Bending elastic moduli of lipid bilayers : modulation by solutes

H.P. Duwe , J. Kaes , E. Sackmann

We present high precision measurements of the bending elastic moduli for bilayers of a variety of different lipids and of modifications of the flexural rigidity by solutes. The measurements are based on the Fourier analysis of thermally excited membrane undulations (vesicle shape fluctuations) using a recently developed dynamic image processing method. Measurements of the bending modulus as a function of the undulation wave vector provide information on the limitation of the excitations by the constraint of finite membrane area (surface tension effects) and by transient lateral tensions arising in each monolayer by restricted diffusion at high wavevectors. Measurements of the autocorrelation function of the undulation amplitudes provide a further test of the theoretical models. Studies of the effect of solutes show that cholesterol increases the bending modulus of dimyristoylphosphatidylcholine from Kc = 1.1 × 10^-12 ergs to 4.2 x 10^-12 ergs (at 30 mole %). Incorporation of about 2 mole % of a short bipolar lipid reduces Kc to the order of kT. A scaling law between the projected radius of gyration, Rg, of these hyperelastic vesicles and the surface area, A (or number of lipid molecules N) of R2g ∝ A 0.94 ± 0.02 was established.

Mots clés: bending; elastic moduli; Fourier analysis; lipid bilayers; organic compounds; surface tension

Domaines: Articles anciens

H.P. Duwe, J. Kaes, E. Sackmann. Bending elastic moduli of lipid bilayers : modulation by solutes. Journal de Physique, 1990, 51 (10), pp.945-961. ⟨10.1051/jphys:019900051010094500⟩. ⟨jpa-00212424⟩