Medical tissue reconstruction material and its manufacturing method

Abstract

To provide a medical tissue reconstruction material having both antibacterial properties and bone conductivity.SOLUTION: Provided is a medical tissue reconstruction material that is a calcium-based material having silver carbonate and silver phosphate on its surface, with the total content of the silver carbonate and the silver phosphate being 5.0×10-4 to 3.3×10-2 mass% of the total material.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a medical tissue reconstruction material that has both antibacterial and osteoconductive properties (bone replacement properties). [Background technology]

[0002] In Japan, which has become a super-aging society, bone diseases are on the rise, and as a result, the number of surgeries using bone regenerative materials is increasing. However, surgical site infections are frequent in surgeries using bone regenerative materials, and once an infection occurs, treatment is difficult and may even lead to limb amputation, resulting in significant impacts in various areas, such as extended hospital stays and increased medical costs.

[0003] An example of a procedure in which surgical site infections frequently occur is high tibial osteotomy for medial knee osteoarthritis (infection rate 5.1%) (see Non-Patent Document 1). Because the incidence of knee osteoarthritis is higher in older people, it is expected that the number of infections will continue to increase in the future. In addition, surgery for tibial plateau fractures (infection rate 12.3%) and calcaneus fractures (infection rate approximately 4%), which are frequent even among younger people, also have high infection rates (see Non-Patent Documents 2 and 3). For these reasons, preventing postoperative infection is an urgent issue.

[0004] Under these circumstances, it is believed that imparting antibacterial properties to bone regeneration materials used in many surgeries would be effective in preventing surgical site infections. As a means of imparting antibacterial properties to bone regeneration materials, for example, the use of silver compounds with antibacterial effects has been proposed (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-210251 [Patent Document 2] International Publication No. WO2017 / 150539 [Non-patent literature]

[0006] [Non-Patent Document 1] Miyazaki et al., Orthopedics and Disasters, 66, 509-512, 2017 [Non-patent document 2] Henkelmann et al.BMC Musculoskeletal Disorders,18,481,2017 [Non-patent document 3] Suzuki et al., Fractures, 42, 232-235, 2020 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a medical tissue reconstruction material that has both antibacterial and osteoconductive properties. [Means for solving the problem]

[0008] As described above, silver compounds have been used to impart antibacterial properties to bone regeneration materials, but the effects on cytotoxicity and osteoconductivity (bone replacement) have not necessarily been taken into consideration. The present inventors discovered that the presence of excessive silver compounds can cause cytotoxicity and inhibition of bone formation, and that it is important to use silver compounds at the minimum necessary concentration and to localize the silver compounds on the surface of the material to effectively exert their antibacterial effect. Furthermore, they discovered that when silver compounds with different timings for exerting their antibacterial effects are localized on the surface, a sustained antibacterial effect can be expected at the minimum necessary concentration, leading to the completion of the present invention.

[0009] That is, the present invention is as follows. [1] A calcium-based material having silver carbonate and silver phosphate on its surface, The total content of silver carbonate and silver phosphate is 5.0 x 10 -4 ~3.3×10 -2 A medical tissue reconstruction material, in mass %. [2] The total content of silver carbonate and silver phosphate is 1.5 × 10 -3 ~1.0×10-2 The medical tissue reconstruction material according to the above [1], characterized in that it is (less than) % by mass. [3] A medical tissue reconstruction material according to [1] or [2] above, characterized in that it contains at least one inorganic compound selected from carbonate-containing calcium phosphate, a mixture of calcium phosphate and a carbonate-containing compound, and bone. [4] The medical tissue reconstruction material according to any one of the above [1] to [3], which is a porous body.

[0010] [5] A method for producing the medical tissue reconstruction material according to any one of [1] to [4] above, A method for producing a medical tissue reconstruction material by exposing a calcium-based material to a solution containing silver ions. [6] A method for producing a medical tissue reconstruction material according to [5] above, characterized by immersing a calcium-based material in a solution containing silver ions. [7] The method for producing a medical tissue reconstruction material according to [5] or [6] above, wherein the solution containing silver ions is an aqueous solution of silver nitrate.

[0011] [8] A method for producing a medical tissue reconstruction material according to any one of [5] to [7] above, characterized in that the calcium-based material is immersed in an aqueous silver nitrate solution in an amount of 0.6 to 41.3 equivalents relative to the calcium-based material. [9] A method for producing a medical tissue reconstruction material according to any one of [5] to [8] above, characterized in that the calcium-based material is immersed in an aqueous silver nitrate solution in an amount of 1.9 to 12.5 equivalents relative to the calcium-based material.

[10] Silver carbonate and silver phosphate in total 5.0 × 10 -4 ~3.3×10 -2 The method for producing a medical tissue reconstruction material according to [8] above, characterized in that it is produced by mass %.

[11] Silver carbonate and silver phosphate in total 1.5 × 10 -3 ~1.0×10 -2 The method for producing a medical tissue reconstruction material according to [9] above, characterized in that it is produced in a mass % (or less) of the above-mentioned material.

[12] A method for producing a medical tissue reconstruction material according to any one of [5] to

[11] above, characterized in that the calcium-based material is at least one inorganic compound selected from carbonate-containing calcium phosphate, a mixture of calcium phosphate and a carbonate-containing compound, and bone. [Effects of the Invention]

[0012] The medical tissue reconstruction material of the present invention is an excellent medical tissue reconstruction material that has both antibacterial and osteoconductive properties. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a graph showing the concentrations of silver compounds (silver phosphate and silver carbonate) in porous carbonate apatite bodies when the bodies are immersed in 5×10 −2 to 5×10 3 equivalents of an aqueous silver nitrate solution for 60 minutes. [Figure 2] These are scanning electron microscope images and silver mapping images of porous carbonate apatite bodies immersed in 0.5 and 50 equivalents of silver nitrate aqueous solutions for 60 minutes. In the images, the white arrowheads indicate silver compounds. [Figure 3] This is a powder X-ray diffraction pattern of porous carbonate apatite after immersion in 5 to 500 equivalents of silver nitrate for 60 minutes. In the figure, the black arrowheads indicate the diffraction lines of silver phosphate. [Figure 4] This is a powder X-ray diffraction pattern of porous carbonate apatite after immersion in 500 equivalents of silver nitrate for 7 days. In the figure, the white circles indicate the diffraction lines of silver phosphate, the white arrowheads indicate the diffraction lines of silver carbonate, and the black arrowheads indicate the diffraction lines of carbonate apatite. [Figure 5] FIG. 1 is a graph showing the silver concentrations in carbonate apatite disks and hydroxyapatite disks after the carbonate apatite disks and hydroxyapatite disks were immersed in aqueous silver nitrate solutions of 5 to 5000 equivalents for 24 hours. [Figure 6] FIG. 1 shows the antibacterial effect of porous carbonate apatite against methicillin-resistant Staphylococcus aureus (MRSA) after the porous carbonate apatite was immersed in an aqueous solution of 0.5 to 5000 equivalents of silver nitrate for 60 minutes. [Figure 7]FIG. 10 is a graph showing the antibacterial effect of porous carbonate apatite against Staphylococcus epidermidis after the porous carbonate apatite was immersed in an aqueous solution of 0.5 to 500 equivalents of silver nitrate for 60 minutes. [Figure 8] FIG. 1 is a graph showing the cytotoxicity of porous carbonate apatite bodies after they have been immersed in 0.5 to 5000 equivalents of aqueous silver nitrate solutions for 60 minutes. [Figure 9] FIG. 1 is a graph showing the antibacterial effects against MRSA of carbonate apatite and hydroxyapatite not immersed in an aqueous silver nitrate solution, and carbonate apatite and hydroxyapatite immersed in an aqueous silver nitrate solution of 5 to 5000 equivalents for 24 hours. [Figure 10] FIG. 1 shows the number of viable bacteria near the implantation site two weeks after implantation of porous carbonate apatite bodies that had been immersed in 5 equivalents of silver nitrate for 60 minutes and unimmersed porous carbonate apatite bodies that had been immersed in an MRSA bacterial solution for 10 minutes and then implanted into a defect in the medial femoral condyle of a rabbit femur. [Figure 11] This figure shows histopathological findings around the implantation site two weeks after implantation of porous carbonate apatite bodies that had been immersed in 5 equivalents of silver nitrate for 60 minutes and unimmersed porous carbonate apatite bodies that had been immersed in MRSA bacterial solution for 10 minutes and then implanted into a defect in the medial femoral condyle of a rabbit femur. DETAILED DESCRIPTION OF THE INVENTION

[0014] The medical tissue reconstruction material of the present invention is a calcium-based material having silver carbonate and silver phosphate on its surface, and the total content of silver carbonate and silver phosphate is 5.0 × 10 -4 ~3.3×10 -2 It is characterized by being in mass %.

[0015] The medical tissue reconstruction material of the present invention contains different types of silver compounds, namely silver carbonate and silver phosphate, and thus can maintain its antibacterial properties. Specifically, when the medical tissue reconstruction material is applied to internal tissue, the silver carbonate exhibits antibacterial activity, and then the silver phosphate exhibits antibacterial activity, thereby maintaining its antibacterial properties for a long period of time. Furthermore, since the silver compound is present only on the surface of the reconstruction material, sufficient antibacterial properties can be achieved by applying the minimum amount of silver compound necessary. Furthermore, since the content of the silver compound is within a specific range, it is possible to prevent cytotoxicity and bone formation inhibition in addition to antibacterial properties, thereby enabling effective tissue reconstruction.

[0016] The medical tissue reconstruction material of the present invention can be used in the medical field or fields related to medical care, for tissue reconstruction procedures such as bone reconstruction, and as scaffolds in regenerative medicine.

[0017] The total content of silver carbonate and silver phosphate (hereinafter, when referring to both, they may be simply referred to as silver compounds) in the medical tissue reconstruction material of the present invention is 5.0 × 10 -4 ~3.3×10 -2 % by mass, but from the viewpoint of antibacterial properties, 1.5 × 10 -3 It is preferable that the content is 2.0×10 mass% or more. -3 It is more preferable that the content is 3.0×10 mass% or more. -3 It is more preferable that the content is 4.0 × 10 -3 It is particularly preferable that the content is 5.0 × 10 -3 % by mass or more. In addition, taking into consideration the effects of cytotoxicity, etc., it is most preferable that the concentration is 2.8 × 10 -2 It is preferably 1.0 × 10 mass% or less. -2 It is more preferable that the content is less than 9.0 × 10 -3 It is more preferably % by mass or less.

[0018] The medical tissue reconstruction material (calcium-based material) of the present invention is primarily composed of an inorganic compound. Such inorganic compounds are not particularly limited as long as they generate both silver carbonate and silver phosphate upon exposure to a solution containing silver ions, i.e., contain both a phosphoric acid component and a carbonate component. Specific examples include carbonate-containing calcium phosphate, a mixture of calcium phosphate and a carbonate-containing compound, and bone, with carbonate-containing calcium phosphate being preferred. Carbonated apatite is particularly preferred as a carbonate-containing calcium phosphate, since it is an inorganic component of human bone, has high osteoconductivity, and ultimately replaces bone. For example, hydroxyapatite, which does not generate silver carbonate, has insufficient antibacterial effect and is therefore not within the scope of the present invention.

[0019] The content of inorganic compounds in the medical tissue reconstruction material of the present invention (calcium-based material excluding silver compounds) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably substantially 100% by mass. Examples of materials other than the inorganic compounds include collagen, chitosan, and polymers such as lactic acid, glycolic acid, polylactic acid, caprolactone, glycerol sebacic acid, hydroxybutyric acid, and dioxanone, or copolymers thereof.

[0020] Although the shape and size of the medical tissue reconstruction material of the present invention are not particularly limited, a porous body is preferable to a dense body in terms of the application of the silver compound to the material surface and tissue reconstruction. Examples of porous bodies include a honeycomb structure having through-holes extending in one direction and a porous body having a large number of randomly arranged pores like a foam. The former honeycomb structure is preferred because it allows for more effective tissue reconstruction.

[0021] As described above, the medical tissue reconstruction material of the present invention is composed mainly of an inorganic compound and has silver carbonate and silver phosphate on its surface, and can also be considered as a structure having a core portion composed mainly of an inorganic compound and a shell portion containing silver carbonate and silver phosphate on the surface of the core portion.

[0022] The medical tissue reconstruction material of the present invention can be produced by exposing a calcium-based material to a solution containing silver ions. The calcium-based material is a material whose main component is an inorganic compound, as described above for the medical tissue reconstruction material of the present invention.

[0023] When a calcium-based material is exposed to a solution containing silver ions, the anions in the calcium-based material react with the silver ions, producing silver carbonate and silver phosphate on the surface of the calcium-based material. Methods for exposing a calcium-based material to a solution containing silver ions include immersing the calcium-based material in the solution and applying the solution to the calcium-based material by spraying, etc., with the former immersion method being preferred because it allows for more efficient application of the silver compound. A silver nitrate aqueous solution is preferred as the solution containing silver ions.

[0024] The silver nitrate concentration in the silver nitrate aqueous solution is preferably 0.6 to 41.3 equivalents relative to the calcium-based material used as raw material. The lower limit is preferably 1.9 equivalents or more relative to the calcium-based material, more preferably 2.5 equivalents or more, even more preferably 3.8 equivalents or more, particularly preferably 5.0 equivalents or more, and most preferably 6.3 equivalents or more. The upper limit is preferably 35 equivalents or less relative to the calcium-based material, more preferably less than 12.5 equivalents, and even more preferably 11.3 equivalents or less.

[0025] Specifically, in the immersion method, the calcium-based material is immersed in a silver nitrate aqueous solution of 0.6 to 41.3 equivalents relative to the calcium-based material, and a total of 5.0 × 10 silver carbonate and silver phosphate are added. -4 ~3.3×10 -2 It is also preferable to immerse the calcium-based material in an aqueous solution of silver nitrate in an amount of 1.9 to 12.5 equivalents relative to the calcium-based material, and generate 1.5×10 silver carbonate and silver phosphate in total. -3 ~1.0×10 -2 It is more preferable to produce less than 100% by mass.

[0026] The temperature of the solution is not particularly limited as long as the silver ion-containing aqueous solution does not freeze or boil, and is preferably 10 to 80° C., more preferably 10 to 30° C. The immersion time is not particularly limited as long as the desired amount of silver carbonate and silver phosphate is produced, and is preferably 10 minutes to 7 days, and more preferably 60 minutes to 24 hours.

[0027] The present invention will be specifically described below with reference to examples, but the technical scope of the present invention is not limited to these examples. [Example]

[0028] [Test Example 1] The carbonate apatite porous body used was a cylindrical honeycomb structure with a diameter of approximately 10 mm and a height of approximately 10 mm, which had a large number of through-holes in the shape of regular square pillars extending in one direction. The length of one side of the through-hole was approximately 300 μm. The carbonate apatite porous bodies in Test Example 1 and subsequent examples were similar.

[0029] Porous carbonate apatite 5×10 -2 ~5×10 3 The specimens were immersed in an equivalent amount of silver nitrate solution at 20°C for 60 minutes. The silver concentration in the specimens after immersion was measured by inductively coupled plasma atomic emission spectrometry. The measurement results are shown in Figure 1.

[0030] As shown in Figure 1, it was revealed that the silver content in the sample increased as the silver nitrate concentration increased. As shown in Test Examples 3 and 4 described later, this silver was derived from silver phosphate and silver carbonate. When the silver nitrate concentration was 5 × 10 relative to the carbonate apatite, -2 , 5×10 -1 , 1.5, 2.5, 3.5, 5, 15, 25, 35, 5×10 1 , 5×10 2 , 5×10 3 When equivalent, each is about 5.5 × 10 -4 , 9.9×10 -4 , 1.2 × 10 -3 , 2.0×10 -3 , 2.8×10-3 , 6.1×10 -3 , 1.2 × 10 -2 , 2.0×10 -2 , 2.8×10 -2 , 3.8×10 -2 , 3.6×10 -1 In other words, it is clear that the concentrations of silver phosphate and silver carbonate can be controlled by the silver nitrate concentration.

[0031] Furthermore, as shown in Test Example 5 below, when hydroxyapatite that does not contain carbonate ions is immersed in a silver nitrate solution under the same conditions as carbonate apatite, the hydroxyapatite produces fewer silver compounds than carbonate apatite. This is because silver carbonate is not produced when hydroxyapatite is used.

[0032] [Test Example 2] Porous carbonate apatite was immersed in 0.5 and 50 equivalents of aqueous silver nitrate solutions at 20°C for 60 minutes. After immersion, the microstructure of the sample surface was observed using a scanning electron microscope, and the silver on the sample surface was mapped using an energy dispersive X-ray analyzer. For comparison, a similar analysis was performed on porous carbonate apatite before immersion in the aqueous silver nitrate solution. The analysis results are shown in Figure 2.

[0033] As shown in Figure 2, silver compounds (indicated by the white arrowheads) that were not observed before immersion in the silver nitrate aqueous solution were observed after immersion. It can be seen that the amount of silver compounds increases as the silver nitrate concentration increases.

[0034] [Test Example 3] Porous carbonate apatite was immersed in 5 to 500 equivalents of silver nitrate at 20°C for 60 minutes, and the crystalline phase after immersion was evaluated by powder X-ray diffraction. Figure 3 shows the powder X-ray diffraction patterns of the sample and silver phosphate (Ag3PO4) before and after immersion.

[0035] As shown in Figure 3, when the sample was immersed in 500 equivalents of silver nitrate, X-ray diffraction lines of silver phosphate were observed in the sample, but when the silver nitrate was 50 equivalents or less, no diffraction lines of silver phosphate were observed. Considering that the detection limit of this analytical method is 0.1 to 1 mass%, and that the silver concentration was less than 0.1 mass% relative to the total mass in Test Example 1 and Test Example 2 at 50 equivalents or less, it is reasonable that no diffraction lines of silver phosphate were observed. Although X-ray diffraction did not confirm diffraction lines of silver phosphate at 50 equivalents or less, the formation of silver compounds is clear from Test Example 1 (Figure 1) and Test Example 2 (Figure 2).

[0036] [Test Example 4] Porous carbonate apatite was immersed in 500 equivalents of silver nitrate at 20°C for 7 days, and the crystalline phase after immersion was evaluated by powder X-ray diffraction. Figure 4 shows the powder X-ray diffraction patterns of the sample, silver phosphate (Ag3PO4), and silver carbonate (Ag2CO3) before and after immersion.

[0037] As shown in FIG. 4, the diffraction lines of silver carbonate and silver phosphate were confirmed in the sample after immersion, making it clear that these crystalline phases had formed.

[0038] [Test Example 5] Carbonate apatite disks (φ8mm × 1.5mm), which are calcium phosphate containing carbonate, and hydroxyapatite disks (φ8mm × 1.5mm), which are calcium phosphate not containing carbonate, were immersed in 5-5000 equivalents of silver nitrate solution at 20°C for 24 hours. The specific surface area of ​​both the carbonate apatite and hydroxyapatite used was 4m 2 g -1 The silver concentration in the sample after immersion was measured by inductively coupled plasma atomic emission spectrometry. The measurement results are shown in Figure 5.

[0039] As shown in Figure 5, it was clear that carbonate apatite had a higher silver content than hydroxyapatite at all silver nitrate concentrations. This is because, as mentioned above, carbonate apatite produces silver carbonate and silver phosphate, while hydroxyapatite produces only silver phosphate.

[0040] [Example 1] Porous carbonate apatite samples were immersed in 0.5 to 5000 equivalents of silver nitrate aqueous solution at 20°C for 60 minutes, and the antibacterial effect against methicillin-resistant Staphylococcus aureus (MRSA) was evaluated in accordance with JIS Z 2801:2010. For comparison, the antibacterial effect of a sample not immersed in silver nitrate was also evaluated in the same manner. Figure 6 shows the relationship between silver nitrate concentration and MRSA survival rate.

[0041] As shown in Figure 6, when the carbonate apatite porous body was immersed in 0.5 equivalents and 1.5 equivalents of silver nitrate solution, the survival rates of MRSA were 7.7% and 7.3%, respectively, and when it was immersed in 2.5 equivalents or more of silver nitrate solution, the survival rate of MRSA was 0%. From Test Example 1, when it was immersed in 2.5 equivalents of silver nitrate solution, the survival rate of MRSA was 2.0 × 10 -3 When immersed in 1.5 equivalents of silver nitrate solution, 1.2 × 10 mass of silver phosphate and silver carbonate were generated. -3 Since it is known that % by mass of silver phosphate and silver carbonate are produced, the threshold concentration of silver phosphate and silver carbonate relative to the total mass for complete killing of MRSA is 1.2 × 10 -3 to 2.0 x 10 -3 It can be seen that the silver phosphate and silver carbonate concentrations are between 9.9 × 10 -4 to 1.2 x 10 -3 In the case of mass %, the number of bacteria was reduced to about 7.5%, so the silver phosphate and silver carbonate concentrations that showed the bactericidal effect were 9.9 × 10 -4 It can be seen that the bactericidal effect is also exhibited in terms of mass percent.

[0042] [Example 2] Porous carbonate apatite samples were immersed in 0.5 to 500 equivalents of silver nitrate aqueous solution at 20°C for 60 minutes, and the antibacterial effect against Staphylococcus epidermidis of these samples was evaluated in accordance with JIS Z 2801:2010. For comparison, the antibacterial effect of a sample not immersed in the silver nitrate aqueous solution against Staphylococcus epidermidis was evaluated in the same manner. The results are shown in Figure 7.

[0043] As shown in Figure 7, when the silver nitrate concentration was 0.5 equivalents, the number of colonies of Staphylococcus epidermidis was 7 × 10 7When the silver nitrate concentration was 5 equivalents or more, the number of colonies of Staphylococcus epidermidis was 0 colonies / mL. The threshold concentration of silver phosphate and silver carbonate relative to the total mass to completely kill Staphylococcus epidermidis was 9.9 × 10 -4 to 6.1 x 10 -3 This result is similar to the antibacterial test using MRSA described in Example 1.

[0044] [Example 3] Porous carbonate apatite samples were immersed in 5 to 5,000 equivalents of silver nitrate for 60 minutes at 20°C, and the cytotoxicity of these samples against mouse calvarial osteoblast-like cells (MC3T3-E1) was evaluated. For comparison, the cytotoxicity of a sample not immersed in silver nitrate was also evaluated. The results of the cytotoxicity test are shown in Figure 8.

[0045] As shown in Figure 8, when the carbonate apatite porous body was immersed in a silver nitrate solution of 35 equivalents or less, no cytotoxicity was observed. When the body was immersed in a silver nitrate solution of 50 equivalents or more, the cell viability dramatically decreased, confirming cytotoxicity. From Test Example 1, it was found that the silver phosphate and silver carbonate concentrations when immersed in a 50 equivalent silver nitrate solution were 3.8 × 10 of the total mass. -2 When immersed in a 35 equivalent silver nitrate solution, the silver phosphate and silver carbonate concentrations are 2.8 × 10 of the total mass. -2 In other words, the threshold concentration of silver phosphate and silver carbonate that shows cytotoxicity is 2.8 × 10 of the total mass. -2 to 3.8 x 10 -2 It exists between % by mass.

[0046] As described in Examples 1 and 2, the silver phosphate and silver carbonate concentrations that exhibit a bactericidal effect of 90% or more are 9.9 × 10 of the total mass. -4 The threshold concentration of silver phosphate and silver carbonate that completely kills bacteria is 1.2 × 10 -3 to 2.0 x 10 -3 From this experimental result, the silver phosphate and silver carbonate concentrations are 9.9 × 10 of the total mass. -4 ~2.8×10 -2 % by mass, it definitely does not show cytotoxicity, shows a bactericidal effect of 90% or more, and is 2.0 × 10 -3~2.8×10 -2 It can be seen that a concentration of 1.0 × 10 mass% is not cytotoxic and can completely kill bacteria. However, since inflammation occurring in the body is a complex immune system reaction involving various cells and factors, there is a risk of unexpected cytotoxicity. Therefore, in actual clinical practice, a lower upper concentration is preferable, taking into account the certainty of cytotoxicity. For example, 1.0 × 10 mass% is preferable. -2 A concentration lower than 100% by mass is considered preferable, and even at such a low concentration, the antibacterial properties are sufficiently exhibited (see Examples 4 and 5).

[0047] [Test Example 6] Carbonate apatite disks (φ8mm × 1.5mm), which are calcium phosphate containing carbonate, and hydroxyapatite disks (φ8mm × 1.5mm), which are calcium phosphate not containing carbonate, were immersed in 5-5000 equivalents of silver nitrate solution at 20°C for 24 hours. The specific surface area of ​​both the carbonate apatite and hydroxyapatite used was 4m 2 g -1 The antibacterial effect against MRSA was evaluated in accordance with JIS Z 2801:2010. For comparison, the antibacterial effect of a sample that was not immersed in the silver nitrate aqueous solution was also evaluated in the same manner. The measurement results are shown in Figure 9.

[0048] As shown in Figure 9, no antibacterial effect was observed in carbonate apatite samples not immersed in silver nitrate solution. However, MRSA was not detected in samples immersed in 0.5 equivalents or more of silver nitrate solution, confirming the antibacterial effect. On the other hand, no antibacterial effect was observed in hydroxyapatite samples immersed in silver nitrate solution of 50 equivalents or less; the MRSA colony count could not be reduced to zero unless the silver nitrate concentration was increased to 5,000 equivalents. Test Example 5 showed that the silver compound concentration in carbonate apatite immersed in 5 equivalents of silver nitrate solution was equivalent to that in hydroxyapatite immersed in 50 equivalents of silver nitrate solution. However, the silver compound concentration in hydroxyapatite immersed in 500 equivalents or more of silver nitrate solution was more than 10 times higher than that in carbonate apatite immersed in 5 equivalents of silver nitrate solution. These results demonstrate that using carbonate apatite as the raw inorganic compound provides a stronger antibacterial effect than using hydroxyapatite as the raw inorganic compound. This is because when carbonate apatite is immersed in a silver nitrate solution, both silver carbonate and silver phosphate are produced, whereas when hydroxyapatite is immersed, only silver phosphate is produced. It was shown that the production of both silver carbonate and silver phosphate enhances the antibacterial effect.

[0049] [Example 4] Porous carbonate apatite samples were immersed in 5 equivalents of silver nitrate at 20°C for 60 minutes, and unimmersed samples were 1×10 7 The implant was immersed in a CFU / mL MRSA solution for 10 minutes and implanted into a defect in the medial femoral condyle of a rabbit (φ6×3 mm). The results of measuring the viable bacterial count near the implant site after two weeks are shown in Figure 10.

[0050] As shown in Figure 10, approximately 22,400 colonies were detected per gram of the unimmersed sample, but no live bacteria were detected in the sample immersed in 5 equivalents of silver nitrate at 20°C for 60 minutes. In other words, in the in vitro tests of Examples 1, 2, and 3, the concentrations of silver phosphate and silver carbonate on the surface of the material were 6.1 x 10 of the total mass. -3 It was known that when the silver phosphate and silver carbonate concentrations on the surface of the material were 6.1 × 10% by mass, they did not show cytotoxicity and exhibited antibacterial properties. -3It was demonstrated that antibacterial effects were observed when the concentration was 0.05 mass %.

[0051] [Example 5] A sample of porous carbonate apatite immersed in 5 equivalents of silver nitrate solution for 60 minutes and a sample not immersed in silver nitrate solution were measured. 7 The tissue was immersed in a solution of MRSA bacteria containing 100 CFU / mL for 10 minutes and then implanted into a defect in the medial femoral condyle of a rabbit femur (φ6×3 mm). Figure 11 shows the histopathological findings around the implantation site after 2 weeks.

[0052] As shown in Figure 11, in the specimen in which a sample immersed in 5 equivalents of silver nitrate for 60 minutes was implanted, no infiltration of inflammatory cells or bone resorption by bacteria was observed around the implantation site, and new bone was formed inside and around the specimen. On the other hand, in the specimen in which a sample not immersed in silver nitrate aqueous solution was implanted, significant infiltration of inflammatory cells and large-scale bone resorption by bacteria occurred around the implantation site, and new bone formation was not observed inside or around the specimen. From the above, it can be concluded that the surface silver phosphate and silver carbonate concentrations obtained by immersion in 5 equivalents of silver nitrate aqueous solution for 60 minutes were 6.1 x 10 of the total mass. -3 It was revealed that the sample with mass% had both antibacterial and osteoconductive properties. [Industrial Applicability]

[0053] The medical tissue reconstruction material of the present invention is industrially useful because it can be used in the medical field or fields related to medical care, such as in tissue reconstruction procedures for bones and the like, and as scaffolds in regenerative medicine.

Claims

1. A calcium-based biomaterial comprising a core portion substantially consisting of at least one calcium-based material selected from carbonate-containing calcium phosphate, a mixture of calcium phosphate and a carbonate-containing compound, and bone, and a shell portion containing silver carbonate and silver phosphate on the surface of the core portion, A medical tissue reconstruction material having a total content of silver carbonate and silver phosphate of 1.5×10 −3 to 1.0×10 −2 mass % (or less).

2. A medical tissue reconstruction material as described in claim 1, characterized in that the calcium-based material of the core portion is carbonate apatite.

3. 3. The medical tissue reconstruction material according to claim 1, which is a porous body.

4. A method for producing the medical tissue reconstruction material according to any one of claims 1 to 3, comprising: A method for producing a medical tissue reconstruction material by exposing a calcium-based material to a solution containing silver ions.

5. 5. The method for producing a medical tissue reconstruction material according to claim 4, wherein the calcium-based material is immersed in a solution containing silver ions.

6. 6. The method for producing a medical tissue reconstruction material according to claim 4, wherein the solution containing silver ions is an aqueous silver nitrate solution.

7. 7. The method for producing a material for medical tissue reconstruction according to claim 4, wherein the calcium-based material is immersed in an aqueous silver nitrate solution in an amount of 1.9 to 12.5 equivalents relative to the calcium-based material.

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