Evaluation of Surface Acetylated Bacterial Cellulose for Antibacterial Wound Dressing Applications

Abstract

Complications during the healing process of skin wounds often arise due to infection by pathogenic bacteria. Bacterial hydrolytic enzymes degrade the host tissue while biofilms can shield the bacterial cells from the host's immune response. Wound dressings with bacteriostatic or bactericidal properties are a promising solution. This study investigated the potential of surface acetylated bacterial cellulose as a novel antibacterial wound dressing. Hydroxyl groups on the surface of bacterial cellulose were substituted with acetyl groups using acetic anhydride in a citric acid-catalyzed reaction. The resulting ester linkages between the acetyl groups and bacterial cellulose surface were hypothesized to be cleaved by bacterial esterases or other hydrolytic enzymes such that acetic acid, a well-known antibacterial compound, will be produced leading to the death of the bacterial cells. Surface acetylation was confirmed via FTIR and its effect on the morphology of bacterial cellulose was analyzed with FESEM and XRD while the degree of substitution was determined by HPLC-UV. Indirect contact human cell cytotoxicity assays using extracts from surface acetylated bacterial cellulose showed no cytotoxic effect on human umbilical vein endothelial cells. Two types of antibacterial assays were performed in which surface acetylated bacterial cellulose was exposed to Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa which were selected as model bacteria for Gram-positive, Gram-negative, and pathogenic bacterial species, respectively. Neither assay showed a reduction of bacterial cell viability. Further research is needed to determine if the acetyl ester linkages on the surface of bacterial cellulose are susceptible to cleavage by bacterial esterase enzymes.