JPH05168690A - Wound coating material and its production - Google Patents

Abstract

PURPOSE:To provide the wound coating material essentially consisting of a fibroin hydrous gel which is higher in strength and resilience than conventional hydrous gels and can be worked to a desired shape. CONSTITUTION:This wound coating material is formed of the water-insoluble fibroin hydrous gel which is deposited near an elect by an electrophoresis from an aq. soln. contg. the fibroin or the gel further treated thereof with a water- retaining agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wound dressing, and more particularly to a wound dressing made of a fibroin hydrogel.

[0002]

2. Description of the Related Art The skin consists of an upper epidermis and a lower dermis. When a burn or abrasion scratch reaches the dermis, if the area of the wound is large, the dermis does not regenerate even if it regenerates, and remains as a scar. This is because the epidermis and dermis cells are different.

Therefore, in the case of such a severe wound, in order to repair the wound cleanly without leaving a scar, a treatment method of collecting and transplanting epidermal tissue from the scalp or sole of the wounded patient is performed. It is being appreciated. This epidermal tissue transplant is performed after waiting for the recovery of the dermal tissue.During that time, since a large amount of fluid leaks from the wound site, the patient has a high risk of causing an infection, so the loss of fluid is prevented and recovery is performed. Need to speed up. Therefore, in order to accelerate the recovery of the wound area of the patient,
Wound dressings are commonly used on the wound surface until the dermal tissue has healed, and representative wound dressings include sterile freeze-dried pig skin.

However, most of the wound dressings need to be removed after the dermis is recovered, and the tissue and the wound dressing adhere to each other, which causes great pain to the patient during the removal. Therefore, a wound dressing material that does not need to be removed from the wound surface by using a material that decomposes in vivo has been developed in recent years and used for treatment. For example, it is one in which collagen, which is the main component of the dermis, is used as a material. However, there have been reported cases in which sufficient strength cannot be obtained or the wound surface is excessively decomposed and the wound surface cannot be sufficiently retained.

Further, many non-woven fabrics which do not expand and contract, irritate the affected part when used on the wound surface and cause pain to the patient. There is also a wound dressing in which fibers are woven to give elasticity to reduce the pain of the patient, but there are some cases in which the treatment scars remain on the scale, and the problem remains.

[0006]

By the way, fibroin, which is widely used in the medical field as a suture thread, is a main component of silk thread and a kind of fibrous protein. When the wound is sutured by using it as a suture, it has a characteristic that it does not need to be removed after healing because it sufficiently holds the wound and is decomposed in the body as it heals. Moreover, even if it remains in the human body, it is considered harmless.

[0007] However, since fibroin is usually fibrous, it is considered that when it is used as a wound dressing material, it stimulates the wound surface. Therefore, it is preferable to process it into a more flexible shape.

Fibroin has the property that it can be processed into a liquid or an aqueous solution by dissolving it in a high-concentration salt solution and desalting it. Further, the aqueous solution can be dried and processed into a sheet film, or can be processed into a hydrous gel state by an operation such as changing the pH of the aqueous solution.

From these properties, it is considered to be suitable as a material for a wound dressing material, and a wound protecting agent composed of a fibroin porous material and a method for producing the same have been disclosed (JP-A-1-254164). issue).

When used as a wound dressing material, among the fibrous, sheet film and gel-like forms, the gel-like form which is less irritating to the wound surface is preferred. However, the water-containing gel prepared by the conventional method of preparing a gel by changing the pH is poor in flexibility and strength and difficult to process into a desired shape, and is used as a practical wound dressing material. The problem remains.

[0011] As described above, the wound dressing includes
At the same time, it is required that the material is decomposed and absorbed in the living body, secondly, it is a material that does not irritate the wound surface, and thirdly, it has a strength capable of sufficiently holding the wound surface. However, no wound dressing material that simultaneously satisfies these three requirements is known, and development is awaited.

The present invention realizes a fibroin hydrous gel which is richer in strength and flexibility than conventional hydrous gels and can be easily processed into a desired shape, and a wound dressing satisfying the above three conditions and a method for producing the same. The challenge is to provide.

[0013]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that a fibroin molded product obtained by electrophoresis from an aqueous solution containing fibroin has high strength. The present invention has been found to be suitable for a wound dressing, and the present invention has been completed.

That is, the present invention comprises a wound dressing containing water-insoluble fibroin hydrogel as a main component, which is obtained by electrophoretically depositing a fibroin-containing aqueous solution in the vicinity of an electrode, or the fibroin hydrogel contains a water retention agent. A method for producing a wound dressing, which comprises the step of depositing a water-insoluble fibroin-containing gel near an electrode by electrophoresis from the wound dressing according to claim 1 and an aqueous solution containing fibroin.

The present invention will be described in detail below. <1> Fibroin hydrogel used in the present invention As described above, the fibroin hydrogel used in the present invention is obtained by precipitating from the aqueous solution containing fibroin near the electrode by electrophoresis.

An aqueous solution containing this fibroin is a raw silk,
Silk and silk raw materials such as silk spinning, raw silk scraps, kiki, bis, scrap cocoons, and burettes are refined by removing sericin and other contaminants by a conventional method, and then, for example, copper-ammonia aqueous solution, copper hydroxide-
Ethylenediamine aqueous solution, rhodanate aqueous solution, lithium bromide aqueous solution, calcium chloride aqueous solution, calcium nitrate,
Or dissolved in a salt solution such as magnesium nitrate aqueous solution,
Furthermore, it can be prepared by dialysis desalting against water.

Alternatively, a silk gland such as a silkworm can be taken out from the living body of an insect and dissolved in water to prepare an aqueous solution of fibroin. The concentration of fibroin in the aqueous fibroin solution used in the present invention is 0.5 to 25% by weight, preferably 2 to 20% by weight. 0.5% by weight
At lower concentrations, the electrical conductivity is reduced and gel formation becomes difficult. On the other hand, when the concentration is higher than 25% by weight, the viscosity becomes too high, the fluidity is deteriorated, and the moldability is deteriorated, which is not preferable.

By filling the inside of the electrolytic cell with this fibroin solution and applying a direct current, the fibroin hydrous gel deposited on the surface of the anode can be obtained. For example, if the surface of the anode is processed into a flat surface, a flat hydrogel can be obtained, and if it is processed into a curved surface, a curved hydrogel can be obtained.

The principle of precipitation of hydrous gel is due to the fact that fibroin molecules are usually negatively charged in an aqueous solution. The DC voltage in the electrolytic cell used in the present invention varies depending on the distance between the electrodes, the conductivity of the electrolytic solution, the concentration of fibroin, etc., but is usually 20V to 15,000V.
Further, the thickness of the hydrous gel obtained by changing the electrical conditions such as voltage, current and time of energization can be adjusted. A carbon material is suitable for the electrode. More preferably, a platinum electrode is used.

In order to prevent generation of hydrogen gas near the cathode during energization, a depolarizing agent, for example, a depolarizer, is added to the aqueous solution of fibroin.
Appropriate amounts of nitric acid, hydrogen peroxide solution, potassium dichromate, manganese oxide and the like may be added.

In addition, a general buffer solution such as a phosphate buffer solution or a Tris buffer solution, or an extremely small amount of salts can be appropriately selected and added to the aqueous solution of fibroin. <2> Wound dressing of the present invention The fibroin hydrogel obtained as described above is used as a wound dressing.

This hydrogel can be used as a wound dressing as it is. Further, depending on the degree of the wound, it may be more preferable to treat the water-containing gel with a water retention agent and use a wound dressing having a low water permeability. For example, when the amount of exudate from the wound surface is relatively small, it is preferable to set the water vapor permeability to a low level so as not to dry the wound dressing.

The water vapor permeability can be adjusted to a low level by treating the surface with a water retention agent. As the water retention agent for treating the surface of the hydrogel containing fibroin used in the present invention, dimethylpolysiloxane having a water blocking effect,
Silicone oil such as methylphenyl polysiloxane, liquid paraffin, hydrocarbons such as squalane, and polyhydric alcohol such as glycerin having a water absorbing effect can be appropriately selected and used.

Examples of the treatment method include a method of dropping the water retention agent on the surface of the hydrogel of fibroin and applying it, and a method of immersing the hydrogel of fibroin in a water retention agent solution. However, when the water retention agent is hydrophobic such as silicone oil, treatment of the water retention agent on the wound contact surface may affect the affinity with the dermal tissue, so the latter method is not suitable. This does not apply when the water retention agent is hydrophilic such as glycerin.

The wound dressing thus obtained may be impregnated with a medicinally active ingredient usually used for treating wounds. Storage of the wound dressing of the present invention should be performed avoiding extremely dry conditions. For example, there is a method of putting a wound dressing material in a polystyrene bag and sealing the mouth of the bag. The storage temperature may be room temperature, but is appropriately set such as keeping at 0 to 10 ° C. depending on the added components.

[0026]

EXAMPLES Examples of the present invention will be described below.

[0027]

Example 1 With a bath ratio of raw silk and 0.5% Marcel soap aqueous solution set to 200, refining was carried out twice at 100 ° C. for 30 minutes, and this was washed with distilled water to obtain refined silk. This refined silk was dissolved in a 9 M aqueous solution of lithium bromide at 40 ° C. and dialyzed with a dialysis membrane made of cellulose until no lithium bromide was detected in the dialyzed water to obtain a 4 wt% aqueous fibroin solution. ..

Next, length 10 cm × width 10 cm × height 3
A platinum electrolysis cell (cm) was filled with 30 ml or more of this fibroin aqueous solution, and the platinum positive electrode, which was slightly smaller than the bottom of the electrolysis cell, was fixed 3 mm above the bottom of the electrolysis cell while being insulated from the electrolysis cell. At this time, it is preferable not to introduce air bubbles between the fibroin aqueous solution and the electrode.

The electrolytic cell is used as a negative electrode, and 1 is provided between the positive electrode and the positive electrode.
When a direct current of 1000 mA at 0 mA was applied for 5 minutes, a fibroin hydrogel having a thickness of 0.1 mm was deposited on the surface of the positive electrode. This was used as a wound dressing.

[0030]

Example 2

Above

In the first embodiment, the direct current application condition is 10 m.
A fibroin hydrogel having a thickness of 0.2 mm was obtained under the same conditions as A, 1000 V, 10 minutes. Glycerin was applied to the surface of one side of this hydrous gel to prepare a wound dressing.

[0032]

Comparative Example 1 A wound dressing was produced according to the method described in JP-A-1-254164. Raw silk was immersed in 0.5% sodium carbonate solution at a heating ratio of 50 times twice at 90 ° C. to remove sericin to obtain fibroin fiber, which was dissolved in saturated calcium chloride ethanol solution. .. The solution was dialyzed and desalted using a cellulose dialysis membrane to obtain a transparent fibroin solution, the pH was adjusted to 4 with citric acid, and the solution was left at room temperature to obtain a fibroin hydrogel. This was used as the wound dressing of Comparative Example 1. (Evaluation) With respect to the wound dressings of Examples 1 and 2 and Comparative Example 1, the results of examining the strength and flexibility of the gel using a card tension meter are shown in Table 1. The card tension meter is a device for measuring the strength and flexibility of gel,
The larger the value, the higher the strength and flexibility. A star-shaped card knife is used.
It measured using the weight of 0 g. Five samples were measured for each wound dressing, and the average value was shown.

[0033]

[Table 1]

From these results, it is clear that the wound dressing of the present invention is superior in strength and flexibility to the conventional fibroin hydrogel.

[0035]

[Examples of use] Wound dressings of Comparative Examples 1 and 2 and Examples, collagen wound dressings (Meipak: Meiji Seika Co., Ltd., fibrous atelocollagen nonwoven fabric) as Comparative Example 2 and Comparative Example 3 below. A wound wound made of nylon (Biobrene: manufactured by Woodloof) is used for a wound site created by scraping the skin up to the dermis using a dermatome on the back surface of a rabbit, and 2 weeks after the treatment is shown.

The results are shown in Table 2.

[0037]

[Table 2]

As is clear from these results, the wound dressing material of the present invention has a better wound healing effect than the conventional wound dressing materials.

[0039]

The wound dressing using the hydrogel of fibroin of the present invention can be easily prepared by using the electrophoresis method. Further, according to the present invention, it is possible to provide a wound dressing material which has sufficient strength and flexibility, does not irritate the wound surface, and is absorbed and decomposed into the body after sufficiently protecting the wound surface.

Claims (3)

[Claims] 1. A wound dressing material containing a water-insoluble fibroin hydrogel as a main component, which is obtained by depositing an aqueous solution containing fibroin near an electrode by electrophoresis. 2. The wound dressing according to claim 1, wherein the hydrogel containing fibroin contains a water retention agent. 3. A method for producing a wound dressing, comprising a step of precipitating a water-insoluble fibroin-containing gel near an electrode by electrophoresis from an aqueous solution containing fibroin.