Dynamics of compound vesicles in shear flow

A detailed study is presented in order to investigate the dynamics of compound vesicles confined in a channel under shear flow. Compound vesicles, which are made of a smaller vesicle embedded within a larger one, are systems of relevant biological importance. Indeed, they can be seen as biomimetic models for multi-compartmentalized cells such as leukocytes, nucleate cells, or vesicles embedding even more vesicles, as in the case of vesosomes, with several possible applications. Despite the relevance, in experiments it is extremely difficult to set independently all the parameters controlling the system, while available numerical studies neglect thermal fluctuations which are relevant in vesicle dynamics. The present study [1] adopts mesoscale hydrodynamic simulations of a model system, explicitly including thermal fluctuations. This allows the observations of a rich phenomenology in the dynamical behavior of compound vesicles, which well matches with the few available experiments [2,3]. Moreover, our study allows a full characterization of the undulating motion under different conditions to an extent never observed before. This latter dynamical state is characterized by periodic oscillation of the inclination and buckling of the external membrane, as illustrated in the figure.