JPH0788206B2 - Method for producing hydroxyapatite fine particle aggregate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aggregate of hydroxyapatite fine particles, which is optimal as a carrier for chromatographic separation or a raw material for a molded body.

[Prior Art] CaO-P ₂ O ₅ system Apatato is mainly developed as biomaterials, among others (sometimes hereinafter referred to as HAP) Hydroxyapatite is the same composition as the material forming the body of the bone, raw When it is inserted into the body, it has a good affinity with living organisms and a good bondability with autologous bone, and is therefore used as a material for artificial bones and artificial teeth. Also the affinity with proteins
It is also used as a packing material for chromatography and as an ion exchange material by utilizing the ion exchange capacity of HAP itself.

Separation / purification of bio-related substances such as proteins has been increasingly demanded in the medical and pharmaceutical fields, and for example, a technique for separating / purifying bio-related substances by high performance liquid chromatography has been attracting attention as an industrial enemy means. The carrier used for such a stationary phase of chromatography is required to have good affinity with the above-mentioned bio-related substance, and HAP satisfying the above requirements has come to be used as a carrier for chromatographic separation. . However
There is a drawback that the separation characteristics change for each production lot due to lack of established technology for controlling the particle size and shape of HAP, and poor reproducibility of HAP Ca / P ratio. Is desired.

High performance liquid chromatography uses a mobile phase of 10 to 30 mm / sec.
In order to cope with such high speed, the carrier is required to have strength enough to withstand high pressure. Further, in order to maintain high chromatographic separation ability, it is necessary to keep the packing of the carrier in the approximate distribution equilibrium state of chromatography as much as possible. In particular, when the particle size of the carrier is about 100 to 150 μm, it is difficult to maintain the equilibrium state under the high-speed state of the mobile phase. Therefore, in order to maintain the equilibrium state at a high speed, it is necessary to make the particle diameter of the carrier sufficiently small and to make the particle diameter uniform.

HAP used as a carrier for chromatographic separation
In general, the one synthesized by the wet method is used as it is or as a granulated product, or the one synthesized by the dry synthesis method is pulverized and classified and used. However particle size
The yield is poor by any method for making fine particles of 10 μm or less, and the above-mentioned problems remain unsolved in terms of shape and particle size distribution.

Various methods other than the above-mentioned methods are known as a method for producing HAP. For example, in the autoclave method, HAP is used.
Become pile-shaped particles, and the wet synthesis method using CaHPO ₄ as a starting material results in a rhombus shape, and it is difficult to obtain fine particles of 10 μm or less by any method. On the other hand, in the method of neutralizing phosphoric acid, fine particle HAP
However, the particles are colloidal, and ideal spherical particles cannot be obtained. Although granulation may be performed by a spray dry method, there is a problem that the yield of fine particles of 10 μm or less is poor.

On the other hand, when the HAP powder is molded and fired and solidified, in order to increase the density of the molded body as much as possible, it is desired that the particle size of the powder be as small as possible and that the particle size distribution be narrow. However, HAP obtained by the above method
The particle size is a coarse particle size of several μm to 10 μm or more. When the size of the primary particle is such large, the packing rate becomes low and it is difficult to increase the density. Therefore, if the particles are made finer, the crystallinity is deteriorated, and since a large amount of water is contained, there is a problem that the shrinkage rate of the dense molded body during firing becomes large and becomes unstable.

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

[Means for Solving the Problems] The present invention capable of achieving the above-mentioned object means that the reactivity of a non-phosphate type reactive Ca compound and a non-Ca salt type phosphorus is adjusted so that a predetermined Ca / P ratio is obtained. Oxygen acid compound is dissolved in water and / or hydrophilic organic solvent at 50 ° C or lower, and this solution is added dropwise to water and / or hydrophilic organic solvent while maintaining the temperature at 70 ° C or higher and pH 4 or higher to form precipitates. Is a method for producing a hydroxyapatite fine particle agglomerate, which is characterized in that an agglomerate having nucleation of the initial crystallized particles as a nucleus is formed by controlling the above, and the precipitate is collected.

[Operation] The present inventors have found that the Ca / P ratio of HAP can be controlled with good reproducibility by previously mixing the respective compounds of Ca and P into a single liquid and then subjecting this to a hydration substitution reaction. Since its technical significance was recognized, a patent application was filed first (Japanese Patent Application No. 62-326516).
issue). And the present inventors, in order to further improve the above technology,
After that, research was repeated. As a result, in the hydration substitution reaction
By appropriately controlling the rate of HAP precipitate formation, it was revealed that aggregates of HAP particles with initial crystallized grains as nuclei were formed, and the shape of these aggregates was spherical and uniform. The present invention has been completed by finding that it is most suitable as a carrier or a raw material for a molded body. Incidentally, as a specific means for controlling the formation rate of the precipitate, it is possible to reduce the degree of supersaturation of the solution with respect to water or a hydrophilic organic solvent and control the dropping rate to such an extent that new crystal nuclei are not easily formed at the time of dropping. Can be mentioned.

The non-phosphate type reactive Ca compound and non-Ca used in the present invention
The salt type reactive oxygen acid compound can be used in water or a hydrophilic organic solvent. For example, as the non-phosphate type reactive Ca compound, CaCl ₂ , Ca (No ₃ ) ₂ and Ca (HCOO) ₂ , Ca (CH ₃ CO
O) ₂ , Ca (OH) ₂ , CaCO _3, etc. and calcium dimethoxide, calcium diethoxide, calcium dipropoxide, etc.
Non-limiting examples include Ca-alkoxides and carboxylates.

As a reactive oxygen compound of non-Ca salt type phosphorus, H ₃ PO ₄
In addition to phosphates such as KH ₂ PO ₄ , NH ₄ H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ and (NH ₄ ) ₃ PO _4, etc., phosphoric acid trimethoxide, phosphoric acid triethoxide, phosphoric acid tripropoxide, phosphorous acid trimethoxide. , Phosphite triethoxide, phosphite tripropoxide, and various phosphorus oxyacid alkoxides and trimethyl phosphate,
Non-limiting examples of various phosphoric acid oxygen esters such as ethyl metaphosphate, monoethyl phosphate, diethyl phosphate, triethyl phosphate, ethyl pyrophosphate, and the like.

The non-phosphate type reactive Ca compound and the non-Ca salt type phosphorus reactive oxygen acid compound are blended so as to have a predetermined Ca / P ratio.
Dissolve in water and / or hydrophilic organic solvent at 50 ° C or below, and dissolve this solution in water and / or hydrophilic solvent at temperature 70
While being kept at a temperature of not less than 0 ° C and a pH of not less than 4 (preferably 8 to 11), the mixture is allowed to undergo a hydration substitution reaction to obtain a precipitate of HAP fine particle aggregates. At this time, the temperature of the solution is set to 50 ° C. or lower in order to control the reaction in the solution.

In addition, keep the temperature of the liquid to be dropped above 70 ℃ and
The reason for maintaining the pH at 4 or higher (preferably 8 to 11) by dropping an alkali such as H, NH ₄ OH is that when the temperature of the liquid to be dripped is less than 70 ° C., HAP produced is a mixed crystal with an amorphous phase. And the crystallinity also deteriorates, and the temperature of the liquid to be dropped is
70 ℃ or more. If the liquid to be dripped is less than pH 4, no precipitate will be generated, and even if it is generated, HAP fine particles will be redissolved and the particle shape and chemical composition of the product will be unstable, so the pH should be 4 or higher (preferably 8 to 11). It is necessary to keep. The particle size can be adjusted by controlling the pH (see Example 1 below).

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

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples merely show one specific example of the method of the present invention, and any modification of the design can be made without departing from the spirit of the preceding and the following. Are included in the technical scope of.

Example 1 Example 1 CaCl ₂ and H ₃ PO ₄ (85% concentration) were dissolved in ion-exchanged water 1 at 25 ° C. so as to have a predetermined Ca / P molar ratio, to prepare a mixed solution.

Next, while maintaining this temperature in ion-exchanged water 1 at 70 ° C,
KO with micro tube pump connected to pH controller
When the H solution was added to control the pH and the mixed solution was added dropwise, a milky white suspension was obtained. 2 this suspension
After holding for a while, filter with a membrane filter to remove Ag.
It was washed with pure water until no white turbidity of the filtrate due to the NO ₃ aqueous solution was observed. The obtained precipitate was dried at 100 ° C. and then subjected to powder X-ray diffraction. According to the result, all were HAP single phase. Observation of the particle shape by a transmission electron microscope revealed that the particles were uniform spherical aggregates of acicular particles. The Ca / P ratio of the obtained HAP was almost in agreement with the blending ratio of the raw materials. Table 1 shows the relationship between pH and particle size at this time.

Example 2 13 g of Ca diethoxide was dissolved in 72.6 g of ethylene glycol, and 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. The suspension thus obtained was filtered and dried in the same manner as in the Example, and the obtained precipitate was separated by X.
Line diffraction revealed that the particles were spherical and uniform HAP fine particle aggregates.

The Ca / P ratio of this aggregate was 1.67.

Example 3 Ca diethoxide 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, add KOH aqueous solution to the pH in ion exchange water at 70 ° C with a microtube connected to a pH controller.
When the mixed solution was added dropwise while controlling the ratio to 7 or more, a milky white suspension was obtained. After the suspension was filtered and dried in the same manner as in Example 1, the precipitate obtained was subjected to X-ray diffraction, and it was confirmed to be a hydroxyapatite single phase. The obtained HAP had the same shape as in Example 1.

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

Claims (1)

[Claims] 1. A non-phosphate type reactive Ca compound and a non-Ca salt type reactive oxygen acid compound of phosphorus so that a predetermined Ca / P ratio is obtained, water and / or a hydrophilic organic solvent at 50 ° C. or lower. And dissolve the solution in water and / or a hydrophilic organic solvent at a temperature
Hydroxyapatite fine particles characterized by being formed by dropping while maintaining at 70 ° C or higher and pH 4 or higher to control the rate of formation of precipitates and forming aggregates with the initial crystallization particles as nuclei and recovering the precipitates. A method for producing an aggregate.