1686 † To whom correspondence should be addressed. E-mail: ycnho@kaeri.re.kr Korean J. Chem. Eng., 26(6), 1686-1688 (2009) DOI: 10.1007/s11814-009-0246-z RAPID COMMUNICATION Characterization of PVA/glycerin hydrogels using γ -irradiation for advanced wound dressings Hui-Jeong Gwon* , **, Youn-Mook Lim*, Sung-Jun An*, Min-Ho Youn*, Seol-Hee Han*, Ho-Nam Chang**, and Young-Chang Nho* ,† *Radiation Research Center for Industry & Environment, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 1266 Sinjeong-dong, Jeongeup-si, Jeonbuk 580-185, Korea **Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science Technology, Daejeon 305-701, Korea (Received 5 March 2009  accepted 31 March 2009) Abstract −The aim of this study was to investigate the enhanced absorption property of PVA/Glycerin (PVA/Gly) hydrogel for advanced wound dressing. A simple crosslinking method was introduced to prepare the PVA/Gly hydrogels with the use of γ-irradiation. An absorption ratio and thermal properties of the PVA/Gly hydrogels can be controlled by varying the irradiation dose and weight ratio of the PVA/Gly. When the PVA/Gly content was 20/5 wt% and the irradiation dose at 25 kGy, the PVA/Gly hydrogels showed excellent absorption properties (>350%). These results imply that the PVA/Gly hydrogel is highly absorbent and converts wound exudates to the hydrogel matrices that create a moist and clean environment in the wound healing process. Therefore, the PVA/Gly hydrogel prepared by this method can be used as an advanced wound dressing. Key words: Absorption, Gamma Irradiation, PVA/Glycerin Hydrogel, Wound Healing INTRODUCTION Hydrogels are three-dimensional hydrophilic polymeric networks that can absorb large amounts of water or a biological fluid without dissolution due to the presence of chemical crosslinks, or physical crosslinks [1,2]. It has been reported that a hydrogel can absorb an excess of wound exudates, protect a wound from secondary infec- tion, and effectively promote the healing process by providing a moisturized wound healing environment [3]. Moreover, these hydro- gels are often used as drug delivery systems because of their ability to swell as well as to release the trapped particles into the surround- ing medium [4]. An ideal wound dressing should absorb body fluids effectively, be painless for a removal, have a high elasticity, good adhesion and easy replacement, and act as a barrier against bacteria [5,6]. Many commercially available synthetic polymers, such as polyvinyl alcohol (PVA), show physicochemical and mechanical properties comparable to those biological tissues to be substituted [7-11]. These PVA based on hydrogels have received increasing attention in biomedical and biochemical applications, because of their permeability, biocompatibility and biodegradability [12-14]. Therefore, PVA hydrogels have been developed for repair of wounds and promotion of a wound healing [7,15]. Glycerin is a sweet color- less, transparent, and odorless syrupy liquid. It is a humectant, i.e. “draws moisture.” It is used in creams, lotions, facial treatments, masks, and other body care products. To prepare hydrogels, a chemical crosslinking has been reported as one of the crosslinking methods [16]. However, in this method, crosslinking agents such as glutaraldehyde, diisocyanates, carbodi- imides and acyl azide are necessary to initiate the process, which reduces their bio-compatibility, due to their inherent cytotoxicity, which also causes further problems with a purification of the final product [17]. γ-Ray irradiation has been recognized as a very suit- able method for the formation of hydrogels. Its main advantages, compared to the other methods, are no necessity to add any initia- tors and crosslinkers to start the process, hence the final product contains only polymer in its structure and the final product does not require a further purification. Moreover, γ -ray irradiation usu- ally allows for the combination of a synthesis and sterilization of polymeric materials in one technological step, thus reducing the costs and production time [18]. These make a γ-ray irradiation a very suitable tool for preparation of hydrogels. In this study, the poly(vinyl alcohol) (PVA) based hydrogel was prepared by using γ -ray irradiation to simplify the crosslinking process and glycerin was used as a moisturizer to improve the hygroscopic nature. The effects of the irradiation dose, the contents of PVA and glycerin on the absorption ratio and thermal properties were investi- gated to create the desired hydrogels for an advanced wound dressing. EXPERIMENT 1. Materials Poly(vinyl alcohol) (PVA) (Mw=8.5×10 4 -1.46×10 5 , 98% hydro- lyzed) was supplied by the Aldrich Chemical Company (WI, USA). Glycerin was supplied by the Showa Company (Japan). These poly- mers were used without further purification. Distilled water was used as a solvent in all the experiments. Fig. 1 shows the molecular structures of PVA and glycerin. 2. Preparation of Hydrogels PVA/Glycerin (PVA/Gly) was dissolved in distilled water at 120 o C