Osmotically induced passage of vesicles through narrow pores

The osmotically induced passage of fluid vesicles through narrow pores is studied theoretically using Monte Carlo simulations and a recently introduced sampling scheme. The free energy barrier for this transport process is calculated explicitly. An essential part of the free energy barrier is based on thermal fluctuations of the membrane shape. Simulation results indicate that, in real systems, the passage can be driven by osmotic pressure alone. The dynamics of the passage process are dominated by the geometry-induced changes of the vesicle volume and the associated water permeation through the vesicle membrane. The passage time is estimated to be of the order of minutes