Systems far from equilibrium can exhibit complex transitory structures, even when equilibrium fluctuations are mundan. The interior of a living cell is packed with large macromolecules (e.g., nucleic acids, proteins and polysaccharides), cytoskeletal filaments, and organelles. Furthermore, this physical crowding in the cellular cytoplasm is highly dynamic continually changing the diffusional properties of embedded solutes, molecular (and ionic) concentration gradients, and phase separation or dynamic micro-compartmentalization of the cytosolic fluid. But how this cytoplasmic macromolecular crowding and accompanying dynamic microcompartmentation affects membrane shapes and molecular organization is largely unknown. Building on the experimental model system developed by Keating, Dimova, and Lipowsky, we reconstitute minimal crowding and conditions for dynamic microcompartmentation inside cell-sized giant vesicles. Specifically, we encapsulate a uniform aqueous phase mixture of two water soluble polymers (namely, dextran and poly(ethylene)glycol), which when subject to osmotic deflation, assumes relative concentrations that produce aqueous two-phase separation (ATPS) in real-time. We find that the onset of vesicular micro-compartmentation in the encapsulated aqueous phase is accompanied by an active membrane remodeling inducing vesicle morphogenesis. Unlike equilibrium configurations characterized by a single bud, we find that multiple buds of essentially uniform size decorate the membrane boundary reflecting a complex interplay between the phase coarsening dynamics during the spinodal decomposition of the ATPS and preferential wetting of the membrane surface by the dextran-rich phase<b>. </b>

Morphological consequences of surface-mediated spinodal decomposition inside giant vesicles

253rd National Meeting (2017)

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