Biological implant and method for manufacturing same

Abstract

One aspect of the present disclosure relates to a biological implant comprising a substrate and silver particles having a diameter of 1 μm or less and supported on the substrate, wherein, in the observation of a cross-section including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more relative to the diameter of the silver particles.

Description

Bioimplant and manufacturing method thereof

[0001] The present disclosure relates to biological implants and methods for making the same.

[0002] Silver is widely used as a material that exhibits antibacterial properties and is also used in medical devices and implants.

[0003] However, if a person ingests a large amount of silver, it can cause argyria, a condition in which silver ions are deposited on the skin, so the amount must be controlled.To ensure safety, the amount of silver to be loaded must be extremely small, and a technology has been reported in which nano-sized silver particles are loaded onto the surface of an implant.

[0004] For example, Patent Document 1 describes a technique in which a colloidal dispersion containing silver particles having an average diameter of 30 nm or less is prepared, a medical device to be treated is immersed in the colloidal dispersion, and an oxide coating is formed by plasma electrolytic oxidation.

[0005] Special Publication No. 2012-528612

[0006] A biological implant according to one aspect of the present disclosure comprises a substrate and silver particles supported on the substrate and having a particle diameter of 1 μm or less, and is characterized in that, upon observation of a cross section including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles.

[0007] Another aspect of the present disclosure provides a biological implant comprising a substrate, silver particles having a particle diameter of 1 μm or less supported on the substrate, and an oxide coating, wherein, upon observation of a cross section including the substrate, the silver particles, and the oxide coating, 30% or more of the surface of the silver particles is embedded in the oxide coating, and at least a portion of the surface of the silver particles is exposed from the oxide coating.

[0008] FIG. 1 is a transmission electron microscope (TEM) photograph showing the state of silver particles supported on the substrate surface of the biological implant of Test Example 1 (A: baked at 250°C, B: baked at 350°C, C: baked at 500°C). FIG. 2 is a graph showing the relationship between heating temperature and the silver particle peeling rate in the tape peeling test of Test Example 1-1. FIG. 3 is a photograph showing the surface state of each sample after wiping in the wiping test of Test Example 1-2. FIG. 4 is a photograph showing the surface state of a latex glove after wiping in the wiping test of Test Example 1-2. FIG. 5 is a scanning electron microscope (SEM) photograph showing the state of silver particles supported on the surface of a test piece in Reference Test Example 1. FIG. 6 is a graph showing the relationship between the concentration of silver particle dispersion and the amount of silver supported in Reference Test Example 1. FIG. 7 is a graph showing the results of the antibiofilm test of Reference Test Example 2. Fig. 9 is a transmission electron microscope (TEM) photograph showing the state of silver particles embedded in an oxide film formed on the surface of the substrate in the biological implant of Test Example 2 (H: height of the silver particle, T: thickness of the oxide film). Fig. 10 is a photograph showing the surface state of each sample after wiping (left) and the surface state of a latex glove after wiping (right) in the wiping test of Test Example 2 (A: heat-treated, B: unheated).

[0009] It is expected that precise control of the amount of silver supported will be possible by using silver particles, as in the technology described in Patent Document 1. However, the use of silver particles carries the risk of particle detachment, and it is difficult to say that simply coating with an oxide film is safe, for example.

[0010] Hereinafter, embodiments of the present disclosure will be specifically described, but the present disclosure is not limited thereto.

[0011] [First Embodiment of Biological Implant] The biological implant according to the first embodiment of the present disclosure comprises a substrate and silver particles having a particle diameter of 1 μm or less supported on the substrate. In a cross-sectional observation including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles.

[0012] By adopting such a configuration, the biological implant of this embodiment can reduce the detachment of the supported silver particles. Silver has excellent antibacterial properties, but is harmful if ingested in large amounts by the human body. Therefore, the biological implant of this embodiment is a biological implant in which the detachment of the supported silver particles is unlikely to occur, and it combines safety and antibacterial properties.

[0013] The bioimplants of this embodiment may be, for example, dental implants, artificial joints such as femoral stems or acetabular shells, and spinal surgical implants such as spinal fixation instrumentation.

[0014] Examples of materials for the substrate include metals, ceramics, and plastics. Examples of metals include titanium, titanium alloys, stainless steel, cobalt-chromium alloys, and zirconium alloys. Examples of titanium alloys include alloys in which at least one of aluminum, tin, zirconium, molybdenum, nickel, palladium, tantalum, niobium, vanadium, and platinum has been added to titanium. Specific examples of titanium alloys include Ti-6Al-4V alloys. Examples of ceramics include alumina, zirconia, alumina-zirconia composite ceramics, and calcium phosphate. Examples of plastics include polyethylene, fluorine-based resins, epoxy resins, PEEK resin, and Bakelite. The shape of the substrate is not particularly limited and may be flat or porous. From the perspective of easily supporting silver particles, the porous shape may be a three-dimensional structure having spaces or voids.

[0015] Any silver particles can be used as long as they have a particle diameter of 1 μm or less. For example, the silver particles may be metallic silver particles or silver compound particles having antibacterial properties. For example, two or more types of silver particles can be mixed and used. For example, two or more types of silver particles having different particle diameters can be mixed and used.

[0016] The shape of the silver particles may be spherical or irregular. In this specification, "particle size" refers to the diameter of the particle in the case of spherical particles, and to the maximum length of the particle in the case of irregular particles. In this embodiment, the particle size of the silver particles is set to 750 nm or less, but may be 500 nm or less, or 300 nm or less. The smaller the particle size of the silver particles, the larger the specific surface area, which increases the force acting per unit volume, making the silver particles less likely to detach. Meanwhile, the lower limit of the particle size is not particularly limited, but is, for example, 5 nm or more. In this embodiment, the particle size of the silver particles is a value measured by observing the silver particle surface with a scanning electron microscope (SEM) at 50,000 magnifications.

[0017] The particle diameter of the silver particles of this embodiment may be the equivalent circle diameter (R2), and even in this case, the particle diameter of the silver particles is 1 μm or less. Furthermore, even when the equivalent circle diameter (R2) is used, the particle diameter of the silver particles may be 750 nm or less, and may be 500 nm or less, or may be 300 nm or less. In this specification, the "equivalent circle diameter" means the diameter of a perfect circle equivalent to the cross-sectional area of ​​a silver particle, or the diameter of a perfect circle equivalent to the area of ​​an individual silver particle confirmed by SEM observation of the surface or field emission scanning electron microscope (FE-SEM) observation of the surface. The equivalent circle diameter can be measured by the method described in the Examples below. The lower limit of the equivalent circle diameter (R2) is not particularly limited, but is, for example, 5 nm or more.

[0018] In the biological implant according to this embodiment, the silver particles are supported on the substrate, and in a cross-sectional observation including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles. By keeping the contact length between the silver particles and the substrate in this range, it is possible to reduce the detachment of the silver particles from the substrate.

[0019] As used herein, the term "cross-section observation" refers to observing a cross-section of a substrate carrying silver particles, cut in a vertical direction by an ion beam, using a transmission electron microscope (TEM). The detailed method will be described in the Examples below.

[0020] The contact length will be described with reference to FIG. 1(B) as a specific example. FIG. 1(B) is a cross-sectional TEM photograph (magnification: 1,000,000 times) of an example of a biological implant of this embodiment. In FIG. 1(B), H represents the height of the silver particle, R represents the particle diameter (maximum diameter) of the silver particle, and L represents the contact length between the substrate and the silver particle. Here, the height (H) of the silver particle refers to the length from the top to the bottom of the silver particle. In the biological implant of this embodiment, L (contact length) / R (particle diameter) is 0.70 or more (70% or more). The upper limit is not particularly limited, but may be, for example, 2.0 or less. Alternatively, in this embodiment, the contact length between the silver particle and the substrate may be 80% or more of the particle diameter of the silver particle.

[0021] Although not shown, when the particle diameter of the silver particles is measured in terms of the circle-equivalent diameter (R2), the ratio L (contact length) / R2 (particle diameter:circle-equivalent diameter) may be 0.75 or more (75% or more), or 0.90 (90% or more). The upper limit is not particularly limited, but may be, for example, 2.5 or less.

[0022] The amount of silver particles carried on the substrate is not particularly limited, but the amount of silver particles per unit area of ​​the substrate is preferably 1 μg / cm ２ or more and 150 μg / cm ２ It is desirable that the amount of silver particles is 1 μg / cm or less. This is believed to further improve the safety and antibacterial properties of the biological implant of this embodiment. ２ 100 μg / cm or more ２ The unit area of ​​the substrate is a value calculated from the apparent surface area, regardless of the shape of the substrate.

[0023] In this embodiment, the amount of supported silver particles can be measured by immersing the substrate carrying the silver particles in a nitric acid solution to dissolve the silver and measuring the total amount of silver in the nitric acid solution. Alternatively, as an alternative method, the amount of silver particles can be measured by observing and analyzing the silver particles on the surface of the substrate using a field emission scanning electron microscope (FE-SEM). Instead of observing and analyzing the silver particles on the surface of the substrate, the amount of supported silver particles can be calculated by observing and analyzing the silver particles present in a partial region of the substrate surface and measuring the amount of silver particles per unit area.

[0024] In the biological implant of this embodiment, it is not necessary for all silver particles supported on the substrate to have an L (contact length) / R (particle diameter) ratio of 0.70 or more, and it is sufficient that a portion of all supported silver particles satisfy the above-mentioned requirement. Of all supported silver particles, the proportion of silver particles for which the contact length (L) between the silver particle and the substrate is 70% or more of the particle diameter (R) of the silver particle may be 50% or more, 70% or more, or even 80% or more.

[0025] The aspect ratio of the silver particles supported on the substrate may be 1.1 or more. This has the advantage of increasing the contact area of ​​the silver particles with the substrate relative to the volume of the silver particles, thereby improving adhesion. In this specification, "aspect ratio" refers to the value obtained by dividing the particle diameter (R) of the silver particles by the height (H) of the silver particles. Similar to the contact length and the like described above, the aspect ratio of the silver particles can be determined by observing a cross section of the silver particles supported on the substrate cut vertically with an ion beam using a transmission electron microscope (TEM). The upper limit of the aspect ratio is not particularly limited, but may be, for example, 2.0 or less.

[0026] In the biological implant of this embodiment, the silver particles may be supported directly on the substrate, or on an oxide film formed on the surface of the substrate by oxidizing the substrate.

[0027] The silver particles may be supported on the entire surface of the substrate, or on a part of the substrate. From the viewpoint of obtaining antibacterial properties of the biological implant, the silver particles may be supported on the entire surface of the substrate.

[0028] The oxide film may be made of, for example, niobium oxide, titanium oxide, tantalum oxide, or zirconia oxide.

[0029] In this embodiment, when the substrate is made of at least one selected from titanium, a titanium alloy, a stainless steel alloy, and a cobalt-chromium alloy, the oxide coating may contain an oxide of a component constituting the substrate. For example, a layer of an oxide made of a component different from the component constituting the substrate may be present between the substrate and the silver particles.

[0030] The thickness of the oxide film is not particularly limited, but may be smaller than the particle diameter of the silver particles supported on the substrate. Since the particle diameter of the silver particles in this embodiment is 1 μm or less, the thickness of the oxide film may be 0.75 μm or less, or may be 200 nm or less.

[0031] [Method for producing the biological implant of the first embodiment] The biological implant of the first embodiment can be obtained by applying a dispersion containing silver particles to a substrate and then heating (heat treating) the substrate in an air atmosphere.

[0032] The shape and surface roughness of the substrate are not particularly limited, and before applying the dispersion liquid, the surface of the substrate may be subjected to polishing treatment, blasting treatment, and / or chemical treatment, etc. Examples of chemical treatment include etching treatment with an acid solution or alkaline heating treatment.

[0033] The dispersion liquid containing silver particles is not particularly limited as long as it is a solution in which silver particles are dispersed in a liquid, and examples of the solvent for the dispersion liquid of this embodiment include water, ethanol, isopropanol, toluene, dimethylformamide, acetone, decane, tetradecane, etc. Furthermore, the dispersion liquid may contain additives, and specific examples of the additives include various surfactants such as polyethylene glycol.

[0034] The average particle diameter (D ５０ The average particle size may be 100 nm or less. The average particle size is a value measured by dynamic light scattering.

[0035] The concentration of silver particles contained in the dispersion may be 100 mg / L or more and 10,000 mg / L or less. A silver particle concentration in this range has the advantages of ensuring the safety of the biological implant and improving the antibacterial properties of the biological implant.

[0036] The method for applying the dispersion to the substrate is not particularly limited, and may be, for example, immersing the substrate in the dispersion containing silver particles. Alternatively, the dispersion may be sprayed onto the surface of the substrate using a dispenser, a sprayer, or a misting device. After the dispersion is applied to the substrate, the dispersion is dried, whereby the silver particles contained in the dispersion adhere to and are supported on the surface of the substrate. The dispersion may be dried by natural drying, or by spin coating, blowing dry air, or the like.

[0037] Alternatively, methods for depositing silver without applying a silver dispersion liquid may be used, such as liquid phase synthesis, sol-gel, electrodeposition, mist CVD, sputtering, or vapor deposition.

[0038] Next, the substrate carrying the silver particles is heated at a temperature of 300°C or higher in an air atmosphere. In this embodiment, "in an air atmosphere" means that the operation is performed under atmospheric conditions without replacing the inside of the heating container with an inert gas or the like. The air atmosphere may be, for example, an atmosphere consisting of approximately 78% nitrogen, approximately 20% oxygen, and approximately 2% other components, which is the composition of air. The heating means is not particularly limited, and may include a method of heating the entire substrate using an electric furnace, or local heating using a laser or microwave. This heating treatment deforms the silver particles and increases the contact area with the substrate. Increasing the contact area between the silver particles and the substrate allows the silver particles to firmly adhere to the substrate, reducing the risk of detachment of the silver particles. The heating temperature may be 300°C or higher, but may also be 350°C or higher. The upper limit of the heating temperature is not particularly limited, but may be 700°C or lower because there is a risk of silver sublimation at temperatures above 700°C.

[0039] [Second Embodiment of Biological Implant] The biological implant according to a second embodiment of the present disclosure includes a substrate, silver particles having a particle diameter of 1 μm or less supported on the substrate, and an oxide coating. When a cross-section including the substrate, the silver particles, and the oxide coating is observed, 30% or more of the silver particle surface is embedded in the oxide coating, and at least a portion of the silver particle surface is exposed from the oxide coating. Because 30% or more of the silver particle surface is embedded in the oxide coating, the biological implant of this embodiment can reduce detachment of the supported silver particles. Furthermore, because at least a portion of the silver particle surface is exposed from the oxide coating, the biological implant of this embodiment has antibacterial properties.

[0040] The bioimplant of this embodiment may be, for example, a dental implant, an artificial joint such as a femoral stem or an acetabular shell, and a spinal surgical implant such as a spinal fixation instrumentation.

[0041] The substrate may be made of the same material as in the first embodiment. The silver particles may also be the same as those described in the first embodiment. In the biological implant of the second embodiment, the substrate may be made of at least one material selected from titanium, a titanium alloy, stainless steel, a cobalt-chromium alloy, alumina, calcium phosphate, and zirconia.

[0042] In the biological implant according to this embodiment, silver particles are supported on a substrate, and the substrate is covered with an oxide film. Furthermore, in a cross-sectional observation including the substrate, the silver particles, and the oxide film, 30% or more of the silver particle surface is embedded in the oxide film. In other words, the silver particles supported on the substrate are embedded in the oxide film that covers the substrate, and the embedding rate of the silver particles in the oxide film is 30% or more.

[0043] As used herein, the term "cross-section observation" refers to observing a cross-section of a substrate having an oxide film and carrying silver particles, cut in a vertical direction with an ion beam, using a transmission electron microscope (TEM). The detailed method will be described in the Examples below.

[0044] The embedding ratio will be described with reference to Fig. 9(A) as a specific example. Fig. 9(A) is a cross-sectional TEM photograph (magnification: 1,000,000 times) of an example of the biological implant of this embodiment, in which H indicates the height of the silver particle and T indicates the thickness of the oxide film. Here, the height (H) of the silver particle means the length from the top to the bottom of the silver particle. In the biological implant of this embodiment, the embedding ratio = oxide film thickness (T) / silver particle height (H) is 0.30 or more (30% or more). The embedding ratio may be 40% or more.

[0045] On the other hand, if the embedment rate is 100%, the silver particles will be completely embedded in the oxide film, which may prevent the antibacterial properties of silver from being obtained. Therefore, in the biological implant of this embodiment, at least a portion of the silver particle surface is exposed from the oxide film. The exposed percentage is not particularly limited, but from the viewpoint of obtaining sufficient antibacterial properties, 40% or more of the silver particle surface may be exposed from the oxide film. Alternatively, 50% or more of the silver particle surface may be exposed from the oxide film. The exposure rate can be calculated by dividing the height of the exposed portion of the silver particle by the height (H) of the silver particle.

[0046] In the biological implant of this embodiment, the range of the amount of silver particles carried on the substrate and the method for measuring the amount may be set in the same manner as in the biological implant of the first embodiment.

[0047] In the biological implant of this embodiment, it is not necessary for all silver particles supported on the substrate to have an embedment rate of 30% or more. For example, it is sufficient that the embedment rate of a portion of all supported silver particles is 30% or more. Of all supported silver particles, 50% or more may have 30% or more of their surfaces embedded in an oxide film and at least a portion of their surfaces exposed from the oxide film. Of all supported silver particles, 60% or more, or even 80% or more may have 30% or more of their surfaces embedded in an oxide film and at least a portion of their surfaces exposed from the oxide film.

[0048] In this embodiment, the aspect ratio of the silver particles supported on the substrate may be 1.1 or more. The aspect ratio here has the same meaning as the aspect ratio in the first embodiment, and the measurement method is also the same. The upper limit of the aspect ratio is not particularly limited, but may be, for example, 2.0 or less.

[0049] In the biological implant of this embodiment, the silver particles may be supported on the entire surface of the substrate, or on a part of the substrate. From the viewpoint of obtaining antibacterial properties of the biological implant, the silver particles may be supported on the entire surface of the substrate.

[0050] In this embodiment, the oxide film may be provided on the entire surface of the substrate, or may be provided only on a portion of the surface of the substrate. For example, when silver particles are supported on a portion of the surface of the substrate, it is desirable that the oxide film be provided on the portion where the silver particles are supported.

[0051] The oxide film may be made of, for example, niobium oxide, titanium oxide, tantalum oxide, or zirconia oxide.

[0052] In this embodiment, when the substrate is made of at least one selected from titanium, a titanium alloy, a stainless steel alloy, and a cobalt-chromium alloy, the oxide coating may contain an oxide of a component constituting the substrate. For example, a layer of an oxide made of a component different from the component constituting the substrate may be present between the substrate and the silver particles.

[0053] The thickness of the oxide film is not particularly limited, but may be smaller than the particle diameter of the silver particles supported on the substrate. Since the particle diameter of the silver particles in this embodiment is 1 μm or less, the thickness of the oxide film may be 0.75 μm or less, or may be 200 nm or less.

[0054] [Method for manufacturing the biological implant of the second embodiment] (Manufacturing method 1) The biological implant of the second embodiment can be obtained, for example, by applying a dispersion containing silver particles to a substrate, and then heating (heat treating) the substrate in an atmosphere containing oxygen or hydrogen.

[0055] In the manufacturing method of this embodiment, the steps up to coating the substrate with a dispersion liquid containing silver particles can be performed in the same manner as in the first embodiment, and therefore a description thereof will be omitted.

[0056] Next, the substrate carrying the silver particles is heated in an atmosphere containing oxygen or water. For example, the substrate carrying the silver particles is heated in a reducing atmosphere containing oxygen or water. Specifically, for example, a hydrogen gas atmosphere containing 1 ppm or less of oxygen or 5 ppm or less of water can be used.

[0057] The heating means is not particularly limited, and may be a method of heating the entire substrate using an electric furnace, or local heating using a laser or microwave. The heat treatment under the atmosphere forms an oxide film covering the silver particles supported on the substrate, increasing the contact area between the silver particles and the substrate containing the formed oxide film. This allows the silver particles to be firmly attached to the substrate, reducing detachment. The heating temperature may be 300°C or higher, or 600°C or higher. The upper limit of the heating temperature is not particularly limited, but may be 700°C or lower in order to reduce the risk of silver sublimation.

[0058] (Manufacturing Method 2) In addition to the above method, the biological implant of the second embodiment can also be obtained by, for example, applying a dispersion containing silver particles to a substrate, then applying a dispersion containing oxide particles thereto, and then heating the substrate at a temperature of 300°C or higher in an air atmosphere.

[0059] In this manufacturing method, the steps up to coating the substrate with a dispersion liquid containing silver particles can be performed in the same manner as in the first embodiment, and therefore the description thereof will be omitted.

[0060] In this embodiment, after the dispersion liquid containing silver particles has been applied to the substrate, a dispersion liquid containing oxide particles is further applied to the substrate.

[0061] The oxide particles contained in the dispersion may be biocompatible ceramic particles. The oxide particles contained in the dispersion may be, for example, at least one selected from niobium oxide, titanium oxide, tantalum oxide, and zirconia oxide. If the oxide particles contained in the dispersion are made of a material that has high bone-binding properties, there is an advantage in that they can promote the healing of the surface of the bioimplant with the bone.

[0062] The dispersion liquid containing oxide particles is not particularly limited as long as it is a solution in which oxide particles are dispersed in a liquid, and examples of the solvent for the dispersion liquid of this embodiment include water, organic solvents such as ethanol, etc. Furthermore, the dispersion liquid may contain additives, and specific examples of the additives include surfactants such as polyvinyl alcohol, ammonia, malic acid, etc.

[0063] The average particle diameter (D ５０ The average particle size may be a value measured by, for example, dynamic light scattering.

[0064] The concentration of oxide particles contained in the dispersion may be 50 g / L or more and 100 g / L or less.

[0065] The method for applying the oxide particle-containing dispersion to the substrate is not particularly limited, but for example, the substrate may be immersed in the dispersion containing oxide particles, or the dispersion may be sprayed onto the surface of the substrate using a dispenser or a spray, and then the dispersion may be dried, so that the oxide particles contained in the dispersion adhere to and are supported on the surface of the substrate. The dispersion may be dried by natural drying, or by spin coating, blowing dry air, or the like.

[0066] Next, the substrate carrying the silver particles and oxide particles is heated at a temperature of 300°C or higher in an air atmosphere. In this embodiment, the "air atmosphere" has the same meaning as the air atmosphere in the first embodiment. The heating means is not particularly limited, and may be a method of heating the entire substrate using an electric furnace, or local heating using a laser or microwave. This heat treatment bonds the oxide particles to form a strong oxide film. When an oxide film is formed by this heat treatment, the silver particles are embedded in the oxide film formed on the surface of the substrate, firmly adhering the silver particles to the substrate and reducing detachment. The heating temperature may be 300°C or higher, but may also be 400°C or higher. The upper limit of the heating temperature is not particularly limited, but may be 700°C or lower because silver begins to sublimate at temperatures above 700°C.

[0067] As described above, this specification discloses various aspects of the technology, but the main technologies among them are summarized below.

[0068] The biological implant according to the first aspect of the present disclosure comprises a substrate and silver particles supported on the substrate and having a particle diameter of 1 μm or less, and is characterized in that, upon observation of a cross section including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles.

[0069] A biological implant according to a second aspect of the present disclosure is the biological implant of the first aspect, wherein the amount of silver particles supported on the substrate per unit area is 1 μg / cm ２ or more and 150 μg / cm ２ The details are as follows.

[0070] A biological implant according to a third aspect of the present disclosure is the biological implant of the second aspect, wherein, of all the silver particles supported on the substrate, the proportion of silver particles whose contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles is 50% or more.

[0071] A biological implant according to a fourth aspect of the present disclosure is the biological implant according to any one of the first to third aspects, in which the silver particles have an aspect ratio of 1.1 or more.

[0072] A biological implant according to a fifth aspect of the present disclosure is the biological implant according to any one of the first to fourth aspects, wherein the substrate is made of at least one selected from titanium, a titanium alloy, a stainless steel alloy, a cobalt-chromium alloy, alumina, calcium phosphate, and zirconia.

[0073] A biological implant according to a sixth aspect of the present disclosure is the biological implant according to any one of the first to fifth aspects, in which the particle diameter of the silver particles supported on the substrate is 750 nm or less.

[0074] A biological implant according to a seventh aspect of the present disclosure is the biological implant according to any one of the first to sixth aspects, wherein the substrate has an oxide coating on the surface.

[0075] A method for producing a biological implant according to an eighth aspect of the present disclosure is a method for producing a biological implant according to any one of the first to seventh aspects, comprising applying a dispersion liquid containing silver particles to a substrate, and then heating the substrate in an air atmosphere at a temperature of 300°C or higher.

[0076] A method for producing a biological implant according to a ninth aspect of the present disclosure is characterized in that, in the method of the eighth aspect, the average particle diameter of the silver particles contained in the dispersion liquid is 100 nm or less.

[0077] A biological implant according to a tenth aspect of the present disclosure comprises a substrate, silver particles having a particle diameter of 1 μm or less supported on the substrate, and an oxide coating, and is characterized in that, upon observation of a cross section including the substrate, the silver particles, and the oxide coating, 30% or more of the surface of the silver particles is embedded in the oxide coating, and at least a portion of the surface of the silver particles is exposed from the oxide coating.

[0078] A biological implant according to an eleventh aspect of the present disclosure is the biological implant of the tenth aspect, wherein the amount of silver particles supported on the substrate per unit area is 1 μg / cm ２ or more and 150 μg / cm ２ The details are as follows.

[0079] A biological implant according to a twelfth aspect of the present disclosure is the biological implant of the tenth or eleventh aspect, wherein, of all the silver particles supported on the substrate, 30% or more of the surface thereof is embedded in an oxide film, and the proportion of silver particles having at least a portion of their surface exposed from the oxide film is 50% or more.

[0080] A biological implant according to a thirteenth aspect of the present disclosure is the biological implant according to any one of the tenth to twelfth aspects, in which the silver particles have an aspect ratio of 1.1 or more.

[0081] A biological implant according to a fourteenth aspect of the present disclosure is the biological implant of any one of the tenth to thirteenth aspects, wherein the substrate is made of at least one selected from titanium, a titanium alloy, stainless steel, a cobalt-chromium alloy, alumina, calcium phosphate, and zirconia.

[0082] A biological implant according to a fifteenth aspect of the present disclosure is the biological implant according to any one of the tenth to fourteenth aspects, in which the thickness of the oxide film is smaller than the particle diameter of the silver particles.

[0083] A biological implant according to a sixteenth aspect of the present disclosure is the biological implant of any one of the tenth to fifteenth aspects, in which the substrate is made of at least one selected from titanium, a titanium alloy, stainless steel, and a cobalt-chromium alloy, and the oxide coating contains an oxide of a component constituting the substrate.

[0084] A method for producing a biological implant according to a seventeenth aspect of the present disclosure is a method for producing a biological implant according to any one of the tenth to sixteenth aspects, comprising applying a dispersion containing silver particles to a substrate and then heating the substrate in an atmosphere containing oxygen or water.

[0085] The method for producing a biological implant according to an eighteenth aspect of the present disclosure is characterized in that, in the method for producing the biological implant according to the seventeenth aspect, the heating temperature is 600° C. or higher.

[0086] A method for producing a biological implant according to a nineteenth aspect of the present disclosure is a method for producing a biological implant according to any one of the tenth to sixteenth aspects, comprising applying a dispersion containing silver particles to a substrate, further applying a dispersion containing oxide particles, and then heating the substrate at a temperature of 300°C or higher in an air atmosphere.

[0087] A method for producing a biological implant according to a twentieth aspect of the present disclosure is characterized in that, in the method for producing a biological implant according to the nineteenth aspect, the oxide particles are at least one selected from niobium oxide, titanium oxide, tantalum oxide, and zirconia oxide.

[0088] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples in any way.

[0089] Test Example 1 [Preparation of Test Piece] (Example 1) First, a titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. Next, the titanium plate was immersed in a silver particle dispersion in which silver particles with a particle diameter of 30 nm were dispersed at a concentration of 5000 mg / L. Thereafter, the titanium plate was dried while being pulled out of the dispersion. Next, the titanium plate carrying the silver particles was heated in an electric furnace ("KM-160" manufactured by Advantec Co., Ltd.) in an air atmosphere at 350°C for 10 minutes, and Test Piece 1 was obtained.

[0090] Example 2 Test piece 2 was obtained in the same manner as in Example 1, except that the heating temperature in the electric furnace was changed to 500°C.

[0091] Comparative Example 1 Test piece 3 was obtained in the same manner as in Example 1, except that the heating temperature in the electric furnace was changed to 250°C.

[0092] [Cross-sectional observation of test specimens] Test specimens 1 to 3 obtained above were cut in the vertical direction using an ion beam (JEM-ARM200F manufactured by JEOL Ltd.) to prepare samples for cross-sectional observation. The samples were observed at 1,000,000 magnification using a transmission electron microscope (TEM) (Hitachi High-Technologies Corporation's H-9500). Cross-sectional photographs of each test specimen are shown in Figure 1 (A): Test specimen 3 (Comparative Example 1), (B): Test specimen 1 (Example 1), and (C): Test specimen 2 (Example 2). Then, by cross-sectional observation using the TEM photograph, the height (H) of the silver particles, the particle diameter (R: maximum diameter) of the silver particles, and the contact length (L) between the substrate and the silver particles in each sample were determined.

[0093] The height (H) of the silver particles was determined by selecting pixel portions corresponding to the top and bottom of the silver particles and connecting the points with a line. The particle diameter (R) was determined by selecting pixel portions corresponding to both ends of the maximum length of the silver particles and connecting the points with a line. The contact length (L) was determined by selecting an arbitrary number of pixels on the interface between the substrate surface (TiO2, which is an oxide film) and the silver particles and connecting the points with a line.

[0094] Furthermore, the equivalent circle diameter (R2) of the particle diameter was also determined. Specifically, an arbitrary number of pixel portions were selected so as to surround the outline of the silver particle, the points were connected with lines, and the number of pixels within the outline was counted to calculate the area of ​​the silver particle, and the equivalent circle diameter (R2) was calculated from the calculated area.

[0095] The height, particle diameter, contact length, and equivalent circle diameter of the silver particles were calculated by analyzing the TEM images read into Python OpenCV. The results are summarized in Table 1.

[0096]

[0097] The results of FIG. 1 and Table 1 confirm that in the test pieces of Examples 1 and 2, which were heated at a temperature of 300°C or higher, the contact length (L) between the silver particles and the substrate was 70% or more of the particle diameter (R) of the silver particles.

[0098] [Evaluation Test] (Test Example 1-1: Tape Peel Resistance) First, samples for a peel test were prepared. In addition to the above-mentioned Test Piece 1 (heated at 350°C) and Test Piece 3 (heated at 250°C), a total of five samples were prepared: a test piece in which a titanium plate was immersed in a silver particle dispersion liquid and dried without heating (unfired, 0°C) in the same manner as in the above Examples, a test piece heated at 450°C, and a test piece heated at 550°C.

[0099] Each of the prepared samples was attached to a test stand, and a peeling tape (Nichiban Cellotape (registered trademark), base material: cellophane, adhesive strength: 3.93 (N / 10 mm)) was attached to the test piece, and then peeled off. The peeled sample and the peeled tape were analyzed using an ICP-MS analyzer (Agilent Technologies "8900"), and the silver particle peeling rate was calculated using the following formula: Particle peeling rate (%) = amount of silver detected from tape / (amount of silver detected from peeled sample + amount of silver detected from tape) × 100

[0100] The results are shown in Figure 2. This test revealed that heating after application suppresses the amount of silver particles that peel off.

[0101] (Test Example 1-2: Wiping Test) As samples for the wiping test, a titanium plate was immersed in a silver particle dispersion, dried, and not heated in the same manner as in the above Examples to prepare test pieces (unbaked, 0°C), as well as test pieces of Comparative Example 1 (heated at 250°C), Example 1 (heated at 350°C), and Example 2 (heated at 500°C). Using these test pieces, the presence or absence of peeling of silver particles due to the wiping test was evaluated. Wiping was performed five times while pressing a surgical latex glove against the surface of the right half of each test piece. Photographs of the surface of each test piece after wiping are shown in Figure 3, and photographs of the surface of the latex glove used for wiping are shown in Figure 4.

[0102] As can be seen from the photographs in Figs. 3 and 4, a large amount of silver particles adhered to the surface of the latex glove in the case of the unbaked or 250°C heated test piece (Comparative Example 1, (L) / (R) = 0.48), whereas in the case of the test piece heated at 350°C or higher (including Examples 1 and 2, (L) / (R) = 0.70 or higher), almost no silver particles adhered to the surface of the latex glove.

[0103] (Reference Test Example 1: Observation of Silver Loading State and Measurement of Silver Loading Amount on Test Piece) A titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. First, as a pretreatment, the titanium plate was subjected to a blast treatment using glass beads ("M-13" manufactured by Potters Ballotini). Next, the blast-treated titanium plate was treated for 1 minute with an acidic chemical solution of "ammonium fluoride + sulfuric acid + hydrogen peroxide." Next, the titanium plate was immersed in a silver particle dispersion in which silver particles with a particle diameter of 30 nm were dispersed at a concentration of 500 mg / L. Thereafter, the titanium plate was dried while being pulled out of the dispersion. Next, the dried titanium plate was heated in an electric furnace ("KM-160" manufactured by Advantec Co., Ltd.) in an air atmosphere at 350°C for 10 minutes to obtain Test Piece A. The obtained test piece A was immersed in a 35% nitric acid solution under pressure to dissolve the silver, and the total amount of silver in the solution was measured by ICP-MS, which was 0.6 μg / cm ２ This was taken as the amount of silver carried on test piece A.

[0104] Furthermore, a silver-loaded amount of 1.5 μg / cm was obtained in the same manner as Test Piece A except for changing the concentration of the silver particle dispersion liquid to be immersed. ２Test piece B (silver particle dispersion concentration 1200 mg / L), silver loading amount 3.0 μg / cm ２ Test piece C (silver particle dispersion concentration 2500 mg / L) and test piece D (silver particle dispersion concentration 2500 mg / L) ２ A test piece D (silver particle dispersion concentration: 5000 mg / L) was prepared.

[0105] - Preparation of silver-unloaded test piece For comparison, a silver-unloaded test piece was prepared as follows. First, a titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. As a pretreatment, the titanium plate was subjected to a blast treatment using glass beads ("M-13" manufactured by Potters Ballotini). Next, the blasted titanium plate was treated for 1 minute with an acidic chemical solution of "ammonium fluoride + sulfuric acid + hydrogen peroxide." Next, the treated titanium plate was heated at 350°C for 10 minutes in an air atmosphere in an electric furnace ("KM-160" manufactured by Advantec Co., Ltd.) to obtain a silver-unloaded test piece.

[0106] Then, backscattered electron images of the surfaces of each of the test pieces A to D and the silver-unloaded test piece were observed at 10,000 magnifications using a scanning electron microscope (SEM) ("S-3400N" manufactured by Hitachi High-Technologies).

[0107] The SEM images and supported silver amounts of the above test pieces are shown in Figure 5. The relationship between the concentration of the silver particle dispersion and the supported silver amount is shown in Figure 6. As shown in Figures 5 and 6, it was confirmed that silver particles were supported on the test piece (titanium plate) in a manner dependent on the concentration of the silver particle dispersion.

[0108] (Reference Test Example 2: Antibacterial Test) A titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. Next, the titanium plate was immersed in a silver particle dispersion in which silver particles with a particle diameter of 30 nm were dispersed at a concentration of 500 mg / L. Thereafter, the titanium plate was dried while being pulled out of the dispersion. Next, the titanium plate carrying the silver particles was heated at 350°C for 10 minutes in an air atmosphere in an electric furnace ("KM-160" manufactured by Advantec Co., Ltd.) to obtain test piece A. The obtained test piece A was immersed in a 35% nitric acid solution under pressure to dissolve the silver, and the total amount of silver in the solution was measured by ICP-MS, which was found to be 0.7 μg / cm ２ This was taken as the amount of silver carried on test piece A.

[0109] Furthermore, a silver-loaded amount of 1.8 μg / cm was obtained in the same manner as Test Piece A except for changing the concentration of the silver particle dispersion liquid to be immersed. ２ Test piece B (silver particle dispersion concentration 1200 mg / L), silver loading amount 3.5 μg / cm ２ Test piece C (silver particle dispersion concentration 2500 mg / L), and test piece D (silver particle dispersion concentration 2500 mg / L), ２ A test piece D (silver particle dispersion concentration: 5000 mg / L) was prepared.

[0110] The antibacterial properties of each test piece were evaluated with reference to JIS Z2801 (2012). Specifically, a bacterial solution of Staphylococcus aureus (culture medium: fetal bovine serum) was applied to each test piece at a bacterial count of 3.2 × 10 ５ A polyethylene film was placed over the test piece, and the bacterial solution was then attached to the test piece. After static culture at 37±1°C for 24±1 hours, the bacterial solution was collected and the number of bacteria was measured using a microbial colorimetric detection kit (Dojindo Laboratories, M439 Microbial Viability Assay Kit-WST) using WST-8 (Patent 2757348) as a colorimetric reagent, and the results were compared with those of an untreated test piece. The results are shown in Figure 7.

[0111] As can be seen from FIG. 7, the silver loading was 1.8 μg / cm ２ The antibacterial properties were confirmed.

[0112] (Reference Test Example 3: Cytotoxicity Test) Furthermore, the silver loading amount was 1.7 to 147.3 μg / cm ２ Using test pieces, a cytotoxicity test was conducted using the ISO 10993-5 (2009) extraction method. Specifically, each test piece was extracted with a solvent (M05 medium) at an extraction rate of 3 cm ２ Extraction was performed at 1 mL / mL for an extraction time of 72 ± 2 hours. The extract was then diluted to a desired concentration (3.1 to 100%) by adding medium, and V79 cells were added to the diluted solution and cultured at 37°C for 6 days. Cytotoxicity was then evaluated by measuring the number of colonies. Evaluation was performed by comparing the colony formation rate with that of a group without extract, and a relative colony formation rate of 70% or higher was evaluated as non-toxic. The results confirmed that the test specimens were non-toxic.

[0113] (Reference Test Example 4: Antibiofilm Test) A titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. First, as a pretreatment, the titanium plate was blasted using glass beads ("M-13" manufactured by Potters Ballotini). Next, the blasted titanium plate was treated with an acidic chemical solution "ammonium fluoride + sulfuric acid + hydrogen peroxide" for 1 minute. Next, the titanium plate was immersed in a silver particle dispersion in which silver particles with a particle diameter of 30 nm were dispersed at a concentration of 1200 mg / L. Thereafter, the titanium plate was dried while being pulled out of the dispersion. Next, the dried titanium plate was heated in an electric furnace ("KM-160" manufactured by Advantec Co., Ltd.) under air atmosphere at 350°C for 10 minutes to obtain test piece A. The obtained test piece A was immersed in a 35% nitric acid solution under pressure to dissolve the silver, and the total silver content in the solution was measured by ICP-MS, which was 1.7 μg / cm ２ This was taken as the amount of silver carried on test piece A.

[0114] Furthermore, a silver-loaded amount of 4.3 μg / cm was obtained in the same manner as Test Piece A except for changing the concentration of the silver particle dispersion liquid to be immersed. ２ Test piece B (silver particle dispersion concentration 2500 mg / L), silver loading amount 8.4 μg / cm ２ A test piece C (silver particle dispersion concentration: 5000 mg / L) was prepared.

[0115] The antibiofilm properties of each test piece were evaluated with reference to ISO 4768 (2023). Specifically, each test piece attached to a glass plate was measured using a 5.7 × 10 ３The specimens were placed in a solution of Staphylococcus epidermidis CFU / mL and cultured at 35±1°C for 48±1°C. After culture, the specimens were stained with crystal violet, wiped with a water-soluble nonwoven fabric, and then recovered. The nonwoven fabric was dissolved, and the absorbance of the resulting solution was measured at a wavelength of 590 nm using a UV mini-1240 (Shimadzu Corporation, optical path length: 1 cm). The anti-biofilm activity value was then calculated using the following formula. The results are shown in Table 2 and Figure 8. Anti-biofilm activity value (R) (%) = (1 - W treated / W untreated) × 100 W untreated: average value of absorbance in non-silver-supported test pieces W treated: average value of absorbance in silver-supported test pieces As shown in Table 2 and Figure 8, anti-biofilm activity of 70% or more was confirmed in each test piece.

[0116]

[0117] <Test Example 2> [Preparation of Test Piece] (Example 3) A titanium plate measuring 25 mm wide x 25 mm deep x 1 mm thick was prepared. Next, the titanium plate was immersed in a silver particle dispersion in which silver particles with a particle diameter of 30 nm were dispersed at a concentration of 5000 mg / L. Thereafter, the titanium plate was dried while being pulled out of the dispersion. Next, the titanium plate carrying the silver particles was heated at 600°C for 60 minutes in a hydrogen gas atmosphere in an electric furnace ("VHLgr20 / 20 / 20" manufactured by Shimadzu Mectem Corporation), to obtain a test piece of Example 3.

[0118] [Cross-sectional observation of test specimens] The test specimens obtained above were cut in the vertical direction using an ion beam (JEOL Ltd., "JEM-ARM200F") to prepare three samples for cross-sectional observation ((A) to (C)). The samples were observed at 1,000,000 magnification using a transmission electron microscope (TEM). Cross-sectional photographs of each test specimen are shown in Figures 9(A) to 9(C). The height (H) of the silver particles and the thickness (T) of the oxide film in each sample were measured from the cross-sectional TEM images, and the embedding ratio (%) was calculated. Furthermore, the particle diameter (R: maximum diameter) of the silver particles was determined using the same method as in Test Example 1, and the aspect ratio of the silver particles was also calculated. The results are summarized in Table 3.

[0119]

[0120] [Evaluation Test] (Test Example 2-1: Wiping Test) A wiping test was conducted on the test piece of Example 3 in the same manner as in Test Example 1-2 above. The results are shown in Figure 10(A). For comparison, Figure 10(B) is a photograph of the results of a test piece that was dried and not heated in Test Example 2-1 (unheated). In both figures, the left side is the surface of the test piece after wiping, and the right side is the surface of the latex glove used for wiping. Comparing Figures 10(A) and (B) reveals that with the test piece of Example 3 (silver particle embedding rate of 30% or more), almost no silver particles adhered to the surface of the latex glove.

Claims

1. A biological implant comprising a substrate and silver particles supported on the substrate and having a particle diameter of 1 μm or less, wherein, upon observation of a cross section including the substrate and the silver particles, the contact length between the silver particles and the substrate is 70% or more of the particle diameter of the silver particles.

2. The amount of silver particles supported on the substrate per unit area is 1 μg / cm ２ or more and 150 μg / cm ２ The biological implant according to claim 1, wherein:

3. A biological implant according to claim 1 or 2, wherein, of all the silver particles supported on the substrate, the proportion of silver particles whose contact length between the silver particle and the substrate is 70% or more of the particle diameter of the silver particle is 50% or more.

4. The biological implant according to any one of claims 1 to 3, wherein the aspect ratio of the silver particles is 1.1 or more.

5. The biological implant according to any one of claims 1 to 4, wherein the substrate is made of at least one selected from titanium, titanium alloy, stainless steel, cobalt-chromium alloy, alumina, calcium phosphate, and zirconia.

6. The biological implant according to any one of claims 1 to 5, wherein the particle diameter of the silver particles carried on the substrate is 750 nm or less.

7. The biological implant according to any one of claims 1 to 6, wherein the substrate has an oxide coating on the surface.

8. A method for producing a biological implant according to any one of claims 1 to 7, comprising applying a dispersion containing silver particles to a substrate, and then heating the substrate in an air atmosphere at a temperature of 300°C or higher.

9. The method for producing a biological implant according to claim 8, wherein the average particle size of the silver particles contained in the dispersion is 100 nm or less.

10. A biological implant comprising a substrate, silver particles having a particle diameter of 1 μm or less supported on the substrate, and an oxide coating, wherein, upon observation of a cross section including the substrate, the silver particles, and the oxide coating, 30% or more of the surface of the silver particles is embedded in the oxide coating, and at least a portion of the surface of the silver particles is exposed from the oxide coating.

11. The amount of silver particles supported on the substrate per unit area is 1 μg / cm ２ or more and 150 μg / cm ２ The biological implant according to claim 10, wherein:

12. A biological implant according to claim 10 or 11, wherein, of all the silver particles supported on the substrate, 30% or more of the surface thereof is embedded in an oxide film, and the proportion of silver particles having at least a portion of the surface exposed from the oxide film is 50% or more.

13. The biological implant according to any one of claims 10 to 12, wherein the silver particles have an aspect ratio of 1.1 or more.

14. The biological implant according to any one of claims 10 to 13, wherein the substrate is made of at least one selected from titanium, titanium alloy, stainless steel, cobalt-chromium alloy, alumina, calcium phosphate, and zirconia.

15. The biological implant according to any one of claims 10 to 14, wherein the thickness of the oxide film is smaller than the particle diameter of the silver particles.

16. A biological implant according to any one of claims 10 to 15, wherein the substrate is made of at least one selected from titanium, a titanium alloy, stainless steel, and a cobalt-chromium alloy, and the oxide coating contains an oxide of a component constituting the substrate.

17. A method for producing a biological implant according to any one of claims 10 to 16, comprising applying a dispersion containing silver particles to a substrate, and then heating the substrate in an atmosphere containing oxygen or water.

18. The method for producing a biological implant according to claim 17, wherein the heating temperature is 600°C or higher.

19. A method for producing a biological implant according to any one of claims 10 to 16, comprising applying a dispersion containing silver particles to a substrate, then applying a dispersion containing oxide particles, and then heating the substrate in an air atmosphere at a temperature of 300°C or higher.

20. The method for producing a biological implant according to claim 19, wherein the oxide particles are at least one selected from niobium oxide, titanium oxide, tantalum oxide, and zirconia oxide.

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