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Preparation of wound dressing using hydrogel polyurethane foam.

The hydrogel type polyurethane (PU) foams were prepared from diisocyanate and polyol with/without hydrophilic moiety for wound dressing to protect infection from outside and to heal skin wound. Biomaterials with hydrogel properties, such as alginate and hyaluronic acid, and antimicrobial agent (silver sulfadiazine, AgSD) were also incorporated in the polyurethane foam. The PU foams have good properties such as mechanical strength, swelling ratio, and cell adhesion for applying to wound dressing. Especially, the wound healing effect of PU foam incorporated hydrogel materials with AgSD was excellent compared to that of PU foam without hydrogel materials.

INTRODUCTION

As technical viewpoint polyurethanes (PU) are of wide applications because they have the advantages in synthesizing with various polymer materials contain different mechanical and physical properties due to polyol and diisocyanate used in synthesis. It is possible to manufacture differently shaped PU, such as film, hydrogel, hydrocolloid, and having different water permeability, swelling ratio, and structures, according to kinds of reactants, ratio of a component, reaction conditions and additives. Therefore, it is necessary to research on the effective wound dressing according to the state of the wound by using the various characteristics of PU. The wound dressing is designed to provide the following capabilities: Control of water loss through evaporation, Inhibition of body fluid loss, Promotion of drainage and prevention of exudates buildup, Protection from external contamination, Sufficient bactericidal effect to inhibit infection and preparation of an optimum wound bed for autografting. In this study we prepared hydrogel type PU foam with high water vapor permeability. Also, we investigated cell adhesion and animal study to examine the wound healing of the PU foam.

MATERIALS AND METHODS

PU was prepared by reaction between toluene diisocyanate (2,4 = 80%, 2,6 = 20%, Tokyo Kasei Kogyo Co. Ltd., Japan) and random copolymer consisting of polyethylene glycol and polypropylene glycol. Biomaterials with hydrogel properties such as alginate (AL), hyaluronic acid (HA), and antimicrobial agent (AgSD) were incorporated into PU foam prepared by a molding method from a viscous PU prepolymer. The amount of AgSD in the wound dressing is 50 [micro]g/[cm.sup.2] to provide adequate bactericidal efficacy. Water permeability, swelling ratio, contact angle, and mechanical properties of PU foam were measured. Release behavior of AgSD and fibroblast adhesion behavior on PU foam with different additives were also studied.

RESULTS AND DISCUSSION

Swelling ratio of PU foam containing hydrogel materials is larger than that of PU foam without hydrogel materials. Swelling is saturated almost within 10 hours. Introducing antimicrobial agent, AgSD, and hydrogel materials such as alginate and hyaluronic acid decreased mechanical strength. The optimum mechanical strength was obtained in 5 wt% contents of hydrogel materials.

[FIGURES 1-2 OMITTED]

In release behavior of AgSD, the initial release amounts are similar in all cases. However, after 20 hours, the amounts of release were increased in No. 4 and No. 6 compared with No. 2. The hydrated molecular structure of alginate or hyaluronic acid may promote to release AgSD. Hyaluronic acid was shown to promote the early granulation tissue formation and the smooth wound surface formation (1).

For the study of adhesion-disadhesion between dressing and wound bed, adhesion behavior of fibroblast on PU foam was investigated. No. 4 and No. 6 cases inhibit fibroblast from adhesion on PU foam. Hyaluronic acid may facilitate adhesion-disadhesion between the cell membrane and the matrix substratum during cell movement.

[FIGURES 3-4 OMITTED]

Animal study of PU foam with hydrogel was performed with rat. In case of hyaluronic acid and AgSD impregnated PU foam, the wound size is decreased around 84 % within 1 week after skin defect. Also there is no found inflammation, yellow crust and dressing deformation.

In conclusion, PU foams with hydrogel having good mechanical strength, good swelling ratio, good release behavior of AgSD and good adhesion -disadhesion with wound bed were successfully prepared. Especially the PU foams containing both alginate and hyaluronic acid with AgSD show good wound healing effect.

REFERENCES

(1.) Kuroyanagi Y., Shioya N., Advances in wound dressing and cultured skin substitute., Wound Healing Center, Kitasata University Hospital, 55-77, Japan, 1994.

(2.) Kuroyanagi Y., Shioya N., Advances in wound dressing and cultured skin substitute., Wound Healing Center, Kitasata University Hospital, 6-15, Japan, 1994.

(3.) Kuroyanagi Y., Kim E., Shioya N., Evaluation of synthetic wound dressing capable of releasing silver sulfadiazine, J. Burn Care Rehabil., 12, 106, 1991.

(4.) Nakamura M., Shioya N., Kuroyanagi Y., Development of a wound dressing: Fundamental evaluation of the efficacy of a wound dressing containing an antibacterial drug, J. Jpn. Plast. Surg., 12, 443, 1992.

Jae-Suk Lee, Young-Sun Cho, Jin-Woo Lee, Hyun-Jung Kim (1), Do-Gi Pyun (1), Myung-Hwan Park1, Taek Rim Yoon (2), Ho-Jin Lee (3) and Yoshimitsu Kuroyanagy (4)

Department of Materials Science and Engineering, Kwangju Institute of Science and Technology (K-JIST), 1 Oryongdong, Puk-gu, Kwangju 500-712, Korea.

Research Institute of C.C. Technology, Rm 701, Kowoon Institute of Technology Innovation, The University of Suwon, PO Box 77, Suwon, Korea (1)

Department of Orthopedics, Chonnam University Hospital, Kwangju, Korea (2)

Department of Polymer Science and Technology Engineering, Hannam University, Taejon, Korea (3)

Department of Plastic and Reconstructive Surgery, School of Medicine, Kitasato University, Kitasato 1-15-1, Sagamihara, Kanagawa, 228-8555, Japan (4)
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Article Details
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Author:Lee, Jae-Suk; Cho, Young-Sun; Lee, Jin-Woo; Kim, Hyun-Jung; Pyun, Do-Gi; Park, Myung-Hwan; Yoon, Tae
Publication:Trends in Biomaterials and Artificial Organs
Geographic Code:9SOUT
Date:Jul 1, 2001
Words:858
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