An application of the optical microscopy to the determination of the curvature elastic modulus of biological and model membranes

A new method is proposed to measure the curvature elastic modulus k c of a membrane, by observing the thermal induced fluctuations of the shape of a spherical vesicle. Observations of the liposomes were carried out under a microscospe working in the regime of Nomarski differential interference contrast. We show that the value of kc thus measured is the curvature elastic modulus of free flip-flop.