N-halamine-based chitosan: preparation, characterization, and antimicrobial function

Upon chlorine bleach treatment, amino groups in chitosan were transformed into N-halamine structures. The transformation was confirmed by UV/VIS, XPS, DSC, and TGA evaluation and iodimetric titration. The N-halalmine-based chitosan provided total kill of 10(8)-10(9) colony forming units (CFU/mL) of E. coli (gram-negative bacteria) and S. aureus (gram-positive bacteria) in 10 and 60 min, respectively. SEM observations demonstrated that the chlorinated chitosan effectively prevented the formation of bacterial biofilms. The antimicrobial activity and bio film controlling function were stable for longer than 1 month; when the functions were lost due to extensive use and/or prolonged storage, they could be readily recharged by another bleach treatment. The antimicrobial mechanism was also discussed.