Electrochemical Fabrication and Properties of Brominated Chitosan Antimicrobial Dressing

Brominated chitosan wound dressing (Chit-Br) with high antimicrobial activity was fabricated by a two-step electrochemical method, which involved a cathodic electrodeposition of pristine chitosan film (Chit) triggered by a localized region of high pH and an anodic bromination of the deposited film in the presence of bromides. The generated brominated chitosan could be peeled from the electrode to get a free-standing film. The structure and incorporated active N-Br content of Chit-Br were characterized via SEM, EDS, FTIR-ATR and iodometric titration. In vitro antimicrobial activities of Chit-Br films were evaluated via antibacterial experiments using E. coli and S. aureus as model pathogens. Results showed that chitosan could be brominated by bromides in-situ generated from electrode reactions, and the bromination was accompanied with oxidation on sugar units. In the test range, N-Br contents of Chit-Br films brominated by varying anodic charges had no statistical difference. Chit-Br films had excellent antimicrobial activities and could kill bacteria by destroying their surface structures.