Dynamics of spontaneous wrapping of microparticles by floppy lipid membranes*

In vivo, proteins are most probably the main actors of membrane deformation. The adsorption of inert particles could enable reproduction of the essential physics of membrane deformation by bound proteins.

In a recent study we have observed experimentally how micron sized particles adhere and are subsequently enveloped by lipid membranes (Spanke, arxiv: 2007.03620 [cond-mat.soft], 2020). The lipid membranes are characterized by a bending rigidity κ_b and a membrane tension σ, which is near zero in our experiments. The polystyrene microparticles we use experience depletion interactions introducing an adhesion energy. Both the adhesion energy and particle size can be varied continuously in our system without changing the underlying composition.

At high adhesion strengths, the particles are enveloped spontaneously. We measure the velocity of this spontaneous wrapping process as well as the forces experienced by the particle using an optical trap.
These results offer insight into the energy landscape of the wrapping process as well as the contact line dynamics.