Physical characterization and cellular uptake of propylene glycol liposomes in vitro

In order to facilitate the intracellular delivery of therapeutic agents, a new type of liposomes-propylene glycol liposomes (PGL) were prepared, and their cell translocation capability in vitro was examined. PGL was composed of hydrogenated egg yolk lecithin, cholesterol, Tween 80 and propylene glycol. With curcumin as a model drug, characterization of loaded PGL were measured including surface morphology, particle size, elasticity, encapsulation efficiency of curcumin and physical stability. Using curcumin-loaded conventional liposomes as the control, the cell uptake capacity of loaded PGL was evaluated by detection the concentration of curcumin in cytoplasm. Compared with conventional liposomes, PGL exhibited such advantages as high encapsulation efficiency (92.74% ± 3.44%), small particle size (182.4 ± 89.2 nm), high deformability (Elasticity index = 48.6) and high stability both at normal temperature (about 25°C) and low temperature at 4°C. From cell experiment in vitro, PGL exhibited the highest uptake of curcumin compared with that of conventional liposomes and free curcumin solution. Little toxic effect on cellular viability was observed by methyl tetrazolium assay. In conclusion, PGL might be developed as a promising intracellular delivery carrier for therapeutic agents.