Fiber sheet structure comprising down-twn fiber bunds and thermoplastic resin

Abstract

The purpose of the present invention is to provide a fiber sheet structure comprising a doubled-twisted tow comprising a gelatin fiber bundle and a thermoplastic resin fiber bundle, the gelatin fiber bundle having a better texture than conventional gelatin fibers and having a high tensile strength and a large elongation at break. Furthermore, the purpose of the present invention is to provide a fiber sheet structure which comprises a doubled-twisted tow comprising a gelatin fiber bundle and a thermoplastic resin fiber bundle, has excellent cell adhesion for fixing cells, and has sliding properties such that inflammation does not easily occur when the fiber sheet structure rubs against biological tissue. A fiber sheet structure having a cell placement surface and a back surface, the back surface having a smaller average pore diameter than the cell placement surface, the fiber sheet structure including a knitted structure including a doubled tow comprising gelatin fiber bundles and thermoplastic resin fiber bundles, the thickness of the fiber sheet structure is 30-5000 [mu] m, the number of gelatin fibers constituting the gelatin fiber bundles is 5-60, the fineness of the gelatin fibers is 0.5-10 dtex, the total number of the gelatin fiber bundles and the thermoplastic resin fiber bundles in the doubled tow is 2-20, and the ratio of the number of the gelatin fiber bundles and the number of the thermoplastic resin fiber bundles in the doubled tow is 5: 1-1: 5.

Description

Technical Field

[0001] The present invention relates to a fiber sheet structure comprising a parallel-twisted fiber bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle. Background Art

[0002] Gelatin is a modified collagen obtained by acid treatment or alkali treatment of the triple helix molecule of collagen obtained from cattle bones, cowhide, pigskin, etc., and extracted with hot water. It has low antigenicity when entering the body, and compared with existing bioabsorbable materials, it is degraded by all enzymes, so it is fast in all stages of bioabsorbability, so it is suitable for use as a bioabsorbable material. In the past, gelatin was processed in the form of powder, sheet or sponge, and was mainly used in food raw materials, photographic emulsions, capsules for medicines, etc. Recently, the excellent biocompatibility (low antigenicity and high bioabsorbability) of gelatin has attracted attention, and it is expected to be used in medical materials such as raw materials for wound / burn treatment or matrix materials for artificial skin. Cells in the body function through three-dimensional interactions. In addition, in the case of considering the scaffold material of three-dimensional cell culture in vitro, when imitating the organism in vitro, three-dimensional cell culture is a means, and it is hoped to be a high-level structure. From the above viewpoints, it is desired to produce high-grade structures such as woven fabrics, knitted fabrics, and braids using long fibers (filaments) having high strength and elongation at break for use in medical applications or as scaffold materials for cell culture.

[0003] For example, Patent Document 1 proposes: extruding an aqueous solution containing water-soluble linear polymers such as gelatin and polyethylene glycol into the air for spinning. Patent Document 2 proposes a method for producing gelatin fibers, which comprises discharging a gelatin solution into a coagulation bath to form gel-like fibers, taking them out and stretching them, and removing the residual solution. Patent Document 3 proposes: heating an aqueous gelatin solution to form a sol state, spinning them in the air, and then immersing them in a crosslinking agent solution to crosslink them. Patent Document 4 proposes a method for producing gelatin fibers, which comprises extruding a gelatin solution containing a solution of an amide compound, an alkali metal or an alkaline earth metal halide salt into an alcohol solution by wet spinning to coagulate the gelatin fibers, and washing the crosslinking agent and other added components.

[0004] When a high-order structure such as a woven fabric, a knitted fabric, or a braid having high strength and elongation at break is used as a medical material, it is necessary to fix cells to the high-order structure and allow them to grow.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-167397;

[0008] Patent document 2: Japanese Patent Application Publication No. 2005-120527;

[0009] Patent Document 3: Japanese Patent Application Publication No. 2005-163204;

[0010] Patent document 4: Japanese Patent Application Publication No. 2001-89929. Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, the long fibers (filaments) composed of gelatin fibers obtained by the above-mentioned prior art cannot be obtained because the unwinding (unwinding) of the wound yarn is difficult. In addition, the gelatin fibers produced by the process of washing and adding ingredients such as cross-linking agents to reduce toxicity have low tensile strength or elongation at break, making it difficult to obtain high-grade structures such as knitted fabrics, woven fabrics, and braids.

[0013] In addition, usually because of the low cell adhesion of gelatin, there is a problem that is difficult to fix cells to cultivate in a short time. On the other hand, although collagen has high cell adhesion, it is only degraded by specific enzymes, so there is a problem of long degradation time in vivo. In addition, when used as raw materials for wound / burn treatment or artificial skin matrix materials, even if it is necessary to rub with biological tissue, it is also difficult to produce the slippage and appropriate intensity of inflammation, although gelatin sponge or gelatin sheet have excellent slippage, there is a problem of low intensity on the other hand. Although the high-level structure consisting of thermoplastic fiber has the intensity that is enough to only withstand sliding, the slippage is low, and there is friction with biological tissue and causes inflammation or causes inflammation by the acid produced by the decomposition of thermoplastic fiber.

[0014] Therefore, an object of the present invention is to provide a fiber sheet structure comprising a parallel twisted yarn bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle, wherein the gelatin fiber bundle has a better texture than existing gelatin fibers and has a high tensile strength and a large elongation at break.

[0015] Moreover, the purpose of the present invention is to provide a fiber sheet structure comprising a twisted yarn bundle composed of a gelatin fiber bundle and a thermoplastic resin fiber bundle, wherein the fiber sheet structure has excellent cell adhesion for fixing cells and has a slippery property that is not prone to inflammation when rubbed against biological tissue.

[0016] Means for solving problems

[0017] Specific means for achieving the above-mentioned subject include the following.

[0018] (First method)

[0019] Plan 1

[0020] A higher order structure comprising bundles of gelatin fibers.

[0021] Plan 2

[0022] The high-order structure described in Scheme 1, wherein the tensile strength of the gelatin fiber bundle is 0.5 to 3.0 cN / dtex and the elongation at break is 30 to 300%.

[0023] Plan 3

[0024] The high-order structure according to embodiment 1 or 2, wherein the swelling ratio of the gelatin fiber bundle when immersed in phosphate-buffered saline at 50° C. for 4 hours is 110 to 350%.

[0025] Plan 4

[0026] The high-order structure according to any one of aspects 1 to 3, wherein the high-order structure further comprises a thermoplastic resin fiber bundle, and the gelatin fiber bundle and the thermoplastic resin fiber bundle are a parallel-twisted bundle.

[0027] Plan 5

[0028] The high-order structure described in claim 4, wherein the tensile strength of the above-mentioned parallel-twisted yarn bundle is 1.0 to 10.0 cN / dtex and the elongation at break is 20 to 250%.

[0029] Plan 6

[0030] The high-order structure according to claim 4 or 5, wherein the swelling ratio of the parallel-twisted filament bundle when immersed in phosphate-buffered saline at 50° C. for 4 hours is 110 to 350%.

[0031] Plan 7

[0032] The higher order structure according to any one of aspects 1 to 6, wherein the weight loss rate of the higher order structure when immersed in phosphate buffered saline at 50° C. for 4 hours is 3 to 30%.

[0033] Plan 8

[0034] The high-order structure according to any one of aspects 1 to 7, wherein the thickness of the high-order structure is 30 to 5000 μm.

[0035] Plan 9

[0036] The high-order structure according to any one of aspects 1 to 8, wherein the porosity of the high-order structure is 60 to 97%.

[0037] Plan 10

[0038] The high-order structure according to claim 4 or 5, wherein the thermoplastic resin is coated with a biodegradable resin.

[0039] Plan 11

[0040] The high-order structure according to any one of aspects 1 to 10, wherein the high-order structure is in the shape of a knitted fabric.

[0041] Plan 12

[0042] A laminated higher order structure comprising the higher order structure according to any one of aspects 1 to 11 and a structure composed of a biodegradable resin.

[0043] Plan 13

[0044] The laminated high-order structure according to claim 12, wherein the structure composed of the biodegradable resin is a nonwoven fabric.

[0045] Plan 14

[0046] The laminated high order structure according to claim 12 or 13, wherein the weight loss rate of the laminated high order structure when immersed in phosphate buffered saline at 50°C for 4 hours is 3 to 30%.

[0047] Plan 15

[0048] The laminated high order structure according to any one of aspects 12 to 14, wherein the thickness of the laminated high order structure is 30 to 5000 μm.

[0049] Plan 16

[0050] The stacked high order structure according to any one of aspects 12 to 15, wherein the porosity of the stacked high order structure is 10 to 90%.

[0051] Plan 17

[0052] The high-order structure according to any one of aspects 1 to 11, wherein the average friction coefficient is 0.15 to 0.60.

[0053] Plan 18

[0054] The laminated high order structure according to any one of aspects 12 to 16 has an average friction coefficient of 0.15 to 0.60.

[0055] Plan 19

[0056] The high-order structure according to any one of aspects 1 to 11, wherein the average variation of the friction coefficient is 0.40 to 1.80.

[0057] Plan 20

[0058] The laminated high order structure according to any one of aspects 12 to 16, wherein an average variation of the friction coefficient is 0.40 to 1.80.

[0059] (Second method)

[0060] Plan 21

[0061] A fiber sheet structure, wherein

[0062] The fiber sheet structure comprises a knitted structure and has a cell-carrying surface and a back surface.

[0063] The average pore size (average pore diameter) of the back surface is smaller than the average pore size of the cell-carrying surface.

[0064] The knitted tissue comprises a parallel twisted yarn bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle.

[0065] The thickness of the fiber sheet structure is 30 to 5000 μm.

[0066] The number of gelatin fibers constituting the gelatin fiber bundle is 5 to 60, and the fineness of the gelatin fibers is 0.5 to 10 dtex.

[0067] The total number of gelatin fiber bundles and thermoplastic resin fiber bundles in the above-mentioned twisted yarn bundles is 2 to 20, and the ratio of the number of gelatin fiber bundles to thermoplastic resin fiber bundles in the above-mentioned twisted yarn bundles is 5:1 to 1:5.

[0068] Plan 22

[0069] The fiber sheet structure according to claim 21, wherein the fiber sheet structure is any one of the following (1) to (4):

[0070] (1) A structure comprising two layers stacked together, wherein the layer on the front side and the layer on the back side are knitted structures, and the knitted structures are plain knitted fabrics or plain stitch structures;

[0071] (2) A structure comprising three layers stacked together, wherein the layer on the surface side is a knitted structure, the layer on the back side is a nonwoven fabric, the intermediate layer between the layer on the surface side and the layer on the back side is a knitted structure, the knitted structure is a plain knitted fabric or a plain stitch structure, and the nonwoven fabric contains gelatin fibers;

[0072] (3) A structure comprising two layers stacked together, wherein the layer on the front side is a knitted structure and the layer on the back side is a nonwoven fabric, the knitted structure is a rib structure, and the nonwoven fabric contains gelatin fibers;

[0073] (4) A knitted structure consisting of ribbed fabric.

[0074] Plan 23

[0075] The fiber sheet structure according to claim 21 or 22, wherein the average pore size of the cell-carrying surface is 5 to 123 μm, the number of pores larger than 150 μm in the cell-carrying surface is 35% or less, and the number of pores in the knitted structure is 600 pores / mm 3 above.

[0076] Plan 24

[0077] The fiber sheet structure according to any one of claims 21 to 23, wherein the swelling ratio of the parallel-twisted yarn bundle when immersed in phosphate-buffered saline at 50° C. for 4 hours is 110 to 350%.

[0078] Plan 25

[0079] The fiber sheet structure according to any one of claims 21 to 24, wherein the parallel-twisted yarn bundle has a tensile strength of 1.0 to 20.0 cN / dtex and a breaking elongation of 20 to 250%.

[0080] Plan 26

[0081] The fiber sheet structure according to any one of aspects 21 to 25, wherein the fiber sheet structure has a weight loss rate of 3 to 30% when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0082] Effects of the Invention

[0083] The fiber sheet structure of the present invention has good texture and contains gelatin fiber bundles having high tensile strength and large elongation at break. Therefore, the fiber sheet structure can be formed using gelatin fiber bundles. The fiber sheet structure of the present invention contains the fiber bundle-shaped gelatin as a component, and becomes a medical material with excellent mechanical strength and biocompatibility (low antigenicity and high bioabsorbability), and can be used as a raw material for wound / burn treatment or a matrix material for artificial skin, etc.

[0084] The fiber sheet structure of the present invention has excellent cell adhesion and cell culture properties for fixing cells. Gelatin is a raw material with biocompatibility (low antigenicity and high bioabsorbability), so it can be suitable for use as a scaffold material for excellent three-dimensional cell culture such as promoting cell differentiation, enhancing cell function, and post-transplant fixation. In addition, the fiber sheet structure of the present invention has softness and slippage close to that of biological tissue in a wet state. Therefore, it can be suitable for use as a raw material for wound / burn treatment or a matrix material for artificial skin, etc., and is not prone to inflammation when rubbed with biological tissue. DETAILED DESCRIPTION

[0085] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, unless otherwise specified, the constituent elements (including element steps, etc.) are not necessary. The same is true for numerical values ​​and their ranges, which do not limit the present invention.

[0086] 《First Implementation Method》

[0087] <Advanced Structure>

[0088] The high-order structure of the first embodiment includes gelatin fiber bundles.

[0089] The high-order structure of the first embodiment can be any structure as long as it contains gelatin fiber bundles, preferably a knitted fabric, a woven fabric, or a braid. From the perspective of shrinkage (handleability), dimensional stability, mechanical properties, and appropriate space for cell growth, a knitted fabric is more preferred.

[0090] If a knitted fabric is trimmed and added to a culture medium, it may curl. As a method of suppressing curling, the knitted fabric can be made by rib knitting or plain knitting, or two knitted fabrics that are curled symmetrically can be sewn together for double-sided knitting. Double-sided knitting not only suppresses curling, but also, when used as a scaffold material, the cell culture medium is easily retained in the mesh of the knitted fabric due to the high hydrophilicity of gelatin, which has the advantage of improving cell culturability.

[0091] The weight loss rate of the high-order structure of the first embodiment when immersed in phosphate-buffered saline at 50°C for 4 hours is preferably 3 to 30%, more preferably 5 to 28%, further preferably 7 to 26%, particularly preferably 7 to 24%, and most preferably 7 to 22%. The weight loss rate is measured at 25 cm 2 The weight of the high-order structure is obtained by wrapping the filter with a 10 μm membrane filter and immersing it in phosphate-buffered saline at 50°C for 4 hours. The membrane filter containing the high-order structure is lifted out of the phosphate-buffered saline and immersed in room temperature water for 30 minutes. The moisture is then absorbed with a Kim Towel. The membrane filter containing the high-order structure is dried at 80°C for 24 hours. The high-order structure is taken out from the membrane filter and the weight is measured. The value is calculated using the following formula.

[0092] Weight loss rate [%] = 100 - [100 × (weight after immersion)] / (weight before immersion)

[0093] If the weight loss rate of the high-level structure of the first embodiment is immersed in phosphate-buffered saline at 50°C for 4 hours is within the above range, the cell adhesion is excellent, and the canceration of the grown cells can be inhibited. When the cells are strongly adhered to the high-level structure, the cells tend to grow in a two-dimensional manner, and it can be mainly suitable for use as an embedded medical material. When the cells are weakly adhered to the high-level structure, the cells tend to grow in a three-dimensional manner such as a sphere, and it can be suitable for use as a scaffold material for three-dimensional cell culture in vitro. In addition, gelatin can be prevented from being easily soluble in the body, and the operability is excellent when used as a medical material or a scaffold material for three-dimensional cell culture.

[0094] The weight loss rate can be controlled by subjecting the gelatin fiber bundle precursor to any of thermal crosslinking, chemical crosslinking using a crosslinking agent, and physical crosslinking using ultraviolet rays, radiation, or electron beams (water resistance treatment).

[0095] The thickness of the high-order structure of the first embodiment is preferably 30 to 5000 μm, more preferably 50 to 3000 μm, further preferably 100 to 2000 μm, and particularly preferably 150 to 1000 μm. If the thickness of the high-order structure is less than 30 μm, the strength of the high-order structure is reduced and it is easily damaged, so it is not preferred. If it exceeds 5000 μm, the high-order structure has sufficient strength for operation, but when used as a scaffold material for cell culture, problems such as cell death due to lack of oxygen near the center of the thickness of the high-order structure will occur. The above thickness can be measured by attaching tape to the end of the high-order structure cut into 3 cm squares to fix the high-order structure, and using a contact thickness gauge.

[0096] The porosity of the higher-order structure of the first embodiment is preferably in the range of 60 to 97%, more preferably 65 to 95%, further preferably 70 to 93%, and particularly preferably 75 to 92%. If the porosity is less than 60%, the elasticity of the higher-order structure is significantly reduced, for example, it is difficult to stick the higher-order structure along the affected area. On the other hand, if the porosity exceeds 97%, it is difficult to fix cells to the higher-order structure because the pores are too large. The above porosity is measured by measuring the thickness and weight of the higher-order structure cut into 5 cm squares, and calculated using the following formula.

[0097] Porosity (%) = 100 × [1-a ÷ {(b + c) ÷ (b ÷ d + c ÷ e)} ÷ (f × 25)]

[0098] a: weight of the high-level structure cut into 5 cm square (g);

[0099] b: fineness of gelatin fiber bundle (dtex);

[0100] c: fineness of thermoplastic fiber bundle (dtex);

[0101] d: gelatin fiber bundle density (g / cm 3 );

[0102] e: Thermoplastic fiber bundle density (g / cm 3 );

[0103] f: thickness of the higher order structure (cm).

[0104] It should be noted that the density of gelatin fiber bundle is 1.27 g / cm 3 As the thermoplastic fiber bundle density, the polyglycolic acid fiber bundle density is 1.53 g / cm 3 , the density of polylactic acid fiber bundle is 1.25g / cm 3 In addition, when the high-order structure is made of gelatin fiber bundles only without using thermoplastic fiber bundles, the above c and e are not included in the calculation.

[0105] The high-order structure of the first embodiment can be produced by a known method for producing knitted fabrics, woven fabrics, braids, and the like.

[0106] The high-order structure of the first embodiment contains gelatin fiber bundles, so that the touch in a wet state is close to that of biological tissue, and thus has the characteristic of being easy to slide compared with the high-order structure composed only of thermoplastic resin fiber bundles. In order to make the touch of the thermoplastic resin fiber bundle close to that of biological tissue, collagen, gelatin, etc. can be coated on the surface of the thermoplastic resin fiber bundle.

[0107] Generally, the higher-order structure composed of thermoplastic resin fiber bundles is hydrophobic, so there is a problem that it is very difficult to make the cell culture fluid infiltrate the higher-order structure. However, the higher-order structure of the first embodiment includes gelatin fiber bundles with excellent hydrophilicity, so the cell culture fluid can be easily infiltrated, and cells can be easily fixed and grown inside the higher-order structure.

[0108] Hereinafter, the high-order structure of the first embodiment will be described in detail.

[0109] (Gelatin fiber bundle)

[0110] The number of gelatin fibers constituting the gelatin fiber bundle of the first embodiment is preferably 2 to 90, more preferably 3 to 60, and even more preferably 4 to 50.

[0111] The fineness of the gelatin fiber bundle is preferably 10 to 600 dtex, more preferably 30 to 500 dtex, and even more preferably 50 to 400 dtex. The fineness of the gelatin fiber bundle is a value measured in grams per 10,000 m.

[0112] When the number of fibers constituting the gelatin fiber bundle and the fineness of the gelatin fiber bundle are within the above range, the quality of the high-order structure, such as texture, stretchability, and dimensional stability, can be improved.

[0113] The fineness of the gelatin fiber bundle can be controlled by the number of fibers constituting the gelatin fiber bundle or the fineness of the gelatin fibers described later.

[0114] The tensile strength of the gelatin fiber bundle of the first embodiment is preferably 0.5 to 3.0 cN / dtex, more preferably 0.7 to 2.8 cN / dtex, and even more preferably 1.0 to 2.5 cN / dtex.

[0115] The tensile strength of the gelatin fiber bundle is measured using, for example, Tensilon (RTC-1210A manufactured by Orientec Corporation).

[0116] The breaking elongation of the gelatin fiber bundle is preferably 30 to 300%, more preferably 30 to 250%, further preferably 40 to 200%, and particularly preferably 50 to 150%. The breaking elongation of the gelatin fiber bundle is measured using Tensilon (RTC-1210A manufactured by Orientec).

[0117] If the tensile strength and elongation at break of the gelatin fiber bundle are within the above ranges, fiber breakage can be prevented during winding and unwinding of the fiber bundle and production of a high-order structure, and the high-order structure can be easily produced.

[0118] The tensile strength and elongation at break of the gelatin fiber bundle can be controlled by the type of gelatin or the spinning conditions described below.

[0119] The weight loss rate of the gelatin fiber bundle of the first embodiment when immersed in phosphate buffered saline at 50°C for 4 hours is preferably 3 to 30%, more preferably 5 to 28%, further preferably 7 to 26%, particularly preferably 7 to 24%, and most preferably 7 to 22%. The weight loss rate is a value calculated by measuring the weight of a 100 mm gelatin fiber bundle, wrapping it with a 10 μm membrane filter, immersing it in phosphate buffered saline at 50°C for 4 hours, lifting the membrane filter containing the gelatin fiber bundle from the phosphate buffered saline, immersing it in room temperature water for 30 minutes, absorbing moisture with a Kim Towel, drying the membrane filter containing the gelatin fiber bundle at 80°C for 24 hours, taking out the fiber bundle from the membrane filter and measuring the weight, and calculating the value by the following formula.

[0120] Weight loss rate [%] = 100 - [100 × (weight after immersion)] / (weight before immersion)

[0121] If the weight loss rate of the gelatin fiber bundle of the first embodiment is immersed in phosphate buffered saline at 50°C for 4 hours is within the above range, the cell adhesion is excellent, and the canceration of the grown cells can be inhibited. When the cells are strongly adhered to the high-level structure, the cells tend to grow in a two-dimensional manner, and it can be mainly suitable for use as an embedded medical material. When the cells are weakly adhered to the high-level structure, the cells tend to grow in a three-dimensional manner such as a sphere, and it can be suitable for use as a scaffold material for three-dimensional cell culture in vitro. In addition, it can prevent gelatin from being easily soluble in the body, and it is excellent in operability when used as a medical material or a scaffold material for three-dimensional cell culture.

[0122] The weight loss rate of the gelatin fiber bundle when immersed in phosphate-buffered saline at 50° C. for 4 hours can be controlled by the degree of insolubilization treatment described later.

[0123] The swelling ratio of the gelatin fiber bundle of the first embodiment when immersed in phosphate buffered saline at 50° C. for 4 hours is preferably 110 to 350%, more preferably 120 to 300%, and further preferably 130 to 300%. The swelling ratio is a value calculated by the following formula by measuring the fiber diameter of gelatin fibers constituting the gelatin fiber bundle using an optical microscope RH2000 manufactured by HIROX, and by measuring the fiber diameter of the gelatin fibers in a wet state after immersing the gelatin fiber bundle in phosphate buffered saline at 50° C. for 4 hours and then lifting the gelatin fiber bundle from the phosphate buffered saline.

[0124] Swelling ratio [%] = 100 × (fiber diameter after immersion) / (fiber diameter before immersion)

[0125] If the swelling ratio of the gelatin fiber bundle of the first embodiment is immersed in phosphate buffered saline at 50°C for 4 hours, the cell adhesion is excellent, and the canceration of the grown cells can be inhibited. When the cells are strongly adhered to the high-level structure, the cells tend to grow in a two-dimensional manner, and it can be mainly suitable for use as an embedded medical material. When the cells are weakly adhered to the high-level structure, the cells tend to grow in a three-dimensional manner such as a sphere, and it can be suitable for use as a scaffold material for three-dimensional cell culture in vitro. In addition, it can prevent gelatin from being easily soluble in the body, and it is excellent in operability when used as a medical material or a scaffold material for three-dimensional cell culture.

[0126] The cross-sectional shapes of the gelatin fibers constituting the gelatin fiber bundle include solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a scaffold material for three-dimensional cell culture, irregular cross-sectional filaments such as flat, star, and triangle are sometimes preferred over solid circles.

[0127] When measuring the tensile strength, elongation at break, weight loss and swelling ratio of the gelatin fiber bundle mentioned above by means of a high-order structure, the high-order structure is cut off with scissors, the ends of the threads are pinched, and threads of more than 5 cm are extracted as samples for measurement.

[0128] (Method for producing high-order structure)

[0129] The method for producing the high-order structure according to the first embodiment is described below, but is not particularly limited.

[0130] The method for producing a high-order structure preferably includes the following steps 1 and 2 and step 3-1 or step 3-2.

[0131] (Step 1) a step of extruding a spinning dope consisting of a gelatin solution containing 30 to 70% by weight of a gelatin raw material into a fiber form from a multi-hole spinneret at a temperature 1 to 15° C. higher than the sol-gel transition temperature of the gelatin spinning dope;

[0132] (Step 2) a step of winding the extruded gelatin fibers onto a bobbin to produce a gelatin fiber bundle precursor;

[0133] (Step 3-1) The step of insolubilizing the gelatin fiber bundle precursor and then organizing it to produce a high-order structure;

[0134] (Step 3-2) A step of organizing the gelatin fiber bundle precursor and then insolubilizing it to produce a high-order structure.

[0135] In the above-mentioned step 2, before the extruded gelatin fiber is wound onto a bobbin, a conveying step is included in which the extruded gelatin fiber is conveyed along the circumferential surface of a conveying roller. When the extruded gelatin fiber reaches the first conveying roller, the moisture regain of the gelatin fiber is preferably 5 to 25% by weight.

[0136] The moisture regain of the gelatin fiber bundle precursor is preferably 5 to 20% by weight.

[0137] The above step 2 includes a step of allowing a mixed solution of at least one selected from ethylene glycol, polyethylene glycol, and glycerin and a lower alcohol to adhere to the extruded gelatin fibers before winding them onto a bobbin.

[0138] In the above step 1, it is preferred that the gel strength of the gelatin is 100 to 350 g, and the sol-gel transition temperature of the gelatin spinning solution is 15 to 60°C.

[0139] The high-order structure of the first embodiment can be produced by extruding a spinning stock solution composed of a gelatin solution from a multi-hole spinneret into a fiber shape, winding the extruded gelatin fibers on a bobbin to produce a gelatin fiber bundle precursor, insolubilizing the gelatin fiber bundle precursor to produce a gelatin fiber bundle, and then organizing the gelatin fiber bundle precursor to produce a high-order structure. Alternatively, as described above, a high-order structure composed of gelatin fiber bundles can be produced by producing a fiber bundle precursor, organizing the fiber bundle precursor, and then insolubilizing the fiber bundle precursor.

[0140] It should be noted that texturizing refers to producing a woven fabric, a knitted fabric or a braid from a fiber bundle or a fiber bundle precursor.

[0141] The gelatin raw material constituting the gelatin solution is obtained as a molecular chain by unwinding the triple helix of collagen from cattle bones, cowhide, pig skin, birds or fish. The manufacturing method of the gelatin raw material includes acid treatment method or lime treatment method, etc. The gelatin raw material used in the first embodiment can be a gelatin raw material manufactured by any method, or it can be a commercially available gelatin raw material. In addition, the commercially available gelatin raw material undergoes various purification processes before extraction in its manufacturing process, so there are few components other than protein. Generally speaking, it is usually composed of more than 85% protein, 8-14% water, less than 2% ash, and less than 1% other (lipids, polysaccharides, etc.). The first embodiment can also use the general gelatin raw material. The gelatin raw material is a thermally modified substance of collagen, so its amino acid composition is roughly the same as that of collagen, but it is very special compared with other proteins. Glycine accounts for about one-third of the whole, and one out of every three in the amino acid sequence is repeated. As a method for distinguishing collagen from gelatin, for example, the 31.5-degree signal obtained by wide-angle X-ray measurement can be observed. The 31.5-degree signal is a signal derived from the triple helical structure of collagen, and when the triple helical structure characterized by collagen is unwound to become gelatin, the signal disappears.

[0142] The molecular weight of the gelatin raw material is not particularly limited, but the gel strength, which is highly correlated with the molecular weight, is preferably 100 to 350 g, more preferably 150 to 320 g, and still more preferably 220 to 310 g from the viewpoint of spinnability. The gel strength refers to the load (g) required to press down 4 mm with a plunger having a diameter of 1 / 2 inch (12.7 mm) on the surface of a prepared gelatin solution after cooling a 6.67% gelatin aqueous solution at 10° C. for 17 hours using a small table-top tester EZ-SX manufactured by Shimadzu Corporation.

[0143] When the gel strength of the gelatin raw material is within the above range, it is possible to prevent the spinnability of the gelatin fiber from being significantly reduced, and further, by suppressing the moisture retention rate in the fiber, it is possible to prevent the fiber from being broken during winding.

[0144] The content of the gelatin raw material in the gelatin solution is preferably 30 to 70% by weight, more preferably 40 to 60% by weight. If the content of the gelatin raw material in the gelatin solution is within the above range, the spinnability of the gelatin fiber can be prevented from being significantly reduced, and the bubbles generated during the gelatin solution manufacturing process are easily degassed, which can prevent the breakage of the fibers during spinning.

[0145] The solvent for dissolving the gelatin raw material is water, and (poly)alcohols, dimethyl sulfoxide, etc. may be added to adjust the viscosity as needed.

[0146] The sol-gel transition temperature of the gelatin solution is preferably 15 to 60° C., more preferably 20 to 60° C., further preferably 20 to 55° C., and particularly preferably 20 to 50° C. The sol-gel transition temperature is measured using, for example, a rheometer ARES manufactured by TA Instruments.

[0147] If the sol-gel transition temperature is within the above range, the adhesion can be suppressed from becoming stronger, the operability when manufacturing gelatin fibers can be improved, and the adhesion of the wound gelatin fibers can be prevented. In addition, the thermal decomposition of gelatin at the spinning temperature and the resulting fiber breakage can be prevented.

[0148] The gelatin fiber bundle precursor is produced by extruding a spinning solution composed of gelatin raw materials and solvents such as water from a multi-hole spinneret into the air to form fibers, orienting the molecular chains of the triple helix molecules of collagen that are untied by stretching just below the spinneret appropriately, and controlling the moisture regain in the fibers appropriately. By controlling the orientation of the molecular chains of the untied triple helix molecules of collagen and the moisture regain in the fibers, the tensile strength and elongation at break of the fibers can be increased, and the adhesion between the fibers can be suppressed.

[0149] The spinning process of extruding the spinning solution from a porous spinneret into the air into a fiber shape can be any of the dry, semi-dry, and wet methods. In the process of drying and removing the solvent, pores can be prevented from being formed on the surface or inside of the fiber, and the tensile strength or elongation at break of the gelatin fiber can be suppressed from decreasing, so it is preferably produced by the dry method. The dry spinning temperature is preferably a temperature 1 to 25°C higher than the sol-gel transition temperature of the spinning solution, and more preferably a temperature 5 to 20°C higher than the sol-gel transition temperature. If it is within the above range, a significant decrease in the drawability can be prevented.

[0150] In the production of the gelatin fiber bundle precursor used in the first embodiment, it is preferred to rapidly reduce the moisture content in the fiber to a range of 5 to 25% by weight immediately after spinning. If the moisture content in the fiber is within the above range, adhesion can be suppressed, and the gelatin fibers discharged from the multi-hole spinneret can be prevented from sticking to each other, or the gelatin fibers can be prevented from sticking to the roller during the production process. In addition, the gelatin fiber precursor wound on the bobbin can be easily unwound from the bobbin. In addition, a significant decrease in the elongation of the filament can be suppressed, and the breakage of the filament can be prevented during the production process of the gelatin fiber bundle and the production process of the high-order structure rewound from the bobbin.

[0151] Before the gelatin fibers extruded from the spinneret are wound onto a bobbin, a conveying step of conveying the fibers along the circumferential surface of a conveying roller may be included.

[0152] When the extruded gelatin fiber reaches the first conveying roller, the moisture regain of the gelatin fiber is preferably 5 to 25% by weight, more preferably 5 to 20% by weight. The moisture regain is measured by winding the gelatin yarn around the first conveying roller, measuring 0.5 g of the wound fiber, and using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) at 150°C / N2 atmosphere.

[0153] When the moisture regain is within the above range, the gelatin fibers can be prevented from adhering to the conveying rollers, and a significant decrease in the elongation of the yarn can be suppressed, thereby preventing yarn breakage.

[0154] The moisture regain can be controlled by drying with dry air or dry hot air or the like.

[0155] In order to prevent the fibers from sticking together due to contact between each other, it is preferable to use a grooved guide roller or the like as the feed roller.

[0156] The moisture regain of the gelatin fiber bundle precursor obtained by winding the gelatin fiber on a bobbin is preferably 5 to 20% by weight, more preferably 5 to 15% by weight. The moisture regain is measured by measuring 0.5 g of the fiber bundle precursor wound on a bobbin using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) at 150°C / N2 atmosphere.

[0157] If the moisture regain is within the above range, the gelatin fiber precursor can be easily unwound from the bobbin, and a significant decrease in the elongation of the yarn can be suppressed, thereby preventing the yarn from breaking during the production process of the high-order structure rewound from the bobbin.

[0158] The moisture regain can be controlled by drying with dry hot air, etc. In addition, after passing through the first conveying roller, the fiber bundle can be dried in time using a winder.

[0159] The gelatin fiber bundle used in the first embodiment is preferably manufactured with a spinning draft (discharge line speed / winding speed) in the range of 0.01 to 2, and more preferably in the range of 0.05 to 1.5. If it is within the above range, the orientation of the molecular chain of the triple helix molecule of the unwound collagen becomes sufficient, which can prevent the decrease in tensile strength. In addition, the fiber diameter can be suppressed from becoming too large, and the moisture regain of the gelatin fiber can be sufficiently reduced before reaching the first conveying roller, resulting in the gelatin fiber being prevented from adhering to the roller. In addition, a significant decrease in the elongation at break can be suppressed, and the breakage of the yarn can be prevented during the manufacturing process of the gelatin fiber bundle and the manufacturing process of the high-order structure rewound from the bobbin.

[0160] Before the gelatin fibers extruded from the spinneret are wound onto the bobbin, a process of attaching an oil agent to the gelatin fibers may be included. Preferably, the oil agent is attached to the fiber surface after the moisture regain in the fiber reaches a range of 5 to 20% by weight. By attaching the oil agent to the fiber surface, multiple gelatin fibers can be gathered into a gelatin fiber bundle for operation. By attaching the oil agent, the operability of the silk is significantly improved in the manufacturing process of the gelatin fiber bundle and the manufacturing process of the high-level structure rewound from the bobbin. From the perspective of the high-level structure of the first embodiment being used as a medical material, it is preferred to use a biocompatible oil agent, such as ethylene glycol, polyethylene glycol, glycerol, etc. It is preferred that these compounds be diluted with lower alcohols such as ethanol, attached to the fiber surface in the form of a mixed solution, and then the lower alcohol is removed by drying. The oil agent can be removed by washing after the high-level structure is made, or it can be formed in an attached state. There is no restriction on the amount of oil agent attached, as long as it is an amount of attachment that allows multiple gelatin fibers to be gathered into a fiber bundle, for example, preferably 0.5 to 5% by weight.

[0161] The fiber cross-sectional shape of gelatin fiber can be any shape. Examples of the fiber cross-sectional shape include solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a three-dimensional cell culture scaffold material, irregular cross-sectional filaments with irregular cross-sections such as flat, star, triangle, etc. are sometimes preferred over solid circle cross-sectional filaments.

[0162] The tensile strength of the gelatin fiber is preferably 0.5 to 3 cN / dtex, more preferably 0.7 to 2.8 cN / dtex, and further preferably 1.0 to 2.5 cN / dtex. The tensile strength of the gelatin fiber is measured by taking out a single yarn from a gelatin fiber bundle precursor, for example, using Tensilon (RTC-1210A manufactured by Orientec).

[0163] The breaking elongation of the gelatin fiber is preferably 30 to 250%, more preferably 40 to 200%, and even more preferably 50 to 150%. The breaking elongation of the gelatin fiber is measured by taking out a single yarn from a gelatin fiber bundle, for example, using Tensilon (RTC-1210A manufactured by Orientec).

[0164] If the tensile strength and elongation at break of the gelatin fiber are within the above ranges, the production of gelatin fiber bundles or the fabrication of high-order structures can be tolerated.

[0165] As a process for insolubilizing the gelatin fiber bundle precursor, the gelatin fiber bundle can be prepared by insolubilizing the gelatin fiber bundle precursor, or the fiber bundle precursor can be organized and then insolubilized to prepare a high-order structure composed of gelatin fiber bundles. Insolubilization (water-insoluble treatment) can be any of thermal crosslinking, chemical crosslinking using a crosslinking agent, and physical crosslinking using ultraviolet rays, radiation, or electron beams, and can also be combined as appropriate. In the case of thermal crosslinking, it can be in the atmosphere or in a vacuum. The temperature during thermal crosslinking is in the range of 110 to 200°C, more preferably 120 to 190°C, and further preferably 130 to 180°C. If the temperature is lower than 100°C, the crosslinking is insufficient, and gelatin is soluble in water in a wet state and cannot be used as a scaffold material. At a temperature higher than 200°C, gelatin undergoes thermal decomposition, and the fiber strength is significantly reduced, so it is not preferred. The degree of crosslinking can be changed in time by combining the heat treatment temperature and the heat treatment time. As for the heat treatment time, it is preferably 3 to 48 hours, and from the perspective of productivity, it is preferably in the range of 4 to 24 hours.

[0166] In the case of chemical crosslinking using a crosslinking agent, pores are formed in the fibers during the washing process to remove the crosslinking agent in the fibers, and the tensile strength or elongation at break of the gelatin fibers may sometimes decrease. In this case, fiber breakage may sometimes occur during the process of making a high-order structure from the insolubilized gelatin fiber bundle. Therefore, in the case of insolubilization treatment by chemical crosslinking, it is preferred to perform chemical crosslinking treatment after the fiber bundle precursor is organized. Examples of the crosslinking agent used in the chemical crosslinking include glutaraldehyde, hexamethylene diisocyanate, and the like.

[0167] The higher order structure produced in the first embodiment can be immersed in, for example, a 20 to 80% glycerol aqueous solution. By immersing the higher order structure in a glycerol aqueous solution, a moist medical material with better followability to the affected area can be obtained.

[0168] The high-order structure of the first embodiment may include additives. Examples of additives include: polyacids such as citric acid (anhydride) and maleic acid (anhydride), magnetic particles such as gamma iron oxide, inorganic substances such as hydroxyapatite, endogenous proteins that promote cell growth or differentiation, collagen, etc. These additives may be applied to the high-order structure, or to gelatin fiber bundles, gelatin fiber bundle precursors, gelatin fibers, or added to gelatin raw materials.

[0169] (Twisted tow)

[0170] The high-order structure of the first embodiment may further include a thermoplastic resin fiber bundle, and the gelatin fiber bundle and the thermoplastic resin fiber bundle may be a parallel-twisted bundle.

[0171] There is no limitation on the thermoplastic resin in the thermoplastic resin fiber bundle, as long as it is a resin used as a medical material, and examples thereof include polyethylene terephthalate (PET), polylactic acid (PLLA, PLLDA), poly-ε-caprolactone (PCL), and their (LA-CL) copolymers, polyglycolic acid (PGA), copolymers of glycolic acid and lactic acid (PLGA), polyglutamic acid, etc. Among them, from the viewpoint that the acid production accompanying the decomposition of the thermoplastic resin fiber bundle is relatively mild and is not easy to cause inflammation, any one of polylactic acid (PLLA, PLLDA), copolymers of glycolic acid and lactic acid (PLGA), polyglycolic acid (PGA), and polyglutamic acid is preferred.

[0172] The number of thermoplastic resin fibers constituting the thermoplastic resin fiber bundle is preferably 5 to 70, more preferably 7 to 50, and even more preferably 10 to 30.

[0173] If it is within the above range, the strength of the higher-order structure containing gelatin can be significantly improved, which is preferred.

[0174] The total number of gelatin fibers and thermoplastic resin fibers constituting the twisted yarn bundle is preferably 10 to 300, more preferably 20 to 280, and even more preferably 25 to 250.

[0175] When the content is within the above range, the high-order structure containing gelatin not only has high strength but also has appropriate sliding properties when wet, and thus, for example, can be embedded in or wrapped around a sliding portion around cartilage.

[0176] The fineness of the thermoplastic resin fiber bundle is preferably 10 to 100 dtex, more preferably 15 to 60 dtex, and even more preferably 20 to 50 dtex.

[0177] If it is within the above range, it is preferred from the viewpoint of improving the quality of the high-order structure, such as the texture, stretchability, and dimensional stability.

[0178] The fineness of the twisted yarn bundle is preferably 20 to 800 dtex, more preferably 40 to 700 dtex, and further preferably 50 to 600 dtex.

[0179] When the content is within the above range, the high-order structure containing gelatin has high strength, improves the quality such as texture, elasticity, and dimensional stability, and has appropriate sliding properties under wet conditions that can be applied to sliding parts such as cartilage peripheries, so it is preferred.

[0180] The tensile strength of the twisted yarn bundle is preferably 1.0 to 20.0 cN / dtex, more preferably 2.0 to 18.0 cN / dtex, further preferably 3.0 to 15.0 cN / dtex, and particularly preferably 4.0 to 12.0 cN / dtex. The tensile strength of the twisted yarn bundle is measured using, for example, Tensilon (RTC-1210A manufactured by Orientec).

[0181] The elongation at break of the parallel twisted yarn bundle is preferably 20 to 250%, more preferably 20 to 200%, further preferably 20 to 150%, and particularly preferably 25 to 150%. The elongation at break of the parallel twisted yarn bundle is measured using Tensilon (RTC-1210A manufactured by Orientec).

[0182] When the tensile strength and elongation at break of the parallel twisted yarn bundle are within the above ranges, yarn breakage can be prevented during winding and unwinding of the parallel twisted yarn bundle or production of a high-order structure, and the high-order structure can be easily produced.

[0183] The weight loss rate of the first embodiment of the twisted yarn bundle when immersed in phosphate buffered saline at 50°C for 4 hours is preferably 3-30%, more preferably 5-28%, further preferably 7-26%, particularly preferably 7-24%, and most preferably 7-22%. The above-mentioned weight loss rate is the weight of a 100 mm twisted yarn bundle, which is wrapped with a 10 μm membrane filter and immersed in phosphate buffered saline at 50°C for 4 hours. The membrane filter containing the twisted yarn bundle is lifted out of the phosphate buffered saline, immersed in room temperature water for 30 minutes, and then the moisture is absorbed with a Kim Towel. The membrane filter containing the twisted yarn bundle is dried at 80°C for 24 hours, and the twisted yarn bundle is taken out from the membrane filter, and the weight is measured, and the value is calculated by the following formula.

[0184] Weight loss rate [%] = 100 - [100 × (weight after immersion)] / (weight before immersion)

[0185] If the weight loss rate of the twisted yarn bundle of the first embodiment is immersed in phosphate buffered saline at 50°C for 4 hours is within the above range, the cell adhesion is excellent, and the canceration of the grown cells can be inhibited. When the cells are strongly adhered to the high-level structure, the cells tend to grow in a two-dimensional manner, and it can be mainly suitable for use as an embedded medical material. When the cells are weakly adhered to the high-level structure, the cells tend to grow in a three-dimensional manner such as a sphere, and it can be suitable for use as a scaffold material for three-dimensional cell culture in vitro. In addition, gelatin can be prevented from being easily soluble in the body, and the operability is excellent when used as a medical material or a scaffold material for three-dimensional cell culture.

[0186] The weight loss rate of the twisted yarn bundle when immersed in phosphate-buffered saline at 50° C. for 4 hours can be controlled by the degree of insolubilization treatment described later.

[0187] The swelling ratio of the twisted yarn bundle of the first embodiment when immersed in phosphate buffered saline at 50° C. for 4 hours is preferably 110 to 350%, more preferably 120 to 300%, and further preferably 130 to 300%. The swelling ratio is a value calculated by the following formula, which is obtained by measuring the bundle diameter of the twisted yarn bundle constituting the twisted yarn bundle using an optical microscope RH2000 manufactured by HIROX, and then taking out the twisted yarn bundle from the phosphate buffered saline after immersing the twisted yarn bundle in phosphate buffered saline at 50° C. for 4 hours and measuring the bundle diameter of the twisted yarn bundle in a wet state.

[0188] Swelling rate [%] = 100 × (diameter of the twisted yarn bundle after dipping) / (diameter of the twisted yarn bundle before dipping)

[0189] If the swelling rate of the twisted yarn bundle of the first embodiment when immersed in phosphate-buffered saline at 50°C for 4 hours is within the above range, the canceration of grown cells can be inhibited. In addition, gelatin can be prevented from being easily soluble in the body, and the handleability is excellent when used as a medical material or a scaffold material for three-dimensional cell culture.

[0190] When measuring the tensile strength, elongation at break, weight loss and swelling ratio of the above-mentioned twisted yarn bundle using a high-order structure, cut the high-order structure with scissors, pinch its yarn end, and extract more than 5 cm of yarn as a sample for measurement.

[0191] The fiber cross-sectional shape of the thermoplastic resin fibers constituting the thermoplastic resin fiber bundle may be any shape, including solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a scaffold material for three-dimensional cell culture, an irregular cross-section is sometimes preferred over a solid circle cross-section.

[0192] The thermoplastic resin fiber used in the high-order structure of the first embodiment may contain additives. Examples of additives include polyacids such as citric acid (anhydride) and maleic acid (anhydride), magnetic particles such as gamma iron oxide, inorganic substances such as hydroxyapatite, endogenous proteins that promote cell growth or differentiation, collagen, or drugs such as anticancer drugs. These additives can be applied to the thermoplastic resin fiber.

[0193] As a method for coating a biodegradable resin such as collagen on a thermoplastic resin fiber bundle, there can be exemplified a method in which the thermoplastic fiber bundle is rewound while removing the oil agent in a washing bath and drying it, then the thermoplastic fiber bundle is immersed in a collagen solution, the collagen is coated on the thermoplastic fiber bundle and dried to be wound up, etc. Collagen has the property of being easily thermally modified, so it is preferably coated and dried at 40°C or less, preferably 30°C or less, and more preferably 25°C or less. If the coating or drying temperature is too low, the collagen solution freezes and cannot be coated, or the drying is insufficient, so it is preferably treated at 0°C or more, preferably 5°C or more, and more preferably 10°C or more. As the concentration of the collagen solution, an acid solution of 0.005 to 3% by weight is preferably used. If the concentration of the collagen solution is less than 0.005% by weight, the thermoplastic resin fiber bundle cannot be converged by collagen, and the handling of the fiber bundle becomes difficult. On the other hand, if it exceeds 3% by weight, the thermoplastic resin fiber bundle becomes hard and the operability is significantly deteriorated. The concentration of the collagen solution is more preferably in the range of 0.01 to 2% by weight. It should be noted that the thermoplastic fiber bundle coated with collagen may be subjected to a heat treatment or a chemical treatment at 100 to 150° C. to make the coated collagen insoluble in water.

[0194] Collagen has a very good cell adhesion property, so for example, a high-level structure composed of a thermoplastic resin fiber bundle and a gelatin fiber bundle coated with collagen has the characteristics of excellent cell culture properties, such that cells do not fall out from the gaps therebetween, cells are fixed in a fibrous form, and the like. In addition, by coating with collagen, the touch is close to that of biological tissue, so the sliding property becomes very good in a wet state.

[0195] In addition, examples of biodegradable resins other than collagen include biogenic resins such as gelatin, and synthetic polymers such as polyglycolic acid (PGA), polylactic acid (PLA), lactic acid / glycolic acid copolymers (PLGA), and polyglutamic acid.

[0196] The ratio of the gelatin fiber bundle to the thermoplastic resin fiber bundle in the twisted yarn bundle (the fineness of the gelatin fiber bundle: the fineness of the thermoplastic resin fiber bundle) is 1:5 to 5:1.

[0197] (Method for producing twisted yarn bundle)

[0198] The thermoplastic resin fiber according to the first embodiment can be produced by melt spinning, or a commercially available thermoplastic resin fiber bundle can be purchased and used.

[0199] The first embodiment of the high-order structure including the twisted fiber bundle is manufactured using the twisted fiber bundle precursor composed of the gelatin fiber bundle precursor and the thermoplastic resin fiber bundle as the starting material. The twisted fiber bundle precursor composed of the gelatin fiber bundle precursor and the thermoplastic resin fiber bundle can be manufactured by supplying a plurality of fiber bundle precursors to a twisting machine.

[0200] The thermoplastic resin fiber bundle may be twisted while being spirally wound around the gelatin fiber bundle precursor, or the gelatin fiber bundle precursor may be twisted while being spirally wound around the thermoplastic resin fiber bundle.

[0201] The gelatin fiber bundle precursor and the thermoplastic resin fiber bundle to which the oil agent is attached may be twisted together by twisting or the like, or the fiber bundles may be entangled and twisted by interlacing or the like.

[0202] The parallel twisted fiber bundle precursor can be made into a parallel twisted fiber bundle by the same method as the above-mentioned process of insolubilizing the gelatin fiber bundle precursor, and then the parallel twisted fiber bundle can be organized to make a high-order structure. Alternatively, the parallel twisted fiber bundle precursor can be organized and then insolubilized to make a high-order structure composed of the parallel twisted fiber bundle.

[0203] The high-order structure including the parallel twisted yarn bundle of the first embodiment may be laminated with sheets such as nonwoven fabric, knitted fabric, woven fabric, etc. For example, in the case of laminating a gelatin or collagen nonwoven fabric, the following method may be used: after the parallel twisted yarn bundle precursor is organized, the nonwoven fabric is laminated on the parallel twisted yarn bundle precursor by electrospinning, etc. The laminated gelatin or collagen nonwoven fabric may be made insoluble in water by cross-linking treatment.

[0204] (Laminated Advanced Structure)

[0205] The higher-order structure of the first embodiment can be a stacked higher-order structure comprising a structure composed of a biodegradable resin. As biodegradable resins, there can be listed: resins from organisms such as gelatin or collagen, polyglycolic acid (PGA), polylactic acid (PLA), lactic acid / glycolic acid copolymers (PLGA), synthetic polymers such as polyglutamic acid. In addition, as stacked structures, there can be listed: shapes such as non-woven fabrics, knitted fabrics, and woven fabrics, preferably non-woven fabrics. The gaps in the higher-order structure (the mesh of the knitted fabric) are much larger than the size of the cells. Therefore, when the higher-order structure is used as a scaffold material for cell culture, the cells fall off from the gaps in the higher-order structure and cannot be fixed, and cell culture requires time. In contrast, if a stacked higher-order structure comprising a higher-order structure and a structure composed of a biodegradable resin is used as a scaffold material for cell culture, the structure composed of the biodegradable resin captures the cells, fixes the cells to the stacked higher-order structure, and can shorten the cell culture time. As a method for manufacturing a stacked high-level structure including a high-level structure and a structure composed of a biodegradable resin, for example, there can be exemplified a method of rewinding a roll of the high-level structure while blowing a non-woven fabric onto the high-level structure by electrospinning or melt-blowing, and then conveying it, and then winding it after hot pressing with a calendar roll or the like; a method of batch hot pressing after laminating a structure composed of a biodegradable resin on a cut high-level structure, etc. As the temperature of hot pressing, 40 to 90°C is preferred, and as the pressure, the range of 5kPa to 3MPa is preferred. If the hot pressing temperature is lower than 40°C, the high-level structure constituting the stacked high-level structure and the structure composed of the biodegradable resin are prone to interlayer delamination. If the temperature is higher than 90°C, the gelatin fibers constituting the high-level structure are fused, which damages the elasticity that is a characteristic of the high-level structure of the first embodiment, and is therefore not preferred. The preferred range of the hot pressing temperature is 40 to 80°C. If the hot pressing pressure is less than 5 kPa, the high-order structure constituting the stacked high-order structure and the structure composed of the biodegradable resin are prone to interlayer delamination, and if it exceeds 3 MPa, the elasticity that is a characteristic of the high-order structure of the first embodiment is impaired, which is not preferred. The more preferred range of the hot pressing pressure is preferably in the range of 400 kPa to 2 MPa.

[0206] The weight loss rate of the laminated high-order structure of the first embodiment when immersed in phosphate-buffered saline at 50° C. for 4 hours is preferably 3 to 30%, more preferably 5 to 28%, and even more preferably 7 to 26%.

[0207] If it is within the above range, the cell adhesion is excellent, and in addition, the canceration of the grown cells can be suppressed. When the cells strongly adhere to the high-level structure, the cells tend to grow in a two-dimensional manner, and can be mainly suitable for use as embedded medical materials. When the cells weakly adhere to the high-level structure, the cells tend to grow in a three-dimensional manner such as a sphere, and can be suitable for use as a scaffold material for three-dimensional cell culture in vitro. In addition, gelatin can be prevented from being easily soluble in vivo, and excellent operability when used as a medical material, a scaffold material for three-dimensional cell culture.

[0208] The thickness of the stacked high-order structure of the first embodiment is preferably 30 to 5000 μm, more preferably 50 to 3000 μm, further preferably 100 to 2000 μm, and particularly preferably 150 to 1000 μm. If the thickness of the stacked high-order structure is less than 30 μm, the strength of the stacked high-order structure is reduced and it is easily damaged, so it is not preferred. If it exceeds 5000 μm, the stacked high-order structure has sufficient strength for operation, but when used as a scaffold material for cell culture, problems such as cell death due to lack of oxygen near the center of the thickness of the stacked high-order structure may occur. The above thickness can be measured by attaching tape to the ends of the stacked high-order structure cut into 3 cm squares to fix the stacked high-order structure, and using a contact thickness gauge.

[0209] The porosity of the stacked high-order structure as the first embodiment is preferably in the range of 60 to 97%, more preferably 65 to 95%, further preferably 70 to 93%, and particularly preferably 75 to 92%. If the porosity is less than 60%, the elasticity of the stacked high-order structure is significantly reduced, for example, it is difficult to stick the stacked high-order structure along the affected area. On the other hand, if the porosity exceeds 97%, the pores are too large, so it is difficult to fix cells to the stacked high-order structure. The above porosity is measured by measuring the thickness and weight of the stacked high-order structure cut into 5 cm squares, and calculated using the following formula.

[0210] Porosity (%) = 100 × [1-a ÷ {(b + c) ÷ (b ÷ d + c ÷ e)} ÷ (f × 25)]

[0211] a: weight of the stacked high-level structure cut into 5 cm square (g);

[0212] b: fineness of gelatin fiber bundle (dtex);

[0213] c: fineness of thermoplastic fiber bundle (dtex);

[0214] d: gelatin fiber bundle density (g / cm 3 );

[0215] e: Thermoplastic fiber bundle density (g / cm 3 );

[0216] f: thickness of the laminated high-order structure (cm).

[0217] It should be noted that the density of gelatin fiber bundle is 1.27 g / cm 3 As the thermoplastic fiber bundle density, the polyglycolic acid fiber bundle density is 1.53 g / cm 3 , the density of polylactic acid fiber bundle is 1.25g / cm 3 In addition, when the high-order structure is made of gelatin fiber bundles only without using thermoplastic fiber bundles, the above c and e are not included in the calculation.

[0218] <Characteristics of high-order structures and stacked high-order structures>

[0219] The high-order structure and the laminated high-order structure of the first embodiment are excellent in texture, slipperiness, and cell adhesion.

[0220] The texture can be evaluated by the feel of the high-order structure and the stacked high-order structure when touched with dry hands. The texture can be evaluated by pinching the two ends of the high-order structure cut into 5 cm squares with both hands and stretching, or by stretching one end upward and the other end downward, and repeating this operation three times. If there is no stretchability, it is easy to become a hard texture and difficult to follow biological tissues, so appropriate stretchability is required.

[0221] The sliding property can be evaluated using a friction tester (model: KES-SE) manufactured by KATO TECH. After the high-level structure and the stacked high-level structure cut into 5 cm squares are immersed in distilled water for 1 hour, the sample is fixed on the measuring table with a metal frame, and a silicon sensor with a load of 50g and a square of 10mm is allowed to crawl at 1.0mm / second to measure the average friction coefficient and the average deviation of the friction coefficient.

[0222] The average friction coefficient of the high-order structure and the stacked high-order structure of the first embodiment is preferably 0.05 to 0.60, more preferably 0.10 to 0.50, further preferably 0.15 to 0.45, and most preferably 0.20 to 0.40. Within the above range, the high-order structure has a sliding property close to that of biological tissues, and is less likely to cause inflammation when rubbing against biological tissues.

[0223] The average deviation of the friction coefficient of the high-level structure of the first embodiment and the stacked high-level structure is preferably 0.40 to 1.60, more preferably 0.45 to 1.45, further preferably 0.50 to 1.40, and most preferably 0.60 to 1.30. If it is within the above range, the high-level structure of the first embodiment has softness and slipperiness close to biological tissue in a wet state. Therefore, it can be suitable for use as a raw material for wound / burn treatment or a matrix material for artificial skin, etc., and is not easy to cause inflammation when rubbed with biological tissue, so it is preferred.

[0224] The high-order structure comprising gelatin fiber bundles of the first embodiment and the stacked high-order structure are excellent in cell adhesion for fixing cells. Cell adhesion is closely related to cell culturing properties, and if cell adhesion is strong, cells are effectively fixed to the high-order structure, and cell culturing properties are excellent. On the other hand, if cell adhesion is low, cells can not be fixed to the high-order structure well, and as a result, cell culturing properties are in a tendency to deteriorate.

[0225] Gelatin is a raw material with biocompatibility (low antigenicity and high bioabsorbability), so it can be suitable as a scaffold material for excellent three-dimensional cell culture such as the fixity after promoting cell differentiation, enhancing cell function, transplantation. In addition, the high-level structure of the 1st embodiment and the stacked high-level structure have the pliability and slipperiness close to biological tissue under wet conditions. Therefore, it can be suitable as raw material or artificial skin matrix material etc. for wound / burn treatment, and it is not easy to produce inflammation when rubbing with biological tissue, so it is preferred.

[0226] The cell adhesion and cell culturing properties of the high-order structures and laminate structures can be evaluated by statically culturing HeLa cells on the structures for 3 days and observing the fluorescently labeled cells under a fluorescence microscope.

[0227] <<Second Implementation Method>>

[0228] <Structure of fiber sheet structure>

[0229] The fiber sheet structure of the present invention comprises a knitted tissue having a cell-carrying surface and a back surface, the average pore size of the back surface is smaller than the average pore size of the cell-carrying surface, the knitted tissue comprises a parallel twisted yarn bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle, the thickness of the fiber sheet structure is 30 to 5000 μm, the number of gelatin fibers constituting the gelatin fiber bundle is 5 to 30, the fineness of the gelatin fiber is 0.5 to 10 dtex, the total number of gelatin fiber bundles and thermoplastic resin fiber bundles in the parallel twisted yarn bundle is 2 to 20, and the ratio of the number of gelatin fiber bundles to the number of thermoplastic resin fiber bundles in the parallel twisted yarn bundle is 5:1 to 1:5.

[0230] The fiber sheet structure of the present invention includes a knitted structure. Knitted structure refers to a fabric structure in which a coil (loop) is continuously made and the next coil is hooked on the coil to form a surface. Knitted structures include weft knitting and warp knitting. Weft knitting is a knitted structure formed by continuously making meshes in the weft direction, and warp knitting is a knitted structure formed by continuously making meshes in the warp direction. Weft knitting includes plain knitted fabrics (plain knitted fabrics), rib knitted fabrics, and double reverse knitted fabrics, and warp knitting includes tricot / raschel warp knitted fabrics.

[0231] The knitted structure in the fiber sheet structure of the present invention includes a parallel-twisted yarn bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle.

[0232] The number of gelatin fibers constituting the gelatin fiber bundle in the fiber sheet structure of the present invention is preferably 5 to 60, more preferably 10 to 40.

[0233] The fineness of the gelatin fiber constituting the gelatin fiber bundle in the fiber sheet structure of the present invention is preferably 0.5 to 10 dtex, more preferably 1 to 8 dtex, and more preferably 2 to 5 dtex. The fineness of the gelatin fiber is a value obtained by measuring the number of grams per 10,000 m. If the fineness of the gelatin fiber is within the above range, the gelatin fiber itself becomes a thin and soft fiber, so that not only can the fuzzing on the gelatin fiber bundle due to broken fibers be suppressed, but also the gelatin fiber bundle can be prevented from becoming hard.

[0234] When the number of gelatin fibers constituting the gelatin fiber bundles in the fiber sheet structure of the present invention and the fineness of the gelatin fibers are within the above ranges, the quality of the fiber sheet structure, such as texture, stretchability, and dimensional stability, can be improved.

[0235] The preferred ranges and measuring methods of the tensile strength and elongation at break of the gelatin fiber bundles in the fiber sheet structure of the present invention are the same as those of the gelatin fiber bundles in the high-order structure of the first embodiment described above.

[0236] The cross-sectional shapes of the gelatin fibers constituting the gelatin fiber bundles in the fiber sheet structure of the present invention include solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a scaffold material for three-dimensional cell culture, irregular cross-sectional filaments such as flat, star, and triangle are sometimes preferred over solid circles.

[0237] When measuring the tensile strength and elongation at break of gelatin fiber bundles in a fiber sheet structure, a gelatin fiber bundle treated under the same insolubilization conditions as in the fiber sheet structure manufacturing process can be used as a measurement sample, or it can be cut with scissors, the ends of the fibers pinched, and more than 5 cm of thread can be pulled out as a measurement sample.

[0238] The thermoplastic resin of the thermoplastic resin fiber bundle in the fiber sheet structure of the present invention is not limited as long as it is a resin used as a medical material, and examples thereof include polyethylene terephthalate (PET), polylactic acid (PLLA, PLLDA), poly-ε-caprolactone (PCL), and their (LA-CL) copolymers, polyglycolic acid (PGA), copolymers of glycolic acid and lactic acid (PLGA), polyglutamic acid, etc. Among them, any one of polylactic acid (PLLA, PLLDA), copolymers of glycolic acid and lactic acid (PLGA), polyglycolic acid (PGA), and polyglutamic acid is preferred from the viewpoint that acid generation accompanying decomposition of the thermoplastic resin fiber bundle is relatively mild and is less likely to cause inflammation.

[0239] The number of thermoplastic resin fibers constituting the thermoplastic resin fiber bundle in the fiber sheet structure of the present invention is preferably 5 to 70, more preferably 7 to 50, and even more preferably 10 to 30. Within the above range, the strength of the fiber sheet structure can be significantly improved, which is preferred.

[0240] The total number of gelatin fiber bundles and thermoplastic resin fiber bundles constituting the parallel twisted yarn bundle in the fiber sheet structure of the present invention is preferably 2 to 20, more preferably 2 to 10. Within the above range, the number of parallel twists of the gelatin fiber bundles and thermoplastic resin fiber bundles can be reduced, and production efficiency can be improved.

[0241] The ratio of the number of gelatin fiber bundles to the number of thermoplastic resin fiber bundles in the twisted yarn bundles in the fiber sheet structure of the present invention is preferably 5:1 to 1:5. Within the above range, the twisted yarn bundles not only have a strength sufficient to withstand the production of the fiber sheet structure, but also have a slipperiness close to that of biological tissues, and are less likely to cause inflammation when rubbed against biological tissues. The more preferred range of the ratio of the number of gelatin fiber bundles to the number of thermoplastic resin fiber bundles in the twisted yarn bundles is 3:1 to 1:3.

[0242] The preferred ranges, measuring methods, and control methods of the tensile strength, elongation at break, weight loss when immersed in phosphate-buffered saline at 50°C for 4 hours, and swelling rate when immersed in phosphate-buffered saline at 50°C for 4 hours of the twisted yarn bundles in the fiber sheet structure of the present invention are the same as the preferred ranges, measuring methods, and control methods of the tensile strength, elongation at break, weight loss when immersed in phosphate-buffered saline at 50°C for 4 hours, and swelling rate when immersed in phosphate-buffered saline at 50°C for 4 hours of the twisted yarn bundles in the high-order structure of the first embodiment described above.

[0243] When the tensile strength, elongation at break, weight loss when immersed in phosphate-buffered saline at 50°C for 4 hours, and swelling ratio when immersed in phosphate-buffered saline at 50°C for 4 hours of the twisted yarn bundle in the above-mentioned fiber sheet structure are measured by the fiber sheet structure, the fiber sheet structure is cut with scissors, the yarn ends are pinched, and a twisted yarn bundle of more than 5 cm is pulled out as a sample for measurement.

[0244] The fiber cross-sectional shape of the thermoplastic resin fiber constituting the thermoplastic resin fiber bundle in the fiber sheet structure of the present invention may be any shape, including solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a scaffold material for three-dimensional cell culture, an irregular cross-sectional shape is sometimes preferred over a solid circle cross-sectional shape.

[0245] The thermoplastic resin fibers used in the fiber sheet structure of the present invention may contain additives similar to the additives that may be contained in the thermoplastic resin fibers used in the high-order structure of the first embodiment described above.

[0246] The fiber sheet structure of the present invention has a cell-carrying surface and a back surface. The cell-carrying surface is the surface on which cells are placed for cell culture and on which cells invade, and is the upper surface when placed in a cell culture container.

[0247] The fiber sheet structure of the present invention has an average pore size on the back side of the cell support that is smaller than the average pore size on the cell support surface. In this case, cells invade the fiber sheet structure from the cell support surface that does not hinder cell invasion and are fixed, which has the effect of inhibiting cells from slipping from the mesh on the back side of the cell support that is smaller than the average pore size on the cell support surface.

[0248] The average pore size of the cell-carrying surface of the fiber sheet structure of the present invention is preferably 5 to 123 μm, more preferably 10 to 115 μm. If the average pore size of the cell-carrying surface is within the above range, cells can be easily invaded from the surface of the fiber sheet structure into the interior of the structure, and cells can be prevented from slipping from the mesh (pores), and cells can be fixed on the fiber sheet structure. The average pore size of the cell-carrying surface in the fiber sheet structure of the present invention can be obtained by using a digital microscope (manufactured by Hirox Co., Ltd., RH-2000) to obtain a 35-fold image (number of pixels: 1920×1200) of the fiber sheet structure cut into 5 cm squares, and then using the 2D measurement software "HRS-2D" with a microscope, the obtained image is divided into pores and parts other than pores by binarization processing, and the software is used to prepare a histogram of pore size at intervals of 10 μm between 60 and 300 μm, and the average pore size is calculated by the following formula using the grade value and degree using the histogram.

[0249] Average pore size (μm) = {(total of grade value × degree)} ÷ (total of degree)

[0250] The average pore size of the cell-carrying back surface of the fiber sheet structure of the present invention is preferably 5 to 115 μm, more preferably 7 to 110 μm.

[0251] The ratio of the number of pores of 150 μm or more in the cell-carrying surface of the fiber sheet structure of the present invention is preferably 35% or less, more preferably 25% or less, further preferably 20% or less, and particularly preferably 15% or less. In the above case, the cells can be prevented from slipping from the mesh (pores), and the cells can be fixed on the fiber sheet structure. The ratio of the number of pores of 150 μm or more in the cell-carrying surface of the fiber sheet structure of the present invention can be calculated by using the above-mentioned histogram for calculating the average pore size, dividing the total number of degrees with a pore size of 150 μm or more by the total number of degrees between 60 and 300 μm, and calculating the ratio of the number of pores with a pore size of 150 μm or more.

[0252] The porosity of the fiber sheet structure of the present invention is preferably 60 to 97%, more preferably 65 to 95%, further preferably 70 to 93%, and particularly preferably 75 to 92%. If the porosity is less than 60%, the elasticity of the fiber sheet structure is significantly reduced, and it is difficult to attach the fiber sheet structure along the affected area. On the other hand, if the porosity exceeds 97%, the pores are too large, so it is difficult to fix cells to the fiber sheet structure. The method for measuring the porosity of the fiber sheet structure of the present invention is the same as the method for measuring the porosity of the high-order structure of the first embodiment described above.

[0253] The number of pores in the knitted structure of the fiber sheet structure of the present invention is preferably 600 pores / mm 3 More than, preferably 1.5×10 3 Pieces / mm 3 More than, preferably 1.8×10 3 Pieces / mm 3 More than, preferably 2.1×10 3 Pieces / mm 3 In the above case, a large number of cells can be transported into the fiber sheet structure, and the cells can be effectively fixed to the fiber sheet structure. The number of pores in the knitted structure in the fiber sheet structure of the present invention is calculated by the following formula using the average pore size and porosity obtained above.

[0254] Number of pores / mm 3 =a×0.01÷(4 / 3×3.14×(0.001×b / 2) 3 )

[0255] a: porosity (%);

[0256] b: pore size (μm).

[0257] The fiber sheet structure of the present invention is preferably a structure formed by stacking two layers, wherein the layer on the cell-carrying surface side and the layer on the back side are knitted tissues, and the knitted tissue is a plain knitted fabric or a plain stitch. Plain knitted fabrics or plain stitches have the characteristics of high flatness and smooth surface due to the few concave-convexities on the surface of the fabric. In addition, a layer of plain knitted fabrics or plain stitches usually curls, causing the sheet structure to become cylindrical. In this case, it is not only difficult to uniformly fix cells to the fiber sheet structure, but also poor in operability. However, by bonding the two layers of the sheet curled upwardly and the sheet curled downwardly, the stresses acting are mutually the same degree, so curling can be suppressed. By suppressing curling, not only can cells be uniformly fixed to the fiber sheet structure, but also operability is improved. Moreover, by stacking two layers, the area where cells are fixed can be increased, and the frequency of cells slipping off the mesh can be greatly reduced, so the result is a fiber sheet structure with excellent cell culturing properties.

[0258] The fiber sheet structure of the present invention is preferably a structure formed by stacking three layers, wherein the layer on the cell-carrying surface side of the structure is a knitted structure, the layer on the back side is a nonwoven fabric, the intermediate layer between the layer on the surface side and the layer on the back side is a knitted structure, the knitted structure is a plain knitted fabric or a plain needle structure, and the nonwoven fabric contains gelatin fibers. Since the nonwoven fabric does not curl due to the absence of residual stress, the stress acting on the intermediate layer between the layer on the surface side and the layer on the back side is set to a knitted structure, and the stresses are the same, so curling can be suppressed. By suppressing curling, not only can the cells be uniformly fixed to the fiber sheet structure, but also the operability is improved. In addition, compared with the knitted fabric structure, the average pore size of the nonwoven fabric is overwhelmingly small, so the cells invading from the cell-carrying surface side can be retained in the fiber sheet structure, resulting in a fiber sheet structure with excellent cell culturing properties.

[0259] The fiber sheet structure of the present invention is preferably a structure formed by stacking two layers, wherein the layer on the cell-carrying surface side is a knitted tissue, and the layer on the back side is a nonwoven fabric, the knitted tissue is a ribbed tissue, and the nonwoven fabric contains gelatin fibers. Rib knitting is a tissue that the surface and the back are the same, so it does not curl. The nonwoven fabric does not curl either, so the structure stacked with the nonwoven fabric does not curl. Therefore, not only can the cells be uniformly fixed to the fiber sheet structure, but the operability is also improved. Compared with the knitted fabric structure, the average pore size of the nonwoven fabric is overwhelmingly small, so the cells invading from the cell-carrying surface side can be retained in the fiber sheet structure, resulting in a fiber sheet structure with excellent cell culturing properties. In addition, compared with the fiber sheet structure formed by overlapping two layers of knitted tissues, the knitted tissue is one layer, so it has the characteristic of being able to make the thickness thinner.

[0260] The fiber sheet structure of the present invention is preferably a knitted structure composed of a rib structure. In the above case, the rib knitting does not curl, so that the cells can be evenly fixed to the fiber sheet structure and the handling is improved. In addition, compared with a fiber sheet structure formed by overlapping two layers of knitted structures, the knitted structure is a single layer, so there is a feature that the thickness can be reduced.

[0261] The thickness of the fiber sheet structure of the present invention is preferably 30 to 5000 μm, more preferably 50 to 3000 μm, further preferably 100 to 2000 μm, and particularly preferably 150 to 1000 μm. In the case of the above range, the fiber sheet structure has high strength and is not easily damaged. In addition, when used as a scaffold material for cell culture, problems such as cell death due to lack of oxygen near the center of the thickness of the fiber sheet structure can be prevented. The thickness of the fiber sheet structure of the present invention can be measured by attaching tape to the ends of the fiber sheet structure cut into 3 cm squares to fix the fiber sheet structure, and using a contact thickness meter.

[0262] The preferred range, measuring method, and control method of the weight loss rate of the fiber sheet structure of the present invention when immersed in phosphate-buffered saline at 50°C for 4 hours are the same as the preferred range, measuring method, and control method of the weight loss rate of the high-order structure of the first embodiment described above when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0263] The fiber sheet structure of the present invention contains gelatin fiber bundles, so that the touch in a wet state is close to that of biological tissue, and therefore has the characteristic of being easy to slide compared to a fiber sheet structure composed only of thermoplastic resin fiber bundles. Generally, a fiber sheet structure composed of thermoplastic resin fiber bundles is hydrophobic, so there is a problem that it is very difficult to make the cell culture fluid infiltrate the fiber sheet structure. However, the fiber sheet structure of the present invention contains gelatin fiber bundles with excellent hydrophilicity, so it can not only make the cell culture fluid easily infiltrated and retained, but also make the body fluid containing oxygen or nutrients diffuse in the body, and it is easy to fix cells inside the fiber sheet structure and make them grow.

[0264] The method for producing the fiber sheet structure of the present invention will be described below, but is not particularly limited.

[0265] The method for producing the fiber sheet structure of the present invention preferably includes the following steps 1 and 2, as well as step 3-1, step 3-2 or step 3-3, and step 4-1 or step 4-2.

[0266] (Step 1) extruding a spinning solution composed of a gelatin solution containing 30 to 70% by weight of a gelatin raw material into a fiber form from a multi-hole spinneret at a temperature 1 to 15° C. higher than the sol-gel transition temperature of the gelatin spinning solution;

[0267] (Step 2) winding the extruded gelatin fibers onto a bobbin to prepare a gelatin fiber bundle precursor;

[0268] (Step 3-1) The gelatin fiber bundle precursor and the thermoplastic resin fiber are twisted and then organized to produce a second high-order structure;

[0269] (Step 3-2) The gelatin fiber bundle precursor and the thermoplastic resin fiber are twisted and then organized, and then the gelatin nonwoven fabric is laminated to produce a second laminated high-grade structure;

[0270] (Step 3-3) The gelatin fiber bundle precursor is insolubilized and then twisted with thermoplastic resin fibers to further organize the fibers, thereby producing a second high-order structure;

[0271] (Step 4-1) Insolubilizing the gelatin contained in the second high-order structure and the second stacked high-order structure obtained in steps 3-1 and 3-2 and then pressing to produce a fiber sheet structure;

[0272] (Step 4-2) Pressing the second high-order structure obtained in step 3-3 to produce a fiber sheet structure;

[0273] In the above-mentioned step 2, it is preferred that a conveying step of conveying the extruded gelatin fiber along the circumferential surface of a conveying roller is included before the extruded gelatin fiber is wound onto a bobbin, and the moisture regain of the extruded gelatin fiber when it reaches the first conveying roller that it initially arrives at is 5 to 25% by weight.

[0274] The moisture regain of the gelatin fiber bundle precursor is preferably 5 to 20% by weight.

[0275] The above step 2 includes a step of allowing a mixed solution of at least one selected from ethylene glycol, polyethylene glycol, and glycerin and a lower alcohol to adhere to the extruded gelatin fibers before winding them onto a bobbin.

[0276] In the above step 1, it is preferred that the gel strength of the gelatin is 100 to 350 g, and the sol-gel transition temperature of the gelatin spinning solution is 15 to 60°C.

[0277] The fiber sheet structure of the present invention can be produced by extruding a spinning stock solution composed of a gelatin solution from a multi-hole spinneret into a fiber shape, winding the extruded gelatin fibers on a bobbin to produce a gelatin fiber bundle precursor, twisting the gelatin fiber bundle precursor and thermoplastic resin fibers together and then texturizing them, and insolubilizing the second high-order structure obtained or the second laminated high-order structure obtained by laminating a nonwoven fabric on the second high-order structure and then pressing it to produce the fiber sheet structure. Alternatively, as described above, the fiber sheet structure can be produced by twisting the gelatin fiber bundle precursor and thermoplastic resin fibers together and then texturizing them, and then pressing the second high-order structure obtained by thus obtaining.

[0278] It should be noted that texturization refers to the production of woven fabrics, knitted fabrics or braids by twisting and twisting yarn bundles.

[0279] The gelatin raw material constituting the gelatin solution in the fiber sheet structure of the present invention is obtained as a molecular chain by unwinding the triple helix of collagen from cattle bones, cowhide, pig skin, bird or fish. The gelatin raw material in the fiber sheet structure of the present invention may be a gelatin raw material manufactured by any of the methods, or may be a commercially available gelatin raw material. In addition, commercially available gelatin raw materials undergo various purification processes before extraction during their manufacturing process, so there are few components other than protein, usually with a protein content of more than 85%, a water content of 8 to 14%, an ash content of less than 2%, and other components (lipids, polysaccharides, etc.) of less than 1%. The present invention may also use the general gelatin raw material. The gelatin raw material is a thermally modified substance of collagen, so its amino acid composition is roughly the same as that of collagen, but it is very special compared to other proteins, with glycine accounting for about one-third of the total, and one out of every three in the amino acid sequence being repeated. As a method for distinguishing collagen from gelatin, for example, the signal around 31.5 degrees obtained in wide-angle X-ray measurement can be observed. The 31.5-degree signal is a signal from the triple helical structure of collagen, and when the triple helical structure characterized by collagen is unwound to become gelatin, the signal disappears.

[0280] The molecular weight of the gelatin raw material is not particularly limited, but the gel strength, which is highly correlated with the molecular weight, is preferably 100 to 350 g, more preferably 150 to 320 g, and still more preferably 220 to 310 g from the viewpoint of spinnability. The gel strength refers to the load (g) required to press down 4 mm with a plunger having a diameter of 1 / 2 inch (12.7 mm) on the surface of a prepared gelatin solution after cooling a 6.67% gelatin aqueous solution at 10° C. for 17 hours using a small table-top tester EZ-SX manufactured by Shimadzu Corporation.

[0281] When the gel strength of the gelatin raw material is within the above range, it is possible to prevent the spinnability of the gelatin fiber from being significantly reduced, and further, by suppressing the moisture retention rate in the fiber, it is possible to prevent the fiber from being broken during winding.

[0282] The content of the gelatin raw material in the gelatin solution is preferably 30 to 70% by weight, more preferably 40 to 60% by weight. If the content of the gelatin raw material in the gelatin solution is within the above range, the spinnability of the gelatin fiber can be prevented from being significantly reduced, and the bubbles generated during the gelatin solution manufacturing process are easily degassed, which can prevent the breakage of the fibers during spinning.

[0283] The solvent for dissolving the gelatin raw material is water, and (poly)alcohols, dimethyl sulfoxide, etc. may be added to adjust the viscosity as needed.

[0284] The sol-gel transition temperature of the gelatin solution is preferably 15 to 60° C., more preferably 20 to 60° C., further preferably 20 to 55° C., and particularly preferably 20 to 50° C. The sol-gel transition temperature is measured using, for example, a rheometer ARES manufactured by TA Instruments.

[0285] If the sol-gel transition temperature is within the above range, the adhesion can be suppressed from becoming stronger, the operability when manufacturing gelatin fibers can be improved, and the adhesion of the wound gelatin fibers can be prevented. In addition, the thermal decomposition of gelatin at the spinning temperature and the resulting fiber breakage can be prevented.

[0286] The gelatin fiber bundle precursor is produced by extruding a spinning solution composed of gelatin raw materials and solvents such as water from a multi-hole spinneret into the air to form fibers, orienting the molecular chains of the triple helix molecules of collagen that are untied by stretching just below the spinneret, and controlling the moisture content in the fibers appropriately. By controlling the orientation of the molecular chains of the untied triple helix molecules of collagen and the moisture regain in the fibers, the tensile strength and elongation at break of the fibers can be increased, and the adhesion between the fibers can be suppressed.

[0287] The spinning process of extruding the spinning solution from a porous spinneret into the air into a fiber shape can be any of the dry, semi-dry, and wet methods. In the process of drying and removing the solvent, pores can be prevented from being formed on the surface or inside of the fiber, and the tensile strength or elongation at break of the gelatin fiber can be suppressed from decreasing, so it is preferably produced by the dry method. The dry spinning temperature is preferably a temperature 1 to 25°C higher than the sol-gel transition temperature of the spinning solution, and more preferably a temperature 5 to 20°C higher than the sol-gel transition temperature. If it is within the above range, a significant decrease in the drawability can be prevented.

[0288] In the production of the gelatin fiber bundle precursor used in the present invention, it is preferred to rapidly reduce the moisture content in the fiber to a range of 5 to 25% by weight immediately after spinning. If the moisture content in the fiber is within the above range, adhesion can be suppressed, and the gelatin fibers discharged from the multi-hole spinneret can be prevented from sticking to each other, or the gelatin fibers can be prevented from sticking to the roller in the production process. In addition, the gelatin fiber precursor wound on the bobbin can be easily unwound from the bobbin. In addition, a significant decrease in the elongation of the filament can be suppressed, and the filament breakage can be prevented in the production process of the gelatin fiber bundle and the production process of the fiber sheet structure rewound from the bobbin.

[0289] Before the gelatin fibers extruded from the spinneret are wound onto a bobbin, a conveying step of conveying the fibers along the circumferential surface of a conveying roller may be included.

[0290] When the extruded gelatin fiber reaches the first conveying roller, the moisture regain of the gelatin fiber is preferably 5 to 25% by weight, more preferably 5 to 20% by weight. The moisture regain is measured by winding the gelatin yarn around the first conveying roller, measuring 0.5 g of the wound fiber, and using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) at 150°C / N2 atmosphere.

[0291] When the moisture regain is within the above range, the gelatin fibers can be prevented from adhering to the conveying rollers, and a significant decrease in the elongation of the yarn can be suppressed, thereby preventing yarn breakage.

[0292] The moisture regain can be controlled by drying with dry air or dry hot air or the like.

[0293] In order to prevent the fibers from sticking together due to contact between each other, it is preferable to use a grooved guide roller or the like as the feed roller.

[0294] The moisture regain of the gelatin fiber bundle precursor obtained by winding the gelatin fiber on a bobbin is preferably 5 to 20% by weight, more preferably 5 to 15% by weight. The moisture regain is measured by measuring 0.5 g of the fiber bundle precursor wound on a bobbin using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) at 150°C / N2 atmosphere.

[0295] When the moisture regain is within the above range, the gelatin fiber precursor can be easily unwound from the bobbin, and a significant decrease in the elongation of the yarn can be suppressed, thereby preventing yarn breakage during the production process of the fiber sheet structure rewound from the bobbin.

[0296] The moisture regain can be controlled by drying with dry hot air, etc. In addition, after passing through the first conveying roller, the fiber bundle can be dried in time using a winder.

[0297] The gelatin fiber bundle used in the present invention is preferably manufactured with a spinning draft (discharge line speed / winding speed) in the range of 0.01 to 2, and more preferably in the range of 0.05 to 1.5. If it is within the above range, the orientation of the triple helical molecules of the unwound collagen becomes sufficient, which can prevent the decrease in tensile strength. In addition, the fiber diameter can be suppressed from becoming too large, and the moisture regain of the gelatin fiber can be sufficiently reduced before reaching the first conveying roller. As a result, the gelatin fiber can be prevented from adhering to the roller. In addition, a significant decrease in the elongation at break can be suppressed, and the broken fibers can be prevented during the manufacturing process of the gelatin fiber bundle and the manufacturing process of the fiber sheet structure rewound from the bobbin.

[0298] Before the gelatin fibers extruded from the spinneret are wound onto the bobbin, a process of attaching an oil agent to the gelatin fibers may be included. Preferably, the oil agent is attached to the fiber surface after the moisture regain in the fiber reaches a range of 5 to 20% by weight. By attaching the oil agent to the fiber surface, multiple gelatin fibers can be gathered into a gelatin fiber bundle for operation. By attaching the oil agent, the operability of the silk is significantly improved in the manufacturing process of the gelatin fiber bundle and the manufacturing process of the fiber sheet structure rewound from the bobbin. From the perspective of using the fiber sheet structure of the present invention as a medical material, it is preferred to use a biocompatible oil agent, for example, ethylene glycol, polyethylene glycol, glycerol, etc. It is preferred that these compounds are diluted with lower alcohols such as ethanol, attached to the fiber surface in the form of a mixed solution, and then the lower alcohol is removed by drying. The oil agent can be removed by washing after the fiber sheet structure is made, or it can be formed in an attached state. There is no restriction on the amount of oil agent attached, as long as it is an amount of attachment that allows multiple gelatin fibers to be gathered into a fiber bundle, for example, preferably 0.5 to 5% by weight.

[0299] The fiber cross-sectional shape of gelatin fiber can be any shape. Examples of the fiber cross-sectional shape include solid circle, hollow, flat, star, triangle, solid circle + fin, hollow + fin, etc. When used as a three-dimensional cell culture scaffold material, irregular cross-sectional filaments with irregular cross-sections such as flat, star, triangle, etc. are sometimes preferred over solid circle cross-sectional filaments.

[0300] The tensile strength of the gelatin fiber is preferably 0.5 to 3 cN / dtex, more preferably 0.7 to 2.8 cN / dtex, and further preferably 1.0 to 2.5 cN / dtex. The tensile strength of the gelatin fiber is measured by taking out a single yarn from a gelatin fiber bundle precursor, for example, using Tensilon (RTC-1210A manufactured by Orientec).

[0301] The breaking elongation of the gelatin fiber is preferably 30 to 250%, more preferably 40 to 200%, and even more preferably 50 to 150%. The breaking elongation of the gelatin fiber is measured by taking out a single yarn from a gelatin fiber bundle, for example, using Tensilon (RTC-1210A manufactured by Orientec).

[0302] When the tensile strength and elongation at break of the gelatin fiber are within the above ranges, the gelatin fiber bundle can be produced or the fiber sheet structure can be prepared.

[0303] As a process for insolubilizing the gelatin fiber bundle precursor, the gelatin fiber bundle precursor may be insolubilized to produce the gelatin fiber bundle, or the fiber bundle precursor may be twisted with thermoplastic resin fibers and then insolubilized to produce a fiber sheet structure composed of gelatin fiber bundles. Insolubilization (water-insoluble treatment) may be any of thermal crosslinking, chemical crosslinking using a crosslinking agent, and physical crosslinking using ultraviolet rays, radiation, or electron beams, and may be combined as appropriate. In the case of thermal crosslinking, it may be performed in the atmosphere or in a vacuum. The temperature during thermal crosslinking is in the range of 110 to 200°C, more preferably 120 to 190°C, and further preferably 130 to 180°C. If the temperature is lower than 100°C, the crosslinking is insufficient, and gelatin dissolves in water in a wet state and cannot be used as a scaffold material. At a temperature higher than 200°C, gelatin undergoes thermal decomposition, resulting in a significant decrease in fiber strength, which is not preferred. The degree of crosslinking can be changed in time by combining the heat treatment temperature and the heat treatment time. The heat treatment time is preferably 3 to 72 hours, and from the viewpoint of productivity, it is preferably in the range of 12 to 50 hours. In the case of chemical crosslinking using a crosslinking agent, pores are formed in the fibers during the washing process to remove the crosslinking agent in the fibers, and the tensile strength or elongation at break of the gelatin fibers is sometimes reduced. In this case, fiber breakage is sometimes caused in the process of making a fiber sheet structure from the insolubilized gelatin fiber bundle. Therefore, in the case of insolubilization treatment by chemical crosslinking, it is preferred to perform chemical crosslinking treatment after organizing the fiber bundle precursor. Examples of the crosslinking agent used in the chemical crosslinking include glutaraldehyde, hexamethylene diisocyanate, and the like.

[0304] The tensile strength or elongation at break of the insolubilized gelatin fiber is measured by extracting a single filament from a gelatin fiber bundle obtained by insolubilizing a gelatin fiber bundle precursor, for example, using Tensilon (RTC-1210A manufactured by Orientec). The elongation at break of the insolubilized single filament is preferably 30 to 250%, more preferably 40 to 200%, and further preferably 50 to 150%. If the tensile strength and elongation at break of the insolubilized single filament are within the above ranges, the fiber sheet structure can be made.

[0305] The thermoplastic resin fibers in the fiber sheet structure of the present invention can be produced by melt spinning, or commercially available thermoplastic resin fiber bundles can be purchased and used.

[0306] The parallel twisted yarn bundle in the fiber sheet structure of the present invention can be produced using a parallel twisted yarn bundle precursor composed of a gelatin fiber bundle precursor and a thermoplastic resin fiber bundle as a starting material. The parallel twisted yarn bundle precursor composed of a gelatin fiber bundle precursor and a thermoplastic resin fiber bundle can be produced by supplying a plurality of fiber bundle precursors to a parallel twisting machine.

[0307] The thermoplastic resin fiber bundle may be twisted while being spirally wound around the gelatin fiber bundle precursor, or the gelatin fiber bundle precursor may be twisted while being spirally wound around the thermoplastic resin fiber bundle.

[0308] The gelatin fiber bundle precursor and the thermoplastic resin fiber bundle to which the oil agent is attached may be twisted together by twisting or the like, or may be twisted together by entanglement of the fiber bundles by interlacing or the like.

[0309] Alternatively, multiple spools of gelatin fiber bundle precursors and multiple spools of thermoplastic resin fiber bundles may be placed on a knitting machine and the gelatin fiber bundle precursors and thermoplastic resin fiber bundles may be twisted together during delivery to the needles of the knitting machine.

[0310] The parallel twisted yarn composed of a gelatin fiber bundle precursor and a thermoplastic resin fiber bundle can be composed of a gelatin fiber bundle and a thermoplastic resin fiber bundle that have been insolubilized in advance. A second higher-order structure can be produced by organizing the parallel twisted yarn bundle after production. A second stacked higher-order structure having a nonwoven fabric stacked on the second higher-order structure can be produced. For example, in the case of stacking gelatin or collagen nonwoven fabrics, the following method can be exemplified: after organizing the second higher-order structure, a nonwoven fabric is stacked on the second higher-order structure by electrospinning or the like. The stacked gelatin or collagen nonwoven fabric can be made insoluble in water by cross-linking treatment.

[0311] The second high-level structure can be made, for example, using Whole Garment (registered trademark) manufactured by Shimadzu Corporation. As a gauge, it can be in the range of 5 to 20 gauges. If it is less than 5 gauges, the fineness of the twisted yarn bundle needs to be high, so it will cause the mesh of the second high-level structure to be clogged, inhibiting the invasion of cells from the cell-carrying surface into the fiber sheet structure. On the other hand, if it exceeds 20 gauges, the fineness of the twisted yarn bundle needs to be low, so the strength of the twisted yarn bundle is weak, so sometimes the yarn breaks when making the second high-level structure. Therefore, the most preferred range is 10 to 20 gauges, and further 13 to 18 gauges.

[0312] The second high-level structure may be a single-sided knitted fabric consisting of one layer (sheet) or a double-sided knitted fabric formed by stacking two layers. The double-sided knitted fabric formed by stacking two layers may be produced by, for example, using WholeGarment (registered trademark) manufactured by Shimadzu Corporation, knitting the two layers separately and knitting the two layers together at the same time.

[0313] As the knitted fabric of the second high-level structure, preferably a plain knitted fabric or a plain stitch, or a rib knitted fabric. Because the surface of the fabric of the plain knitted fabric or the plain stitch is less uneven, the flatness is high and the surface is smooth, so it has a slipperiness close to that of biological tissue. On the other hand, curling can cause the sheet structure to become cylindrical, so it is not only difficult to evenly fix the cells on the fiber sheet structure, but also the operability is deteriorated. Therefore, by weaving in two layers of a plain knitted fabric or a plain knitted fabric sheet with upward convex curling and a plain knitted fabric or a plain knitted fabric sheet with downward convex curling, the stresses acting are made to be the same degree, and a structure formed by stacking two layers that suppress curling is made. Moreover, by stacking two layers, the surface area of ​​the fixed cells is increased, and the frequency of the cells sliding off the mesh can be greatly reduced, and as a result, a fiber sheet structure with excellent cell culture properties is formed. Moreover, by stacking a nonwoven fabric whose average pore size is overwhelmingly smaller than that of the knitted fabric, the cells invading from the cell-carrying surface side can be left more in the fiber sheet structure, and as a result, a fiber sheet structure with excellent cell culture properties is formed.

[0314] Rib knitting does not curl because the surface and the back are the same organization, but the surface of the fabric is more uneven than that of plain knitted fabric or plain knitted fabric. However, the unevenness of the fabric surface can be eliminated by the pressing process of the fiber sheet structure manufacturing process, and the surface can be smooth and close to the sliding property of biological tissue. Since rib knitting does not curl, cells can be evenly fixed to the fiber sheet structure. Therefore, it is not necessary to make 2 layers. By stacking non-woven fabrics with an average pore size that is overwhelmingly smaller than that of knitted fabrics, more cells invading from the cell-carrying surface side can be left in the fiber sheet structure. Moreover, compared with the fiber sheet structure with two layers of knitted tissues overlapped, the knitted tissue is 1 layer, so the thickness of the fiber sheet structure can be thinned, making it a softer texture.

[0315] The average pore size of the second high-order structure used to make the fiber sheet structure is preferably in the range of 20 to 200 μm. The fiber sheet structure is manufactured by applying a temperature of 40 to 100°C to one side of the second high-order structure or the second laminated high-order structure (nonwoven fabric surface) and performing a press treatment. By the press treatment, the meshes on the surface and back of the second high-order structure are crushed, but the meshes on the surface to which the temperature is applied are more crushed than the surface not to which the temperature is applied, resulting in a fiber sheet structure having a back side with a smaller average pore size than the cell-carrying surface, and the surface and the back side being asymmetrical. If the average pore size of the second high-order structure is in the range of 20 to 200 μm, a fiber sheet structure having excellent cell culturing properties is obtained by press treatment, in which the average pore size of the cell-carrying surface is 5 to 123 μm, and the number of pores larger than 150 μm on the cell-carrying surface is less than 35%. If the average pore size of the second higher-order structure is less than 20 μm, the mesh of the fiber sheet structure is blocked by the pressing process, thereby inhibiting the cells from invading the fiber sheet structure from the cell-carrying surface. If it exceeds 200 μm, the mesh cannot be fully crushed by the pressing process, and the cells will slip from the mesh of the fiber sheet structure. The average pore size of the second higher-order structure is in the range of 25 to 150 μm, more preferably 30 to 130 μm.

[0316] The fiber sheet structure of the present invention has a cell-carrying surface and a back surface, and the average pore size of the back surface is smaller than the average pore size of the cell-carrying surface, and is a biaxially asymmetric fiber sheet structure. This biaxially asymmetric fiber sheet structure is manufactured, for example, by applying a temperature of 40 to 100° C. to a single surface of the second high-level structure or the nonwoven fabric surface of the second laminated high-level structure while pressing after removing the oil or knitting machine oil attached to the second high-level structure or the second laminated high-level structure by washing. The reason is not yet clear, but it is speculated as follows: by removing the oil or knitting machine oil, the convergence of the fiber bundle is reduced, and in this state, the linear expansion of the gelatin fiber and the thermoplastic resin fiber due to heat is different, so the fiber bundle is further untied, and the fiber bundle is widened by pressing. By adopting this method, a biaxially asymmetric fiber sheet structure having a cell-carrying surface and a back surface, and the average pore size of the back surface is smaller than the average pore size of the cell-carrying surface, can be manufactured. As an apparatus for pressing the fiber sheet structure by applying temperature to only one side, a temperature-adjustable hydraulic press (oil pressure press) or a calender roll can be exemplified.

[0317] The fiber sheet structure produced in the present invention can be immersed in a 20-80% glycerol aqueous solution, for example. By immersing the fiber sheet structure in a glycerol aqueous solution, a moist medical material with better followability to the affected area can be obtained.

[0318] The fiber sheet structure of the present invention may contain additives. Examples of additives include polyacids such as citric acid (anhydride) and maleic acid (anhydride), magnetic particles such as gamma iron oxide, inorganic substances such as hydroxyapatite, endogenous proteins that promote cell growth or differentiation, collagen, etc. These additives may be applied to the fiber sheet structure, or to gelatin fiber bundles, gelatin fiber bundle precursors, gelatin fibers, or added to gelatin raw materials.

[0319] <Characteristics of fiber sheet structure>

[0320] The fiber sheet structure of the present invention is excellent in texture, slipperiness, cell adhesion, and cell culturing properties.

[0321] The texture of the fiber sheet structure of the present invention can be evaluated by the feel of the fiber sheet structure when it is touched with dry hands. The texture is evaluated by pinching both ends of a fiber sheet structure cut into 5 cm squares with both hands and stretching it, or by stretching one end upward and the other end downward, and repeating this operation three times. If there is no stretchability, the texture is likely to be hard and difficult to follow biological tissues, so appropriate stretchability is required.

[0322] The sliding property of the fiber sheet structure of the present invention can be evaluated using a friction tester (model: KES-SE) manufactured by KATO TECH. After the fiber sheet structure cut into 5 cm squares is immersed in distilled water for 1 hour, the sample is fixed on a measuring table with a metal frame, and a 10 mm square silicon sensor with a load of 50 g is allowed to crawl at 1.0 mm / sec to measure the average friction coefficient and the average deviation of the friction coefficient.

[0323] The average friction coefficient of the fiber sheet structure of the present invention is preferably 0.05 to 0.60, more preferably 0.10 to 0.50, further preferably 0.15 to 0.45, and most preferably 0.20 to 0.40. Within the above range, the fiber sheet structure has a sliding property close to that of biological tissues and is less likely to cause inflammation when rubbing against biological tissues.

[0324] The average deviation of the friction coefficient of the fiber sheet structure of the present invention is preferably 0.40 to 1.60, more preferably 0.45 to 1.45, further preferably 0.50 to 1.40, and most preferably 0.55 to 1.35. If it is within the above range, the fiber sheet structure of the present invention has softness and slipperiness close to that of biological tissue in a wet state. Therefore, it can be suitably used as a raw material for wound / burn treatment or a matrix material for artificial skin, etc., and is less likely to cause inflammation when rubbed against biological tissue, so it is preferred.

[0325] The fiber sheet structure of the present invention has excellent cell adhesion for fixing cells. Cell adhesion is closely related to cell culturing properties. If the cell adhesion is strong, the cells are effectively fixed to the fiber sheet structure and the cell culturing properties are excellent. On the other hand, if the cell adhesion is low, the cells cannot be well fixed to the fiber sheet structure, and as a result, the cell culturing properties tend to deteriorate. Regarding cell culturing properties, NIH3T3 cells can be statically cultured on a fiber sheet structure set in a 24-well plate for 7 days, and then 100 μL of WST-1 is added. After standing for 3 hours in a CO2 incubator (37°C, CO2 concentration of 5%), 300 μL is transferred to a 96-well plate, and the absorbance (450nm, reference wavelength 630nm) is measured using an ELISA reader (VERSAMax), and the evaluation is performed based on the number of cell cultures obtained. The number of cell cultures is preferably 10×10 4 cells / mL or more, more preferably 20×10 4 cells / mL or more, and further 25×10 4 More than cells / mL.

[0326] Gelatin is a raw material with biocompatibility (low antigenicity and high bioabsorbability), and therefore can be used as a scaffold material for three-dimensional cell culture with excellent properties such as promoting cell differentiation, enhancing cell function, and post-transplant fixation. In addition, the fiber sheet structure of the present invention has softness and slipperiness close to that of biological tissues in a wet state. Therefore, it can be used as a raw material for wound / burn treatment or a matrix material for artificial skin, and is not prone to inflammation when rubbed against biological tissues, so it is preferred.

[0327] Regarding the cell adhesion of the fiber sheet structure, NIH3T3 cells can be statically cultured on the structure for 7 days, and the fluorescently labeled cells can be observed under a fluorescence microscope to evaluate the cell adhesion.

[0328] Since the fiber sheet structure of the present invention does not curl, it can not only fix cells uniformly, but also has excellent operability. The presence or absence of curl can be determined by punching the fiber sheet structure with a punch punch to make a φ14 mm circular sheet, immersing the sheet in a beaker filled with 50°C phosphate buffered saline for 4 hours, and visually confirming the presence or absence of curl.

[0329] Example

[0330] The following examples are given to further specifically illustrate the fiber sheet structure of the present invention. The materials, usage amounts, ratios, processing sequences, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the purpose of the present invention. Therefore, the scope of the fiber sheet structure of the present invention should not be interpreted as being limited by the specific examples shown below.

[0331] <Measurement method, evaluation method>

[0332] The measuring methods and evaluation methods used in Examples and Comparative Examples are as follows.

[0333] [Fiber fineness]

[0334] The fineness of the thermoplastic resin fiber bundle was measured with an automatic vibration fineness measuring instrument Denier Computer DC-77A (manufactured by Search (KK)) at a temperature of 20±2°C and a relative humidity of 65±2% with N=3, and the average value was taken as the fineness. The fineness of the thermoplastic resin fiber was calculated by dividing the fineness of the thermoplastic resin fiber bundle by the number of thermoplastic resin fibers constituting the fiber bundle.

[0335] The gelatin fiber bundle precursor or gelatin fiber bundle was cut into 100 mm pieces, and the weight was measured using an electronic balance (XP6V manufactured by METTLER TOLEDO) with N=3, and the average value was converted into dtex as the fineness. The fineness of the gelatin fiber was calculated by dividing the fineness of the gelatin fiber bundle precursor or the fineness of the gelatin fiber bundle by the number of gelatin fibers constituting the fiber bundle.

[0336] [Mechanical strength of fiber]

[0337] The mechanical strength of gelatin fibers and insoluble gelatin fibers was measured using Tensilon (RTC-1210A manufactured by Orientec) at N = 5. The tensile strength and elongation at break of gelatin fibers were measured at a tensile speed of 20 mm / min and a chuck distance of 50 mm.

[0338] [Mechanical strength of fiber bundles and twisted yarn bundles]

[0339] The mechanical strength of the gelatin fiber bundle or the twisted yarn bundle was measured using Tensilon (RTC-1210A manufactured by Orientec) with N = 5. It should be noted that the tensile speed was set to 20 mm / min and the chuck spacing was set to 50 mm, and the tensile strength and elongation at break of the gelatin fiber bundle or the twisted yarn bundle, and the upper yield stress and lower yield stress of the gelatin fiber bundle were measured.

[0340] [Weight loss rate of gelatin fiber bundles and twisted yarn bundles]

[0341] Measure the weight of a 100 mm gelatin fiber bundle or a twisted yarn bundle, wrap it with a 10 μm membrane filter, and immerse it in phosphate-buffered saline at 50°C for 4 hours. Next, lift the membrane filter containing the gelatin fiber bundle or the twisted yarn bundle from the phosphate-buffered saline and immerse it in room temperature water for 30 minutes. After that, use a KimTowel to absorb the moisture, dry the membrane filter containing the gelatin fiber bundle or the twisted yarn bundle at 80°C for 24 hours, take out the fiber bundle from the membrane filter, and measure the weight. The weight loss rate is calculated using the following formula. Perform this operation with N=3, and take the average value as the weight loss rate.

[0342] Weight loss rate [%] = 100 - [100 × (weight after immersion)] / (weight before immersion)

[0343] [Weight loss rate of high-order structures, laminated high-order structures and fiber sheet structures]

[0344] Measuring 25cm 2 The weight of the high-level structure, stacked high-level structure or fiber sheet structure is measured by wrapping it with a 10μm membrane filter and immersing it in phosphate-buffered saline at 50°C for 4 hours. The membrane filter containing the high-level structure, stacked high-level structure or fiber sheet structure is lifted out of the phosphate-buffered saline and immersed in room temperature water for 30 minutes. The moisture is then absorbed with a KimTowel. The membrane filter containing the high-level structure, stacked high-level structure and fiber sheet structure is dried at 80°C for 24 hours. The high-level structure, stacked high-level structure or fiber sheet structure is taken out from the membrane filter and the weight is measured. The weight loss rate is calculated by the following formula. This operation is performed with N=3, and the average value is taken as the weight loss rate.

[0345] Weight loss rate [%] = 100 - [100 × (weight after immersion)] / (weight before immersion)

[0346] [Thickness of high-order structure, laminated high-order structure and fiber sheet structure]

[0347] Tape was pasted on the end of the high-level structure, stacked high-level structure or fiber sheet structure cut into 3 cm square to fix the high-level structure, stacked high-level structure or fiber sheet structure, and the measurement was performed using a contact thickness meter [LITEMATIC VL-50, manufactured by Mitutoyo]. A cylindrical terminal with a diameter of 5 mm was used as the measurement terminal, and a load of 7 g was adjusted during the measurement. The thickness of any 5 points of the high-level structure, stacked high-level structure or fiber sheet structure was measured, and the average value was used as the thickness of the high-level structure, stacked high-level structure or fiber sheet structure.

[0348] [Average pore size of high-order structures, stacked high-order structures, and fiber sheet structures]

[0349] Regarding the average pore size on the cell-carrying surface, a 35x image (number of pixels: 1920×1200) of a high-order structure, a stacked high-order structure or a fiber sheet structure cut into 5 cm squares was obtained using a digital microscope (manufactured by Hirox Co., Ltd., RH-2000). The image was then divided into pores and portions other than pores by binarization using the 2D measurement software "HRS-2D" with a microscope. The software was used to create a histogram of the pore size at intervals of 10 μm between 60 and 300 μm. The histogram was used to calculate the average pore size using the grade value and degree using the following formula.

[0350] Average pore size (μm) = {(total of grade value × degree)} ÷ (total of degree)

[0351] [Ratio of the number of pores of 150 μm or more in the cell-supporting surface of the higher-order structure, laminated higher-order structure, and fiber sheet structure]

[0352] The ratio of the number of pores of 150 μm or larger in the cell-supporting surface of the higher order structure, laminated higher order structure or fiber sheet structure is calculated by dividing the total number of pores of 150 μm or larger by the total number of pores of 60 to 300 μm using the above-mentioned histogram for calculating the average pore size.

[0353] [Porosity of high-order structures, stacked high-order structures, and fiber sheet structures]

[0354] The thickness and weight of a 5 cm square cut out of the high-order structure, the laminated high-order structure or the fiber sheet structure were measured, and the porosity was calculated using the following formula.

[0355] Porosity (%) = 100 × [1-a ÷ {(b + c) ÷ (b ÷ d + c ÷ e)} ÷ (f × 25)]

[0356] a: weight (g) of a high-level structure, a stacked high-level structure or a fiber sheet structure cut into 5 cm squares;

[0357] b: fineness of gelatin fiber bundle (dtex);

[0358] c: fineness of thermoplastic fiber bundle (dtex);

[0359] d: gelatin fiber bundle density (g / cm 3 );

[0360] e: Thermoplastic fiber bundle density (g / cm 3 );

[0361] f: thickness of the higher order structure, laminated higher order structure or fiber sheet structure (cm).

[0362] It should be noted that the gelatin fiber bundle density is 1.27 g / cm 3 As the thermoplastic fiber bundle density, the polyglycolic acid fiber bundle density is 1.53 g / cm 3 , the density of polylactic acid fiber bundle is 1.25g / cm 3 In addition, when the high-order structure is made of gelatin fiber bundles only without using thermoplastic fiber bundles, the above c and e are not included in the calculation.

[0363] [Number of pores in higher order structures, laminated higher order structures, and fiber sheet structures]

[0364] The number of pores in the high-order structure, the stacked high-order structure or the fiber sheet structure is calculated by the following formula using the average pore diameter and porosity obtained above.

[0365] Number of pores / mm 3 =a×0.01÷(4 / 3×3.14×(0.001×b / 2) 3 )

[0366] a: porosity (%);

[0367] b: pore size (μm).

[0368] [Swelling rate of gelatin fiber bundles]

[0369] The fiber diameter of the gelatin fibers constituting the gelatin fiber bundle was measured using an optical microscope RH2000 manufactured by HIROX. Next, a gelatin fiber bundle of 10 to 30 mm was immersed in a phosphate buffered saline at 50°C for 4 hours, and then the gelatin fiber bundle was lifted out of the phosphate buffered saline. The fiber diameter of the gelatin fibers constituting the gelatin fiber bundle was measured in a wet state, and the swelling rate was calculated using the following formula. This operation was performed with N=3, and the average value was taken as the swelling rate.

[0370] Swelling ratio [%] = 100 × (fiber diameter after immersion) / (fiber diameter before immersion)

[0371] [Swelling rate of twisted yarn bundle]

[0372] The bundle diameter of the twisted yarn was measured using an optical microscope RH2000 manufactured by HIROX. Next, the 10 to 30 mm twisted yarn bundle was immersed in 50°C phosphate buffered saline for 4 hours, and then the twisted yarn bundle was pulled out of the phosphate buffered saline, and the fiber diameter of the twisted yarn was measured in a wet state. The swelling rate was calculated using the following formula. This operation was performed with N=3, and the average value was taken as the swelling rate.

[0373] Swelling rate [%] = 100 × (diameter of the twisted yarn bundle after dipping) / (diameter of the twisted yarn bundle before dipping)

[0374] [Moisture regain of fiber bundle precursor]

[0375] 0.5 g of the fiber bundle precursor wound on a bobbin was measured using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) at 150°C / N2 atmosphere. [Moisture regain of gelatin fiber when reaching the conveyor roller]

[0376] The gelatin yarn was wound around the first conveying roller, and 0.5 g of the wound fiber was measured using a Karl Fischer moisture regain meter (EV-2010 manufactured by HIRANUMA) in a 150° C. / N 2 atmosphere.

[0377] [Freezing strength]

[0378] The 6.67% gelatin aqueous solution was cooled at 10° C. for 17 hours. Next, the load (g) required to press down 4 mm with a plunger having a diameter of 1 / 2 inch (12.7 mm) on the prepared frozen surface using a small table-top tester EZ-SX manufactured by Shimadzu Corporation was taken as the frozen strength.

[0379] [Sol-Gel Transition Temperature]

[0380] The temperature dependence of the viscoelasticity of the gelatin spinning solution when the temperature was increased at 1 K / min in the temperature range of 20-70°C was measured using a rheometer ARES manufactured by TA Instrument. The temperature at which the relationship between the storage elastic modulus and the loss elastic modulus was replaced was taken as the sol-gel transition temperature.

[0381] [Textures of high-level structures, laminated high-level structures, and fiber sheet structures]

[0382] Texture was evaluated by sensory evaluation by touching the high-order structure, laminated high-order structure or fiber sheet structure with dry hands.

[0383] ◎: Soft and stretchable texture;

[0384] ○: The obtained structure lost its stretchability, but became a stretchable wet texture by immersing in a 60% glycerol aqueous solution;

[0385] △: Although it is stretchable, it has a rough texture.

[0386] ×: It is impossible to produce a structure and the texture is hard.

[0387] [Average friction coefficient and average deviation of friction coefficient of high-order structures, laminated high-order structures and fiber sheet structures]

[0388] The average friction coefficient and average deviation of the friction coefficient of the high-order structure, stacked high-order structure or fiber sheet structure are evaluated using a friction tester (model: KES-SE) manufactured by KATO TECH. After the high-order structure, stacked high-order structure or fiber sheet structure cut into 5 cm square is immersed in distilled water for 1 hour, the sample is fixed on the measuring table with a metal frame, and a silicon sensor with a load of 50g and a square of 10mm is crawled at 1.0mm / second to measure the average friction coefficient and the average deviation of the friction coefficient. After performing this operation with N=3, the sample is rotated 90°C and the operation is repeated. The amplitude of the surface friction coefficient (minimum and maximum values) and the amplitude of the average deviation of the friction coefficient (minimum and maximum values) are used as the measured values.

[0389] [Curl measurement of higher order structures, laminated higher order structures and fiber sheet structures]

[0390] The high-order structure, laminated high-order structure or fiber sheet structure was punched out with a punch punch to produce a 14 mm φ circular sheet, which was immersed in a beaker of 50°C phosphate-buffered saline for 4 hours and evaluated by visually checking for curling.

[0391] [Evaluation of the number of cells cultured in the fiber sheet structure]

[0392] The cell culture of the high-order structures, stacked high-order structures and fiber sheet structures was carried out using NIH3T3 cells in the following order, and the number of cells after 7 days of cell culture was evaluated by WST-1 measurement. First, the fiber sheet structure was punched out with a φ14mm punch, wrapped in an aluminum bag, and sterilized by electron beam. The sterilized fiber sheet structure was placed on a 24-well plate coated with MPC, with the cell-carrying surface facing up, 1mL of phosphate-buffered saline was added, and the plate was allowed to stand for 10 minutes to allow the fiber sheet structure to swell. After swelling, the phosphate-buffered saline was removed using a 1000mL pipette, and 1mL of 1.5×10 4 Cell suspension of cells / ml. It should be noted that the cell suspension is adjusted in the following order. Culture the cells in a CO2 incubator (37°C, CO2 concentration of 5%) in advance, remove the culture medium from the T225 flask, wash twice with 22.5mL of phosphate-buffered saline, add 22.5mL of 0.25% trypsin, and let it stand in the CO2 incubator for 5 minutes. After confirming the peeling under a microscope, recover it into a centrifuge tube. After washing with 22.5mL of culture medium, centrifuge (220g, 3 minutes) to remove the supernatant. The obtained cell pellet is lysed with culture medium, and the cell number is determined using a Muse cell analyzer (0500-3115), and the cell suspension is adjusted to a cell concentration of 1.5×10 4cells / mL. It should be noted that the culture medium was adjusted by adding 53mL FBS, 1 / 1000 amount of kanamycin, and 1 / 100 amount of penicillin-streptomycin-amphotericin B suspension to 1000mL DMEM medium. After inoculation, the culture was started by standing in a CO2 incubator (MCO-170AICUVH-PJ) (37°C, CO2 concentration of 5%). After 3 days and 6 days, the culture medium was removed with a 1000mL pipette, and 1mL of culture medium was added to exchange the culture medium. On the 7th day, 100μL WST-1 was added, and after standing in a CO2 incubator (37°C, CO2 concentration of 5%) for 3 hours, 300μL was transferred to a 96-well plate, and the absorbance was measured (450nm, control wavelength 630nm) using an enzyme reader (VERSAMax) to evaluate the number of cells. It should be noted that the standard curve for evaluating the cell number was prepared as follows: the cell suspension was adjusted to 0.5×10 4 , 1.0×10 4 , 2.0×10 4 , 3.0×10 4 4.0×10 4 , 6.0×10 4 , 8.0×10 4 100 μL of WST-1 was added to a suspension of 10 cells / ml, and after standing in a CO2 incubator (37°C, CO2 concentration of 5%) for 3 hours, 300 μL was transferred to a 96-well plate and the absorbance was measured using an ELISA reader (450 nm, reference wavelength 630 nm).

[0393] [Cell Adhesion of Fiber Sheet Structure]

[0394] Regarding cell adhesion, NIH3T3 cells were statically cultured on the structures for 7 days, and the fluorescently labeled cells were observed under a fluorescence microscope to evaluate the degree of cell adhesion.

[0395] ◎: Two-dimensional cell growth as if adhered to the structure was observed, and the cells were fixed on the surface of the structure.

[0396] ○: Although the two-dimensional cell growth is mainly like adhesion to the structure, some three-dimensional cell growth cell masses slowly adhere to the surface of the structure.

[0397] △: Cell masses mainly composed of three-dimensional cell growth, slowly adhering to the surface of the structure.

[0398] ×: Adhesion of the structure to the cells was not observed.

[0399] [Cell Adhesion and Cell Culture Properties of High-Level Structures and Stacked High-Level Structures]

[0400] The cell adhesion and cell culturing properties of the high-level structures and stacked structures were evaluated by culturing HeLa cells on the structures for 3 days and observing the fluorescently labeled cells under a fluorescence microscope. The high-level structures and stacked structures were placed on a 12-well plate coated with MPC, and culture medium was added to swell the structures. D-MEM / 10% FBS and penicillin / streptomycin were used in the culture medium. After swelling, the excess culture medium was discarded and 2×10 6 / ml of HeLa cell suspension. Add 1ml / well to the structure and culture it statically at 37°C, 5% CO2 for 3 days. After culture, discard the supernatant and wash with phosphate-buffered saline at 1ml / well. After washing, add 1ml / well of OPTI-MEM medium containing 2μM calcein AM as a fluorescent reagent. Culture it statically at 37°C, 5% CO2 for 2 hours, and observe it qualitatively under a fluorescence microscope to evaluate cell adhesion and cell culturing properties.

[0401] The cell adhesion was evaluated based on the degree of adhesion of cells to the higher order structures and laminated higher order structures.

[0402] ◎: Two-dimensional cell growth as if adhered to the structure was observed, and the cells were fixed on the surface of the structure.

[0403] ○: Although the two-dimensional cell growth is mainly like adhesion to the structure, some three-dimensional cell growth cell masses slowly adhere to the surface of the structure.

[0404] △: Cell masses mainly composed of three-dimensional cell growth, slowly adhering to the surface of the structure.

[0405] ×: Adhesion of the structure to the cells was not observed.

[0406] Cell culturability was evaluated by qualitatively observing luminescence from cells stained with fluorescent reagents under a fluorescent microscope.

[0407] ⊚: Strong fluorescence emission was observed on the entire surface of the structure.

[0408] ○: Strong fluorescence was observed from the portion other than the gaps in the structure (the meshes of the knitted fabric).

[0409] Δ: Weak fluorescence was observed from the portion other than the gaps in the structure (the meshes of the knitted fabric).

[0410] ×: No fluorescence was observed.

[0411] <Production Example 1>

[0412] 50% by weight of water was added to 50% by weight of gelatin (produced by Nitta Gelatin, type A pigskin gelatin) with a gel strength of 293 g, and after standing for 30 minutes, it was kneaded and defoamed using a vacuum defoaming mixer (ARV-310P manufactured by Thinky) to prepare a gelatin spinning stock solution for spinning. The sol-gel transition temperature of the gelatin spinning stock solution was 37°C.

[0413] The prepared gelatin spinning stock solution was heated to 50°C, extruded into fibers from a 6-hole spinneret with an aperture of 150 μm (perfect circle) at a temperature of 50°C, and the extruded gelatin fibers were transported along the circumference of a conveying roller located 1.8 m away from the extrusion port at a speed of 30 m / min, and wound up on a bobbin through a winding roller, thereby obtaining a gelatin fiber bundle precursor consisting of 6 gelatin fibers. The extruded gelatin fibers were air-dried during transportation, and were wound up on a bobbin after being attached with an oil agent (a mixed solution of 10% ethylene glycol and 90% ethanol). The moisture regain of the gelatin fibers when they reached the conveying roller was 15% by weight. The moisture regain of the gelatin fiber bundle precursor was 13% by weight, and no fusion between the fiber bundles was observed, and the unwinding property from the bobbin was also good. In addition, the fineness of the wound gelatin fiber bundle precursor was 48 dtex, and the tensile strength and tensile elongation of the gelatin fibers taken out from the gelatin fiber bundle precursor were 1.1 cN / dtex and 74%, respectively.

[0414] The bobbin of the wound gelatin fiber bundle precursor was heat treated in the atmosphere at 140°C for 24 hours to obtain a water-insoluble gelatin fiber bundle. The fineness of the gelatin fiber bundle is 48 dtex, and the tensile strength and tensile elongation are 1.2 cN / dtex and 84% respectively. The fineness of one gelatin fiber is 8 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 84% (1.2 cN / dtex).

[0415] In addition, the weight loss rate of the gelatin fiber bundle immersed in phosphate-buffered saline at 50° C. for 4 hours was 18%, and the swelling rate was 240%.

[0416] Next, a high-order structure was obtained using a circular knitting machine (model MR-1 manufactured by Maruzen Sangyo Co., Ltd.) using a gelatin fiber bundle. The weight loss of the high-order structure after immersion in phosphate-buffered saline at 50°C for 4 hours was 18%, and 1.2% of the 18% weight loss was due to the oil. In addition, the thickness of the high-order structure was 83 μm and the porosity was 91%.

[0417] <Production Example 2>

[0418] A gelatin fiber bundle precursor (fineness 48 dtex) consisting of 6 gelatin fibers before heat treatment was prepared using the same method as in Manufacturing Example 1. A knitted fabric was produced using the gelatin fiber bundle precursor using a circular knitting machine. Next, a high-order structure consisting of gelatin fiber bundles was obtained by heat treatment in the atmosphere at 140°C for 24 hours to make it insoluble in water. The tensile strength and tensile elongation of the gelatin fiber bundle obtained by decomposing the high-order structure were 1.2 cN / dtex and 84%, respectively, and the fineness of one gelatin fiber was 8 dtex. It should be noted that the gelatin fiber bundle reached an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and broke (1.2 cN / dtex) when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 84%.

[0419] In addition, the weight loss rate of the gelatin fiber bundle immersed in phosphate buffered saline at 50°C for 4 hours was 18%, and the swelling rate was 240%. The weight loss rate of the high-order structure immersed in phosphate buffered saline at 50°C for 4 hours was 18%. In addition, the thickness of the high-order structure was 83 μm and the porosity was 91%.

[0420] <Production Example 3>

[0421] A gelatin fiber bundle precursor consisting of 6 gelatin fibers before heat treatment was prepared using the same method as in Manufacturing Example 1. A knitted fabric was prepared using the gelatin fiber bundle precursor using a circular knitting machine. Next, the knitted fabric was immersed in a 12.5% ​​glutaraldehyde aqueous solution for 5 minutes, then washed with water and dried to make it insoluble in water, thereby obtaining a high-order structure consisting of gelatin fiber bundles. The tensile strength and tensile elongation of the gelatin fiber obtained by decomposing the high-order structure are 0.8 cN / dtex and 65%, respectively, and the fineness of one gelatin fiber is 8 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.8 cN / dtex) at an elongation of 4%, and breaks when stretched from a lower yield point (lower yield stress: 0.70 cN / dtex) at an elongation of 15% to an elongation of 65% (0.78 cN / dtex).

[0422] In addition, the weight loss rate of the gelatin fiber bundle immersed in phosphate buffered saline at 50°C for 4 hours was 9%, and the swelling rate was 138%. The weight loss rate of the high-order structure immersed in phosphate buffered saline at 50°C for 4 hours was 9%. In addition, the thickness of the high-order structure was 83 μm and the porosity was 91%.

[0423] <Production Example 4>

[0424] A gelatin fiber bundle precursor consisting of 24 gelatin fibers before heat treatment was prepared using the same method as in Example 1, except that the yarn discharged from a 24-hole spinneret with an aperture of 150 μm (perfect circle) was transported at 90 m / min. The moisture regain of the gelatin fiber when it reached the transport roller was 13% by weight. The moisture regain of the gelatin fiber bundle precursor was 10% by weight, and no fusion between the fiber bundles was observed, and the unwinding property from the bobbin was also good. In addition, the fineness of the wound gelatin fiber bundle precursor was 133.6 dtex, and the tensile strength and tensile elongation of the gelatin fiber were 1.6 cN / dtex and 50%, respectively. A knitted fabric was produced using the gelatin fiber bundle precursor using a circular knitting machine. Next, a high-order structure consisting of gelatin fiber bundles was obtained by heat treatment in the atmosphere at 140°C for 24 hours to make it insoluble in water. The tensile strength and tensile elongation of the gelatin fiber bundle obtained by decomposing the high-order structure are 1.6 cN / dtex and 50%, respectively, and the fineness of one gelatin fiber is 5.6 dtex. It should be noted that the gelatin fiber bundle reaches the upper yield point (upper yield stress: 1.2 cN / dtex) at an elongation of 5%, and breaks when stretched from the lower yield point (lower yield stress: 1.15 cN / dtex) at an elongation of 15% to an elongation of 50% (1.6 cN / dtex). In addition, the weight loss rate of the gelatin fiber bundle immersed in phosphate-buffered saline at 50°C for 4 hours was 17%, and the swelling rate was 230%.

[0425] The weight loss rate of the high-order structure after immersion in phosphate-buffered saline at 50° C. for 4 hours was 19%. The thickness of the high-order structure was 132 μm, and the porosity was 84%.

[0426] <Production Example 5>

[0427] A high-order structure composed of gelatin fiber bundles was prepared by the same method as in Manufacturing Example 1, except that the coiled gelatin fiber bundle precursor was heat-treated at 180°C for 6 hours in vacuum instead of at 140°C in the atmosphere for 24 hours. The fineness of the gelatin fiber bundle is 46 dtex, and the tensile strength and tensile elongation are 1.5 cN / dtex and 62%, respectively. The fineness of one gelatin fiber is 8 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 1.15 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 1.05 cN / dtex) at an elongation of 15% to an elongation of 62% (1.5 cN / dtex). In addition, the weight loss rate of the gelatin fiber bundle immersed in phosphate-buffered saline at 50°C for 4 hours was 9%, and the swelling rate was 138%. The weight loss of the high-order structure after immersion in phosphate-buffered saline at 50°C for 4 hours was 9%, and 1.2% of the 9% weight loss was due to the oil. The thickness of the high-order structure was 83 μm, and the porosity was 91%.

[0428] <Production Example 6>

[0429] A gelatin fiber bundle precursor consisting of 15 gelatin fibers before heat treatment was prepared by the same method as in Example 1, except that the yarn discharged from a 15-hole spinneret with an aperture of 150 μm (perfect circle) was transported at 60 m / min. The fineness of the wound gelatin fiber bundle precursor was 58.6 dtex, and the tensile strength and tensile elongation of the gelatin fiber were 1.1 cN / dtex and 77%, respectively. A twisted yarn bundle precursor having 30 filaments and a fineness of 93.6 dtex was prepared by spirally winding a thermoplastic resin fiber bundle consisting of polyglycolic acid having 15 filaments and a fineness of 35.0 dtex around the gelatin fiber bundle precursor. A knitted fabric was prepared using the twisted yarn bundle precursor using a circular knitting machine. Next, a high-order structure consisting of a twisted yarn bundle containing a gelatin fiber bundle and a thermoplastic resin fiber bundle was obtained by heat treatment in the atmosphere at 140°C for 24 hours to make it insoluble in water. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the high-order structure are 7.2 cN / dtex and 35%, respectively. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor in the atmosphere at 140°C for 24 hours is 58.6 dtex, the tensile strength and tensile elongation are 1.2 cN / dtex and 79%, respectively, and the fineness of one gelatin fiber is 3.9 dtex. It should be noted that the gelatin fiber bundle reaches the upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from the lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex). In addition, the weight loss rate of the parallel twisted yarn of gelatin fiber bundle and thermoplastic resin fiber bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. The weight loss rate of the high-order structure immersed in phosphate buffered saline at 50°C for 4 hours was 12%. In addition, the thickness of the high-order structure was 125μm and the porosity was 87%.

[0430] <Production Example 7>

[0431] A high-order structure consisting of a twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles was prepared by the same method as in Manufacturing Example 6, except that the twisting of a thermoplastic resin fiber bundle consisting of polyglycolic acid with 15 filaments and a fineness of 35.0 dtex while spirally winding around a gelatin fiber bundle precursor was changed to the twisting of a thermoplastic resin fiber bundle consisting of polyglycolic acid with 15 filaments and a fineness of 35.0 dtex while spirally winding around a gelatin fiber bundle precursor. The number of filaments in the twisted yarn bundle precursor was 30 and the fineness was 93.6 dtex. The tensile strength and tensile elongation of the twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the high-order structure were 7.2 cN / dtex and 35%, respectively. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor in the atmosphere at 140°C for 24 hours is 58.6 dtex, the tensile strength and tensile elongation are 1.2 cN / dtex and 79% respectively, and the fineness of one gelatin fiber is 3.9 dtex. It should be noted that the gelatin fiber bundle reaches the upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from the lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex). In addition, the weight loss rate of the twisted bundle of the gelatin fiber bundle and the thermoplastic resin fiber bundle immersed in 50°C phosphate buffered saline for 4 hours is 12%, and the swelling rate is 145%. The weight loss rate of the advanced structure immersed in 50°C phosphate buffered saline for 4 hours is 12%. The thickness of the high-order structure was 125 μm, and the porosity was 87%.

[0432] <Production Example 8>

[0433] A high-order structure consisting of a parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles was prepared by the same method as in Manufacturing Example 7, except that the heat treatment at 140°C in the atmosphere for 24 hours was changed to a heat treatment at 160°C in vacuum for 12 hours. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the high-order structure were 6.8 cN / dtex and 32%, respectively. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor at 160°C in vacuum for 12 hours was 58.6 dtex, and the tensile strength and tensile elongation were 1.3 cN / dtex and 65%, respectively, and the fineness of one gelatin fiber was 3.9 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 1.0 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 0.95 cN / dtex) at an elongation of 15% to an elongation of 65% (1.3 cN / dtex). In addition, the weight loss rate of the twisted yarn bundle of the gelatin fiber bundle and the thermoplastic resin fiber bundle immersed in 50°C phosphate buffered saline for 4 hours is 9%, and the swelling rate is 135%. The weight loss rate of the high-level structure immersed in 50°C phosphate buffered saline for 4 hours is 9%. In addition, the thickness of the high-level structure is 125 μm and the porosity is 87%.

[0434] <Production Example 9>

[0435] A gelatin fiber bundle precursor consisting of 15 gelatin fibers before heat treatment was prepared using the same method as in Manufacturing Example 1, except that a 6-hole spinneret with an aperture of 150 μm (perfect circle) was changed to a 15-hole spinneret with an aperture of 150 μm (perfect circle), and the extruded gelatin fibers were transported at 60 m / min instead of 30 m / min. The fineness of the wound gelatin fiber bundle precursor was 58.6 dtex, and the tensile strength and tensile elongation of the gelatin fibers taken out from the gelatin fiber bundle precursor were 1.1 cN / dtex and 77%, respectively. It should be noted that the moisture regain of the gelatin fibers when they reached the conveying roller was 12% by weight. The moisture regain of the gelatin fiber bundle precursor was 10% by weight, and no fusion between the fiber bundles was observed, and the unwinding property from the bobbin was also good.

[0436] Next, a thermoplastic resin fiber bundle consisting of polyglycolic acid with 15 filaments and a fineness of 35.0 dtex was unwound at 30 m / min while being washed with an aqueous solution bath containing 40 wt% ethanol to remove the oil agent, and then contact dried by a hot roller at 70°C, and then immersed / dried in a collagen aqueous solution of a cell matrix (IC type) manufactured by Nitta Gelatin, thereby obtaining a thermoplastic resin fiber bundle coated with collagen. A thermoplastic resin fiber bundle coated with collagen with 15 filaments and a fineness of 35 dtex was twisted while being spirally wound around a gelatin fiber bundle precursor, to produce a parallel twisted fiber bundle precursor with 30 filaments and a fineness of 93.6 dtex. Using the parallel twisted fiber bundle precursor, a knitted fabric was produced using a circular knitting machine. Next, by heat treating the gelatin fiber bundle precursor at 140°C in the air for 24 hours to make it insoluble in water, a higher-order structure consisting of a parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles was obtained. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the higher-order structure were 7.2 cN / dtex and 35%, respectively. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor at 140°C in the air for 24 hours was 58.6 dtex, and the tensile strength and tensile elongation were 1.2 cN / dtex and 79%, respectively, and the fineness of one gelatin fiber was 3.9 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks (1.2 cN / dtex) when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79%. In addition, the weight loss rate of the twisted bundle of gelatin fiber bundles and thermoplastic resin fiber bundles immersed in 50°C phosphate buffered saline for 4 hours was 12%, and the swelling rate was 145%. The weight loss rate of the high-order structure immersed in 50°C phosphate buffered saline for 4 hours was 12%. In addition, the thickness of the high-order structure was 125 μm and the porosity was 87%.

[0437] <Production Example 10>

[0438] A high-order structure consisting of a parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles was obtained by the same method as in Manufacturing Example 9, except that the polyglycolic acid having 15 filaments and a fineness of 35.0 dtex was changed to polylactic acid having 15 filaments and a fineness of 33.0 dtex. The parallel twisted yarn bundle precursor had 30 filaments and a fineness of 91.6 dtex. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the high-order structure were 5.5 cN / dtex and 36%, respectively. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor in the atmosphere at 140°C for 24 hours was 58.6 dtex, and the tensile strength and tensile elongation were 1.2 cN / dtex and 79%, respectively, and the fineness of one gelatin fiber was 3.9 dtex. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks (1.2 cN / dtex) when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79%. In addition, the weight loss rate of the twisted bundle of gelatin fiber bundles and thermoplastic resin fiber bundles immersed in 50°C phosphate buffered saline for 4 hours was 12%, and the swelling rate was 145%. The weight loss rate of the high-level structure immersed in 50°C phosphate buffered saline for 4 hours was 12%. In addition, the thickness of the high-level structure was 125 μm and the porosity was 89%.

[0439] <Production Example 11>

[0440] The high-order structure obtained in Manufacturing Example 6 was attached to the base of an electrospinning device (NANON-04 manufactured by MECC), and the gelatin spinning stock solution obtained by dissolving 20% ​​by weight of gelatin in an acetic acid aqueous solution containing 30% by weight of acetic acid was electrospun for 1 minute at room temperature, voltage 20 kV, discharge volume 0.3 cc / min, and a distance of 10 cm from the nozzle tip to the high-order structure, to produce a laminated high-order structure precursor consisting of a gelatin nonwoven fabric and a high-order structure. After the laminated high-order structure precursor was dried at room temperature under vacuum for 24 hours, it was pressed on one side of the gelatin nonwoven fabric at 70°C and 800 KPa for 60 seconds, and then heat-treated at 160°C under vacuum for 12 hours, thereby obtaining a laminated high-order structure in which the gelatin nonwoven fabric was laminated on the high-order structure. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the stacked high-order structure are 6.8 cN / dtex and 32%, respectively. In addition, the weight loss rate of the parallel twisted yarn bundle of gelatin fiber bundles and thermoplastic resin fiber bundles immersed in 50°C phosphate buffered saline for 4 hours is 9%, and the swelling rate is 135%. The weight loss rate of the stacked high-order structure immersed in 50°C phosphate buffered saline for 4 hours is 9%, and 1.0% of the 9% weight loss rate comes from the oil agent. In addition, the thickness of the stacked high-order structure is 125μm and the porosity is 87%.

[0441] <Production Example 12>

[0442] A stacked high-level structure having a gelatin nonwoven fabric stacked on the high-level structure was obtained by the same method as in Manufacturing Example 11, except that the heat treatment at 160°C in vacuum for 12 hours was changed to a heat treatment at 140°C in the atmosphere for 24 hours. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the stacked high-level structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the parallel twisted yarn bundle of gelatin fiber bundles and thermoplastic resin fiber bundles immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%.

[0443] The weight loss of the laminated high-order structure after immersion in phosphate-buffered saline at 50°C for 4 hours was 12%, of which 1.0% was attributed to the oil. The laminated high-order structure had a thickness of 125 μm and a porosity of 87%.

[0444] <Production Example 13>

[0445] The high-order structure obtained in Manufacturing Example 6 was pasted on the base of an electrospinning device (NANON-04 manufactured by MECC), and the collagen spinning stock solution obtained by dissolving 10% by weight of the collagen in an acetic acid aqueous solution containing 84% by weight of acetic acid was electrospun for 1 minute at room temperature, voltage 20kV, discharge volume 0.3cc / minute, and a distance of 10cm from the nozzle tip to the high-order structure, to produce a stacked high-order structure precursor consisting of a collagen non-woven fabric and a high-order structure. After the stacked high-order structure precursor was dried at room temperature under vacuum for 24 hours, it was pressed at 80°C and 800KPa for 60 seconds, and then heat-treated at 140°C under vacuum for 24 hours, thereby obtaining a stacked high-order structure with a collagen non-woven fabric stacked on the high-order structure. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the stacked high-order structure are 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles immersed in phosphate buffered saline at 50°C for 4 hours is 12%, and the swelling rate is 145%.

[0446] The weight loss of the laminated high-order structure after immersion in phosphate-buffered saline at 50°C for 4 hours was 13%, and 1.0% of the 13% weight loss was due to the oil. The thickness of the laminated high-order structure was 125 μm and the porosity was 87%.

[0447] <Production Example 14>

[0448] A gelatin single-hole yarn precursor before heat treatment was prepared by the same method as in Example 1, except that the yarn discharged from a single-hole spinneret with an aperture of 150 μm (perfect circle) was wound at 10 m / min. The moisture regain of the wound gelatin single-hole yarn precursor was 17% by weight, no fusion between the fibers was observed, and the unwinding property from the bobbin was also good. In addition, the fineness of the wound gelatin single-hole yarn precursor was 128 dtex, and the tensile strength and tensile elongation of the gelatin fiber (gelatin single-hole yarn precursor) were 0.6 cN / dtex and 63%, respectively.

[0449] The wound bobbin of gelatin single-hole yarn precursor was heat-treated in the atmosphere at 140°C for 24 hours to obtain water-insoluble gelatin single-hole yarn. The fineness of the gelatin single-hole yarn after insolubilization treatment was 128 dtex, and the tensile strength and tensile elongation were 0.7 cN / dtex and 122%, respectively. In addition, the weight loss rate of the gelatin single-hole yarn immersed in phosphate buffered saline at 50°C for 4 hours was 19%, and the swelling rate was 280%.

[0450] Next, I tried to make a knitted fabric using a circular knitting machine using gelatin single-hole yarn, but I kept missing stitches and could not get a knitted fabric.

[0451] <Production Example 15>

[0452] An attempt was made to produce a knitted fabric using a circular knitting machine using commercially available PET single-hole yarn having a fineness of 110 dtex, but needles were often missed and no knitted fabric could be obtained.

[0453] <Production Example 16>

[0454] A gelatin single-hole yarn precursor before heat treatment was prepared by the same method as in Example 1, except that the yarn discharged from a single-hole spinneret with an aperture of 150 μm (perfect circle) was wound at 30 m / min. The moisture regain of the gelatin single-hole yarn precursor was 15% by weight, no fusion between the fibers was observed, and the unwinding property from the bobbin was also good. In addition, the fineness of the wound gelatin single-hole yarn precursor was 8 dtex, and the tensile strength and tensile elongation of the gelatin fiber (gelatin single-hole yarn precursor) were 1.0 cN / dtex and 72%, respectively.

[0455] The wound bobbin of gelatin single-hole yarn precursor was heat-treated in the atmosphere at 140°C for 24 hours to obtain water-insoluble gelatin single-hole yarn. The fineness of the gelatin single-hole yarn is 8 dtex, and the tensile strength and tensile elongation are 1.2 cN / dtex and 84%, respectively. In addition, the weight loss rate of the gelatin single-hole yarn immersed in 50°C phosphate buffered saline for 4 hours was 18%. Next, the gelatin single-hole yarn was used to try to make knitted fabrics using a circular knitting machine. Due to the weak yarn strength, the yarn often broke and the knitted fabric could not be obtained.

[0456] <Production Example 17>

[0457] A high-order structure was made using a thermoplastic resin fiber bundle consisting of polylactic acid with 15 filaments and a fineness of 33.0 dtex using a circular knitting machine. The tensile strength and tensile elongation of the thermoplastic resin fiber bundle obtained by decomposing the high-order structure were 4.5 cN / dtex and 33%, respectively. In addition, the weight loss rate of the thermoplastic resin fiber bundle immersed in 50°C phosphate buffered saline for 4 hours was 0% and the swelling rate was 100%. The weight loss rate of the high-order structure immersed in 50°C phosphate buffered saline for 4 hours was 0%. In addition, the thickness of the high-order structure was 78μm and the porosity was 85%.

[0458] <Production Example 18>

[0459] Using the twisted yarn precursor of Manufacturing Example 6, a double-sided knitted fabric (second high-level structure) having a thickness of 2040 μm, an average pore size of 95 μm, and a porosity of 94% was prepared using Whole Garment (registered trademark) (SWG (registered trademark) 041N2) with two layers of overlapping plain stitches. The double-sided knitted fabric was heat-treated at 140°C for 24 hours under vacuum to be insolubilized, and then a temperature of 70°C was applied to the single side of the double-sided knitted fabric and pressed at 800 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the twisted yarn bundle containing the gelatin fiber bundle and the thermoplastic resin fiber bundle obtained by decomposing the fiber sheet structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor under vacuum at 140°C for 24 hours has a fineness of 58.6 dtex, a tensile strength and a tensile elongation of 1.2 cN / dtex and 79%, respectively, and a fineness of 3.9 dtex for one gelatin fiber. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex).

[0460] <Production Example 19>

[0461] Using the twisted yarn precursor of Manufacturing Example 6, a double-sided knitted fabric (second high-level structure) with a thickness of 1670 μm, an average pore size of 127 μm, and a porosity of 93% was produced by overlapping two layers of plain stitches using Whole Garment (registered trademark) (SWG (registered trademark) 041N2). The double-sided knitted fabric was heat-treated at 140°C for 24 hours under vacuum to be insolubilized, and then a temperature of 60°C was applied to the single side and pressed at 700 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the twisted yarn bundle containing the gelatin fiber bundle and the thermoplastic resin fiber bundle obtained by decomposing the fiber sheet structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor under vacuum at 140°C for 24 hours has a fineness of 58.6 dtex, a tensile strength and a tensile elongation of 1.2 cN / dtex and 79%, respectively, and a fineness of 3.9 dtex for one gelatin fiber. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex).

[0462] <Production Example 20>

[0463] Using the twisted yarn precursor of Manufacturing Example 6, a double-sided knitted fabric (second high-order structure) having a thickness of 1940 μm, an average pore size of 150 μm, and a porosity of 95% was produced by overlapping two layers of plain stitches using Whole Garment (registered trademark) (SWG (registered trademark) 041N2). The double-sided knitted fabric was heat-treated at 140°C for 24 hours under vacuum to be insolubilized, and then a temperature of 70°C was applied to the single-sided side and pressed at 800 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the twisted yarn bundle containing the gelatin fiber bundle and the thermoplastic resin fiber bundle obtained by decomposing the second high-order structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor under vacuum for 24 hours is 58.6 dtex, the tensile strength and tensile elongation are 1.2 cN / dtex and 79% respectively, and the fineness of one gelatin fiber is 3.9 dtex. It should be noted that the gelatin fiber bundle reaches the upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from the lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex).

[0464] <Production Example 21>

[0465] Using the twisted yarn precursor of Manufacturing Example 7, a double-sided knitted fabric (second high-level structure) having a thickness of 2040 μm, an average pore size of 95 μm, and a porosity of 94% was produced by overlapping two layers of plain stitches using Whole Garment (registered trademark) (SWG (registered trademark) 041N2). The double-sided knitted fabric was heat-treated at 140°C for 24 hours under vacuum to be insolubilized, and a temperature of 70°C was applied to the single-sided side and pressed at 800 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the twisted yarn bundle containing the gelatin fiber bundle and the thermoplastic resin fiber bundle obtained by decomposing the fiber sheet structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor under vacuum at 140°C for 24 hours has a fineness of 58.6 dtex, a tensile strength and a tensile elongation of 1.2 cN / dtex and 79%, respectively, and a fineness of 3.9 dtex for one gelatin fiber. It should be noted that the gelatin fiber bundle reaches an upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and breaks when stretched from a lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to an elongation of 79% (1.2 cN / dtex).

[0466] <Production Example 22>

[0467] Four parallel twisted yarn precursors of Production Example 6 and four thermoplastic resin fiber bundles were used to prepare parallel twisted yarn precursors containing four gelatin fiber bundle precursors and four thermoplastic resin fiber bundles, and a single-sided knitted fabric (second high-order structure) having a thickness of 940 μm, an average pore size of 125 μm, and a porosity of 94% was prepared by rib knitting using WholeGarment (registered trademark) (SWG (registered trademark) 041N2). The single-sided knitted fabric was insolubilized at 140° C. for 24 hours under vacuum, and a temperature of 70° C. was applied to the single-sided side and pressed at 800 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the parallel twisted yarn containing the gelatin fiber bundle and the thermoplastic resin fiber bundle obtained by decomposing the fiber sheet structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor in the atmosphere at 140°C for 24 hours was 58.6 dtex, and the tensile strength and tensile elongation were 1.2 cN / dtex and 79% respectively, and the fineness of one gelatin fiber was 3.9 dtex. It should be noted that the gelatin fiber bundle reached the upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and was stretched from the lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to a break at an elongation of 79% (1.2 cN / dtex).

[0468] <Production Example 23>

[0469] The double knitted fabric (second higher order structure) of Manufacturing Example 19 was attached to the base of an electrospinning apparatus (NANON-04 manufactured by MECC), and a gelatin spinning stock solution obtained by dissolving 20% ​​by weight of gelatin in an acetic acid aqueous solution containing 30% by weight of acetic acid was electrospun for 1 minute at room temperature, voltage 20 kV, discharge rate 0.3 cc / min, and a distance of 10 cm from the nozzle tip to the second higher order structure. A second laminated higher order structure consisting of a gelatin nonwoven fabric and a second higher order structure was prepared. The second laminated higher order structure was insolubilized by heat treatment at 140°C for 24 hours under vacuum, and then a temperature of 60°C was applied to one side, and pressed at 700 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the fiber sheet structure were 7.2 cN / dtex and 35%, respectively. In addition, the weight loss rate of the twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours was 12%, and the swelling rate was 145%. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor in the atmosphere at 140°C for 24 hours was 58.6 dtex, and the tensile strength and tensile elongation were 1.2 cN / dtex and 79% respectively, and the fineness of one gelatin fiber was 3.9 dtex. It should be noted that the gelatin fiber bundle reached the upper yield point (upper yield stress: 0.85 cN / dtex) at an elongation of 5%, and was stretched from the lower yield point (lower yield stress: 0.80 cN / dtex) at an elongation of 15% to a break at an elongation of 79% (1.2 cN / dtex).

[0470] <Production Example 24>

[0471] The single-jersey knitted fabric (second higher-order structure) of Production Example 22 was attached to the base of an electrospinning apparatus (NANON-04 manufactured by MECC), and a gelatin spinning stock solution obtained by dissolving 20% ​​by weight of gelatin in an acetic acid aqueous solution containing 30% by weight of acetic acid was electrospun for 1 minute at room temperature, a voltage of 20 kV, an output of 0.3 cc / min, and a distance of 10 cm from the nozzle tip to the second higher-order structure. A second laminated higher-order structure consisting of a gelatin nonwoven fabric and a second higher-order structure was prepared. The second laminated higher-order structure was insolubilized by heat treatment at 160° C. for 12 hours under vacuum, and then a temperature of 70° C. was applied to the surface on the gelatin nonwoven fabric side and pressed at 800 KPa for 60 seconds to obtain a fiber sheet structure. The tensile strength and tensile elongation of the parallel twisted yarn bundle containing gelatin fiber bundles and thermoplastic resin fiber bundles obtained by decomposing the fiber sheet structure are 6.8 cN / dtex and 32%, respectively. In addition, the weight loss rate of the parallel twisted yarn bundle immersed in phosphate buffered saline at 50°C for 4 hours is 9%, and the swelling rate is 135%. It should be noted that the fineness of the gelatin fiber bundle obtained by heat treating the gelatin fiber bundle precursor at 160°C under vacuum for 24 hours is 52.5 dtex, the tensile strength and tensile elongation are 1.1 cN / dtex and 70%, respectively, and the fineness of one gelatin fiber is 3.5 dtex. It should be noted that the gelatin fiber bundle reaches the upper yield point (upper yield stress: 0.82 cN / dtex) at an elongation of 5%, and is stretched from the lower yield point (lower yield stress: 0.75 cN / dtex) at an elongation of 14% to break at an elongation of 56% (0.9 cN / dtex).

[0472] <Reference Example 1>

[0473] The high-order structure obtained in Manufacturing Example 1 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0474] <Reference Example 2>

[0475] The high-order structure obtained in Production Example 2 was evaluated for its texture.

[0476] <Reference Example 3>

[0477] The high-order structure obtained in Manufacturing Example 3 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0478] <Reference Example 4>

[0479] The high-order structure obtained in Production Example 4 was evaluated for its texture.

[0480] <Reference Example 5>

[0481] The high-order structure obtained in Manufacturing Example 5 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0482] <Reference Example 6>

[0483] The high-order structure obtained in Manufacturing Example 6 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0484] <Reference Example 7>

[0485] The high-order structure obtained in Manufacturing Example 7 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0486] <Reference Example 8>

[0487] The high-order structure obtained in Manufacturing Example 8 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0488] <Reference Example 9>

[0489] The high-order structure obtained in Manufacturing Example 9 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0490] <Reference Example 10>

[0491] The high-order structure obtained in Manufacturing Example 10 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0492] <Reference Example 11>

[0493] The stacked high-order structure obtained in Manufacturing Example 11 was evaluated for average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0494] <Reference Example 12>

[0495] The stacked high-order structure obtained in Manufacturing Example 12 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0496] <Reference Example 13>

[0497] The stacked high-order structure obtained in Manufacturing Example 13 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence or absence of curling, and cell adhesion and cell culturing properties using HeLa cells.

[0498] The evaluation results of Reference Examples 1 to 13 are shown in Tables 1 and 2.

[0499] <Example 1>

[0500] The fiber sheet structure obtained in Manufacturing Example 18 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0501] <Example 2>

[0502] The fiber sheet structure obtained in Manufacturing Example 19 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0503] <Example 3>

[0504] The fiber sheet structure obtained in Manufacturing Example 20 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0505] <Example 4>

[0506] The fiber sheet structure obtained in Manufacturing Example 21 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0507] <Example 5>

[0508] The fiber sheet structure obtained in Manufacturing Example 22 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0509] <Example 6>

[0510] The fiber sheet structure obtained in Manufacturing Example 23 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, and cell adhesion and number of cell cultures using NIH3T3 cells when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0511] <Example 7>

[0512] The fiber sheet structure obtained in Manufacturing Example 24 was evaluated for weight loss rate, thickness, porosity, average pore size, ratio of pores larger than 150 μm, number of pores, texture, average friction coefficient, average deviation of friction coefficient, presence or absence of curling, cell adhesion using NIH3T3 cells, and number of cell cultures when immersed in phosphate-buffered saline at 50°C for 4 hours.

[0513] <Comparative Example 1>

[0514] The texture of the fiber in Production Example 14 was evaluated.

[0515] <Comparative Example 2>

[0516] The texture of the fiber in Production Example 15 was evaluated.

[0517] <Comparative Example 3>

[0518] The texture of the fiber in Production Example 16 was evaluated.

[0519] <Comparative Example 4>

[0520] The high-order structure obtained in Manufacturing Example 17 was evaluated for texture, average friction coefficient, average deviation of friction coefficient, average pore size, proportion (%) of pores larger than 150 μm, number of pores, presence or absence of curling, and cell adhesion and cell culturing properties using NIH3T3 cells.

[0521] <Comparative Example 5>

[0522] The collagen sheet of Bio-Gide (a double-layer structure of a collagen sheet and a collagen nonwoven fabric) produced by Geistlich was used to evaluate the average friction coefficient, the average deviation of the friction coefficient, the presence or absence of curling, and the cell adhesion and cell culture number using NIH3T3 cells. The evaluation results of the embodiments and comparative examples are shown in Tables 3 and 4.

[0523] [Table 1]

[0524]

[0525] [Table 2]

[0526]

[0527] [Table 3]

[0528]

[0529] [Table 4]

[0530]

[0531] The results shown in Table 4 show that the fiber sheet structure obtained in the example has good texture, moderate slipperiness, and excellent cell adhesion and culturing properties after cell fixation. The SEM images confirmed that the cells invaded the inner layer of the fiber sheet structure and grew by crawling from the fixable part to the fiber and filling the joints between the fibers.

[0532] Industrial Applicability

[0533] The fiber sheet structure of the present invention is a medical material with excellent mechanical strength and biocompatibility (low antigenicity and high bioabsorbability), and can be suitably used as a raw material for wound / burn treatment or a matrix material for artificial skin, etc. In addition, it can be suitably used as a scaffold material for three-dimensional cell culture with excellent properties such as promoting cell differentiation, enhancing cell function, and post-transplant fixation.

Claims

1. A fiber sheet structure, wherein: The fiber sheet structure comprises a knitted structure and has a cell-carrying surface and a back surface. The average pore size of the back surface is smaller than the average pore size of the cell-carrying surface. The knitted tissue comprises a parallel twisted yarn bundle consisting of a gelatin fiber bundle and a thermoplastic resin fiber bundle. The thickness of the fiber sheet structure is 30 to 5000 μm. The number of gelatin fibers constituting the gelatin fiber bundle is 5 to 60, and the fineness of the gelatin fibers is 0.5 to 10 dtex. The total number of gelatin fiber bundles and thermoplastic resin fiber bundles in the above-mentioned twisted yarn bundles is 2 to 20, and the ratio of the number of gelatin fiber bundles to thermoplastic resin fiber bundles in the above-mentioned twisted yarn bundles is 5:1 to 1:

5.

2. The fiber sheet structure according to claim 1, wherein The fiber sheet structure is any one of the following (1) to (4): (1) A structure comprising two layers stacked together, wherein the layer on the front side and the layer on the back side are knitted structures, and the knitted structures are plain knitted fabrics or plain stitch structures; (2) A structure comprising three layers stacked together, wherein the layer on the surface side is a knitted structure, the layer on the back side is a nonwoven fabric, the intermediate layer between the layer on the surface side and the layer on the back side is a knitted structure, the knitted structure is a plain knitted fabric or a plain stitch structure, and the nonwoven fabric contains gelatin fibers; (3) A structure comprising two layers stacked together, wherein the layer on the front side is a knitted structure and the layer on the back side is a nonwoven fabric, the knitted structure is a rib structure, and the nonwoven fabric contains gelatin fibers; (4) A knitted structure consisting of ribbed fabric.

3. The fiber sheet structure according to claim 1 or 2, wherein: The average pore size of the cell-carrying surface is 5 to 123 μm, and the number of pores larger than 150 μm in the cell-carrying surface is less than 35%, and the number of pores in the knitted tissue is 600 / mm 3 above.

4. The fiber sheet structure according to claim 3, wherein: When the twisted yarn bundle is immersed in phosphate-buffered saline at 50° C. for 4 hours, the swelling ratio is 110 to 350%.

5. The fiber sheet structure according to claim 3, wherein: The tensile strength of the twisted yarn bundle is 1.0 to 20.0 cN / dtex, and the elongation at break is 20 to 250%.

6. The fiber sheet structure according to claim 3, wherein: The weight loss rate of the fiber sheet structure when immersed in phosphate-buffered saline at 50° C. for 4 hours is 3 to 30%.

Images