Antibacterial activity of chitosan tripolyphosphate nanoparticles loaded with various metal ions

The aim of this study was to prepare and select chitosan nanoparticles loaded metal ions with high antibacterial activities. Chitosan nanoparticles were prepared based on ionic gelation between chitosan and sodium tripolyphosphate. Then, Ag+, Cu2+, Zn2+, Mn2+, or Fe2+ was individually loaded onto chitosan nanoparticles. Their particle sizes and zeta potentials were measured. Their antibacterial activities were evaluated by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli 25922, Salmonella choleraesuis ATCC 50020 and Staphylococcus aureus 25923 in vitro. Results showed that antibacterial activity was significantly enhanced by the metal ions loaded, except for Fe2+. Especially for chitosan nanoparticles loaded Cu2+, the MIC and MBC against E. coli 25922, S.choleraesuis ATCC 50020 and S. aureus 25923 were 21–42 times lower than that of Cu2+, respectively. Moreover, it was found that antibacterial activity was directly proportional to zeta potential.