Control of wound infections using a bilayer chitosan wound dressing with sustainable antibiotic delivery

A novel bilayer chitosan membrane was prepared by a combined wet/dry phase inversion method and evaluated as a wound dressing. This new type of bilayer chitosan wound dressing, consisting of a dense upper layer (skin layer) and a sponge-like lower layer (sublayer), is very suitable for use as a topical delivery of silver sulfadiazine (AgSD) for the control of wound infections. Physical characterization of the bilayer wound dressing showed that it has excellent oxygen permeability, that it controls the water vapor transmission rate, and that it promotes water uptake capability. AgSD dissolved from bilayer chitosan dressings to release silver and sulfadiazine. The release of sulfadiazine from the bilayer chitosan dressing displayed a burst release on the first day and then tapered off to a much slower release. However, the release of silver from the bilayer chitosan dressing displayed a slow release profile with a sustained increase of silver concentration. The cultures of Pseudomonas aeruginosa and Staphylococcus aureus in agar plates showed effective antimicrobial activity for 1 week. In vivo antibacterial tests confirmed that this wound dressing is effective for long-term inhibition of the growth of Pseudomonas aeruginosa and Staphylococcus aureus at an infected wound site. The results in this study indicate that the AgSD-incorporated bilayer chitosan wound dressing may be a material with potential antibacterial capability for the treatment of infected wounds. (C) 2001 John Wiley & Sons, Inc. J Biomed Mater Res 59: 438-449, 2002.