The effects of surface properties of liposomes on their activity against Pseudomonas aeruginosa PAO-1 biofilm
Hisako Ibaraki, Takanori Kanazawa, Wan-Yi Chien, Hidemasa Nakaminami, Masakazu Aoki, Kosuke Ozawa, Hiroshi Kaneko, Yuuki Takashima, Norihisa Noguchi, Yasuo Seta
Abstract
Bacterial biofilms (BBFs) are frequently formed on medical devices such as catheters. They act as barriers and reduce the concentration of antimicrobial agents that reach the bacteria located on the inside of BBFs. Hence, BBF-forming bacteria cause intractable and chronic infections. At present, there is no effective treatment for BBF-associated infections. We aimed to develop the liposomes that can efficiently deliver antimicrobial agents to bacteria located inside BBFs. First, we designed liposomes with different surface properties using ionic lipids, cholesterol, and PEG-modified lipids. The minimum inhibitory concentration (MIC), permeability, retention, and anti-BBF effect of liposomes against Pseudomonas aeruginosa PAO-1 were examined. The MIC test showed that no antimicrobial activity was found in the liposomes tested. Cationic liposomes had high anti-BBF effect and retention on BBF, whereas anionic liposomes showed high permeability to BBF. In addition, PEG modification increased the anti-BBF effect but reduced the retention of liposomes on BBF. In conclusion, controlling surface charge and PEG modification contribute to the effectiveness of liposomes against BBFs. Liposomes for which surface properties can be easily controlled will become an effective tool for the treatment of BBF-associated infections.