Track analysis of the passage of rhodamine-labeled liposomes across porcine jejunal mucus in a microchannel device.

AIM:  To investigate how surface charge and hydrophilicity affect the mucopermeation of liposomes across intestinal mucus.

METHODOLOGY: Rhodamine-labeled liposomes (∼120-130 nm) with different surface charges were investigated for their capacity to flux across fresh porcine jejunal mucus in a microchannel device. Fluorescent microscopy and tracking analysis were used to measure liposome movement, while fluorescence lifetime imaging microscopy was utilized to determine mucus pH.

RESULTS: Mucopermeation was dependent on hydrophilicity and surface charge - anionic liposomes permeated more than cationic. The most cationic liposomal prototype agglomerated mucus. Presence of Na+ , K+ and Mg2+ increased both speed and straightness of the pathways for all prototypes. Cationic but not anionic liposomes caused acidification (pH 2.5).

CONCLUSION: Acidification caused by cationic liposomes explains their ability to interfere with mucus stability. Surface charge of liposomes strongly influences mucopermeation capability.