JPH02149408A - Preparation of fine particle aggregate of hydroxyapatite - Google Patents

Abstract

PURPOSE:To obtain the aggregate fine particles having uniform fine spherical shape by dropping a soln. in water and/or a hydrophilic org. solvent of a non phosphate type reactive Ca compd. and a non Ca salt type reactive oxyacid compd. of P into water and/or the hydrophilic org. solvent. CONSTITUTION:A non phosphate type reactive Ca compd. (e.g. CaCl2) and a non Ca salt type reactive oxyacid compd. of P (e.g. H3PO4) are dissolved in water and/or a hydrophilic org. solvent (e.g. methanol) at <=50 deg.C in a specified proportion by mole of Ca/P. While holding the temp. of the soln. at >=70 deg.C, the pH of the soln. is adjusted to >=4 by adding an alkali such as NaOH, KOH, etc. Then the soln. is dropped into water and/or a hydrophilic org. solvent while controlling a velocity for forming a precipitate. Thus, aggregate bodies formed around initially precipitated particles are obtd. The precipitate is then recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing hydroxyapatite fine particle aggregates, which are suitable as carriers for chromatographic separation and raw materials for molded bodies.

[Prior art] Ca0-P20@-based apatite has been developed mainly as a biomaterial, and among them, hydroxyapatite (hereinafter sometimes referred to as HAP) has the same composition as the substance that forms the bones of the human body, and is not used in vivo. When implanted, it has good compatibility with living organisms and has good bonding properties with autologous bone, so it is used as a material for artificial bones, artificial teeth, etc. It is also used as a packing material for chromatography, an ion exchange material, etc. by utilizing its affinity with proteins and the ion exchange ability of HAP itself.

BACKGROUND ART Separation and purification of biologically related substances such as proteins are increasingly required in the medical and pharmaceutical fields, and techniques for separating and purifying biologically related substances using, for example, high-performance liquid chromatography are attracting attention as an industrial means. The carrier used for the stationary phase in such chromatography is required to have good affinity with the above-mentioned biological substances, and RAP that satisfies the above requirements has come to be used as a carrier for chromatographic separation. . However, there are drawbacks such as the fact that technology for controlling the particle size and shape of HAP has not been established, and the reproducibility of the Ca/P ratio of MAP is poor, resulting in the separation characteristics changing from production lot to production lot. is desired.

High performance liquid chromatography uses a mobile phase of 10 to 3 Q
The purpose is to speed up the separation by flowing at a high speed of H/sec, but in order to cope with such high speed, the carrier is required to have sufficient strength to withstand high pressure. Furthermore, in order to maintain a high separation ability by chromatography, it is necessary to maintain the packing of the carrier in an approximate distribution equilibrium state for chromatography as much as possible. Especially when the particle size of the carrier is 100
If the size is about 150 μm, it is difficult to maintain the above-mentioned equilibrium state under the high speed state of the mobile phase. Therefore, in order to maintain the above-mentioned equilibrium state under high-speed conditions, it is necessary to make the particle size of the carrier sufficiently fine and to make the particle size uniform.

HAP used as a carrier for chromatography separation
Generally, those synthesized by a wet method are used as they are or in the form of granules, or those synthesized by a dry method are pulverized and classified. However, in order to produce fine particles with a particle size of 10 μm or less, the yield is poor regardless of which method is used, and furthermore, the above-mentioned problems in terms of shape, particle size distribution, etc. remain unsolved.

In addition to the above-mentioned methods, there are many other known methods for producing HAP. For example, in the autoclave method, HAP becomes pile-shaped particles, while in the wet synthesis method using CaHPO4 as a starting material, it becomes diamond-shaped. Moreover, it is difficult to obtain particles with a particle size of 10 μm or less by any method. On the other hand, with the method of neutralizing phosphoric acid, fine particulate HAP can be obtained, but it becomes colloidal and the ideal spherical and uniform particles cannot be obtained.Additionally, granulation is sometimes carried out by spray drying, but the particle diameter is 10 μm.
There is a problem that the yield of the following fine particles is poor.

In order to make the density of the compact as high as possible when molding -1 MAP powder and solidifying it by firing, it is desired that the particle size of the powder be as small as possible and that the particle size distribution be as narrow as possible. However, H obtained by the above method
AP particles are coarse particles ranging in size from several μm to 10 μm or more, and when the size of secondary particles is this large, the filling rate becomes low and it is difficult to increase the density. If an attempt is made to make the particles finer, the crystallinity deteriorates, and since the compact contains a large amount of water, the shrinkage rate during firing of the dense compact becomes large and the compact becomes unstable.

[Problems to be Solved by the Invention] The present invention has been made to solve these technical problems, and its purpose is to make the particle shape spherical, to make the particle size uniform and fine, and to make Ca/ The object of the present invention is to provide a method for producing a single aggregate of hydroxyapatite fine particles, which can control the P ratio with good reproducibility and is optimal as a carrier for chromatography separation or as a raw material for a molded body.

[3! [Means for Solving the Problems] The present invention that has achieved the above object is to use a non-phosphate reactive Ca compound and a non-Ca compound such that a predetermined Ca/P ratio
A reactive oxygen acid compound of salt-type phosphorus is dissolved in water and/or a hydrophilic organic solvent at a temperature of 50°C or lower, and this solution is dissolved in water and/or a hydrophilic organic solvent while maintaining a temperature of 70°C or higher and a pH of 4 or higher. This is a method for producing hydroxyapatite fine particle aggregates, the gist of which is to form aggregates with initially crystallized particles as cores by dropping the particles dropwise and control the rate of precipitation formation, and to collect the precipitates.

[Function] The present inventors have discovered that if the respective compounds of Ca and P are mixed in advance to form a single liquid, and then subjected to a hydration displacement reaction, the C of HAP can be reduced.
It was discovered that the a/P ratio could be controlled with good reproducibility, and its technical significance was recognized, so a patent application was filed (Japanese Patent Application No. 326516/1982). The inventors of the present invention continued to conduct research in order to further improve the above technology. As a result, it was found that if the formation rate of [(AP precipitate) in the hydration displacement reaction is appropriately controlled, aggregates in which HAP particles gather around the initial crystallized particles as cores can be formed, and the shape of these aggregates is spherical and We discovered that it is ideal as a chromatography separation carrier and a raw material for molded bodies because it is produced uniformly.
The invention has been completed. In addition, as a specific means to control the rate of precipitation formation, it is possible to reduce the degree of supersaturation of the above solution with respect to water or a hydrophilic organic solvent, and to control the dropping rate to such an extent that new crystal nuclei are difficult to form independently during dropping. Can be mentioned.

The non-phosphate reactive Ca compound and the non-Ca salt reactive oxygen acid compound used in the present invention are those that are soluble in water or hydrophilic flN solvents, such as non-phosphate reactive Ca compounds. Compounds include CaClt, Ca(NOs
)2.

Ca (8C00)2, Ca (CHs Coo)2
.

Non-limiting examples include Ca(O)i)z, CaCO5, etc., Ca-alkoxides such as calcium dimethoxide, calcium jetoxide, and calcium dibropoxide, and carboxylic acid salts.

In addition, as a non-Ca salt type phosphorus reactive oxygen acid compound, 8
3PO4 or KHaPO4゜NHa 82 PO4
, (NH4)2HPO4.

In addition to phosphates such as (NH4)s Po, 4, etc., alkoxides of f1 phosphorus oxygen acids such as phosphoric acid trimethoxide, phosphoric triethoxide, phosphoric acid tripropoxide, phosphorous trimethoxide, phosphorous triethoxide, phosphorous tripropoxide, etc. trimethyl phosphate, ethyl metaphosphate monoethyl phosphate, diethyl phosphate.

Non-limiting examples include esters of various phosphorus oxygen acids such as triethyl phosphate and ethyl birophosphate.

The non-phosphate type reactive Ca compound and the non-Ca salt type reactive oxygen acid compound of phosphorus are mixed in water and/or a wood-philic organic solvent at a temperature of 50°C or less in such a manner that a predetermined Ca/P ratio is achieved. Melt the solution and add the melt to water and/or a hydrophilic solvent at a temperature of 70°C or higher and a pH of 4 or higher (preferably 8 to 1).
1), and a hydration displacement reaction is carried out to obtain a HAP particle aggregate precipitate. At this time, the temperature of the melt was set at 50℃.
The reason for the following is to control the reaction in the melt.

In addition, while keeping the temperature of the dripping liquid above 70℃,
The reason for keeping the pH at 4 or higher (preferably 8 to 11) by dropping an alkali such as , NaOH, or NH40H is because if the temperature of the dropping liquid is below 70°C, the formed HAP becomes a mixed crystal with an amorphous phase. This is because the temperature of the liquid to be dropped should be 70° C. or higher. If the dropping solution has a pH of less than 4, no precipitate will be formed, and even if it does, the HAP fine particles will re-melt and the particle shape and chemical composition of the product will become unstable.
). The particle size can also be adjusted by controlling the pH (see Example 1 below).

Examples of the hydrophilic organic solvent other than water in the liquid for dissolving the Ca compound and the P compound or the liquid to which the dissolved liquid is dropped include methanol, ethanol, acetone, ether, etc. The liquid and the dripping liquid may be the same or different.

The present invention will be explained in more detail below with reference to examples, but the following examples merely show one specific example of the method of the present invention, and the design may not be changed in any way for the purpose of the above and below. Also included in the technical scope of the present invention.

[Example] Tonaoga Yu CaC1z and HsPO4 (85% concentration) were mixed with predetermined Ca
/P molar ratio was dissolved in 25°C ion-exchanged water IIl to obtain a mixed solution.

Next, while maintaining this temperature in the ion-exchanged water 11 at 70°C, the pH was controlled by adding a KOH aqueous solution using a microtube pump connected to a pH controller, and the mixture was added dropwise to obtain a milky white suspension. Ta. After holding this suspension for 2 hours, it was filtered with a membrane filter and AgN0. The filtrate was washed with pure water until no clouding of the filtrate due to the aqueous solution was observed. The obtained precipitate was 100
According to the results of powder X-ray diffraction after drying at .degree. C., all the materials were a single phase of HAP. Furthermore, observation of the particle shape using a transmission electron microscope revealed that it was a uniform spherical aggregate made up of needle-like particles. The Ca/P ratio of the obtained AP (AP) was almost the same as the blending ratio of the raw materials. Table 1 shows the relationship between the pH and the particle size.

Table J
This was mixed with 100 cc of ethyl alcohol in which 10 g of triethyl phosphite was dissolved to prepare a mixed solution. When the above mixed solution was added dropwise to a solution of 32 g of acetic anhydride dissolved in 100 cc of ethyl alcohol, a milky white suspension was obtained. After filtering and drying the suspension in the same manner as in Examples, the resulting precipitate was subjected to X-ray diffraction, and it was found to be spherical and uniform HAP fine particle aggregates.

Further, the Ca/P ratio of this aggregate was 1.67.

Example 3 Ca jetoxide and trimethyl phosphate were dissolved in ethyl alcohol at 25° C. to obtain a mixed solution so that the Ca/P ratio was a predetermined value. Next, KO was placed in ion-exchanged water at 70°C using a microtube connected to a pH controller.
The mixed solution was added dropwise while controlling the pH to 7 or more by adding an aqueous H solution, to obtain a milky white suspension. The question?
After filtering and drying the ji3 liquid in the same manner as in Example 1, the resulting precipitate was subjected to X-ray diffraction, and it was confirmed that it was a single phase of hydroxyapatite. In addition, the obtained HAP is
It had the same shape as in Example 1.

[Effects of the Invention] As described above, according to the present invention, a hydroxyapatite fine particle aggregate suitable as a carrier for chromatography separation or a raw material for a molded body was obtained.

Claims (1)

[Claims] Non-phosphate reactive Ca is added to achieve a predetermined Ca/P ratio.
Compounds and reactive oxygen acid compounds of phosphorus in non-Ca salt form
Dissolved in water and/or hydrophilic organic solvent at 0°C or lower,
This solution was added to water and/or a hydrophilic organic solvent at a temperature of 70°C.
Hydroxyapatite fine particle agglomeration method is characterized in that it is added dropwise while maintaining the temperature at ℃ or above and pH 4 or above, and forms an aggregate with initially crystallized particles as a nucleus by controlling the rate of precipitation formation, and then collects the precipitate. Method of manufacturing aggregates.