Liposomes with Water as a pH-Responsive Functionality for Targeting of Acidic Tumor and Infection Sites

A lipid named DCPA was synthesized under microwave-assisted heating. DCPA possesses a pyridine betaine, hydrophilic group that can be complexed with water through hydrogen bonding (DCPA-H₂ O). DCPA-H₂ O liposomes became protonated relatively fast already at pH<6.8, due to the high HOMO binding energy of DCPA-H₂ O. In murine models, DCPA-H₂ O liposomes had longer blood circulation times than natural DPPC or cationic DCPM liposomes, while after tail-vein injection DCPA-H₂ O liposomes targeted faster to solid tumors and intra-abdominal infectious biofilms. Therapeutic efficacy in a murine, infected wound-healing model of tail-vein injected ciprofloxacin-loaded DCPA-H₂ O liposomes exceeded the ones of clinically applied ciprofloxacin as well as of ciprofloxacin-loaded DPPC or DCPM liposomes.