Membranes are dynamic features of living cells that undergo continuous changes to facilitate many cellular functions including but not limited to motility, cell division, and phagocytosis. Although many of these processes are protein-assisted, functionality can also emerge through simple physical stresses and perturbations coupled with ability of the cellular membrane to regulate their area. This remarkable property of surface area homeostasis, which buffers membrane tension, is often achieved through strikingly simple and chemically non-specific physical-processes such as (1) folding, which traffics molecules with the contiguous end-membrane system; (2) endocytosis, which lowers the surface area; and (3) exocytosis, which expands it. With membrane being at the forefront of such perturbations, it becomes crucial to understand how membranes respond to physical stresses. Stress response of membranes has been widely studied using cell mimics such as giant unilamellar vesicles (GUVs). In most of these cases, the perturbation is isotropically applied, which rarely is the case of the native cell environment. We observe that when a degree of stress anisotropy is introduced (facilitated by weak adhesion of GUV basal region to the substrate in our case) coupled along with a global osmotic deflation, the vesicle undergoes rampant inward multivesiculations in conformity with tensional homeostasis. This cluster of microscopic invaginations is spherical and generally 3-4 um in radius. This is structurally distinct from free GUV deformations on deflation. Strikingly, even though these invaginations germinate in the basal planes, the accompanying density contrast drives them to accumulate at the distal surface producing a global morphological polarity reminiscent of many adherent eukaryotic cells.

Polarized deformations: Response of giant vesicles to osmotic deflation under confinement

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.