JP2021031352A - Manufacturing body of madreporic body, and madreporic body - Google Patents

Abstract

To provide an artificial aggregate having mechanical strength and biocompatibility in the optimum balance; and to provide a madreporic body containing apatite and collagen used for a cell scaffolding material or the like, especially a madreporic body containing apatite/collagen composite fibers.SOLUTION: A manufacturing method of a madreporic body includes steps of; preparing a dried madreporic body containing apatite and collagen; irradiating the madreporic body with a radiation; and bridging at least some components of the madreporic body irradiated with the radiation.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a porous body containing apatite and collagen, which is suitable for an artificial aggregate, a scaffolding material for cells, and the like, and a porous body containing apatite and collagen.

Artificial bone made of apatite has an affinity for autologous bone and can be directly bonded to autologous bone, so its usefulness has been evaluated, and it is clinically applied in orthopedics, neurosurgery, plastic surgery, oral surgery, etc. Has been done. The mechanical strength and biocompatibility of a porous body composed of apatite and collagen are almost inversely proportional, and the biocompatibility tends to decrease as the mechanical strength increases. Therefore, it is necessary to design a porous body having these characteristics in an optimum balance according to each application. In a porous body composed of apatite and collagen, these properties can be adjusted to some extent by the material composition, porosity, pore size, etc., and it has become possible to design the porous body according to the purpose. However, in recent years, artificial bones have been used in a wide variety of applications, and the differences in desirable properties have become large. Therefore, a porous body that is satisfactory for all applications only by controlling the material composition, porosity, pore diameter, etc. It's getting harder to get.

Japanese Patent Application Laid-Open No. 11-513590 (Patent Document 1) discloses a porous body containing a network in which collagen and, if necessary, other binders are bound to hydroxyapatite. Since this porous body is biodegradable, autologous bone is formed in the porous body, and the porous body itself is absorbed in the body. Therefore, this porous body can be used for spinal fixation, bone defect compensation, fracture repair, peripheral defect transplantation, and the like. However, the porous matrix described in Patent Document 1 not only is difficult for the operator to handle in the surgical site due to its low mechanical strength, but also causes self-destruction due to the absorption of the material relatively early after the operation, resulting in self-destruction. There is a problem that the biocompatibility is remarkably lowered.

Japanese Patent Application Laid-Open No. 2009-132601 (Patent Document 2) discloses a porous body containing apatite / collagen complex fibers having a half-life of strength in phosphate buffered saline of 0.8 to 1.6 hours. However, since the porous body containing the apatite / collagen complex fiber described in Patent Document 2 has a relatively high absorption rate in the living body, its structure may not be maintained for a period required for bone regeneration, and improvement is desired. It is rare.

Special Table 11-513590 Gazette Japanese Unexamined Patent Publication No. 2009-132601

Therefore, an object of the present invention is an artificial aggregate having an optimum balance between mechanical strength and biocompatibility, a porous body containing apatite and collagen used as a scaffolding material for cells, and particularly an apatite / collagen complex. The purpose is to provide a porous body containing fibers.

As a result of diligent research in view of the above objectives, the present inventors have performed a sterilization treatment (γ-ray irradiation treatment), which is usually performed after the cross-linking treatment, in the cross-linking treatment when producing a porous body containing apatite and collagen. We have found that the strength of the porous body can be improved and the absorption rate in the living body can be reduced by performing the process before and then performing the cross-linking treatment, and came up with the present invention.

That is, the method of the present invention for producing a porous body is
The process of preparing a dried porous body containing apatite and collagen, and
The step of irradiating the porous body with radiation and
It is characterized by including a step of cross-linking at least a part of the components of the irradiated porous body.

The step of preparing the dried porous body containing apatite and collagen preferably includes a treatment of preparing a dispersion containing apatite / collagen complex fibers and freeze-drying the obtained dispersion.

The step of irradiating the radiation preferably includes a process of irradiating a dose of 16 to 35 kGy of γ-rays.

The thermal cross-linking step preferably includes a thermal dehydration cross-linking treatment under the conditions of 100 to 160 ° C. and 0 to 100 hPa.

The mass ratio of the porous apatite to collagen is preferably 9/1 to 6/4.

The porous body of the present invention is a dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
It is characterized by a compressive elastic modulus of 40 to 80 kPa.

The other porous body of the present invention is a dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
It is characterized in that the compressive elastic modulus of the porous body after being immersed in physiological saline for 28 days is 15 to 30 kPa.

Yet another porous body of the present invention is a dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
It is characterized in that the weight after being immersed in physiological saline for 28 days and dried is 82 to 90% of the weight before immersion.

The porous body of the present invention preferably contains apatite / collagen composite fibers.

Since the porous body containing apatite and collagen of the present invention has an excellent balance between mechanical strength and biocompatibility in the living body, it can be suitably used for artificial aggregates, cell scaffolding materials and the like.

It is a schematic diagram for demonstrating the conventional method for producing a porous body containing apatite and collagen, and the method of this invention. It is a CT image taken immediately after, 7 days, 10 days, and 14 days after the implantation of the apatite / collagen porous body of Example 1 and Comparative Example 1 implanted in the rat muscle layer.

[1] Porous body containing apatite and collagen The porous body containing apatite and collagen of the present invention is a so-called apatite / collagen composite fiber composed of a plurality of fiber layers formed by aggregating apatite / collagen composite fibers. It is preferably a porous body containing. The mass ratio of apatite to collagen is preferably 9/1 to 6/4 in this apatite / collagen complex fiber.

The apatite / collagen complex fiber has a plate-shaped fiber layer having a thickness of about 10 to 500 μm, and forms a large number of fine pores by overlapping in a random direction and a random number of layers. Pillars formed by aggregating apatite / collagen complex fibers are scattered between the fiber layers. Microscopically, the overlapping direction of the fiber layers is only supported by scattered columns, so the apatite / collagen porous material is considered to be relatively brittle in this direction, while the strength is increased in the layer direction. It is considered to have. However, as described above, since the overlapping of the fiber layers is random, when viewed macroscopically, the overlapping directions of the fiber layers are averaged, and the ratio of the strengths depending on the orientation is not so large.

The pores formed by the interspersed columns between the fiber layers are approximately plate-like. The thickness of the substantially plate-shaped pores is about 0.5 to 10 times that of the fiber layer. When the porous body containing the apatite / collagen complex fiber is embedded in the living body, blood vessels and relatively large proteins easily enter into the substantially plate-shaped pores, which is considered to promote bone formation.

The porous body of the present invention preferably has a compressive elastic modulus of 40 to 80 kPa. The compressive elastic modulus is more preferably 75 kPa or less, further preferably 70 kPa or less, and further preferably 65 kPa or less. When the compressive elastic modulus is within the above-mentioned preferable range, the porous body does not easily collapse during surgery and has an appropriate softness, so that it can be easily filled. In one embodiment, the compressive modulus may be 40-50 kPa.

The porous body of the present invention preferably has a compressive elastic modulus of 15 to 30 kPa after being immersed in physiological saline for 28 days. In another embodiment, the compressive modulus after immersion may be 15 to 25 kPa. In another embodiment, the compressive modulus after immersion may be 15 to 20 kPa. Further, the weight after being immersed in physiological saline for 28 days and dried is preferably 82 to 90% of the weight before immersion. In another embodiment, the weight after drying may be 82-85% of the weight before immersion. A large decrease in compressive modulus or weight during the immersion period suggests that the degree of collapse or absorption of the porous body during the period is relatively high. When the decrease in compressive elastic modulus or the weight reduction is at least the above lower limit value, the porous body can be appropriately maintained for a period until bone is formed. Early bone formation is possible when the decrease in compressive modulus or weight reduction is equal to or less than the above upper limit.

[2] Method for Producing Porous Body Containing Apatite and Collagen In the method of the present invention for producing a porous body containing apatite and collagen, a dispersion containing apatite and collagen is dried, and the obtained porous body is irradiated with radiation. It is characterized in that collagen in a porous body is crosslinked after being sterilized by irradiating with.

First, the difference between the conventional method for producing a porous body containing apatite and collagen and the method of the present invention will be briefly described. In the conventional method, as shown in FIG. 1, a porous body obtained by freeze-drying a dispersion containing (A) apatite and collagen is subjected to (B) cross-linking treatment to obtain a cross-linked product. (C) This crosslinked product is manufactured by irradiating it with γ-rays and sterilizing it. Collagen molecules are crosslinked with each other by the cross-linking treatment, and the strength of the porous body is ensured. However, in the conventional method, since the γ-ray irradiation treatment is further performed after the cross-linking treatment, the collagen molecule and the cross-linked portion are cleaved by the γ-ray, which causes a decrease in strength.

On the other hand, in the method of the present invention, (a) a porous body obtained by freeze-drying a dispersion containing apatite and collagen was (b) first irradiated with radiation (γ-rays) to sterilize the porous body. After that, it is manufactured by (c) cross-linking treatment. According to the method of the present invention, collagen molecules and the like cleaved by the γ-ray irradiation treatment are crosslinked and reinforced by the subsequent cross-linking treatment, and therefore, as compared with the case where the γ-ray treatment is finally performed as in the conventional method. , High strength can be maintained.

Hereinafter, the method of the present invention will be described in detail by taking as an example a case of producing a porous body containing apatite / collagen composite fiber.

(1) Preparation of apatite / collagen complex fiber
(a) Raw material Apatite / collagen composite fiber is made from collagen, phosphoric acid or a salt thereof, and a calcium salt. The collagen is not particularly limited, and collagen extracted from animals or the like can be used. The species, tissue site, age, etc. of the animal from which it is derived are not particularly limited. Generally, collagen obtained from the skin, bones, cartilage, tendons, organs and the like of mammals (for example, cows, pigs, horses, rabbits and rats) and birds (for example, chickens) can be used. Collagen-like proteins obtained from the skin, bones, cartilage, fins, scales, organs and the like of fish (for example, cod, flounder, flatfish, salmon, trout, tuna, mackerel, Thailand, sardines and sharks) may be used. The collagen extraction method is not particularly limited, and a general extraction method can be used. Further, collagen obtained by a gene recombination technique may be used instead of the one extracted from animal tissue.

Examples of phosphoric acid or a salt thereof (hereinafter simply referred to as "phosphoric acid (salt)") include phosphoric acid, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate. Examples of the calcium salt include calcium carbonate, calcium acetate and calcium hydroxide. It is preferable to add the phosphate and the calcium salt in the form of a uniform aqueous solution or suspension, respectively.

The mass ratio of apatite / collagen in the product can be controlled by the mass ratio of the apatite raw material [phosphate (salt) and calcium salt] used and collagen. Therefore, the mass ratio of the apatite raw material to be used and collagen is appropriately determined by the composition ratio of the target apatite / collagen composite fiber. The ratio of apatite / collagen in the apatite / collagen composite fiber is preferably 9/1 to 6/4 (mass ratio), and particularly preferably about 8/2 (mass ratio).

(b) Preparation of solution The concentrations of the phosphoric acid (salt) aqueous solution and the calcium salt aqueous solution are not particularly limited as long as the phosphate (salt) and the calcium salt are in a desired blending ratio, but for the convenience of the dropping operation described later, The concentration of the aqueous phosphate (salt) solution is preferably about 50 to 250 mM, and the concentration of the aqueous calcium salt solution is preferably about 200 to 600 mM. Collagen is generally added in the state of an aqueous phosphoric acid solution to the above-mentioned aqueous solution of phosphoric acid (salt) in advance. The phosphoric acid aqueous solution of collagen preferably has a collagen concentration of 0.5 to 1% by mass and a phosphoric acid concentration of 10 to 30 mM. More preferably, the collagen concentration is 0.8 to 0.9% by mass and the phosphoric acid concentration is 15 to 25 mM, and particularly preferably, the collagen concentration is about 0.85% by mass and the phosphoric acid concentration is about 20 mM.

(c) Production of apatite / collagen complex fiber Add approximately the same amount of water as the amount of calcium salt aqueous solution to be added (preferably 0.5 to 2 times, more preferably 0.8 to 1.2 times as much as the calcium salt aqueous solution to be added). Place in a reaction vessel in advance and heat to about 40 ° C. A phosphoric acid (salt) aqueous solution and a calcium salt aqueous solution containing collagen are simultaneously added dropwise thereto. The length of the apatite / collagen complex fiber to be synthesized can be controlled by the dropping conditions. The dropping speed is preferably about 10 to 50 ml / min, and the reaction solution is preferably stirred at about 50 to 300 rpm. During the dropping, it is preferable to maintain the calcium ion concentration in the reaction solution at 3.75 mM or less and the phosphate ion concentration at 2.25 mM or less. As a result, the pH of the reaction solution is maintained at 8.9 to 9.1. When the concentration of calcium ion and / or phosphate ion exceeds the above range, self-assembly of the complex is hindered. In the present specification, "self-organization" means that hydroxyapatite (calcium phosphate having an apatite structure) has an orientation peculiar to living bone along collagen fibers, that is, the C axis of hydroxyapatite follows collagen fibers. It means that it is oriented like this. Under the above dropping conditions, the apatite / collagen composite fiber is self-assembled with a length of 1 mm or less, which is suitable as a raw material for the porous body.

After completion of the dropping, the slurry-like dispersion of apatite / collagen composite fibers is freeze-dried. Freeze-drying is carried out by vacuuming in a frozen state at −10 ° C. or lower and rapidly drying.

(2) Preparation of dispersion containing apatite / collagen complex fiber Add water, aqueous phosphoric acid solution, etc. to the apatite / collagen complex fiber and stir to prepare a paste-like dispersion. The content of the liquid contained in this dispersion is preferably 80 to 99% by volume, more preferably 90 to 97% by volume. That is, the content of the composite fiber is preferably 1 to 20% by volume, more preferably 3 to 10% by volume. It is preferable to attach water vapor to the apatite / collagen composite fiber in advance. In this case, it is necessary to subtract the amount of water vapor attached to the apatite / collagen composite fiber to determine the amount of water to be added.

The porosity P (%) of the porous body to be produced depends on the volume ratio of the apatite / collagen composite fiber in the dispersion and the liquid, and the following formula (1):
P = Y / (X + Y) × 100 ・ ・ ・ (1)
[However, X indicates the volume of the apatite / collagen complex fiber in the dispersion, and Y indicates the volume of the liquid in the dispersion. ] Is represented by. Therefore, the porosity P of the porous body can be controlled by the amount of the liquid added. By stirring the dispersion after adding the liquid, the apatite / collagen complex fibers are cut and the distribution width of the fiber length is increased, so that the strength of the produced porous body is improved.

A binder is added to the dispersion of the composite fibers, and the mixture is further stirred. Binders include collagen, gelatin, polylactic acid, polyglycolic acid, copolymer of lactic acid and glycolic acid, polycaprolactone, carboxymethyl cellulose, cellulose ester, dextrose, dextran, chitosan, hyaluronic acid, ficol, chondroitin sulfate, polyvinyl alcohol, polyacrylic. Examples thereof include acid, polyethylene glycol, polypropylene glycol, water-soluble polyacrylate, and water-soluble polymethacrylate. Collagen and gelatin are particularly preferable, and collagen is most preferable. The amount of the binder added is preferably 1 to 10% by mass, more preferably 3 to 6% by mass, based on 100% by mass of the apatite / collagen composite fiber. As in the case of composite fibers, the binder is preferably added in the form of an aqueous phosphoric acid solution. The concentration of the phosphoric acid aqueous solution of the binder is not particularly limited, but practically, the concentration of the binder is 0.8 to 0.9% by mass (for example, 0.85% by mass), and the concentration of phosphoric acid is 15 to 25 mM (for example, 20 mM). ..

(3) Gelation of dispersion A sodium hydroxide solution is added to the dispersion that has become acidic due to the addition of an aqueous phosphoric acid (salt) solution of a binder such as collagen to adjust the pH to about 7. The pH of the dispersion is preferably 6.8 to 7.6, more preferably 7.0 to 7.4. By setting the pH of the dispersion to 6.8 to 7.6, for example, the fibrosis of collagen added as a binder can be promoted.

Add a concentrated solution of about 2.5 to 10 times that of phosphate buffered solution (PBS) to the dispersion and stir to adjust the ionic strength to 0.2 to 0.8. A more preferable ionic strength is an ionic strength (about 0.2 to 0.8) similar to that of PBS. By increasing the ionic strength of the dispersion, for example, the filamentation of collagen added as a binder can be promoted.

After placing the dispersion in a mold, the dispersion is gelled by keeping it at a temperature of 35-43 ° C. The holding temperature is more preferably 35 to 40 ° C. In order to sufficiently gel the dispersion, the holding time is preferably 0.5 to 3.5 hours, more preferably 1 to 3 hours. By keeping the temperature of the dispersion at 35 to 43 ° C., for example, collagen added as a binder becomes fibrous and the dispersion becomes a gel. The gelation of the dispersion prevents the apatite / collagen complex fibers from settling in the dispersion, and makes it possible to produce a uniform porous body.

(4) Freezing and drying the gel body Freeze the gel body containing the apatite / collagen complex fiber. The average pore size of the target apatite / collagen porous body depends on the time required for freezing the gel body. The freezing temperature is preferably −100 to 0 ° C., more preferably −100 to −10 ° C., and particularly preferably −80 to −20 ° C. Below -100 ° C, the average pore size of the resulting apatite / collagen porous material is too small. Above 0 ° C., it does not freeze or it takes a long time to freeze, and the average pore diameter of the porous body is too large.

The frozen gel body is dried by freeze-drying to form a porous body. That is, as in the case of apatite / collagen composite fibers, the fibers are evacuated in a frozen state at −10 ° C. or lower and rapidly dried. Freeze-drying may be carried out until the dispersion is sufficiently dried, and the time is not particularly limited, but it is generally about 24 to 72 hours.

(5) Radiation treatment The porous body obtained by freeze-drying is irradiated with radiation and sterilized. Gamma rays are preferable as the radiation. Irradiation with γ-rays is preferably performed so that the absorbed dose is 16 to 35 kGy [unit: Gy (gray)]. Cobalt-60 is generally used as the radiation source. As an irradiation method, the operation of entering the irradiation chamber by a belt conveyor, going out after a certain period of time, and then re-entering the irradiation chamber is repeated until a certain absorbed dose is reached, or the irradiation is performed by placing it in the irradiation chamber. There is static irradiation, etc.

(6) Cross-linking treatment The porous body after irradiation with radiation (γ-rays) is subjected to cross-linking treatment. As the cross-linking treatment, either a physical cross-linking method (a method using γ-rays, ultraviolet rays, thermal dehydration, electron beams, etc.) or a chemical cross-linking method (a method using a cross-linking agent or a condensing agent) may be adopted. By the cross-linking treatment, the added burners, the added binder and collagen in the apatite / collagen complex fiber, and the collagen in the apatite / collagen complex fiber are cross-linked to improve the mechanical strength of the porous body.

As the cross-linking treatment, physical cross-linking is preferable, and thermal dehydration cross-linking is particularly preferable. Thermal dehydration cross-linking is performed by holding the lyophilized porous body under normal pressure to reduced pressure at 100 to 200 ° C. for 10 to 12 hours. The pressure and temperature conditions for thermal dehydration crosslinking are selected depending on the type of binder and the mechanical strength required for the porous body, but more preferably 0 to 100 hPa and 120 to 160 ° C.

In the case of chemical cross-linking, it is carried out by immersing the porous body after irradiation with radiation (γ-rays) in a solution of a cross-linking agent. Examples of the cross-linking agent include aldehyde-based cross-linking agents (glutar aldehyde, formaldehyde, etc.), isocyanate-based cross-linking agents (hexamethylene diisocyanate, etc.), and carposite-based cross-linking agents (1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride. Etc.), polyepoxy-based cross-linking agents (ethylene glycol diethyl ether, etc.), transglutaminase and the like. Of these cross-linking agents, glutal aldehyde is particularly preferable from the viewpoint of easy control of the degree of cross-linking and biocompatibility of the obtained porous body.

When cross-linking with glutaraldehyde, the concentration of the glutaraldehyde solution is preferably 0.005 to 0.015% by mass, more preferably 0.005 to 0.01% by mass. When alcohol such as ethanol is used as the solvent for the glutaaldehyde solution, the porous body can be dehydrated at the same time as cross-linking the binder such as collagen. By performing dehydration at the same time as cross-linking, a cross-linking reaction can occur in a state where the apatite / collagen complex fibers are contracted, and the elasticity of the resulting porous body can be improved. After the cross-linking treatment, the porous body is immersed in an aqueous solution of glycine of about 2% by mass in order to remove unreacted glutaraldehyde, and then washed with water. Further, the porous body is dehydrated by immersing it in ethanol, and then dried at room temperature.

The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Comparative Example 1
(Synthesis of apatite / collagen complex fiber)
235 g of a phosphoric acid aqueous solution of collagen (collagen concentration: 0.85% by mass, phosphoric acid concentration: 20 mM) was added to 168 ml of a 120 mM phosphoric acid aqueous solution and stirred to prepare a diluted collagen phosphoric acid aqueous solution. On the other hand, 200 ml of a 400 mM calcium hydroxide suspension was prepared. 200 ml of pure water was placed in the reaction vessel and heated to 40 ° C. Aqueous diluted collagen phosphate solution and calcium hydroxide suspension are simultaneously added dropwise to this reaction vessel at a rate of about 30 ml / min, and the obtained reaction solution is stirred at 200 rpm to obtain apatite / collagen complex fibers. A slurry containing the above was prepared. The pH of the reaction solution during dropping was maintained at 8.9 to 9.1. The fiber length of the produced apatite / collagen complex was approximately 1 mm or less. The slurry containing the apatite / collagen complex fiber was freeze-dried to obtain a powder of the apatite / collagen complex fiber. The compounding ratio of apatite / collagen in the apatite / collagen composite fiber was 8/2 on a mass basis.

(Preparation of paste-like dispersion)
To 1 part by mass of the obtained apatite / collagen composite fiber powder, 6.12 parts by mass of physiological saline and 0.057 parts by mass of a 1N NaOH aqueous solution were added and stirred to obtain a paste-like dispersion. 1.90 parts by mass of an aqueous collagen solution (collagen concentration: 0.51%) was added to this paste-like dispersion and stirred to obtain a dispersion of apatite / collagen complex fibers. The solid content concentration of the dispersion was 5% by volume, and the compounding ratio of the apatite / collagen complex and collagen was 1: 0.01 (mass ratio).

(Molding, lyophilization and cross-linking)
The obtained haste-like dispersion was placed in a molding die and held at 37 ° C. for 2 hours for gelation to obtain a jelly-like molded product. This molded product was frozen at −60 ° C., then dried using a freeze dryer, and then thermally dehydrated and crosslinked at 140 ° C. to obtain a porous body containing apatite / collagen composite fibers.

(Processing and gamma ray processing)
The obtained porous body containing the apatite / collagen complex fiber was cut into a size of 10 mm × 10 mm × 4 mm and irradiated with γ-rays at a dose of 35 kGy to obtain the apatite / collagen complex fiber of Comparative Example 1. A porous body containing the mixture was obtained.

Example 1
In Comparative Example 1, the apatite / collagen composite fiber freeze-dried body was processed and treated with γ-rays before the cross-linking treatment (thermal dehydration cross-linking) in the same manner as in Comparative Example 1. A porous body containing collagen complex fibers was obtained. That is, the porous body containing the apatite / collagen composite fiber of Example 1 was obtained by subjecting the freeze-dried porous body to heat dehydration cross-linking treatment after processing and γ-ray treatment. ..

[Strength measurement]
The strength of the porous body containing the apatite / collagen complex fibers obtained in Example 1 and Comparative Example 1 was determined by the method described below. The measurement was performed 6 times for different samples, and the average value was calculated. The results are shown in Table 1.
(1) Immerse a 10 mm × 10 mm × 10 mm sample in pure water, depressurize for about 1 minute, degas, and return to atmospheric pressure.
(2) Take out the degassed sample from pure water and apply 25% strain four times at a speed of 10 mm / min using a texture analyzer (Shimadzu Corporation).
(3) From the measurement curve at the time of the 4th compression, obtain the compressive force when the strain is 10% with respect to the thickness of the sample before the 4th compression.
(4) Obtain the compressive elastic modulus Ec (kPa) from the following equation.
Ec = 1000 × F / (A × ε)
[However, F is the compressive force (N) when the strain obtained by measurement is 10%, A is the cross-sectional area of the sample before compression (mm ² ), and ε is the coefficient corresponding to the amount of strain, which is 10%. In the case of compressive strain of, ε = 0.1. ]

[Saline treatment]
The apatite / collagen porous material (10 mm × 10 mm × 10 mm) of Example 1 and Comparative Example 1 was immersed in physiological saline and stored at 37.5 ° C. for 28 days, after which (a) measurement of compressive modulus and measurement of compressive elasticity were performed. (b) Weights were measured after they were dried. The weight ratio after the physiological saline treatment was determined, assuming that the weight before immersion in the physiological saline was 100%. The results are shown in Table 2.

[Animal experimentation]
The apatite / collagen porous material (5 mm × 5 mm × 5 mm) of Example 1 and Comparative Example 1 was implanted in the rat muscle layer, and CT imaging was performed immediately after implantation, 7 days, 10 days, and 14 days after implantation. It was. The result is shown in figure 2.

In the apatite / collagen porous body of Comparative Example 1 in which γ-ray irradiation was performed after the cross-linking treatment, a considerable part of the material was absorbed in 7 days after implantation, whereas in the example in which the cross-linking treatment was performed after γ-ray irradiation. A large amount of material remained in the apatite / collagen porous body of 1. After 14 days, absorption was progressing in the apatite / collagen porous material of Comparative Example 1, but the material remained in the apatite / collagen porous material of Example 1.

Claims (9)

The process of preparing a dried porous body containing apatite and collagen, and
The step of irradiating the porous body with radiation and
A method for producing a porous body, which comprises a step of cross-linking at least a part of the components of the porous body irradiated with radiation. In the method for producing a porous body according to claim 1,
The step of preparing a dried porous body containing apatite and collagen comprises a process of preparing a dispersion containing apatite / collagen composite fibers and freeze-drying the obtained dispersion. How to make a body. In the method for producing a porous body according to claim 1 or 2.
A method for producing a porous body, wherein the step of irradiating the radiation includes a process of irradiating a γ-ray with a dose of 16 to 35 kGy. In the method for producing a porous body according to any one of claims 1 to 3.
The method for producing a porous body, which comprises a heat dehydration cross-linking treatment in which the heat-crosslinking step is performed under the conditions of 100 to 160 ° C. and 0 to 100 hPa. In the method for producing a porous body according to any one of claims 1 to 4.
A method for producing a porous body, which comprises a mass ratio of apatite to collagen of the porous body of 9/1 to 6/4. A dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
A porous body characterized by a compressive elastic modulus of 40 to 80 kPa. A dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
A porous body having a compressive elastic modulus of 15 to 30 kPa after being immersed in physiological saline for 28 days. A dried porous body containing apatite and collagen.
The mass ratio of the porous apatite to collagen is 9/1 to 6/4.
A porous body characterized in that the weight after being immersed in physiological saline for 28 days and dried is 82 to 90% of the weight before immersion. In the porous body according to any one of claims 6 to 8.
A porous body characterized by containing apatite / collagen complex fibers.