Supported Lipid Bilayers (SLBs) are composed of a bilayer of lipid molecules which are supported on a solid surface. They have proven to be an excellent model for biological cell membranes and are formed when a buffered solution of lipid vesicles is flowed over a surface. The successful formation of an SLB depends in large part on the size and nature of the interaction between the lipid vesicles and the surface. If the interaction is strong and attractive then SLB formation will occur, but if it is weak or repulsive then either vesicles will adsorb intact on the surface but will not rupture and form an SLB, or they will not adsorb to the surface at all. We have used a combination of Quartz Crystal Microbalance (QCM) measurements, and calculations of the interaction energy between the vesicles and surface using DLVO theory, to investigate the role of salt concentration and cation identity in the formation of SLBs. The calculations and experimental data have shown that at higher salt concentrations the strength of the lipid-surface interaction energy is governed by the relative strength of the double layer interaction, whereas at low salt concentrations it is the hydration force which dominates. The different effects of the group I cations on the vesicle-surface interaction at different salt concentrations provides an alternative method for forming SLBs in conditions in which they do not usually form.

Modulation of lipid-surface interactions by group I cations at different salt concentrations

ACS Spring 2022

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