End-capping of amphiphilic nanotubes with phospholipid vesicles: impact of the phospholipid on the cap formation and vesicle loading under osmotic conditions.

Soft amphiphilic nanotubes are capped with vesicles comprised of either overall neutral, zwitterionic phospholipids, or those that carry a net charge. The phase transition temperature of the zwitterionic phospholipids plays a crucial role in the phase separation that leads to the end-capped nanotubes. The cationic vesicle caps can be loaded into the nanotubes via osmosis whereas the anionic vesicle caps are stable under hyper-osmotic conditions. Furthermore, no additional salt needs to be added for the cationic vesicle caps to induce the loading of the vesicles into the nanotubes due to the presence of counterions.