The influence of sucrose on the elasticity of SOPC lipid membrane studied by the analysis of thermally induced shape fluctuations

The influence of different sucrose concentrations (0, 100, 200, 300, 400 mM) in the aqueous phase on the bending elasticity modulus, kc, of a lipid membrane was studied using the analysis of thermally induced shape fluctuations of giant quasispherical vesicles. Stroboscopic illumination was applied to cancel the effect of the camera integration (smearing) and to improve the precision of the measurement (almost two-fold). The experiment confirmed that the sucrose reduces the bending elasticity modulus of the lipid membrane. We established a difference in the values of the bending elasticity modulae, obtained by thermally induced shape fluctuations method and micropipette technique [V. Vitkova, J. Genova, M. D. Mitov, I. Bivas, Sugars in the aqueous phase change the mechanical properties of lipid mono- and bilayers, Mol. Cryst. Liq. Cryst., in press] and this difference depends on the sucrose concentration. It was experimentally shown that SOPC vesicles electroformed in 300 and 400 mM sucrose concentration in the water phase do not show any aging effect after a period of 3–9 days after the formation.