Sugars in the aqueous phase change the mechanical properties of lipid mono- and bilayers

We applied two independent methods to measure the bending elasticity of SOPC lipid membranes in the presence of different sucrose concentrations in the aqueous phase. The micropipette technique was used to study the membrane bending rigidity in the concentration range of (0.11-0.30) mol/l of sucrose, while for sucrose concentrations 0 mol/l and 0.05 mol/l the thermal fluctuation analysis of quasi-spherical vesicles was applied. Both methods revealed a strong reduction of the bending elastic modulus, when sucrose is present in the water. Using micromanipulation of emulsion droplets, we investigated the sucrose influence on the stretching elasticity of SOPC lipid monolayers at the oil-water interface. Our results showed an almost two-fold reduction of the stretching elasticity modulus of the lipid monolayer in the presence of 0.18 mol/l of sucrose in the aqueous phase. The experimental results, reported here, reveal a strong influence of sugar molecules on the elasticity of lipid mono- and bilayers.