# Detachment of fluid membrane from substrate and vesiculation

## TL;DR

This study uses meshless membrane simulations to analyze how fluid membranes detach from substrates and form vesicles, revealing the roles of adhesion strength, spontaneous curvature, and membrane pinning in the detachment and vesiculation processes.

## Contribution

It provides new insights into the detachment dynamics of fluid membranes, especially the effects of spontaneous curvature and membrane pinning on vesicle formation and rolling behavior.

## Key findings

- Strong adhesion influences the minimum spontaneous curvature for detachment.
- Weak adhesion leads to detachment at smaller spontaneous curvatures due to thermal undulation.
- Membrane pinning slows detachment and promotes straight or concave edges, facilitating vesiculation.

## Abstract

The detachment dynamics of a fluid membrane with an isotropic spontaneous curvature from a flat substrate are studied by using meshless membrane simulations. The membrane is detached from an open edge leading to vesicle formation. With strong adhesion, the competition between the bending and adhesion energies determines the minimum value of the spontaneous curvature for the detachment. In contrast, with weak adhesion, a detachment occurs at smaller spontaneous curvatures due to the membrane thermal undulation. When parts of the membrane are pinned on the substrate, the detachment becomes slower and a remained membrane patch forms straight or concave membrane edges. The edge undulation induces vesiculation of long strips and disk-shaped patches. Therefore, membrane rolling is obtained only for membrane strips shorter than the wavelength for deformation into unduloid. This suggests that the rolling observed for Ca$^{2+}$-dependent membrane-binding proteins, annexins A3, A4, A5, and A13, results from by the anisotropic spontaneous curvature induced by the proteins.