Topology and kinetic pathways of colloidosome assembly and disassembly

Significance Lipid membranes are nanometer-thin soap-like films composed of molecules with hydrophilic and hydrophobic segments. To minimize their edge energy, lipid membranes form closed spherical shells or vesicles, ubiquitous and versatile structures in cells with applications in encapsulation, molecular transport, and drug delivery. Controlling vesicle topology is essential in these processes. Rapid dynamics and small scales make it challenging to study the topological transitions of lipid vesicles. We developed fluid colloidosomes, which are micrometer-sized analogs of lipid vesicles assembled from rod-like particles. Their unique features enable real-time visualization of colloidosome assembly and disassembly pathways. Intriguingly, closed vesicles transition to flat disks via an intermediate state that is topologically distinct from the initial and final states.