KR20070008328A - Method for producing hydroxyapatite having spherical particle shape in nanometer to micrometer size - Google Patents

Abstract

A method for producing hydroxyapatite is provided to simplify production process and reduce production cost by skipping an additional heat treatment process of removing organic materials for obtaining the spherical particle shape, and obtain spherical fine particles of hydroxyapatite having a particle diameter range of nanometer to 30 mum or less, preferably 10 nm to 20 mum so that the spherical fine particles of hydroxyapatite can be used in a medical field and the like. A method for producing spherical particles of hydroxyapatite having a particle diameter of nanometer to 30 mum or less comprises: a step(1) of preparing an aqueous solution comprising dicalcium phosphate anhydrate(CaHPO4), dicalcium phosphate dihydrate(CaHPO4À2H2O), or a mixture thereof, and an organic acid; a step(2) of adjusting pH of a resulting aqueous solution of the step(1) to a range of 6.0 to 8.5; a step(3) of applying heat to the pH adjusted aqueous solution of the step(2) to form a sediment; and a step(4) of filtering and drying the sediment. The organic acid is citric acid, acetic acid, malic acid or lactic acid. The method further comprises the step of adding an inorganic acid to the aqueous solution comprising dicalcium phosphate anhydrate(CaHPO4), dicalcium phosphate dihydrate(CaHPO4À2H2O), or a mixture thereof, and an organic acid in an amount of less than 50 ml/liter of the aqueous solution in the step(1). The step(3) is performed by agitating the aqueous solution at an aqueous solution temperature of 70 to 80 deg.C for 30 minutes to 6 hours.

Description

METHODS FOR PRODUCING HYDROXYAPATITE HAVING SPHERICAL PARTICLE SHAPE IN NANOMETER TO MICROMETER SIZE}

1 is a view showing the results of X-ray diffraction analysis of the apatite hydroxide prepared in Example 1 of the present invention.

Figure 2 is a scanning electron micrograph showing the particle shape and size of the apatite hydroxide prepared in Example 1 of the present invention.

3 is a scanning electron micrograph showing the particle shape and size of the apatite hydroxide prepared by Example 7 of the present invention.

The present invention relates to a method for producing apatite hydroxide having the shape of nanometer to micrometer sized spherical particles, and more particularly, dicalcium phosphate anhydrate (DCPA, CaHPO ₄ ) or monohydrogen phosphate. By adjusting the pH of an aqueous solution in which calcium dihydrate (Dicalcium Phosphate Dihyrate, DCPD, CaHPO ₄ · 2H ₂ O) is dissolved, and inducing it to a supersaturated state, the nanometer to 30 μm or less, preferably 10 nm to A method for producing apatite hydroxide from spherical particles having a diameter of 20 μm.

Apatite hydroxide is a major component of minerals that accounts for about 70% of the human bone. This hydroxide apatite, which is the same component as the hard tissues of the human body such as bone, has high biocompatibility and is therefore particularly widely used in fields such as medical materials.

Examples of the method for preparing apatite hydroxide include solid-phase method prepared by reacting calcium salt and phosphate at a high temperature of 1000 ° C. or higher, hydrothermal method in which calcium salt and phosphate react in a hydrothermal solvent under high temperature and high pressure conditions, and water-soluble calcium salt and phosphate salt. Wet methods that are prepared using a liquid medium, such as precipitation, hydrolysis, sol-gel, and the like, which are reacted in aqueous solution, are commonly known. However, since the apatite hydroxide prepared by the conventional methods as described above has an amorphous particle shape mainly formed by disordered aggregation of crystals such as needles, rods, and flakes, etc. In order to obtain apatite hydroxide having a spherical particle shape, a separate additional process must be introduced in addition to the apatite hydroxide manufacturing process as described above.

As a method for producing apatite hydroxide having a spherical particle shape, for example, a spray drying method as disclosed in US Pat. No. 4,388,994, US Pat. No. 5,858,318 and US Pat. However, the spray drying method as disclosed in the above-mentioned prior arts must use organic binders and dispersants, etc. in order to maintain the spherical particle shape, and the apatite hydroxide particles thus prepared are added in order to be used for medical purposes. Since organic materials such as binders and dispersants must be removed, additional organic material removal processes such as heat treatment are required. In addition, the particle size of the spherical apatite hydroxide prepared by such a spray drying method is about 80 to 100㎛ in diameter, too large to be used as a raw material for medical materials, in some cases may be significantly limited.

On the other hand, in order to solve the problems of the conventional spray drying method as described above, by producing apatite hydroxide by a wet method using a supersaturation process, a method for obtaining spherical particles without additional use of organic materials such as binders is disclosed in Korea. Patent 2004-79190 is disclosed. However, according to this method, although the shape of the particles is obtained in a spherical shape, but the size is not obtained below the level of 30 ~ 50㎛ diameter, the field requiring a particle size of nanometer to several micrometer level There is still a problem that is not suitable for use in.

The present invention is to solve the problems of the prior art as described above, the object of the present invention, does not require the use of organic materials to obtain the spherical particle shape is not required a separate heat treatment process for its removal Since the manufacturing process can be simplified and the cost can be reduced, and apatite hydroxide can be obtained from very small spherical particles having a diameter of nanometer to 30 μm or less, preferably 10 nm to 20 μm, It is to provide a method for producing apatite hydroxide suitable for use in the medical field and the like requiring a particle size of several micrometers.

According to the present invention, (1) calcium dihydrogen phosphate anhydride (Dicalcium Phosphate Anhydrate, DCPA, CaHPO ₄ ), dicalcium phosphate dihydrate (DCPD, CaHPO ₄ .2H ₂ O) or mixtures thereof Preparing an aqueous solution comprising an organic acid; (2) adjusting the pH of the aqueous solution as a result of step (1) to 6.0 to 8.5, preferably 6.5 to 8.0; (3) forming a precipitate by applying heat to the pH-adjusted aqueous solution in step (2); And (4) filtering and drying the precipitate, a method for producing apatite hydroxide from spherical particles having a diameter of nanometer to 30 μm or less, preferably 10 nm to 20 μm is provided.

In the production method of the present invention, the calcium monohydrogen phosphate anhydride or calcium monohydrogen phosphate dihydrate used as a raw material is preferably in the form of a powder, and commercially available ones may be purchased and used, otherwise, generally known What was produced by the method of filtering, drying, and grinding the precipitate obtained by the precipitation method (molar ratio of calcium / phosphorus = 1.0, pH = 6-7) which reacts the aqueous solution containing a calcium salt with the aqueous solution containing a phosphate can also be used. . In the case where the calcium monohydrogen phosphate anhydride or calcium dihydrogen phosphate dihydrate used as a raw material is produced and used directly by the precipitation method, it is particularly preferable to use a material having a purity of 98% or more as a source compound of calcium and phosphorus. It is preferable in the manufacture of.

In the production method of the present invention, citric acid, acetic acid, malic acid, lactic acid and the like can be used as the organic acid, and in particular, citric acid is preferably used in view of the reaction yield.

In the production method of the present invention, in the aqueous solution containing the calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate or a mixture thereof and an organic acid, the calcium monohydrogen phosphate compound is 0.5 to 25 g / L in water as a medium. It is included in the concentration of, it is preferable that the organic acid is contained in a molar concentration of 0.01 ~ 1M. If the concentration of the calcium monohydrogen phosphate compound is less than 0.5g / L, the production efficiency is too low, if it exceeds 25g / L, the concentration is so high that it is difficult to produce apatite having a desired level of spherical and particle size Lose. In addition, since the organic acid is used to increase the solubility of the calcium monohydrogen phosphate compound, when the amount of the calcium monohydrogen phosphate compound contained in the aqueous solution is increased, it is preferable to increase the amount of the organic acid accordingly. If the concentration is less than 0.01 M, the dissolution of the calcium dihydrogen phosphate compound becomes insufficient, and if it exceeds 1 M, the supersaturation induction becomes difficult in a later step, and the particle generation becomes insufficient.

According to one embodiment of the present invention, the step (1), for example, after preparing 1 L of an aqueous organic acid solution of 0.01 ~ 1M, here calcium monohydrogen phosphate anhydrous, calcium dihydrogen phosphate dihydrate or a mixture thereof 0.5 ~ 25 g may be added, stirred and dissolved. The dissolution may be performed at room temperature, and may be heated to 50 ° C. or lower to increase the dissolution rate.

In the step (1) of the production method of the present invention, in order to increase the dissolution rate of the calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate or a mixture thereof, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, etc. The same inorganic acid may be further added within 50 ml per liter of aqueous solution. When the amount of the inorganic acid added exceeds 50 ml per liter of the aqueous solution, it is difficult to induce supersaturation in a subsequent step, and the particle generation is insufficient. As said inorganic acid, hydrochloric acid is preferable.

In the step (2) of the production method of the present invention, the pH of the aqueous solution is adjusted to 6.0 ~ 8.5, preferably 6.5 ~ 8.0 in the result of the step (1), if the pH is less than 6.0, the production of apatite hydroxide itself Becomes difficult and exceeds 8.5, it is difficult to obtain a desired level of spherical particles. The pH is preferably adjusted using an aqueous solution of an inorganic base such as an aqueous sodium hydroxide solution, and is not particularly limited. However, when the aqueous sodium hydroxide solution is used, the concentration is 1 M when the concentration of the organic acid is 0.1 M or more. When it is 0.1 M or less, it is desirable to set it as 0.2M from a viewpoint of pH control.

In one preferred embodiment of the production method of the present invention, citric acid is dissolved in the case of dissolving calcium monohydrogen phosphate (DCPA) or calcium dihydrogen phosphate dihydrate (DCPD) using citric acid as the organic acid. The proper concentration and the appropriate dissolution amount of calcium dihydrogen phosphate and the resultant pH adjusted by treating with aqueous sodium hydroxide solution are shown in Table 1 below. The values given in Table 1 are based on 1 liter of aqueous solution.

TABLE 1

In the step (3) of the production method of the present invention, by adding heat to the pH-controlled aqueous solution in the step (2), the supersaturation is induced to form apatite hydroxide precipitates. At this time, it is preferable to remove solid impurities that may be present in the pH adjusted aqueous solution in order to form particles having a desired level of spherical shape. Therefore, in the step (3) of the preferred embodiment of the present invention, after filtering the aqueous solution of pH adjustment in the step (2) with a filter to remove the solid impurities in the aqueous solution, by applying heat to the filtration result solution, Apatite hydroxide precipitates are formed. As the filter, a filter of about 0.2 μm may be used.

In addition, the formation of the apatite hydroxide precipitate in the step (3) of the production method of the present invention is carried out by inducing supersaturation by adding heat to the pH-controlled aqueous solution while stirring, the heating is 70 ~ It is preferable to maintain about 80 degreeC, and it is preferable to stir for 30 minutes-6 hours within such a temperature range. If the temperature of the aqueous solution is too low or the stirring time is too short, the formation of apatite hydroxide precipitation is not sufficient, if the temperature of the aqueous solution is too high, the evaporation of water in the aqueous solution is excessive, the hydroxide having a desired shape and particle size If it is difficult to obtain apatite, and the stirring time is too long, workability and process efficiency may be deteriorated.

In the step (4) of the production method of the present invention, the apatite hydroxide precipitate formed in the step (3) is filtered and dried. The drying is preferably lyophilization rather than thermal drying, because during thermal drying there is a high risk of damage to the particle structure due to the rapid evaporation of water molecules trapped in the precipitate.

According to the production method as described above, apatite hydroxide of spherical particles having a diameter of nanometers to 30 µm or less, preferably 10 nm to 20 µm is obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1

[Production of Calcium Dihydrogen Phosphate Anhydride]

500 ml of 1 M aqueous calcium nitrate tetrahydrate solution (Ca (NO ₃ ) ₂ .4H ₂ O) and 500 ml of 1 M aqueous ammonium dihydrogen phosphate solution ((NH ₄ ) ₂ HPO ₄ ) were prepared, mixed, and the pH was adjusted. Stir for 6 hours while maintaining at 6-7. After stirring, the mixture was filtered, washed, and dried at 80 ° C. for 12 hours, followed by grinding to obtain calcium dihydrogen phosphate anhydride.

[Production of Apatite Hydroxide]

20 g of calcium monohydrogen phosphate anhydride obtained above was added to 1 L of an aqueous 0.5 M citric acid solution, which was stirred and dissolved. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust the pH to 7.0 and then filtered through a 0.2 μm filter. Heat was added to the resulting filtrate and stirred for 1 hour while maintaining the temperature of the aqueous solution at 70-80 ° C. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis was performed on the prepared apatite hydroxide, and the results are shown in FIG. 1. In addition, in order to observe the particle shape and size, the prepared apatite hydroxide was photographed with a scanning electron microscope, the photo is shown in FIG.

1 shows a characteristic peak of the apatite hydroxide well, from which it can be seen that the apatite hydroxide was prepared according to this embodiment, according to Figure 2, a relatively uniform spherical hydroxide having a diameter of about 0.5 ㎛ It can also be seen that the apatite particles were produced.

Example 2

10 g of calcium monohydrogen phosphate anhydride obtained in Example 1 was added to 1 L of an aqueous 0.3 M citric acid solution, and 12 ml of hydrochloric acid was further added, followed by stirring to dissolve it. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust its pH to 7.5, which was then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 3 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis and scanning electron microscopy were performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1.

Example 3

15 g of calcium dihydrogen phosphate anhydride obtained in Example 1 was added to 1 L of an aqueous 0.3 M citric acid solution, followed by stirring to dissolve it. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust the pH to 7.0 and then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 2 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis and scanning electron microscopy were performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1.

Example 4

15 g of calcium dihydrogen phosphate anhydride obtained in Example 1 was added to 1 L of an aqueous 0.5 M citric acid solution, followed by stirring to dissolve it. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust its pH to 7.5, which was then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 2 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis and scanning electron microscopy were performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1.

Example 5

5 g of calcium dihydrogen phosphate anhydride obtained in Example 1 was added to 1 L of 0.1 M citric acid aqueous solution, followed by stirring to dissolve it. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust the pH to 7.0 and then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 3 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis and scanning electron microscopy were performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1.

Example 6

5 g of calcium dihydrogen phosphate anhydride obtained in Example 1 was added to 1 L of an aqueous 0.3 M citric acid solution, followed by stirring to dissolve it. An aqueous 1 M sodium hydroxide (NaOH) solution was added thereto under pH measurement to adjust its pH to 8.0, which was then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 3 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis and scanning electron microscopy were performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1.

Example 7

0.01 M citric acid solution containing 13 g of hydrochloric acid containing 1 g of calcium dihydrogen phosphate anhydride and 1.25 g of calcium dihydrogen phosphate dihydrate (product name: DCP (Super Clean) -D, manufacturer: Daljae Chemical) obtained in Example 1 2 L was added and then stirred to dissolve it. An aqueous 0.2 M sodium hydroxide (NaOH) solution was added thereto under pH measurement, and the pH was adjusted to 7.0, which was then filtered through a 0.2 μm filter. Heat was added to the resultant filtrate and stirred for 5 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis was performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1. In addition, the prepared hydroxyapatite was photographed with a scanning electron microscope, the photo is shown in FIG. According to Figure 3, it can be seen that the spherical apatite hydroxide particles having a diameter of about 5 ~ 10㎛ was prepared.

Comparative example

1.5 g of apatite hydroxide was added to 1 L of an aqueous solution containing 21 ml of hydrochloric acid and dissolved. After adding 1 liter of 2M aqueous solution of urea (urea) and mixing, it filtered with a 0.2 micrometer filter. Heat was added to the resultant filtrate and stirred for 5 hours while maintaining the temperature of the aqueous solution at 70 ~ 80 ℃. After completion of the stirring, the resulting precipitate was filtered and then lyophilized using a freeze dryer to prepare apatite hydroxide of spherical particles.

X-ray diffraction analysis was performed on the prepared apatite hydroxide in the same manner as in Example 1, and the results were similar to those of Example 1. In addition, the prepared apatite hydroxide was photographed with a scanning electron microscope, and as a result, it was found that spherical apatite hydroxide particles having a diameter of about 40 ~ 50㎛.

As described above, according to the present invention, spherical apatite hydroxide particles having a diameter of 10 nm to 20 μm can be obtained with a uniform particle size distribution without the need for a separate heat treatment such as a spray drying method. The spherical fine particles of apatite hydroxide having a uniform particle size distribution obtained according to the present invention can be suitably used as a raw material for medical materials, a raw material for bioceramic sintered compacts, a raw material for scaffolds for tissue engineering, or a filler of an organic / inorganic composite.

Claims (9)

(1) preparing an aqueous solution comprising calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate or a mixture thereof and an organic acid; (2) adjusting the pH of the aqueous solution as a result of step (1) to 6.0 to 8.5; (3) forming a precipitate by applying heat to the pH-adjusted aqueous solution in step (2); And (4) filtering and drying the precipitate, wherein the apatite is prepared from spherical particles having a diameter of from about nanometers to about 30 μm. The method of claim 1 wherein the organic acid is citric acid, acetic acid, malic acid or lactic acid. The aqueous solution comprising the calcium monohydrogen phosphate anhydride, calcium monohydrogen phosphate dihydrate or a mixture thereof and an organic acid, wherein the calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate or a mixture thereof The method characterized in that it is included at a concentration of 0.5 ~ 25g / L. The method according to claim 1, wherein the aqueous solution containing the calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate or a mixture thereof and an organic acid contains 0.01 to 1 M in molar concentration. The method according to claim 1, wherein in step (1), further adding an inorganic acid to an aqueous solution containing the calcium monohydrogen phosphate anhydride, calcium dihydrogen phosphate dihydrate, or a mixture thereof and an organic acid within 50 ml per liter of the aqueous solution. How to feature. 6. The method of claim 5, wherein the inorganic acid is hydrochloric acid, sulfuric acid, nitric acid or perchloric acid. The method according to claim 1, wherein in step (3), the aqueous solution whose pH is adjusted in step (2) is filtered with a filter, and then heat is applied to the resultant filtrate to form apatite hydroxide precipitates. Way. The method of claim 1, wherein step (3) is performed by stirring the aqueous solution for 30 minutes to 6 hours under an aqueous solution temperature of 70 to 80 ° C. The method according to claim 1, wherein the drying in the step (4) is lyophilization.

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