Collagen yarn, method for producing collagen yarn, and biomaterial

Abstract

The collagen yarn includes collagen nanofibrils, the diameter of the collagen yarn is 10 [mu] m or more and 50 [mu] m or less, the total length of the collagen yarn has a length of 2 * 105 times or more of the diameter, the collagen nanofibrils exhibit high directionality along the longitudinal direction of the collagen yarn, and the diameter of the collagen yarn is 10 [mu] m or more and 50 [mu] m or less. The high directionality is represented by a refractive index difference of 4.3 * 10 <-4 > or more as determined by birefringence measurement for a hydrated collagen yarn obtained by immersing the collagen yarn in a neutral phosphate buffer.

Description

Technical Field

[0001] This invention relates to collagen yarn, a method for manufacturing collagen yarn, and biomaterials. Background Technology

[0002] As disclosed in Japanese Patent Application Publication No. 2019-085373 (Patent Document 1), artificial collagen yarn made by mimicking collagen fibers in living organisms has been developed. Artificial tendons obtained by bundling the aforementioned artificial collagen yarn, and membrane materials woven from the aforementioned artificial collagen yarn, may be useful as cell scaffold materials, and the application of the aforementioned artificial tendons and membrane materials as medical materials is anticipated.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2019-085373 Non-patent literature Non-patent literature 1: Haynl C et al. NANO LETTERS 2016:16:5917-5922 Non-patent literature 2: Paten JA et al. ACS Nano 2016:10:5027-5040 Summary of the Invention

[0004] The problem that the invention aims to solve By using artificial collagen yarn with at least the following four characteristics, it may be possible to artificially reproduce collagen fibers in living organisms.

[0005] 1) It is safe for living organisms.

[0006] 2) It has a fineness similar to that of collagen fibers (approximately 20 μm in diameter) in living organisms.

[0007] 3) The collagen nanofibers constituting the artificial collagen yarn are oriented into the interior of the artificial collagen yarn, preferably into the core.

[0008] 4) It has sufficient length to manufacture artificial tendons and membrane materials.

[0009] While the highly oriented collagen fiber bundles disclosed in Patent Document 1 are oriented towards the interior of the artificial collagen yarn, even in the case of the finest diameter, they are only about 100 μm in diameter, requiring further improvement to reproduce collagen fibers in living organisms. The method disclosed in Haynl C et al. NANO LETTERS 2016:16:5917-5922 (Non-Patent Document 1) combines conventional wet spinning with microflow technology, enabling the continuous production of artificial collagen yarns with a diameter of approximately 4 μm. However, it is known that while collagen fibers on the yarn surface are oriented in wet spinning, the internal collagen fibers are not. The flow-induced crystallization collagen method disclosed in Paten JA et al. ACS Nano 2016:10:5027-5040 (Non-Patent Document 2), while enabling the orientation of collagen nanofibers towards the interior and core of the artificial collagen yarn, struggles to achieve the sufficient length required for manufacturing artificial tendons and membrane materials. Therefore, there is an urgent need to develop artificial collagen yarn that can artificially reproduce the collagen fibers in living organisms.

[0010] In view of the above, the object of the present invention is to provide collagen yarn that can artificially reproduce collagen fibers in living organisms, a method for manufacturing collagen yarn, and biomaterials.

[0011] Solution for solving the problem The inventors conducted in-depth research to solve the aforementioned technical problems, and thus completed this invention. The inventors conceived of a method for producing collagen yarn by: passing a raw material containing a neutral collagen solution of a high concentration (e.g., 3.0% by mass or more and 5.0% by mass or less) through a flow path with a narrow diameter (e.g., an inner diameter of 100 μm or more and 300 μm or less), at a high shear rate (e.g., 100 s). －1 The above) is discharged into a coagulation bath filled with a high-concentration (70% by volume or more and 95% by volume or less) ethanol solution. The following facts were discovered, thus enabling the present invention: the collagen yarn obtained by the above manufacturing method has a diameter of 50 μm or less, the collagen nanofibers constituting the collagen yarn are oriented into the interior of the collagen yarn, preferably into the core, and have a diameter of 2 × 10⁻⁶. 5 More than twice the length.

[0012] The present invention has the following features.

[0013] [1] The collagen yarn of the present invention is a collagen yarn containing collagen nanofibers, wherein the diameter of the collagen yarn is 10 μm or more and 50 μm or less, and the total length of the collagen yarn has 2 × 10 of the diameter. 5The collagen nanofibers, with a length exceeding twice that of the collagen yarn, exhibit high orientation along the length direction. This high orientation is demonstrated by a refractive index difference of 4.3 × 10⁻⁶, obtained through birefringence measurement using hydrated collagen yarn as an example. －4 As described above, the hydrated collagen yarn is obtained by immersing the collagen yarn in a neutral phosphate buffer solution.

[0014] [2] Preferably, the collagen nanofibers are composed of determinate collagen.

[0015] [3] Preferably, the total length has 1×10 of the diameter. 6 More than twice the length.

[0016] [4] The method for manufacturing collagen yarn of the present invention includes: a step of preparing a neutral collagen solution containing collagen at a concentration of 3.0% by mass or more and 5.0% by mass or less; and a step of obtaining collagen yarn by discharging the neutral collagen solution into an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less, wherein the collagen is determinated collagen, and in the step of obtaining the collagen yarn, the neutral collagen solution is passed through a flow path with an inner diameter of 100 μm or more and 300 μm or less, and the flow is carried out in 100 s. －1 Above and 1500s －1 The following shear rates are discharged into the above ethanol solution.

[0017] [5] Preferably, the above-mentioned method for manufacturing collagen yarn further includes a step of stretching the collagen yarn by winding it at a winding speed of 1.5 times or more and 4.0 times or less than the discharge line speed.

[0018] [6] Preferably, the above-mentioned neutral collagen solution contains the above-mentioned collagen at a concentration of 4.5% by mass or more and 5.0% by mass or less.

[0019] [7] Preferably, the shearing rate is 300 s. －1 Above and 1000s －1 the following.

[0020] [8] The biomaterial of the present invention comprises the above-mentioned collagen yarn.

[0021] [9] Preferably, the above-mentioned biomaterial is an artificial tendon or membrane material.

[0022] Invention Effects According to the present invention, a collagen yarn capable of artificially reproducing collagen fibers in a living organism, a method for manufacturing the collagen yarn, and a biomaterial can be provided. Attached Figure Description

[0023] Figure 1 The image is a scanning electron microscope image obtained by taking a cross section along the axial direction of the collagen yarn of this embodiment.

[0024] Figure 2 This is an explanatory diagram used to evaluate the high orientation of the collagen nanofibers constituting the collagen yarn of this embodiment, illustrating the case of performing birefringence measurement on hydrated collagen yarn by line analysis.

[0025] Figure 3 The image is obtained by taking a picture of the appearance of the biomaterial (artificial tendon) obtained from the collagen yarn of this embodiment using a digital camera.

[0026] Figure 4 This is a flowchart illustrating an example of a method for manufacturing collagen yarn according to this embodiment.

[0027] Figure 5 This is a schematic diagram of a manufacturing apparatus for producing the collagen yarn of this embodiment.

[0028] Figure 6 This is another schematic diagram of a manufacturing apparatus for producing the collagen yarn of this embodiment. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention (hereinafter also referred to as "this embodiment") will be described in further detail. In this specification, the expression "A to B" refers to the upper and lower limits of a range (i.e., above A and below B). When A has no unit but B has a unit, the unit of A is the same as the unit of B. The term "alignment" refers to the uniform alignment of the axes of collagen nanofibrils formed by the regular arrangement of multiple collagen molecules. In some prior art documents, the term "orientation," which refers not only to the alignment of the axes of the collagen nanofibrils but also to their direction, is used synonymously with "alignment," but in this specification, the two are used separately.

[0030] In this specification, the “interior” of collagen yarn refers to the entire portion excluding the surface of the collagen yarn. The “core” of collagen yarn refers to the central portion appearing on the cut surface obtained by cutting the collagen yarn in a plane perpendicular to the axis of the collagen yarn, and in particular, refers to the portion of the aforementioned central portion that is continuous along the axial direction.

[0031] [Collagen yarn] The collagen yarn of this embodiment is a collagen yarn containing collagen nanofibers. The diameter of the collagen yarn is 10 μm or more and 50 μm or less. The total length of the collagen yarn has 2 × 10⁻⁶ times the diameter mentioned above. 5 The length is more than twice that of the collagen nanofibers. The aforementioned collagen nanofibers exhibit high orientation along the length of the aforementioned collagen yarn. This high orientation, determined by birefringence measurement using hydrated collagen yarn, shows a refractive index difference of 4.3 × 10⁻⁶. －4 The above description is provided. The hydrated collagen yarn described above is obtained by impregnating the collagen yarn in a neutral phosphate buffer solution. Collagen yarn with these characteristics can artificially reproduce collagen fibers found in living organisms. Therefore, the collagen yarn described above may be used as a biomaterial such as artificial tendons or membrane materials.

[0032] <Collagen Nanofibers> Figure 1 These are scanning electron microscope images obtained by photographing a cross-section along the axial direction of the collagen yarn in this embodiment. For example... Figure 1 As shown, the collagen yarn 1 comprises collagen nanofibers 11. Collagen nanofibers 11 refer to collagen fibers that spontaneously aggregate and arrange themselves by humidifying numerous collagen molecules in a neutral environment, exhibiting an overall yarn-like appearance with a thickness of approximately 100 nm. Collagen nanofibers 11 can be obtained from collagen with fiber-forming ability (fiber-forming collagen). Preferably, the following types of fiber-forming collagen are used: type I collagen, which constitutes bone, skin, tendons, and ligaments; type II collagen, which constitutes cartilage; and type III collagen contained in biological tissues composed of type I collagen. These fiber-forming collagens can be obtained by extraction and purification from biological tissues using conventional methods, or by obtaining commercially available products (e.g., trade name: "Collagen BM", manufactured by Nitta Gelatin Co., Ltd.). The aforementioned fibroblast-forming collagen can be formed by individual types of collagen or by a mixture of multiple types of collagen. There are no particular restrictions on the animal species from which this fibroblast-forming collagen originates. However, from the viewpoint of use as a biological material, collagen derived from mammals such as pigs and cattle is preferred.

[0033] Collagen nanofibers 11 are preferably composed of atelocollagen. This provides collagen yarn with low antigenicity and high biocompatibility. "Atelocollagen" refers to atelocollagen prepared by enzymatically removing the telopeptides at the N- and C-termini of collagen molecules using proteolytic enzymes such as pepsin, rennet, cathepsin D, and renin. In particular, among the atelocollagen constituting the aforementioned collagen nanofibers, mammalian atelocollagen, which is recognized as a raw material for medical devices, is preferred; more preferably, it is derived from pig skin.

[0034] <Diameter> The diameter of the collagen yarn 1 is 10 μm or more and 50 μm or less. From the viewpoint of application in biomaterials such as artificial tendons or membrane materials, the diameter of the collagen yarn 1 is preferably 10 μm or more and 40 μm or less, more preferably 20 μm or more and 30 μm or less. When the diameter of the collagen yarn 1 is less than 10 μm, it may be too thin and lack sufficient strength, resulting in poor winding properties, such as the possibility of cutting during winding. When the diameter of the collagen yarn 1 exceeds 50 μm, it may be too thick to reproduce the function of collagen fibers in living organisms (e.g., cell scaffold function). The diameter of the collagen yarn 1 can be determined by image analysis of an image of the cross-section of the collagen yarn 1 obtained by scanning electron microscopy, and the diameter of a circle with the same area as that cross-section (equivalent circle diameter) can be regarded as the diameter of the collagen yarn 1.

[0035] <Full Length> The total length of collagen yarn 1 has 2 × 10 of the aforementioned diameter. 5 The length is more than 10 times that of the diameter. Therefore, a single collagen yarn 1 can have a length sufficient to fabricate artificial tendons and membrane materials as biomaterials. From the viewpoint of fabricating the aforementioned artificial tendons and membrane materials using a single collagen yarn 1, the total length is preferably 1 × 10⁻⁶ times the diameter. 6 The length is more than twice that of the collagen yarn 1. Specifically, the total length of the collagen yarn 1 is preferably 10m or more, more preferably 100m or more, and most preferably 200m or more. There is no particular upper limit to the total length of the collagen yarn 1. For example, from the viewpoint of manufacturing the aforementioned artificial tendon and membrane materials, a total length of 1000m for the collagen yarn 1 is ideal. The total length of the collagen yarn 1 can be determined by measuring the length that can be wound without being cut when wound through the collagen yarn obtained by the collagen yarn manufacturing method described later.

[0036] High Orientation Collagen nanofibers 11 exhibit high orientation along the length of collagen yarn 1. This high orientation is demonstrated by a refractive index difference of 4.3 × 10⁻⁶ determined through birefringence measurements using hydrated collagen yarn. －4 The above description refers to the process of hydrating collagen yarn. The hydrated collagen yarn described above is obtained by impregnating collagen yarn 1 in a neutral phosphate buffer. In this specification, "high orientation" means that the collagen nanofibers 11 constituting the collagen yarn 1 are oriented at least internally, preferably towards the core, of the collagen yarn 1. The neutral phosphate buffer is not particularly limited in terms of pH, ion concentration, or the amount of sodium chloride added, as long as it provides conditions that allow the collagen fibers to exist stably. However, from the viewpoint of minimizing salt precipitation, reducing stiffness of the hydrated collagen yarn, and facilitating handling, a low-concentration (e.g., 10 mM) sodium hydrogen phosphate solution adjusted to pH 7 and free of sodium chloride is preferably used as the neutral phosphate buffer.

[0037] The aforementioned high orientation is achieved through a refractive index difference of 4.3 × 10⁻⁶. －4 The reasons for this are as follows. Specifically, as described below, the refractive index difference is the optical path difference generated when intrinsically polarized light passes through the interior of the hydrated collagen yarn, divided by the thickness of the hydrated collagen yarn. A larger refractive index difference means that the axes of the numerous collagen nanofibers 11 within the hydrated collagen yarn are more uniformly aligned. Furthermore, the refractive index difference is 4.3 × 10⁻⁶. －4 The above value is as follows: compared with the cross-sectional image of the hydrated collagen yarn mentioned above, the result is a value that can only be obtained when the collagen nanofibers 11 are oriented to at least the interior of the collagen yarn 1, preferably to the core.

[0038] Therefore, even when the collagen yarn 1 is digested or decomposed by enzymes in the body and its interior is exposed, it can still recognize cells due to its high orientation, thus functioning as a cell scaffold material. The following describes a birefringence measurement using hydrated collagen yarn, which is used to evaluate the high orientation of collagen nanofibers 11.

[0039] (Birefringence measurement) In this embodiment, the high orientation of the collagen nanofibers 11, as described above, is determined by birefringence measurement using hydrated collagen yarn, resulting in a refractive index difference of 4.3 × 10⁻⁶. －4The above is an explanation. Birefringence measurement refers to using a known two-dimensional birefringence measuring device (e.g., trade name: "WPA-200", manufactured by Photonic Lattice) to determine the phase difference (retardation, in nm) of light produced when circularly polarized light is incident on the aforementioned hydrated collagen yarn. This refractive index difference can be obtained by dividing the phase difference by the thickness of the hydrated collagen yarn (i.e., the distance the light travels).

[0040] Since the cross-section of the hydrated collagen yarn is approximately circular, line analysis of a two-dimensional phase difference image can be used to calculate the refractive index difference. The phase difference obtained from the line analysis is plotted in a mountain-shaped curve with the position perpendicular to the axial direction of the hydrated collagen yarn (hereinafter also referred to as the "width direction") as the horizontal axis and the phase difference as the vertical axis. The phase difference data used in the calculation of the refractive index difference is obtained from the central 50% of the mountain-shaped curve. For convenience, the thickness used in the calculation can be 0.95 times the width of the hydrated collagen yarn, which is measured separately using a known digital microscope. This is because the thickness of the hydrated collagen yarn decreases sharply at the edges of the mountain-shaped curve, but the thickness at the central 50% is approximately equal to the diameter × 0.95. Furthermore, the refractive index difference can be calculated by performing the line analysis at any five points on the hydrated collagen yarn and averaging the five values ​​obtained therefrom. For example, when the shape of a mountain is shown in the scale of pixels 0 to 8 on the horizontal axis, "50% of the central part of the mountain shape" refers to the central 4 ± 2 pixels (width) of the shape portion (see reference). Figure 2 ).

[0041] Figure 2 This is an explanatory diagram used to evaluate the high orientation of the collagen nanofibers constituting the collagen yarn of this embodiment, illustrating the case of birefringence measurement performed on hydrated collagen yarn by line analysis. Figure 2 The image shown is a diagram (left) depicting a birefringence measurement performed on the hydrated collagen yarn 10 using line analysis; and a graph (right) showing the position of the hydrated collagen yarn 10 in the width direction obtained by the birefringence measurement as the horizontal axis and the phase difference of the position as the vertical axis. Figure 2 The refractive index difference of the hydrated collagen yarn 10 shown can be calculated as 5.88 × 10⁻⁶ based on the curve and the thickness of the hydrated collagen yarn 10. －4 .

[0042] Here, the hydrated collagen yarn 10 is obtained by hydrating collagen yarn 1 in a neutral phosphate buffer and then introducing chemical cross-linking. Specifically, the hydrated collagen yarn 10 is prepared by immersing the collagen yarn in an excess of neutral (pH 6.5–7.5) phosphate buffer until the collagen yarn 1 or the pre-dried collagen yarn in an ethanol solution reaches saturation with swelling, and then adding 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) to introduce chemical cross-linking into the collagen. The concentration of EDC in the phosphate buffer does not affect the birefringence measurement, but from the viewpoint of imparting softness that stabilizes the collagen yarn and prevents it from becoming brittle during handling, a concentration in the range of 10 mM to 200 mM is preferred. Preferably, before the birefringence measurement, the hydrated collagen yarn 10 is transferred again to an excess of phosphate buffer to remove residual cross-linking agent and byproducts from the yarn. EDC does not stain collagen or intercalate between collagen molecules, making it suitable as a collagen cross-linking agent for optical analysis.

[0043] The preferred refractive index difference is 5.0 × 10⁻⁶. －4 The above, more preferably 7.0×10 －4 The above explains why collagen yarn 1 possesses superior orientation, particularly towards the core, with the collagen nanofibers 11 constituting it oriented towards the interior of the collagen yarn 1, thus making it more effective as a cell scaffold material. This is especially true when the refractive index difference is less than 4.3 × 10⁻⁶. －4 In this case, there is a concern that the collagen nanofibers 11 may not be oriented into the interior of the collagen yarn 1. There is no particular upper limit to the aforementioned refractive index difference; for example, it can be 12 × 10⁻⁶. －4 If the collagen yarn is obtained through the manufacturing method described later, then the aforementioned refractive index difference is 12 × 10⁻⁶. －4 The following is the reality.

[0044] <Effects> Based on the above, the collagen yarn of this embodiment can achieve the characteristics described in 1) to 4), and therefore may be able to artificially reproduce collagen fibers in living organisms. That is, by using determinate collagen as a raw material, the collagen yarn is safe for living organisms. The collagen yarn can have a diameter approximately 20 μm, similar to the diameter of collagen fibers in living organisms. Based on the aforementioned high orientation, the collagen yarn allows collagen nanofibers to be oriented into the interior of the collagen yarn, preferably into the core. Furthermore, the total length of the collagen yarn is sufficient for manufacturing artificial tendons and membrane materials.

[0045] [Biomaterials] The biomaterial of this embodiment comprises the aforementioned collagen yarn. In this biomaterial, the collagen yarn is obtained by artificially reproducing collagen fibers found in living organisms, and therefore can function as a cell scaffold material within a living organism. In particular, since the aforementioned biomaterial can function as a cell scaffold material, it is preferably an artificial tendon or membrane material. Therefore, the application of the aforementioned biomaterial as an artificial tendon or membrane material in the medical field and elsewhere is anticipated.

[0046] Figure 3 The image is obtained by photographing the appearance of the biomaterial (artificial tendon) obtained from the collagen yarn of this embodiment using a digital camera. For example... Figure 3 As shown, the biomaterial obtained from the above-mentioned collagen yarn can be used to construct an artificial tendon 200 based on the characteristics of 1) to 4) above. Figure 3 The artificial tendon 200 shown is an example of a bundle of 2000 collagen yarns (specifically, the collagen yarn of sample 6 in the examples described later) with a diameter of 26.8 ± 1.5 μm and a total length of 110 m, with a length of 55 mm and a cross-sectional diameter of 1.7 mm. The length and cross-sectional diameter of the artificial tendon can be adjusted to specified values ​​by the diameter of the collagen yarn and the number of bundles. Moreover, although the illustration is omitted, when the biomaterial obtained from the above-mentioned collagen yarn is a membrane material, the membrane material can be formed, for example, by weaving the collagen yarn.

[0047] [Manufacturing method of collagen yarn] There are no particular limitations on the method for manufacturing the above-mentioned collagen yarn, as long as it can produce yarn with the above-mentioned characteristics. However, the above-mentioned collagen yarn can be obtained with good yield by using the following manufacturing method. That is, the method for manufacturing collagen yarn in this embodiment includes: a step of preparing a neutral collagen solution containing collagen at a concentration of 3.0% by mass or more and 5.0% by mass or less; and a step of obtaining collagen yarn by discharging the above-mentioned neutral collagen solution into an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less. The above-mentioned collagen is determinated collagen. In the step of obtaining the above-mentioned collagen yarn, the above-mentioned neutral collagen solution is passed through a flow path with an inner diameter of 100 μm or more and 300 μm or less, and the flow rate is 100 s. －1 Above and 1500s －1The following shear rate is applied to the ethanol solution. Furthermore, the method for manufacturing the collagen yarn preferably includes a step of stretching the collagen yarn by winding it at a winding speed of 1.5 to 4.0 times the discharge line speed. This is because, by winding the collagen yarn at a speed greater than the discharge line speed, the collagen solution immediately discharged into the ethanol solution is stretched and fiberized (coagulated), and the yarn diameter becomes thinner and the orientation of the fibrils becomes higher. By using a method for manufacturing collagen yarn with these characteristics, collagen yarn that can artificially reproduce collagen fibers found in living organisms can be obtained.

[0048] Specifically, the above manufacturing method preferably has, for example, Figure 4 The process is shown in the flowchart. Figure 4 This is a flowchart illustrating an example of a method for manufacturing collagen yarn according to this embodiment. Figure 4 The method for manufacturing the aforementioned collagen yarn includes: a step S10 (first step: preparation step) of preparing a neutral collagen solution containing collagen at a concentration of 3.0% by mass or more and 5.0% by mass or less; and a step S20 (second step: obtaining collagen yarn) of obtaining collagen yarn by discharging the aforementioned neutral collagen solution into an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less. Figure 4 The method for manufacturing the collagen yarn preferably further includes a step S30 (third step: stretching the collagen yarn) in which the collagen yarn is stretched by winding it at a winding speed of 1.5 times or more and 4.0 times or less than the discharge line speed.

[0049] In this specification, "neutral collagen solution" refers to a liquid containing collagen molecules dissolved in a neutral solvent (such as phosphate-buffered saline or other salt-containing solvents) in a state where the collagen molecules are not fibrotic. Therefore, a neutral collagen solution is distinguished from a cloudy dispersion in which collagen molecules are fibrotic and dispersed in the solvent, even if the solvent is neutral. During the preparation of a neutral collagen solution, sometimes some collagen may irreversibly fibrose, causing the solution to appear slightly cloudy; however, this does not affect the present invention as long as the optical density at a wavelength of 600 nm and a path length of 10 mm does not exceed 0.5. Furthermore, a neutral collagen solution is also distinguished from a liquid containing collagen molecules dissolved in an acidic solvent. For example, the pH of the aforementioned neutral collagen solution is preferably 6.0 or higher and 9.0 or lower.

[0050] The inventors presume the following reasons for obtaining collagen yarn capable of artificially reproducing collagen fibers in a living organism through the above-described manufacturing method. First, the neutral collagen solution contains collagen at a high concentration of 3.0% by mass or more and 5.0% by mass or less (preferably 4.5% by mass or more and 5.0% by mass or less). This "high concentration" refers to a concentration close to the limit where, even with a large amount of collagen in the neutral solvent, the collagen will not fibrose and precipitate as long as the liquid temperature is maintained below 10°C. It should be noted that the inventors have found that the concentration at which collagen in the neutral solvent can maintain a molecularly dispersed state is approximately 5.0% by mass. It can be said that the above-described neutral collagen solution is a solution close to saturation for collagen molecules. Therefore, when the collagen molecules in the above-described neutral collagen solution are discharged into a coagulation bath filled with an ethanol solution in step S20 of obtaining the collagen yarn, the neutral solvent (especially water) is dehydrated by the ethanol, thereby instantly fibrousizing. Therefore, collagen molecules in the aforementioned neutral collagen solution can be precipitated in the form of collagen yarn composed of collagen nanofibrils bundled with fibrous collagen molecules. Furthermore, the aforementioned neutral collagen solution is discharged at a high shear rate through a flow path with an inner diameter of 100 μm or more and 300 μm or less. In this case, the collagen molecules in the aforementioned neutral collagen solution are oriented along the flow direction and discharged from the aforementioned flow path.

[0051] In other words, through the above-described manufacturing method, collagen molecules in the neutral collagen solution are first discharged into the coagulation bath in a unidirectional state through the narrow flow path described above. Furthermore, in the coagulation bath, the collagen molecules, previously fibrous, gradually soften their unidirectional state along the flow direction, forming bundles of collagen nanofibers. These bundles are then spun into collagen yarn composed of the collagen nanofibers. In this case, the collagen nanofibers can exhibit high orientation within the collagen yarn, preferably even up to the core. By appropriately adjusting the inner diameter and shear rate of the flow path, the collagen yarn can achieve a desired diameter. The above manufacturing method does not, in principle, limit the length of the desired collagen yarn. Furthermore, by using, for example, determinate collagen as the collagen molecules, a collagen yarn safe for living organisms can be obtained. Based on the above, it can be concluded that the above-described manufacturing method can produce collagen yarn that artificially reproduces collagen fibers found in living organisms.

[0052] The following is based on reference Figure 4 , Figure 5 as well as Figure 6 The following sections will describe the steps involved in the above-described method for manufacturing collagen yarn and the general outline of the apparatus used to manufacture the collagen yarn in the above-described method. Figure 5This is a schematic diagram of a manufacturing apparatus for producing the collagen yarn of this embodiment. Figure 6 This is another schematic diagram of a manufacturing apparatus for producing the collagen yarn of this embodiment. The above-described method for manufacturing collagen yarn is performed, for example, using... Figure 5 The manufacturing apparatus shown in step S20 produces collagen yarn. Alternatively, it can be used... Figure 6 The manufacturing apparatus shown performs step S20 of obtaining collagen yarn and step S30 of stretching collagen yarn. Hereinafter, after providing an overview of the manufacturing apparatus, each step in the method for manufacturing collagen yarn will be described in detail.

[0053] <Manufacturing apparatus for producing collagen yarn> like Figure 5 As shown, a manufacturing apparatus 100 for producing collagen yarn 1 includes: a container 101 containing a neutral collagen solution; a needle 102 serving as a flow path for discharging the neutral collagen solution from the container 101 to the outside; and a drive device 103 (e.g., an injection pump) generating a shear rate for discharging the neutral collagen solution to the outside through the needle 102. The manufacturing apparatus 100 also includes a coagulation bath 104 containing the neutral collagen solution being discharged to the outside. This coagulation bath 104 is filled with an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less. As described above, collagen in the neutral collagen solution is discharged through the needle 102 into the coagulation bath 104, thereby precipitating as collagen yarn 1 in the aforementioned ethanol solution.

[0054] The container 101 is not particularly limited in shape or other aspects as long as it has the function of holding a neutral collagen solution and discharging the solution to the outside through the needle 102. The container 101 preferably includes, for example, a syringe for holding the neutral collagen solution and a plunger that discharges the solution from the syringe through the needle 102 by being driven by a drive device 103. Thus, the needle 102 can be easily installed into the syringe using the so-called syringe technique. The syringe and plunger can be appropriately sized depending on the amount of neutral collagen solution contained. The syringe and plunger can be made of resin, glass, or metal. As the drive device 103, various pumps or the like that can perform the above function by using pressure to draw up or transport liquids, gases, etc. can be used. For example, when industrializing this manufacturing method, an air-pressure drive device or the like can be used.

[0055] The inner diameter of needle 102 is 100 μm or more and 300 μm or less. Preferably, the inner diameter of needle 102 is 125 μm or more and 250 μm or less. Therefore, in step S20 of obtaining collagen yarn, the shear rate of the neutral collagen solution discharged from needle 102 can be appropriately adjusted using drive device 103, thus obtaining collagen yarn 1 with a desired diameter. The shear rate of the neutral collagen solution discharged from needle 102 is 100 s. －1 Above and 1500s －1 From the viewpoint of easily adjusting the diameter of the collagen yarn, the above-mentioned shearing speed is preferably 300s. －1 Above and 1000s －1 The following is an example. The shearing rate is defined as follows: the radius of needle 102 is set as r (mm), and the flow rate of the discharged neutral collagen solution is set as Q (mm). 3 ·s －1 When ), it is 4Q / πr 3 (Unit: s) －1 (π is the mathematical constant pi). However, when the collagen concentration in the neutral collagen solution is high and the needle diameter is small, the actual Q may be lower than the input value, depending on the performance of the drive device. In such cases, it is necessary to find the condition under which the winding speed of the winding roller 105 is balanced with the discharge speed of the collagen yarn 1, and then calculate the actual Q.

[0056] like Figure 6 As shown, the manufacturing apparatus 100 preferably includes, in order to perform the stretching collagen yarn step S30, a winding roller 105 for winding the collagen yarn 1 precipitated in the ethanol solution of the coagulation bath 104; and a motor 106 for driving the winding roller 105. The manufacturing apparatus 100 further preferably includes a relay roller 107 disposed between the coagulation bath 104 and the winding roller 105 to relay the collagen yarn 1 from the ethanol solution to the winding roller 105. By including the relay roller 107, the manufacturing apparatus 100 can wind the collagen yarn 1 onto the winding roller 105 without knotting during winding. Conventionally known rollers and motors can be used as the winding roller 105, motor 106, and relay roller 107, as long as each has the required function.

[0057] <The various steps involved in the manufacturing process of collagen yarn> (First step: Preparation) The method for manufacturing collagen yarn according to this embodiment includes a step S10 of preparing a neutral collagen solution containing collagen at a concentration of 3.0% by mass or more and 5.0% by mass or less. The collagen is determinated collagen. The purpose of the preparation step S10 is to prepare a neutral collagen solution as a raw material for obtaining collagen yarn 1.

[0058] A neutral collagen solution can be prepared by mixing an acidic determinate collagen solution with a concentration greater than the target concentration and a neutral solvent (e.g., a salt-containing solvent such as phosphate buffer or physiological saline) using conventionally known methods, so that the determinate collagen concentration is 3.0% by mass or more and 5.0% by mass or less. Thus, in step S20 of obtaining collagen yarn described later, when the above-mentioned neutral collagen solution is discharged into a coagulation bath filled with an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less, the collagen molecules instantly fibrose in the coagulation bath, thereby obtaining collagen yarn 1. As described above, the pH of the neutral collagen solution is preferably 6.0 or more and 9.0 or less. The neutral collagen solution prepared in this step is contained in a container 101 (especially a syringe) of the manufacturing apparatus 100. Air bubbles contained in the neutral collagen solution are preferably removed by conventionally known methods such as centrifuges. If air bubbles are present, the collagen yarn may break during manufacturing, thus deteriorating the yield.

[0059] When the collagen concentration in the aforementioned neutral collagen solution is less than 3.0% by mass, in step S20 of obtaining collagen yarn, the collagen molecules are difficult to instantly fibrillate in the coagulation bath, raising concerns that the desired collagen yarn 1 may not be obtained. When the collagen concentration in the aforementioned neutral collagen solution is greater than 5.0% by mass, even when the liquid temperature is maintained below 10°C, the collagen will still fibrillate in the neutral solvent, raising concerns that the desired collagen yarn 1 may not be obtained. Preferably, the aforementioned neutral collagen solution contains collagen (especially determinated collagen) at a concentration of 4.5% by mass or more and 5.0% by mass or less.

[0060] (Second process: the process of obtaining collagen yarn) The method for manufacturing collagen yarn according to this embodiment includes a step S20 of obtaining collagen yarn by discharging the above-mentioned neutral collagen solution into an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less. In step S20 of obtaining collagen yarn, the above-mentioned neutral collagen solution is passed through a flow path with an inner diameter of 100 μm or more and 300 μm or less, at a flow rate of 100 s. －1 Above and 1500s －1 The following shear rate is discharged into the ethanol solution. The purpose of step S20 in obtaining collagen yarn is to orient collagen molecules in the neutral collagen solution along the flow direction through a narrow flow path and then discharge them into the ethanol solution, thereby causing the collagen molecules to instantly fibrose.

[0061] Specifically, step S20, which yields collagen yarn, is performed by the aforementioned manufacturing apparatus 100. In step S20, a neutral collagen solution contained in container 101 of the manufacturing apparatus 100 is first processed by a generator for 100 seconds... －1 Above and 1500s －1 The plunger is driven by a drive device 103 with a shear rate of 103. As a result, the neutral collagen solution is discharged from container 101 through needle 102 with an inner diameter of 100 μm or more and 300 μm or less into coagulation bath 104. Further, in coagulation bath 104, the collagen (terminus-free collagen) in the neutral collagen solution is instantaneously fibrous, thereby precipitating as collagen yarn 1.

[0062] When the concentration of the ethanol solution is less than 70% by volume, there is a concern that it may be difficult to instantaneously fibrillate the determinate collagen in the neutral collagen solution in the coagulation bath 104. When the concentration of the ethanol solution is greater than 95% by volume, the dehydration rate of the discharged neutral collagen solution is too fast, which may easily cause yarn breakage. In the manufacturing apparatus 100, when the inner diameter of the needle 102 is less than 100 μm, there is a concern that the pressure required for extrusion becomes too high and the desired shear rate cannot be obtained, or that the flow of the neutral collagen solution immediately after exiting the flow path is unstable and yarn breakage occurs. When the inner diameter of the needle 102 is greater than 300 μm, there is a concern that collagen yarn with the desired fineness cannot be obtained, or that it is difficult to dry during winding.

[0063] Furthermore, in step S20, which yields collagen yarn, the shearing speed is less than 100 s. －1 In such cases, there is a concern that collagen molecules in the aforementioned neutral collagen solution may not be able to be oriented along the flow direction and expelled into the ethanol solution. This is especially true when the shear rate is greater than 1500 s⁻¹. －1 In such cases, due to the outflow swelling effect caused by the flow expansion of the neutral collagen solution discharged from the flow path, there is a concern that collagen molecules in the neutral collagen solution may not be able to be oriented along the flow direction and discharged into the ethanol solution. The shear rate is preferably 300 s. －1 Above and 1000s －1 the following.

[0064] In step S20 of obtaining collagen yarn, the collagen yarn 1 can be finally removed from the coagulation bath 104 and wound while drying. The collagen yarn 1 removed from the coagulation bath 104 is moistened with an ethanol solution, but the ethanol solution evaporates immediately in the air. Therefore, the collagen yarn 1 can be easily dried. Regarding the collagen yarn 1 obtained by the above manufacturing method, the collagen nanofibers constituting the collagen yarn 1 can exist in a manner with high orientation, extending to the interior of the collagen yarn 1, preferably to the core. Moreover, the above manufacturing method does not limit the length of the collagen yarn 1 in principle. Furthermore, by appropriately adjusting the inner diameter of the needle 102 and the shearing speed, the diameter of the collagen yarn 1 can be set to 10 μm or more and 50 μm or less. By making the collagen yarn 1 composed of determinate collagen, safety for organisms can also be ensured. Based on the above, collagen yarn that can artificially reproduce collagen fibers in organisms can be obtained.

[0065] (Third process: stretching collagen yarn) The method for manufacturing collagen yarn in this embodiment preferably further includes a step S30 of stretching the collagen yarn by winding it at a winding speed of 1.5 times to 4.0 times the discharge line speed. The purpose of the step S30 of stretching the collagen yarn is to achieve the following three points: to make the collagen yarn 1 finer to the same degree as collagen fibers in living organisms; to improve the orientation of collagen fibers; and to increase the production speed of the collagen yarn.

[0066] Specifically, the process S30 of stretching collagen yarn is as follows: Figure 6 The manufacturing apparatus 100 shown is used for this process. Specifically, in the manufacturing apparatus 100, the collagen yarn 1 precipitated in the coagulation bath 104 is relayed by the relay roller 107 and wound onto the winding roller 105 driven by the motor 106. Preferably, the winding speed of the collagen yarn 1 wound by the winding roller 105 is set to 1.5 times or more and 4.0 times or less of the discharge line speed at which the neutral collagen solution is discharged from the container 101 to the coagulation bath 104 through the needle 102. More preferably, the winding speed is set to 2.0 times or more and 3.5 times or less of the discharge line speed. Therefore, when the collagen in the neutral collagen solution is precipitated as collagen yarn 1 while being spun in the coagulation bath 104, the collagen yarn 1 can be stretched, thereby reducing the diameter of the collagen yarn 1 to, for example, 30 μm or less. Furthermore, the total length of the collagen yarn 1 can be made approximately 1 × 10⁻⁶ mm relative to the diameter. 6 More than twice the length. Based on the above, a collagen yarn 1 that can artificially reproduce collagen fibers in living organisms can be obtained with a finer and longer design. The winding speed of the collagen yarn 1 can be calculated based on the rotational speed of the motor and the diameter of the roller. The flow rate of the discharged neutral collagen solution is set as Q (mm).3 ·s －1 When the radius of the flow path is set to r (mm), the discharge linear velocity of the neutral collagen solution can be determined by Q / πr. 2 (Unit: mm·s) －1 The value of Q is calculated using the formula (Q = 3.6 m / h). However, as mentioned above, sometimes it is necessary to calculate the actual Q.

[0067] Example The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments. In these embodiments, the inventors use, for example... Figure 5 or Figure 6 The manufacturing apparatus shown produced collagen yarn for each sample. In the following description, samples 1 to 6 are examples of collagen yarn within the scope of the present invention, and samples 11 to 19 are comparative examples.

[0068] [Making of Collagen Yarn] <Sample 1> (First step: Preparation) First, an acidic determinated collagen solution (trade name: "Collagen BM", manufactured by Nitta Gelatin Co., Ltd., collagen concentration 0.571%) was prepared. Further, to neutralize the acidic determinated collagen solution, a pH 7 buffer (12×NPB) was prepared, containing 140 mM sodium chloride and 50 mM sodium hydrogen phosphate buffer (hereinafter, 1×NPB) at a concentration 12 times higher. The acidic determinated collagen solution was concentrated to a concentration of 2–8% by mass using an evaporator at 29°C, thereby obtaining a concentrated collagen solution. The accurate concentration of the concentrated collagen solution was determined based on the dry weight of the acidic determinated collagen solution. The ratio of the concentrated collagen solution, purified water, and 12×NPB was appropriately adjusted to prepare a neutral collagen solution as shown in Table 1, with a buffer concentration of 1×NPB. A neutral collagen solution containing 4.8% by mass was prepared based on the above. It should be noted that neutral collagen solutions generally lack fluidity and have small volumes, making direct pH measurement difficult. Therefore, a solution (apparent solution) was prepared by replacing the above-mentioned concentrated collagen solution with dilute hydrochloric acid at pH 3. Based on this apparent solution and the mixing ratio adjusted as described above, a pH measurement solution containing pure water and 12×NPB was prepared, and its pH was measured using a pH meter. At this point, the pH of the pH measurement solution was confirmed to be within the range of 7.1 to 7.4.

[0069] (Second process: the process of obtaining collagen yarn) Next, the neutral collagen solution contained in the above container is drained through a needle with an inner diameter of 182 μm into a coagulation bath 104 filled with 90% vol% ethanol solution (refer to...). Figure 5 The shearing rate at this point is set to 1000 s. －1 This condition is equivalent to a discharge line speed of 82 m / h. In the coagulation bath, the collagen (terminated collagen) in the neutral collagen solution instantly fibrillates, thereby precipitating as collagen yarn and accumulating in the coagulation bath. Then, the collagen yarn is wound with a winding roller. At this time, the collagen yarn does not experience cutting or other defects during the process from discharge to winding, and is evaluated as having good spinnability. Based on the above, collagen yarn of sample 1 was obtained.

[0070] <Sample 2 to Sample 4> A collagen solution (neutral collagen solution) as shown in Table 1 was prepared, and the needle inner diameter, shearing speed, and discharge line speed of the manufacturing apparatus were set as shown in Table 1. Otherwise, collagen yarns of samples 2 to 4 were obtained using the same method as for producing sample 1. The collagen yarns of samples 2 to 4 did not experience any cutting or other defects during the process from discharge to winding, and were evaluated as having good spinnability.

[0071] <Sample 5> Prepare the collagen solution (neutral collagen solution) shown in Table 1, and set the needle inner diameter, shearing speed, and discharge line speed of the manufacturing apparatus as shown in Table 1. Further, the collagen yarn precipitated in the coagulation bath is wound using a winding roller driven by a motor within the manufacturing apparatus. The winding speed of the collagen yarn wound with the winding roller is set to 2.0 times the discharge line speed at which the neutral collagen solution is discharged from the container through the needle into the coagulation bath. The collagen is stretched during the process of the discharged collagen solution becoming yarn (see Table 1). Figure 6 In addition, collagen yarn for sample 5 was obtained using the same method as that used to produce collagen yarn for sample 1. The collagen yarn for sample 5 did not experience any cutting or other defects during the process from discharge to winding, and was therefore evaluated as having good spinnability.

[0072] <Sample 6> The winding speed of the collagen yarn was set to 2.5 times the discharge linear speed at which the neutral collagen solution was discharged from the container into the coagulation bath through a needle. Otherwise, collagen yarn of sample 6 was obtained using the same method as that used to prepare sample 5. Sample 6's collagen yarn did not experience any cutting or other defects during the process from discharge to winding, and was therefore evaluated as having good spinnability.

[0073] <Sample 11 to Sample 12> Prepare the collagen solution (neutral collagen solution) shown in Table 1, and set the needle inner diameter, shearing speed, and discharge line speed of the manufacturing apparatus as shown in Table 1. Otherwise, collagen yarns for samples 11 to 12 were obtained using the same method as for preparing sample 1. As shown in Table 1, in the preparation of collagen yarns for samples 11 to 12, the shearing speed was set to 2000 s. －1 The collagen yarns did not experience any cutting or breakage during the entire process from discharge to winding, indicating good spinnability.

[0074] <Samples 13-15> Samples 13 to 15 were obtained by referring to the manufacturing method described in Patent Document 1. Specifically, the collagen concentration of the neutral collagen solution was set to 2.5%, a needle with a diameter of 521 μm was used, and the shear rate and feed rate were set as shown in Table 1. The coagulation bath was changed from ethanol to a 10 mM phosphate buffer solution at pH 7.0 (heated to 37°C). Otherwise, the collagen yarn of Sample 13 was obtained by following the same method as that used to prepare the collagen yarn of Sample 1. Further, the collagen concentration of the neutral collagen solution was set to 5.0%, and the collagen yarn of Sample 14 was obtained by following the same method as that used to prepare Sample 13. The collagen concentration of the neutral collagen solution was set to 2.5%, and 90% ethanol was connected after the phosphate buffer solution as the coagulation bath. Otherwise, the collagen yarn of Sample 15 was obtained by following the same method as that used to prepare Sample 14. Samples 13 and 15 were evaluated as having low spinning speeds and good spinnability. On the other hand, the collagen yarn in sample 14 broke frequently during winding, and was therefore evaluated as having poor spinnability.

[0075] <Sample 16 to Sample 19> Prepare the collagen solution (acidic collagen solution with pH 3) shown in Table 1, and set the needle inner diameter, shearing speed, and discharge line speed of the manufacturing apparatus as shown in Table 1. Otherwise, collagen yarns for samples 16 to 19 were obtained using the same method as for preparing sample 1. As shown in Table 1, in the preparation of collagen yarns for samples 16 and 17, the needle inner diameter was set to 1500 μm, and the shearing speed was set to 20 s. －1 In the fabrication of collagen yarn for sample 16, the collagen concentration in the acidic collagen solution was set to 0.6% by mass. In the fabrication of collagen yarn for sample 17, the collagen concentration in the acidic collagen solution was set to 5.0% by mass. In the fabrication of collagen yarn for sample 18, the collagen concentration in the acidic collagen solution was set to 0.6% by mass, and the shearing speed was set to 20 s. －1These samples 16 to 19 were obtained as a reproduction experiment of the prior art wet spinning.

[0076] As a result, regarding sample 16, the collagen solution discharged into the coagulation bath precipitated due to mutual fusion, and the collagen yarn was not spun (poor spinnability). Regarding sample 17, only the surface of the collagen yarn became cloudy in the coagulation bath, presumably indicating fiber formation, while the interior remained transparent within minutes (poor spinnability). Regarding sample 18, the collagen fused into clumps before becoming yarn-like in the coagulation bath and was not spun (poor spinnability). The collagen yarn in sample 19 became translucent and accumulated at the bottom of the coagulation bath, and could then be wound (good spinnability).

[0077] Table 1 summarizes the key points of collagen yarn production for samples 1 to 6 and samples 11 to 19 (collagen solution, needle inner diameter, shearing speed, discharge line speed, spinning properties, etc.). [Evaluation of Collagen Yarn] Using the collagen yarns of samples 1-6, 11-13, 15, and 19 as subjects, the diameter (mean and standard deviation), total length, and refractive index difference (mean and standard deviation) were determined using the method described above. Furthermore, using the collagen yarns of samples 1-6, 11-13, 15, and 19 as subjects, the Young's modulus (mean and standard deviation) was measured using the following method, thereby evaluating the strength. The results are shown in Table 2. Regarding the collagen yarns of samples 14 and 16-18, since they could not be wound, the above-mentioned evaluations could not be performed.

[0078] Young's modulus was calculated based on the initial slope of the stress-strain curve obtained through tensile testing. Collagen yarn was cut into approximately 40mm pieces, and both ends were secured with plastic tape to a sample length of 20mm. The collagen yarn was fixed to the chucks of a strength testing machine (product name "TA.XTplus", manufactured by Stable Micro Systems) with a chuck spacing of 20mm, and a strength test was performed at a deformation rate of 1mm / s, thus obtaining a load-displacement curve. The stress was calculated by dividing the load by the cross-sectional area of ​​the collagen yarn (average value of n=5), which was separately measured using a scanning electron microscope, and the strain was calculated by dividing the displacement (mm) by the initial chuck spacing (mm), thereby converting the load-displacement curve into a stress-strain curve. The Young's modulus (n=5) was calculated from the slope of the linear region appearing in the strain range of 0.002 to 0.008. When the Young's modulus was 2.0 GPa or higher, the collagen yarn was evaluated as having sufficient strength for use as a biomaterial. [Inspection] The collagen yarns of samples 1 to 6 have a diameter of 10 μm or more and 50 μm or less, and a total length of 2 × 10⁻⁶ mm. 5 More than twice the length. The refractive index difference is 4.3 × 10⁻⁶. －4 The collagen nanofibers constituting the collagen yarn were evaluated as exhibiting high orientation along the length of the collagen yarn. Furthermore, the Young's modulus was 2.0 GPa or higher, thus indicating sufficient strength for use as a biomaterial. The aforementioned 2.0 GPa value corresponds to the elastic modulus of collagen yarn obtained through conventional wet spinning, where collagen is fully fibrillated in a neutral coagulation bath. Based on the above, it is implied that the collagen yarns of Samples 1 to 6 can artificially reproduce collagen fibers in living organisms and can be used as biomaterials such as artificial tendons or membranes.

[0079] On the other hand, the collagen yarns of samples 11 and 12 have a diameter greater than 50 μm and a refractive index difference less than 4.3 × 10⁻⁶. －4 The collagen yarn in sample 13 has a diameter greater than 50 μm, a total length of 0.2–0.5 m, and a refractive index difference of less than 4.3 × 10⁻⁶. －4 For the collagen yarn of sample 15, the yarn shrank significantly upon drying, clearly indicating it is not useful as a biological material; therefore, diameter and tensile tests were not performed. Furthermore, the refractive index difference of the collagen yarn of sample 15 was less than 4.3 × 10⁻⁶. －4 The collagen yarn in sample 19 has a diameter greater than 50 μm and a refractive index difference less than 4.3 × 10⁻⁶. －4 It should be noted that, regarding the collagen yarns of samples 14 and 16-18, it is impossible for them to be wound as yarns. Therefore, the collagen yarns of samples 11-19 cannot be evaluated as artificially reproducing collagen fibers in living organisms.

[0080] The embodiments and examples of the present invention have been described above, but it is initially intended that the above-described embodiments and examples be appropriately combined.

[0081] It should be considered that the implementation methods and embodiments disclosed herein are exemplary rather than limiting in all respects. The scope of the invention is not shown by the foregoing description, but by the technical solutions, and is intended to include all modifications with the same meaning and scope as the technical solutions.

[0082] Explanation of reference numerals in the attached figures 1: Collagen yarn; 11: Collagen nanofibers; 10: Hydrated collagen yarn; 200: Artificial tendon; 100: Manufacturing device; 101: Container; 102: Needle (flow path); 103: Drive device; 104: Coagulation bath; 105: Winding roller; 106: Motor; 107: Intermediate roller.

Claims

1. A collagen yarn comprising collagen nanofibers, The diameter of the collagen yarn is greater than 10 μm and less than 50 μm. The collagen yarn has a total length of 2 × 10 of the diameter. 5 More than twice the length, The collagen nanofibers exhibit high orientation along the length of the collagen yarn. The high orientation was determined by a refractive index difference of 4.3 × 10⁻⁶, based on birefringence measurements using hydrated collagen yarn. －4 The above indicates that, The hydrated collagen yarn is obtained by impregnating the collagen yarn in a neutral phosphate buffer solution.

2. The collagen yarn according to claim 1, wherein, The collagen nanofibers are composed of determinate collagen.

3. The collagen yarn according to claim 1 or 2, wherein, The total length has 1×10 of the diameter. 6 More than twice the length.

4. A method for manufacturing collagen yarn, comprising: A process for preparing a neutral collagen solution containing collagen at a concentration of 3.0% by mass or more and 5.0% by mass or less; as well as The process of obtaining collagen yarn by discharging the neutral collagen solution into an ethanol solution with a concentration of 70% by volume or more and 95% by volume or less. The collagen mentioned is determinated collagen. In the process of obtaining the collagen yarn, the neutral collagen solution is passed through a flow path with an inner diameter of 100 μm or more and 300 μm or less, at a flow rate of 100 s. －1 Above and 1500s －1 The following shear rates are discharged into the ethanol solution.

5. The method for manufacturing collagen yarn according to claim 4, further comprising: The process of stretching the collagen yarn by winding it at a speed of 1.5 times to 4.0 times the discharge line speed.

6. The method for manufacturing collagen yarn according to claim 4 or 5, wherein, The neutral collagen solution contains collagen at a concentration of 4.5% by mass or more and 5.0% by mass or less.

7. The method for manufacturing collagen yarn according to any one of claims 4 to 6, wherein, The shearing rate is 300s. －1 Above and 1000s －1 the following.

8. A biomaterial comprising collagen yarn as described in any one of claims 1 to 3.

9. The biomaterial according to claim 8, wherein, The biomaterial is an artificial tendon or membrane material.

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