JPH03228811A - Production of calcium phosphate - Google Patents

Abstract

PURPOSE:To obtain calcium phosphate powder showing excellent biological safeness by effecting the mechanochemical reaction of calcium carbonate and calcium hydrogen phosphate in a water slurry state, pulverizing the reaction product and then calcinating this powder. CONSTITUTION:The starting material is prepared by weighing the powder of calcium hydrogen phosphate or its dihydrate and the powder of high purity calcium carbonate, preferably having <=0.5mu particle size, so as to obtain a specified Ca/P ratio. This material is then changed into a water slurry of about 10wt.% concn. by adding water, preferably kept at >=30 deg.C, and is made to react mechanochemically in a ball mill, preferably for 24 hours. This slurry is then dried at 80 deg.C, preferably for 8 hours. The dried sample is pulverized and calcined, preferably at 720-1150 deg.C for 1-10 hours or longer to provide the objective calcium phosphate as a porous or dense body.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to bone filling agents, artificial tooth roots, artificial joints, bone pins,
The present invention relates to a method for producing calcium phosphate powder used as a raw material for bioceramics such as percutaneous terminals and artificial bones, and particularly relates to a method for producing biologically safe calcium phosphate powder that does not cause hemolysis or the like.

[Prior Art] Recently, research and development of bioactive calcium phosphate materials used for bone grafting materials, artificial tooth roots, etc. has been actively conducted.

Dry synthesis methods using high-temperature solid phase reactions and wet synthesis methods are known as methods for producing calcium phosphate, but with either method, it is difficult to obtain highly pure products. However, there have been problems in that manufacturing is difficult and expensive.

Therefore, as a method to solve these problems and easily and inexpensively produce high-purity calcium phosphate, β-tricalcium phosphate (hereinafter referred to as β-TCP) was developed using a so-called wet pulverization synthesis method using a mechanochemical reaction. do)
A method for producing the powder is disclosed in JP-A-62-87406 and the like.

In the examples shown in this publication, two cases in which the Ca/P ratio is 1.5 or 1.67 are tested, and it is described that powders with a large specific surface area can be obtained.

However, the biological safety of synthesized β-TCP and HAP has not been sufficiently investigated.

That is, in the above-mentioned JP-A-62-87406, the atomic ratio of Ca/P is simply adjusted to 1.5 and the calcination temperature is set to 750°C, but the calcination time depends on the diffraction intensity of X-rays. It has been shown that the crystallinity changes, and furthermore,
When fired at a high temperature of 750°C or higher, the diffraction intensity increases, and 1
It has been shown that at a temperature of 150° C. or higher, β-TCP transforms to α-TCP and the crystallinity also changes.

[Problems to be solved by the invention] As described above, when calcium phosphate powder is simply synthesized by a mechanochemical method, depending on the firing temperature and firing time,
Ca that does not completely form arbitrary crystals and causes hemolysis
It contains unreacted substances such as (OH) 2 and is thought to exhibit hemolytic properties.

In addition, “8 Ordinance Magazine Vol. 59.18: (-191
According to a report by Mitsuo Nagashio in , 1985J, calcium phosphate ceramics have been shown to have not only hemolytic properties but also antigenic properties.

Furthermore, P139-144 of “Safety evaluation method for medical and dental biomaterials: Published by Science Forum”
In the column "Cytotoxicity test using colony formation method" listed in , it is shown that ceramic materials such as TCP and HA are cytotoxic due to differences in their manufacturing method, firing temperature, etc. .

However, such hemolysis, antigenicity, and cytotoxicity are undesirable because they lack biological safety as biomaterials.

Therefore, an object of the present invention is to provide a method for producing calcium phosphate powder with excellent biological safety.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention uses a powder of calcium hydrogen phosphate or its dihydrate as a starting material, and a powder of calcium hydrogen phosphate or its dihydrate. High-purity calcium carbonate powder of 5 μm or less is weighed so as to have a predetermined Ca/P ratio, for example, the final product is tricalcium phosphate (Ca3 (PO2)2
), weigh 0.05 mol and 1 mol of Q so that the atomic ratio of Ca/P is 1.5, add pure water at a temperature of 30°C or higher, and add 10% by weight. The slurry was made into an aqueous slurry and reacted mechanochemically for 24 hours using a ball mill.
Dry at 0°C for at least 8 hours. After pulverizing the dried sample, the powder is fired at a temperature of 720 to 1150°C for 1 to 10 hours or more and is used as the primary raw material for sintering dense bodies and porous bodies. It is designed to synthesize.

[Effects] By taking such measures, the following effects are achieved. That is, an aqueous slurry is prepared by setting the temperature of pure water mixed with the starting material at 30°C or higher, and the firing temperature and firing time when firing this slurry are 720°C to 10°C.
Biological safety can be ensured without causing hemolysis, antigenicity, or cytotoxicity by heating at a temperature of 150°C for 1 to 10 hours (the lower the temperature, the longer the time). Calcium phosphate is produced.

[Example] An embodiment of this invention will be described below.

First, CaCO3 with high purity (99.99%) and a particle size of 0.5 μm or less and Ca11PO4 with high purity (99% or more).
2■] 20 to 0. 05mol and Q,
Take 1 mol of each and place in a pot mill along with 200 ml of 30°C pure water and a zirconia ball. After rotating this pot mill at 12 rpm for 24 hours to perform a wet grinding reaction, the slurry is transferred to a stainless steel tray and dried at 80° C. for 8 hours or more. Furthermore, the dried sample is crushed, and the crushed sample is placed in a high-purity alumina box and heat-treated at a temperature of 720 to 1150°C for 1 to 10 hours (the lower the temperature, the longer the time) to perform firing and sintering. to synthesize a calcium phosphate compound.

Here, an experimental example in which the firing temperature and time were varied will be described.

Table 1 shows the relationship between the firing conditions, the presence or absence of hemolytic properties, and cytotoxicity according to this experiment.

For the determination of hemolytic properties, please refer to page 5 of “Safety Evaluation Method for Medical and Dental Biomaterials ■Published by Science Forum”.
The test was carried out as follows based on the method of "hemolytic test based on International Dental Federation (FDI) standards" described in 3-56. Add 1.00 ml of physiological saline to 10 g of a sample of calcium phosphate compound, and heat at 121°C in an autoclave.
After treatment for 60 minutes, 0.2 ml of heparinized blood was added to the collected supernatant (A) and left at 37° C. for 60 minutes. The liquid was centrifuged at 300 rpm for 10 minutes, and the absorbance of the supernatant liquid (B) was measured using a spectrophotometer.
The judgment was made by comparing the absorbance of the solution and B solution.

In addition, the determination of cytotoxicity was also carried out as follows based on the method of "Cytotoxicity test using colony formation method" described on pages 139 to 144 of "Methods for evaluating the safety of medical and dental biomaterials." Ta. Fibroblast-like cells ■-79 derived from Chinese hamsters were diluted with culture medium and dispensed into a plastic cultivation dish containing a synthesized disc-shaped calcium phosphate compound, and incubated at 37°C.
The determination was made by observing the ability to form colonies when cultured in a 5% CO2 incubator for 8 days.

As shown in Table 1, the shorter the firing time and the lower the temperature, the more hemolytic and cytotoxic properties are exhibited, and the longer the firing time and the higher the temperature, the less hemolytic and cell morphology changes. It can be seen that no hemolysis or cytotoxicity occurs when calcined for 10 hours at 720°C, 8 hours at 900°C, 3 hours at 1000°C, and 1 hour at 1150°C.

In addition, when we investigated the antigenicity of those that did not have hemolytic properties, none of them were found to have antigenicity.

The antigenicity was determined by the subcutaneous implantation method described in pages 93 to 96 of the above-mentioned "Method for evaluating the safety of medical and dental biomaterials."

This experimental example shows that a biologically safe calcium phosphate compound that does not cause hemolysis or cytotoxicity can be obtained by firing at 720 to 1150°C for 1 to 10 hours or more (the lower the temperature, the longer the time). I understand.

Furthermore, as a comparative example, β-TCP was synthesized by dry synthesis method by mixing β-calcium pyrophosphate and calcium carbonate at a molar ratio of 1.2 and calcining the mixture at 1000°C for 2 hours.
Further, similar experiments were conducted using a sintered body obtained by press-molding and sintering at 1150° C. for 3 hours. β-TCP synthesized by this dry synthesis method showed hemolytic and cytotoxic properties, and could not be used as a biological ashes.

Next, an experimental example in which the temperature of pure water was varied will be explained.

Table 2 shows the temperature, presence or absence of hemolysis, and cytotoxicity of pure water in this experiment.

The calcium phosphate compound was synthesized in the same manner as in the above example, except that only the temperature of pure water was changed, and the firing time and temperature were both 720° C. and 10 hours.

[Table 2 As shown in Table 2, the results of this experiment showed that pure water exhibits hemolytic, antigenic, and cytotoxic properties when the temperature is 10°C;
It exhibited slight hemolyticity, antigenicity, and cytotoxicity at 0°C and 25°C, but did not exhibit hemolyticity, antigenicity, and cytotoxicity at 30°C or higher.

This shows that biologically safe calcium phosphate compounds without hemolysis and cytotoxicity can be obtained by synthesizing the pure water at a temperature of 30° C. or higher.

This is thought to be because the higher the temperature of pure water, the more uniform the mixing of the aqueous slurry, and the more uniform the composition of the produced calcium phosphate compound.

Next, an experimental example will be described in which the mixing molar ratio of the starting materials CaCO3 and CaHPO4.2H20 is changed, that is, the Ca/P ratio of the calcium phosphate to be synthesized is changed.

Table 3 shows the relationship between the Ca/P ratio, the presence or absence of hemolytic properties, and cytotoxicity. In addition, the production is CaCO
By changing the molar ratio of 3 and CaHPO4・2H20, C
The synthesis was carried out in the same manner as in the above example except that the a/P ratio was changed, the temperature of pure water was 30°C, and the firing time and temperature were all unified at 720°C for 10 hours.

2 1 According to this experimental example, none of the calcium phosphate compounds caused hemolysis or cytotoxicity. In other words, if the synthesis is performed with a calcination time of 10 hours or more and a pure water temperature of 30°C, even if the Ca/P ratio of the calcium phosphate compound changes, that is, HAP (
It can be seen that any calcium phosphate compound, such as hydroxyapatite), TCP (recalcium phosphate), etc., can be used to obtain a calcium phosphate compound that does not cause hemolysis or cytotoxicity.

[Effect of the invention] As explained above, according to the present invention, the temperature is reduced to 30°C.
Make a slurry using the above purified water and
By producing calcium phosphate by baking at a temperature of 00°C for 1 to 10 hours or more, calcium phosphate with excellent biological safety can be obtained without causing hemolysis or cytotoxicity.

Claims (4)

[Claims] (1) Calcium carbonate and calcium hydrogen phosphate or its dihydrate powder are mixed at a molar ratio of calcium to phosphorus (
Ca/P ratio) was weighed to a predetermined value, and pure water was added to make an aqueous slurry with a concentration of about 10% by weight. Using a ball mill, the slurry was mechanochemically reacted, and the slurry was
A method for producing calcium phosphate, which comprises completely drying at 0° C., pulverizing the powder, and firing the powder to produce a porous body or a dense body. (2) The method for producing calcium phosphate according to claim 1, wherein the particle size of the calcium carbonate powder is 0.5 μm or less. (3) The method for producing calcium phosphate according to claim 1, wherein the temperature of the pure water is 30°C or higher. (4) The firing temperature when firing the powder is 720 to 1
The method for producing calcium phosphate according to claim 1, characterized in that the firing time is 1 to 10 hours or more at 150°C.