While ions are expected to bind or remain close to charged interfaces, there is a great deal of curiosity about what these ions that are widely found in nature, do near or at dipolar (net neutral, zwitterionic) interfaces. Our comprehensive study shows how the structure of ions and zwitterionic lipids regulates the interactions between the ions and dipolar membranes.

• We found that multivalent ions can adsorb onto dipolar lipid membranes, charge the membrane (and reproduce the behaviour of charged lipids), only if the lipid tails are saturated, where ion dipole interactions are stronger than tail entropy. We also found that osmotic stress can lead to desorption of these ions (read more). 
• Mixtures of saturated and unsaturated lipids phase separate. Using the ion adsorption properties of dipolar lipids, and a hybrid lipid (containing a saturated and an unsaturated tail) that can sit at the interface between domains, we showed how to measure and regulate the size of lipid domains. The domain size decreases with the concentration of the hybrid lipid, which acts as a 2D surfactant and reduces the line-tension between domains (read more).