Material for promoting release of oxygen from red blood cells, and wound covering material containing said material

Abstract

[Problem] It is known that in wound healing, when pH in blood decreases, oxygen is released from hemoglobin, blood oxygen concentration rises, division of regenerated epithelial cells is promoted, and healing is promoted. Wound therapeutic agents such as creams or ointments are weakly acidic, and therefore, the described healing promoting effect can be expected; however, in being applied by the fingers, the wound therapeutic agent will need to be wiped off, and other adverse handling-related attributes are encountered, there being a risk presented of further damage to the wound when the agent is applied. The purpose of the invention is to provide a material for promoting the release of oxygen from red blood cells that has exceptional handling-related attributes and is capable of promoting division of regenerated epithelial cells and promoting healing of a wound. [Solution] A material for promoting the release of oxygen from red blood cells characterized in being a sheet-form material containing an acid-type carboxy-group-containing material, the amount of acid-type carboxy groups contained in the material being 0.05-10.0 mmol / g.

Description

Material for promoting oxygen release from red blood cells and wound dressing containing the same

[0001] The present invention relates to a material for promoting oxygen release from red blood cells and a wound dressing containing the same.

[0002] Physical damage to body surface tissues caused by external or internal factors is called a wound. Hygienic materials placed to cover the surface of such wounds (wound surfaces) are called wound dressings, and they serve the purposes of protecting the wound surface, preventing drying (moisturizing), absorbing exudates (liquid absorption), and inhibiting bacterial infection. Compared to the conventional mainstream method of covering the wound surface with gauze and disinfecting it with an antiseptic solution, wound dressings maintain a moist state on the wound surface, preventing cell activation and enabling effective wound healing. Various wound dressings have been reported (e.g., Patent Documents 1 and 2).

[0003] On the other hand, it is known that during the wound healing process, an increase in the oxygen concentration in the blood promotes the division of regenerating epithelial cells, thereby promoting wound healing (Non-Patent Document 1). The binding strength between hemoglobin and oxygen in blood decreases as the pH decreases, so this phenomenon can be utilized to increase the oxygen concentration in the blood. From this perspective, wound treatment agents such as creams and ointments, which are generally weakly acidic, can be expected to lower the pH of the blood and promote wound healing.

[0004] Japanese Patent Application Laid-Open No. 10-201838 Japanese Patent Application Laid-Open No. 2000-210375

[0005] Aichi Prefectural Hospital Pharmacists Association Journal, 2005, Vol. 33, No. 3, pp. 6-16

[0006] However, wound treatments such as creams and ointments are applied with the fingers, which makes them inconvenient to use as they need to be wiped off after use, and they can further damage the wound when applied, so this is not necessarily the best method.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a material that promotes oxygen release from red blood cells, which is easy to work with and can promote the division of regenerated epithelial cells and aid in wound healing.

[0008] As a result of extensive research into achieving the above-mentioned object, the inventors have discovered that an acid-type carboxyl group-containing material can be used as a material to promote oxygen release from red blood cells, which is easy to work with in treatment, and have arrived at the present invention.

[0009] That is, the present invention is achieved by the following means. (1) A material for promoting oxygen release from red blood cells, which is a sheet-like material containing an acid-type carboxy group-containing material, characterized in that the amount of acid-type carboxy groups contained in the material is 0.05 mmol / g or more and 10.0 mmol / g or less. (2) The material for promoting oxygen release from red blood cells according to (1), characterized in that the amount of acid-type carboxy groups in the acid-type carboxy group-containing material is more than 1.5 mmol / g and 10.0 mmol / g or less. (3) The material for promoting oxygen release from red blood cells according to (1), characterized in that the content of the acid-type carboxy group-containing material is 1 to 100% by mass. (4) The material for promoting oxygen release from red blood cells according to (1), characterized in that the acid-type carboxy group-containing material has the shape of a fiber, particle, or film. (5) The material for promoting oxygen release from red blood cells according to (1), characterized in that the acid-type carboxy group-containing material is a core-sheath composite fiber consisting of a sheath portion having an acid-type carboxy group-containing polymer and a core portion having an acrylonitrile-based polymer. (6) The material for promoting oxygen release from red blood cells according to any one of (1) to (5), which is in the form of a nonwoven fabric, a woven fabric, a knitted fabric, paper, or a film. (7) A wound dressing containing the material for promoting oxygen release from red blood cells according to (6). (8) The wound dressing according to (7), which is characterized in that a material having water vapor permeability is laminated on the material for promoting oxygen release from red blood cells. (9) The wound dressing according to (8), which is characterized in that the material having water vapor permeability is a silicone film or a polyurethane film.

[0010] The oxygen release-promoting material of the present invention can efficiently release oxygen from red blood cells. Furthermore, the acid-type carboxyl group-containing material of the present invention has been widely used in clothing and other materials, and various processing methods have been established, so it can be widely used as a wound dressing material.

[0011] The oxygen release promoter of the present invention is a sheet-shaped material containing an acid-type carboxy group-containing material. The oxygen release promoter of the present invention contains 0.05 mmol / g to 10.0 mmol / g, preferably 0.2 mmol / g to 8.0 mmol / g, of acid-type carboxy groups relative to the mass of the promoter. If the amount of acid-type carboxy groups in the promoter is less than 0.05 mmol / g, oxygen release from red blood cells may not be sufficiently promoted. On the other hand, if the amount of acid-type carboxy groups in the promoter exceeds 10.0 mmol / g, production at a practical level may be difficult, or even if production is possible, processing to achieve satisfactory physical properties may be difficult. In the present invention, an acid-type carboxy group refers to "-COOH," and a salt-type carboxy group is one in which the hydrogen ion of an acid-type carboxy group is replaced with another ion.

[0012] In the acid type carboxy group-containing material used in the oxygen release-promoting material of the present invention, the amount of acid type carboxy groups is preferably more than 1.5 mmol / g and not more than 10.0 mmol / g, more preferably more than 2.0 mmol / g and not more than 10.0 mmol / g, even more preferably more than 5.0 mmol / g and not more than 10.0 mmol / g, and most preferably more than 5.0 mmol / g and not more than 8.0 mmol / g. If the amount of acid type carboxy groups is 1.5 mmol / g or less, oxygen release from red blood cells may not be sufficiently promoted, while if it exceeds 10.0 mmol / g, it may be difficult to produce at a practical level, or even if it can be produced, it may not be possible to process it to achieve satisfactory physical properties.

[0013] The oxygen release-promoting material of the present invention preferably contains the acid type carboxy group-containing material in an amount of 1 to 100% by mass, more preferably 3 to 50% by mass, and even more preferably 5 to 30% by mass. If the amount is less than 1% by mass, oxygen release from red blood cells may not be sufficiently promoted.

[0014] The acid type carboxyl group-containing material may be in the form of fibers, particles, films, or the like. In the case of fibers, there are a wide variety of processing methods available for imparting the desired shape, making it easy to apply to various forms. Furthermore, since there is no need to use a surface-coating agent such as a binder during such processing, the deterioration of the oxygen release-promoting function due to coating can be avoided.

[0015] The acid-type carboxy group-containing material may be at least partially composed of an acid-type carboxy group-containing polymer. Specific examples of such acid-type carboxy group-containing polymers include polyacrylic acid, polymethacrylic acid, polymaleic acid, and copolymers of acrylic acid, methacrylic acid, and maleic acid. Also usable are products obtained by crosslinking water-soluble vinyl polymers having acid-type carboxy groups with a crosslinking compound, as disclosed in JP-A-2009-173690.

[0016] Examples of the fibrous acid-type carboxyl group-containing material include fibers obtained by acid-treating crosslinked acrylate fibers obtained by subjecting the fibers to a crosslinking introduction treatment using a crosslinking agent such as hydrazine and a hydrolysis treatment using an alkaline compound, and fibers obtainable by the method described in JP-A-2013-147774.

[0017] Examples of the crosslinked acrylate fibers include, for example, crosslinked acrylate fibers in which an increase in nitrogen content of 1.0 to 5.0% by weight is introduced by crosslinking acrylic fibers having an acrylonitrile content of 85 to 95% by weight with a hydrazine compound, as described in JP 2000-314082 A, and in which a portion of the remaining nitrile groups are converted to alkali metal salt-type carboxy groups of 3.0 to 6.0 meq / g by hydrolysis. Such crosslinked acrylate fibers can be used after converting the salt-type carboxy groups to acid-type carboxy groups by, for example, immersing them in a nitric acid aqueous solution. The amount of acid-type carboxy groups can be adjusted by changing the agent concentration, reaction time, reaction temperature, etc. in the hydrolysis treatment.

[0018] Furthermore, when a fiber-shaped acid-type carboxy group-containing material is used as a sheath-core composite fiber consisting of a sheath containing an acid-type carboxy group-containing polymer and a core containing an acrylonitrile-based polymer, the degradation of fiber properties caused by increasing the amount of acid-type carboxy groups can be suppressed, thereby achieving both the function of promoting oxygen release from red blood cells and fiber properties. Examples of such core-sheath composite fibers include those obtained by subjecting the fiber surface of an acrylonitrile-based fiber to the aforementioned crosslinking and hydrolysis treatments to produce a metal salt-type acrylate-based fiber, as described in JP 2023-67820 A, followed by immersion in a nitric acid aqueous solution to convert the salt-type carboxy groups to acid-type carboxy groups, and commercially available products in which the salt-type carboxy groups have been converted to acid-type carboxy groups. An example of such a commercially available product is the acrylonitrile-based absorbent sheath-core fiber "LANSeal" manufactured by Toyobo Co., Ltd., which has a sheath composed of a salt-type carboxy group-containing polymer and a core composed of an acrylonitrile-based polymer. Furthermore, because Lanseal has excellent water absorption properties, when used as a wound dressing, for example, it can absorb sweat, exudates, etc., keeping the wound moist and enabling effective wound treatment.

[0019] Examples of particulate acid carboxy group-containing materials include cation exchange resins and crosslinked particles having acid carboxy groups that can be produced by the method described in JP-A-2013-147473.

[0020] The form of the oxygen release-promoting material of the present invention is not particularly limited, but is preferably in the form of a sheet such as a nonwoven fabric, woven fabric, knitted fabric, paper, or film. The sheet form makes it easier to apply to a wound dressing, which will be described later.

[0021] In the method for producing the oxygen release-promoting material of the present invention, when the acid-type carboxyl group-containing material is in the form of fiber, it is preferable to use the material alone or together with other fiber materials to form nonwoven fabrics, woven fabrics, knitted fabrics, paper, etc., according to a conventionally known method. The other fiber materials are not particularly limited, and natural fibers, organic fibers, semi-synthetic fibers, and synthetic fibers can be used, and inorganic fibers, glass fibers, etc. can also be used depending on the application. Specific examples include cotton, linen, silk, wool, nylon, rayon, polyester, and acrylic fibers.

[0022] When the acid type carboxy group-containing material is in a particulate form, it can be supported on the surface of nonwoven fabric, woven fabric, knitted fabric, paper, film, or the like made of other materials using a binder or the like.

[0023] The oxygen release-promoting material of the present invention described above is suitable as a material for constituting a wound dressing. That is, the oxygen release-promoting material of the present invention can efficiently release oxygen from red blood cells, and when used as a wound dressing, the released oxygen promotes the division of regenerating epithelial cells and promotes wound healing. Furthermore, since it can be in the form of a nonwoven fabric, woven fabric, knitted fabric, paper, or film, unlike ointments, it does not require wiping and is easy to work with.

[0024] Although the oxygen release-promoting material of the present invention can be used alone as a wound dressing, it becomes even more suitable as a wound dressing when it is laminated with a water vapor permeable material. That is, by laminating a water vapor permeable material on the side opposite the wound surface, it is possible to protect the wound surface from external contamination such as bacteria and moisture while allowing moisture derived from exudate and insensible perspiration from the wound surface to dissipate appropriately.

[0025] The water vapor permeable material is not limited, but examples include silicone film and polyurethane film, which are suitable because they are flexible and can easily conform to the shape of the affected area.

[0026] As a method for laminating and integrating a material having water vapor permeability onto the oxygen release-promoting material of the present invention, a method of applying a known pressure-sensitive adhesive or adhesive having water vapor permeability and laminating and integrating them can be mentioned.

[0027] Examples are given below to facilitate understanding of the present invention, but these are merely illustrative and the gist of the present invention is not limited thereto. In the examples, parts and percentages are expressed by mass unless otherwise specified.

[0028] <Measurement of the amount of acid carboxyl groups> Approximately 1 g of a thoroughly dried sample was weighed (W1 [g]), 200 ml of water was added to this, and a titration curve was obtained using a 0.1 mol / l aqueous sodium hydroxide solution according to a standard method. From the titration curve, the amount of aqueous sodium hydroxide consumed by the acid carboxyl groups (V1 [ml]) was determined, and the amount of acid carboxyl groups was calculated using the following formula: Amount of acid carboxyl groups [mmol / g] = 0.1 × V1 / W1

[0029] <Measurement of pH of horse blood after treatment> 0.3 g of the evaluation sample was added to horse blood (manufactured by Japan Bioserum Co., Ltd.) and allowed to stand at room temperature for 5 minutes. Then, the evaluation sample was removed and the pH of the horse blood was measured.

[0030] <Oxygen Release Rate> Hemoglobin bound to oxygen (oxyhemoglobin) and hemoglobin not bound to oxygen (deoxyhemoglobin) have different three-dimensional structures, and therefore also have different infrared absorption curves. Specifically, the relationship between the absorbance at a wavelength of 665 nm (A665) and the absorbance at a wavelength of 880 nm (A880) is such that A665<A880 for oxyhemoglobin, whereas A665>A880 for deoxyhemoglobin. Utilizing this relationship, the oxygen release rate was evaluated by the following method.

[0031] 0.3 g of the evaluation sample was added to horse blood (manufactured by Japan Bioserum Co., Ltd.) and allowed to stand at room temperature for 5 minutes. The evaluation sample was then removed and the horse blood was collected and diluted 100 times with physiological saline, after which A665 and A880 were measured and the oxygen release rate was calculated using the following formula. If the oxygen release rate is 1.175 or higher, it indicates that more oxygen is released than in normal cases, i.e., venous blood. Oxygen release rate = A665 / A880

[0032] Example 1 Acrylic fiber A was obtained by dissolving 10 parts of an acrylonitrile polymer consisting of 90% acrylonitrile and 10% methyl acrylate in 90 parts of a 48% aqueous solution of sodium rhodanide in a spinning solution, followed by spinning, drawing and drying according to a conventional method.

[0033] Acrylic fiber A was subjected to a crosslinking treatment in a 15% hydrazine aqueous solution at 110°C for 3 hours and then washed with water. Next, it was subjected to an acid treatment in an 8% nitric acid aqueous solution at 110°C for 1 hour and then washed with water. Subsequently, it was subjected to a hydrolysis treatment at 90°C in a 5% sodium hydroxide aqueous solution and then washed with water. The amount of carboxy groups in the fiber was adjusted by changing the treatment time. Thereafter, it was subjected to an acid treatment in a 10% nitric acid aqueous solution at room temperature for 24 hours and then washed with water, to obtain a fibrous acid-type carboxy group-containing material.

[0034] The fibrous acid-type carboxyl group-containing material containing 5.2 mmol / g of acid-type carboxyl groups prepared as described above was mixed with the acrylic fiber A described above in a mass ratio of 1:99, and a nonwoven fabric sample was prepared by needle punching. The evaluation results of the sample are shown in Table 1.

[0035] Example 2 A nonwoven fabric sample was prepared in the same manner as in Example 1, except that the mass ratio of the fibrous acid-type carboxyl group-containing material to the acrylic fiber A was changed to 5:95. The evaluation results are shown in Table 1.

[0036] Example 3 A nonwoven fabric sample was prepared in the same manner as in Example 1, except that the mass ratio of the fibrous acid-type carboxyl group-containing material to the acrylic fiber A was changed to 100:0. The evaluation results are shown in Table 1.

[0037] Example 4 Nonwoven fabric samples were prepared in the same manner as in Example 2, except that the amount of acid carboxy groups in the fibrous acid carboxy group-containing material was changed from 5.2 mmol / g to 9.5 mmol / g. The evaluation results are shown in Table 1.

[0038] Example 5: Acrylic fiber A was coated with a mixed aqueous solution containing 0.13% hydrazine and 35% sodium hydroxide, then wrung to achieve a 100% fiber absorption rate. The fiber was then subjected to a crosslinking hydrolysis treatment at 106°C for 15 minutes and washed with water. The washed fiber was then immersed in a 0.1% sulfuric acid aqueous solution at 30°C for 1 hour, dehydrated, treated with an oil, dehydrated, opened, and dried to obtain a core-sheath composite fiber containing an acid-type carboxyl group-containing polymer in the sheath and an acrylonitrile-based polymer in the core. The resulting fiber-shaped acid-type carboxyl group-containing material containing 1.8 mmol / g of acid-type carboxyl groups was mixed with the aforementioned acrylic fiber A in a mass ratio of 5:95, and a nonwoven fabric sample was prepared by needle punching. The evaluation results of the sample are shown in Table 1.

[0039] Comparative Example 1 A nonwoven fabric sample was prepared in the same manner as in Example 1, except that the mass ratio of the fibrous acid-type carboxyl group-containing material to the acrylic fiber A was changed to 0:100. The evaluation results are shown in Table 1.

[0040] <Comparative Example 2> A nonwoven fabric sample was prepared in the same manner as in Example 1, except that the amount of acid carboxy groups in the fibrous acid carboxy group-containing material was changed from 5.2 mmol / g to 3.0 mmol / g. The evaluation results are shown in Table 1.

[0041]

[0042] As can be seen from Table 1, the oxygen release rate was good in each of the Examples of the present invention, and the Examples were useful as oxygen release promoters. On the other hand, in Comparative Examples 1 and 2, the amount of acid-type carboxyl groups in the promoter was small, and a sufficient oxygen release rate was not obtained.

Claims

1. A material for promoting oxygen release from red blood cells, which is a sheet-shaped material containing an acid-type carboxyl group-containing material, characterized in that the amount of acid-type carboxyl groups contained in the material is 0.05 mmol / g or more and 10.0 mmol / g or less.

2. A material for promoting oxygen release from red blood cells as described in claim 1, characterized in that the amount of acid carboxy groups in the acid carboxy group-containing material is more than 1.5 mmol / g and not more than 10.0 mmol / g.

3. The material for promoting oxygen release from red blood cells according to claim 1, characterized in that the content of the acid type carboxyl group-containing material is 1 to 100% by mass.

4. The material for promoting oxygen release from red blood cells according to claim 1, characterized in that the acid type carboxyl group-containing material has a fibrous, particulate or film shape.

5. The material for promoting oxygen release from red blood cells as described in claim 1, characterized in that the acid-type carboxyl group-containing material is a core-sheath composite fiber consisting of a sheath portion having an acid-type carboxyl group-containing polymer and a core portion having an acrylonitrile-based polymer.

6. The material for promoting oxygen release from red blood cells according to any one of claims 1 to 5, characterized in that it has the form of any one of nonwoven fabric, woven fabric, knitted fabric, paper and film.

7. A wound dressing material containing the material for promoting oxygen release from red blood cells according to claim 6.

8. The wound dressing material according to claim 7, characterized in that a material having water vapor permeability is laminated to the material that promotes oxygen release from red blood cells.

9. The wound dressing according to claim 8, characterized in that the water vapor permeable material is a silicone film or a polyurethane film.

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