Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2002-04-04
2004-02-17
Barts, Samuel (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S055000, C536S055100, C536S018700, C536S123100, C536S055300
Reexamination Certificate
active
06693180
ABSTRACT:
FIELD OF THE INVENTION
The invention herein relates to a wound dressing, particularly, relates to a composite sponge wound dressing made of &bgr;-Chitin and Chitosan for accelerating wound repair.
BACKGROUND OF THE INVENTION
Normally, wound dressing needs to provide some basic physical and biological function, such as avoiding water or liquid loss, human skin-like with flexibility, gas permeation, water vapor flux, absorbing wound exudate, mechanical strength, anti-bacterial or sterilization without causing wound aggravation, adherence to wound, non-toxicity, improvement of epithelization, analgesia, hemostasis, and non-irritant etc. Therefore, there were varies of wound dressing being developed for satisfying the aforementioned requirements.
Chitin is a nature cellulose-like macromolecule extracted from crab or shrimp waste shells. Prudden et al. has developed the research of the wound repair since 1970, and the wound dressing has been commercialized as medical product named “bas-Chitin W”, produced by UNITIKA, Japan, and its clinical manifestation was good, as disclosed in Nishinihon Journal of Dermatology Fukuoka Japan, vol. 54, no. 5, pp. 998-1008, 1992. There were many different wound dressing, such as non-woven and porous composition and membrane, each of them was applied in different wound respectively, and its clinical manifestation was good (such as “bedsore treatment” disclosed in Nishinihon Journal of Dermatology Fukuoka Japan, vol. 52, no. 2, pp. 761-764,1990; “wound dressing experiment” disclosed in Nishinihon Journal of Dermatology Fukuoka Japan, vol. 50 no. 4, pp. 712-724, 1998; “incision treatment” disclosed in Nishinihon Journal of Dermatology Fukuoka Japan, vol. 48, no. 6, pp. 1119-1122). However, the Chitin extracted from crab or shrimp shells is &agr;-Chitin, and its energy of stereo structure between the molecules is very stable, therefore, it has a stronger molecular structure, which needs some special organic solvent to dissolve (like LiCL/N,N-dimethyl acetamide), as a result, it is limited in developing its application, and furthermore, the solvent may cause problems of safety issue and environment pollution.
In general, according to the different structure of molecules, there are three Chitins: &agr;-Chitin (such as extracted from crab or shrimp shells), &bgr;-Chitin (such as extracted from the cuttlefish cartilage), and &ggr;-Chitin. The energy of stereo structure between the molecules of &agr;-Chitin is the most stable, therefore, it has the strongest molecular structure, which needs some special organic solvent to dissolve (such as LiCL/N,N-dimethyl acetamide), as a result, it is limited in developing its application, and furthermore, the solvent may cause problems of safety issue and environment pollution. Due to the energy of stereo structure between the molecules of &bgr;-Chitin is not very stable, it can absorb liquid, and can be formed in short staple by high speed blending. The Japan Patent Publication Number 07-47113, “Therapeutic Agent”, discloses porous &bgr;-Chitin producing by high speed blending and freeze-drying method, and also, the Japan Patent publication number 03-41131, “Production of porous Chitin molding”, uses the same method to produce the porous &bgr;-Chitin. However, the &bgr;-Chitin produced in accordance with the above method has lower tensile strength (dry/wet). The heaviest loading is 0.46 kg and tensile strength is 0.046 kg/cm
2
(dry), and 0.06 kg loading and 0.006 kg/cm
2
tensile strength (wet). Being a wound dressing, it may cause breakage when absorbing the wound exudate, so it is inconvenience for surgery operation.
Chitosan is a macromolecules production through deacetylation from Chitin. The U.S. Pat. No. 4,532,134, “method of achieving hemostasis, inhibiting fibroplasias, and promoting tissue regeneration in a tissue wound”, indicates that the medical property of Chitosan includes hemostasis, hindered of growth of fibroblast, and improving tissue regeneration. Besides, Japan Patent Publication Number 08-224293, “Multilayered body for treating wound”, also indicates that the medical property of Chitosan includes activating macrophage and leukocyte, anti-bacterial, and further preventing wound suppurated. Therefore, the present invention provides a composite sponge wound dressing made of &bgr;-Chitin and Chitosan, which not only can absorb liquid, but also can keep good tensile strength.
SUMMERY OF THE INVENTION
This invention provides a composite sponge wound dressing made of &bgr;-Chitin and Chitosan and method for producing the same. Putting &bgr;-Chitin into D.I. water, and then blending them with high speed until forming a hydrogel &bgr;-Chitin, at the same time, filtering Chitosan by solving thereof, next, mixing said hydrogel &bgr;-Chitin and said Chitosan to form a sponge by freeze-drying. Immersing said sponge in an alkaline liquid for forming salt by neutralization, after salt formed, clean said sponge to neutral. At last, said sponge is cleaned repeatedly with D.I. Water and formed a composite sponge wound dressing made of &bgr;-Chitin and Chitosan by vacuum drying. In the preferred embodiment, when the mixing ratio of Chitosan and &bgr;-Chitin being between 0.1~1, the composite sponge wound dressing has a better absorption and tensile strength.
REFERENCES:
patent: 0 477 979 (1991-09-01), None
Ogasawara et al., Chemistry of Materials (2000), 12 (10), 2835-2837; (abstract sent).
Hsu Chun-Yuan
Lee Jui-Sheng
Lin Wei-Hsin
Barts Samuel
China Textile Institute
Henry Michael C.
Troxell Law Office PLLC
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