Fabrication and Characterization of Macroporous Chitosan/PVA Composite Sponges for Wound Dressing
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Fabrication and Characterization of Macroporous Chitosan/PVA Composite Sponges for Wound Dressing Changfeng Chen1,2*, Li Liu1, Qiong Wang2, Tao Huang1, Yue`e Fang1* 1 Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, China 230026 2 Department of Chemistry, University of Maine, Orono, ME, USA 04469 ABSTRACT The present investigation involves the synthesis of chitosan based composite sponges in view of their applications in wound dressing, antibacterial and haemostatic. A facile CO2 bubbles template freeze-drying method was developed for the fabrication of macroporous chitosan- poly(vinyl alcohol) (PVA) composite sponges with a typical porosity of 50% and pore size of 100-300 µm. The composite sponges show a high water absorption rate up to 60 times of its weight and a water vapor transmission rate of 30 ~ 70g/m2 • h. Effects of the content of cross-linking agent and PVA on mechanical properties and moisture permeability were examined. Improved strength and flexibility of the chitosan sponges were observed with the presence of PVA. Further, the antibacterial and haemostatic activities have been demonstrated. The Chitosan/PVA sponges of high liquid absorption, appropriate moisture permeability, excellent antimicrobial and haemostatic activities have a great potential for wound dressing applications. INTRODUCTION One of the widely studied polymers for wound dressing applications is chitosan, which is natural, biocompatible, biodegradable, non-toxic, and possess antibacterial and unique hemostatic capabilities[1,2]. Chitosan(CS) based sponges with reasonable strength and elasticity are of high interest as it allow slow drug release to a wound while the spongy form absorbs the wound fluid[2,3]. Recently, Denkbas et al. using a solvent evaporation technique prepared and characterized chitosan sponges encapsulated with a model antibiotic drug, norfloxacin, as wound dressing material. Li et.al.[3] and Jayakumar et.al.[4] using freeze-drying methods prepared chitosan based sponges for wound care. These sponges had a typical microporous structure and exhibited enhanced liquid absorbing capacity and cell interaction due to high surface/volume ratio. However, one major limitation for chitosan materials is its brittle behavior. Chitosan (CS) based sponges with reasonable strength and elasticity are of high interest as it allow slow drug release to a wound while the spongy form absorbs the wound fluid[2,3]. Blends with other synthetic materials and cross-linking are believed to be an effective way to improve mechanical strength. In this work, polyvinyl alcohol (PVA), a nontoxic, water soluble polymer, was blended with chitosan to improve the mechanical properties of chitosan[5,6]. CS/PVA composite sponges were prepared using a facile bubble assisted freeze-drying method. A solution of NaHCO3 was added to neutralize the acidic chitosan solution, and the acid-base reaction intrinsically produced bubbles as templates for the formation of macroporous structure. Glutaraldehyde w
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