Surgery: splint – brace – or bandage – Bandage structure – Skin laceration or wound cover
Patent
1997-09-04
1999-09-14
Apley, Richard J.
Surgery: splint, brace, or bandage
Bandage structure
Skin laceration or wound cover
602 6, 602 42, 602 43, 1061241, A61F 1300
Patent
active
059515066
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a wound covering material.
BACKGROUND ART
A covering material to be applied to a skin defect as an artificial skin is called a wound covering material. A pig skin, chitin and so on have already been developed for such a wound cover. These materials, however, have drawbacks in that a new skin developing under the artificial skin may be removed as the artificial skin is being removed. Further, there has recently been developed a wound covering material referred to as "Dioactive CGF" and this wound covering material is less likely to remove the new skin developing under the artificial skin, upon removal of the wound covering material. This wound covering material, however, is said to be slower in the speed of forming a new skin below, as compared to a pig skin.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a wound covering material that can smoothly accelerate the growth of new skin thereunder and that can be removed without removal of the new skin therewith.
As a result of extensive studies and research to achieve the object as described hereinabove, the present invention provides a wound covering material comprising a non-crystalline fibroin film.
The wound covering material (hereinafter referred to sometimes as a "covering material") according to the present invention can be prepared by using an aqueous fibroin solution as a raw material and processing it into a film.
For the preparation of an aqueous fibroin solution, a silky substance is purified by removing sericin. The silky substance may include, for example, cocoons, cocoon thread, silk yarn, silk cloth and waste thereof. The purification of the silky substance may be carried out, for example, by boiling the silky substance in an enzyme or in an aqueous solution of an alkali such as sodium carbonate, sodium hydrogen carbonate or the like, washing the resulting silky substance with water, and immersing it in warm water, thereby causing chemical substances such as sericin, sodium carbonate and so on to be eluted and removing them. It is preferred that the purified silky substance is then sterilized with ethylene oxide gas, in an autoclave or by any other means.
The silky substance purified in the way as described hereinabove is then dissolved in pure water containing a dissolution aid. The dissolution aid to be employed in this case may include, for example, an acid, a neutral salt-such as calcium chloride, lithium bromide or the like or ethanol.
The aqueous solution in which the silky substance is dissolved is subjected to dialysis by means of a semipermeable membrane tube or the like, thereby yielding an aqueous fibroin solution from which the dissolution aid has been removed.
The concentration of fibroin in the aqueous fibroin solution may be 2% by weight or higher, preferably 5% by weight or higher, although it is usually in the range of from 5% to 20% by weight. The amount of impurities other than fibroin in the aqueous fibroin solution may be 0.01% by weight or lower, preferably 0.0001% by weight or lower. In this case, there is the possibility that sericin, chlorine or the like may be contained as impurities.
The process of forming the aqueous fibroin solution into a film may comprise casting the aqueous fibroin solution on a flat and smooth surface of a solid member and removing the water contained therein by evaporating it. It is of great importance in this case that the resulting fibroin film is not made crystalline and that it becomes a substantially non-crystalline film. In order to achieve this, it is preferred to adjust the speed of removing the water by evaporation from the aqueous fibroin solution in the process of film formation and it is possible to prevent crystallization of the resulting film by increasing the speed of the evaporation of the water.
The crystallization of the fibroin film occurs in the process of drying the aqueous fibroin solution when it takes a long time to dry while the concentration of the aqueous fibroin solution is 30% or hig
REFERENCES:
patent: 4325741 (1982-04-01), Otoi et al.
patent: 5252285 (1993-10-01), Lock
patent: 5263983 (1993-11-01), Yoshizato et al.
Apley Richard J.
Forestry and Fishries
Hart Kelvin
Japan as represented by National Institute of Sericultural ans
Ministry of Agriculture
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