Thermal effect on a viscously deformed liposome in a laser trap.

The viscous drag and mechanical deformation of a single vesicle under hydrodynamics flow during the phase transition of a lipid bilayer is determined by optical tweezers experiments with the aid of computational fluid dynamics simulations. Based on the experimental geometry of the vesicle under hydrodynamics flow, the surface stresses and drag force are numerically calculated. It is found that the vesicle is less rigid and the viscous drag force of the vesicle decreases with the increase of temperature at low Reynolds number flow during sample heating. Interestingly, these mechanical properties are reversible and depend strongly on the liposome's thermotropic phase transition temperature. Overall, this study provides new insights into highly coupled thermal and hydrodynamics effects on the biomechanical properties of model membrane vesicle in physiological flow systems.