Abstract: Antibacterial peptide (AP) G-K liposomes were prepared by thin film evaporation-sonication method. The effects of formulated ingredients and processing conditions on the average particle diameter and encapsulation efficiency of liposomes were examined. The stability and antibacterial activity were analyzed as well. The results showed that spherical liposomes with average particle size of (128.27 ± 2.69) nm, encapsulation efficiency of 62.83%, and effective loading of AP G-K of 5.08% were obtained when phospholipid at 7.5 mg/mL in PBS buffer was blended with cholesterol and AP G-K at a mass ratio of 6:1 and 4:1 separately with sonication at 300 W. The liposomes were more stable when stored at 4 ℃ than at 25 ℃. Growth curve and propidium iodide staining experiments showed that AP G-K liposomes had a strong antibacterial effect on Escherichia coli in a slow-release way.

Key words: antibacterial peptide, liposome, Escherichia coli, particle size, encapsulation efficiency