Endocytosis is a
key cellular process involved in the uptake of
nutrients, pathogens, or the therapy of diseases. Most studies have
focused on spherical objects, whereas biologically relevant shapes
can be highly anisotropic. In this letter, we use an experimental
model system based on Giant Unilamellar Vesicles (GUVs) and dumbbell-shaped
colloidal particles to mimic and investigate the first stage of the
passive endocytic process: engulfment of an anisotropic object by
the membrane. Our model has specific ligand–receptor interactions
realized by mobile receptors on the vesicles and immobile ligands
on the particles. Through a series of experiments, theory, and molecular
dynamics simulations, we quantify the wrapping process of anisotropic
dumbbells by GUVs and identify distinct stages of the wrapping pathway.
We find that the strong curvature variation in the neck of the dumbbell
as well as membrane tension are crucial in determining both the speed
of wrapping and the final states.