Spontaneous curvature of fluid vesicles induced by trans-bilayer sugar asymmetry

We present measurements of the effective spontaneous curvature of fluid lip id bilayers as a function of trans-bilayer asymmetry. Experiments are perfo rmed on micrometer-scale vesicles in sugar solutions with varying species a cross the membrane. There are two effects leading to a preferred curvature of such a vesicle. The spontaneous curvatures of the two monolayers as well as their area difference combine into an effective spontaneous curvature o f the membrane. Our technique for measuring this parameter allows us to use vesicle morphology as a probe for general membrane-solute interactions aff ecting elasticity.