An Experimental System to Observe Multicomponent Vesicle Swinging and Tumbling in Shear Flow

In this work, we present preliminary experimental results of the swinging and tumbling dynamics of multicomponent vesicles in planar shear flow. A recent theoretical study predicted a new regime for multicomponent vesicles that is not seen for single component vesicles: a tumbling phase with periodic phase-lagging of the material relative to the vesicle's elongated axis (Gera, Salac, Spagnolie, JFM 935:A39, 2022). To test these predictions experimentally, we developed a novel device using rotating belts to observe vesicles at the stagnation line of steady-state flow. We will present particle image velocimetry measurements of the generated shear rate and demonstrate how well this device approximates the infinite planar shear flow. We will discuss DOPC-DPPC-cholesterol vesicle synthesis with osmotic deflation that generates vesicles with fewer lipid domains that are most likely to undergo the newly predicted regime with inclination angle variations that are experimentally measurable. Our preliminary measurements of multicomponent vesicles dynamics in shear flow will be reported. This work contributes experimental findings that complement the recent analytical and numerical studies of heterogenous biological membrane mechanics.