Preparation of carboxymethyl chitosan/copper composites and their antibacterial properties

Water-soluble carboxymethyl chitosan/copper (CMCS/Cu) composites were first successfully prepared by solution reduction method. The CMCS/Cu composites presented flower-like architectures, consisting of several intercrossing sheets, and reaction conditions had an important effect on the morphology of resulting products. The antibacterial activities of CMCS/Cu composite against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) were also performed by the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC), cup diffusion method and optical density (OD600). Results indicated that CMCS/Cu composites are selective in their antibacterial action. They display more effective antibacterial activity against B. subtilis than other three stains, and better bactericidal activity against S. aureus, E. coli and P. aeruginosa than B. subtilis. There is no bactericidal ability against B. subtilis in the tested concentration range, which indicates that B. subtilis may be a copper-tolerant bacterium.