MOTION OF A MASSIVE MICROSPHERE BOUND TO A SPHERICAL VESICLE

We study the motion of a small solid particle (a few micrometers in si ze) attached to the membrane of a spherical giant lipid vesicle. By me ans of optical manipulation, the particle is first brought near the to p of the vesicle, and released. We determine the friction experienced by the particle moving along the vesicle surface under the action of g ravity. From experiments with latex and glass beads, we check that SOP C membranes are fluid at room temperature (static shear modulus mu = 0 ) and estimate the shear viscosity of SOPC bilayers: eta(m) approximat e to 3.10(-6) surface poise.