannic acid solution added is 5% of the mass of solution A, ultrasonicating at 50°C for 1.5 h with an ultrasonic power of 6 kW, then adding 1 wt% calcium stearate, stirring at room temperature for 10 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 12 h to obtain powder B;

[0054] S1-4: Add 3 parts by weight of Baicalin to 100 parts by weight of 60% ethanol solution at 60°C, ultrasonicate for 30 minutes, then add 5 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 2 hours at a stirring speed of 500 r / min, wash with deionized water and ethanol, and then dry in a vacuum drying oven at 60°C for 12 hours to obtain the hydroxyapatite.

[0055] Example 3

[0056] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0057] S1-1: Calcium sulfate is added to 80°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and ammonium dihydrogen phosphate is added to an equal mass of deionized water to prepare an ammonium dihydrogen phosphate solution with a concentration of 0.03M;

[0058] S1-2: Add the ammonium dihydrogen phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 800 r / min, wherein the dropping speed of the ammonium dihydrogen phosphate solution is 0.6 mL / min, adjust the pH of the solution to 11 using ethylenediamine, and perform ultrasound for 30 min to obtain solution A;

[0059] S1-3: Add 1.5 mM tannic acid solution to solution A, wherein the amount of tannic acid solution added is 15% of the mass of solution A, ultrasonicate at 60°C for 1.5 h with an ultrasonic power of 8 kW, then add 1 wt% calcium stearate, stir at room temperature for 14 h, wash with deionized water and anhydrous ethanol, and then freeze-dry in a -40°C freeze dryer for 16 h to obtain powder B;

[0060] S1-4: Add 5 parts by weight of Baicalin to 100 parts by weight of 60°C 80% ethanol solution, ultrasonicate for 30 minutes, then add 15 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 4 hours at a stirring speed of 700 r / min, wash with deionized water and ethanol, and then dry in a 60°C vacuum drying oven for 16 hours to obtain the hydroxyapatite.

[0061] Example 4

[0062] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0063] S1-1: Add calcium carbonate to 70°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add sodium dihydrogen phosphate to an equal mass of deionized water to prepare a sodium dihydrogen phosphate solution with a concentration of 0.03M;

[0064] S1-2: adding the sodium dihydrogen phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 700 r / min, wherein the sodium dihydrogen phosphate solution is added at a rate of 0.5 mL / min, adjusting the pH of the solution to 10.5 using ethylenediamine, and ultrasonicating for 30 min to obtain solution A;

[0065] S1-3: 1 mM tannic acid solution was added to solution A, wherein the amount of tannic acid solution added was 10% of the mass of solution A, and ultrasonicated at 55°C for 1.5 h with an ultrasonic power of 7 kW, followed by adding 1 wt% calcium stearate, stirring at room temperature for 12 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 14 h to obtain powder B;

[0066] S1-4: Add 4 parts by weight of Baicalin to 100 parts by weight of 60°C 70% ethanol solution, ultrasonicate for 30 minutes, then add 10 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 3 hours at a stirring speed of 600 r / min, wash with deionized water and ethanol, and then dry in a 60°C vacuum drying oven for 14 hours to obtain the hydroxyapatite.

[0067] Example 5

[0068] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0069] S1-1: Add calcium carbonate to 70°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add dipotassium hydrogen phosphate to an equal mass of deionized water to prepare a dipotassium hydrogen phosphate solution with a concentration of 0.03M;

[0070] S1-2: Add the potassium hydrogen phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 700 r / min, wherein the dropping speed of the potassium hydrogen phosphate solution is 0.5 mL / min, adjust the pH of the solution to 10.5 using ethylenediamine, and perform ultrasound for 30 min to obtain solution A;

[0071] S1-3: 1 mM tannic acid solution was added to solution A, wherein the amount of tannic acid solution added was 10% of the mass of solution A, and ultrasonicated at 55°C for 1.5 h with an ultrasonic power of 7 kW, followed by adding 1 wt% calcium stearate, stirring at room temperature for 12 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 14 h to obtain powder B;

[0072] S1-4: Add 4 parts by weight of Baicalin to 100 parts by weight of 60°C 70% ethanol solution, ultrasonicate for 30 minutes, then add 10 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 3 hours at a stirring speed of 600 r / min, wash with deionized water and ethanol, and then dry in a 60°C vacuum drying oven for 14 hours to obtain the hydroxyapatite.

[0073] Example 6

[0074] A preparation process of flaky amorphous hydroxyapatite, the specific process of the preparation process is as follows:

[0075] S1-1: Add calcium carbonate to 70°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add sodium phosphate to an equal mass of deionized water to prepare a sodium phosphate solution with a concentration of 0.03M;

[0076] S1-2: adding the sodium phosphate solution to the calcium-containing reagent using a microinjection pump at a stirring speed of 700 r / min, wherein the sodium phosphate solution is added at a rate of 0.5 mL / min, adjusting the pH of the solution to 10.5 using ethylenediamine, and ultrasonicating for 30 min to obtain solution A;

[0077] S1-3: 1 mM tannic acid solution was added to solution A, wherein the amount of tannic acid solution added was 10% of the mass of solution A, and ultrasonicated at 55°C for 1.5 h with an ultrasonic power of 7 kW, followed by adding 1 wt% calcium stearate, stirring at room temperature for 12 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 14 h to obtain powder B;

[0078] S1-4: Add 4 parts by weight of Baicalin to 100 parts by weight of 60°C 70% ethanol solution, ultrasonicate for 30 minutes, then add 10 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 3 hours at a stirring speed of 600 r / min, wash with deionized water and ethanol, and then dry in a 60°C vacuum drying oven for 14 hours to obtain the hydroxyapatite.

[0079] Comparative Example 1

[0080] Commercially available rod-shaped hydroxyapatite was used instead of powder B to carry out steps S1-4 in Example 1. The commercially available rod-shaped hydroxyapatite was purchased from Shanghai Yien Chemical Technology Co., Ltd.

[0081] Performance Testing

[0082] The antibacterial properties of the hydroxyapatite prepared in the examples and comparative examples were tested according to GB / T21510-2008 standard. The indicator bacteria were Escherichia coli and Staphylococcus aureus, and the initial bacterial solution concentration was 1×10 6 cfu / mL.

[0083] The experimental data are summarized in the following table:

[0084]

[0085] It can be seen from the data of Examples 1 to 6 and Comparative Example 1 that, compared with hydroxyapatite of common morphology, the hydroxyapatite prepared in the present invention has a more significant inhibitory effect on Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli.

[0086] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for preparing flaky amorphous hydroxyapatite, characterized in that: The specific process of the preparation process is as follows: S1-1: Add a calcium source to 60-80°C deionized water to prepare a calcium-containing reagent with a concentration of 0.05M, and add phosphate to an equal mass of deionized water to prepare a phosphate solution with a concentration of 0.03M; S1-2: adding the phosphate solution dropwise to the calcium-containing reagent using a microinjection pump at a stirring speed of 600 to 800 r / min, adjusting the pH of the solution to 10 to 11 using ethylenediamine, and ultrasonicating for 30 minutes to obtain solution A; S1-3: adding 0.5-1.5 mM tannic acid solution to solution A, ultrasonicating at 50-60°C for 1.5 h, then adding 1 wt% calcium stearate, stirring at room temperature for 10-14 h, washing with deionized water and anhydrous ethanol, and then freeze-drying in a -40°C freeze dryer for 12-16 h to obtain powder B; S1-4: Add 3 to 5 parts by weight of Baicalin to 100 parts by weight of 60°C ethanol solution, ultrasonicate for 30 minutes, then add 5 to 15 parts by weight of powder B, raise the temperature to 80°C and continue stirring for 2 to 4 hours, wash with deionized water and ethanol, and then place in a 60°C vacuum drying oven to dry for 12 to 16 hours to obtain the hydroxyapatite.

2. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The calcium source in S1-1 includes one or a combination of two or more of calcium carbonate, calcium chloride or calcium sulfate.

3. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The phosphate in S1-1 is a water-soluble phosphate.

4. The process for preparing a flaky amorphous hydroxyapatite according to claim 3, characterized in that: The phosphate in S1-1 includes one or a combination of two or more of diammonium dihydrogen phosphate, diammonium hydrogen phosphate, potassium salt or sodium salt of phosphate.

5. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The dropping speed of the phosphate solution in S1-2 is 0.4-0.6 mL / min.

6. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The amount of tannic acid solution added in S1-3 is 5-15% of the mass of solution A.

7. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The ultrasonic power in S1-3 is 6-8 kW.

8. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The mass fraction of the ethanol solution in S1-4 is 60-80%.

9. The process for preparing a flaky amorphous hydroxyapatite according to claim 1, characterized in that: The stirring speed in S1-4 is 500-700 r / min.

10. A flaky amorphous hydroxyapatite obtained by the preparation process according to any one of claims 1 to 8.

11. A use of the plate-like amorphous hydroxyapatite as claimed in claim 9, characterized in that: The hydroxyapatite can be applied to the fields of oral care and restoration.

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