Antibacterial activity of oleoyl-chitosan nanoparticles: A novel antibacterial dispersion system

A novel chitosan antibacterial dispersion system was prepared by oleoyl-chitosan (O-chitosan) nanoparticles (OCNP), and the antibacterial activity against Escherichia coli and Staphylococcus aureus was investigated. Results showed that OCNP could be well distributed in nutrient broth and had strong antibacterial activity. The minimum inhibitory concentrations (MICs) of all OCNP samples ranged from 31.25 to 125 mg/l against E. coli. For S. aureus, the MIC of all samples was 125 mg/l. OCNP of low chitosan molecular weight (MW) appeared most effective against E. coli. For S. aureus, the effect of chitosan MW on the antibacterial activity of OCNP was not pronounced. E. coli was most susceptible to OCNP of O-chitosan with degrees of substitution (DS) 5%, while no marked difference was found among OCNP of O-chitosan with different DS against S. aureus. OCNP exhibited the most pronounced antibacterial activity at pH 6.0 in the experimental range. The integrity of cell membranes was destroyed when bacterial suspensions were treated with OCNP.