Synthetic Chain‐Substituted Phospholipids: Ion Transport Across Their Bilayer Membranes

The passage of ions through phospholipid vesicles is facilitated by building alkyl substituents into the lipid chains. The effect of the size, position, and number of substituents on the ion flux can be studied by monitoring the decrease in fluorescence of a pH‐sensitive dye within the vesicles on lowering the pH of the surrounding water. Substituents in the middle of the chains were most efficient in altering the flux. Such studies are of interest for the development of systems for controlled drug release.