Pearling of cylindrical vesicles induced by acoustofluidics

The mechanical transformation of lipid membranes in biological structures plays a key role in the morphogenesis of cells and tissues. However, the mechanism by which active forces influence the shape transition of lipid vesicles remains unclear. Herein, we propose an acoustofluidics method to deform the cylindrical vesicles. The study combines theoretical and experimental approaches to investigate the shape behavior of cylindrical vesicles in an acoustic field. Analytical equations are established to describe the manipulation of radial deformation and elongation in cylindrical vesicles. Pearling of these vesicles is induced by the competition between membrane tension and drag force. In conditions of weak drag force, cylindrical vesicles under tension minimize their free energy through surface fluctuations, resulting in a beaded structure. This transformation creates a beads-on-a-string formation, consisting of uniformly sized spherical vesicles connected by fine lipid nanotubes. The findings offer a non-contact method to enhance the understanding and control of the shape dynamics in membranes within active matter systems.