Nonequilibrium patterns in phase-separating ternary membranes

Abstract

We present a nonequilibrium approach for the study of a two-dimensional phase-separating ternary mixture. When the component that promotes phase separation is dynamically exchanged with the medium, the separation process is halted and actively maintained finite-size segregation domains appear in the system. In addition to this effect, already reported in our earlier work [J. Gómez, F. Sagués, and R. Reigada, Phys. Rev. E 77, 021907 (2008)], the use of a generic Ginzburg-Landau formalism and the inclusion of thermal fluctuations provide a more dynamic description of the resulting domain organization. Its size, shape, and stability properties are studied. Larger and more circular and stable domains are formed when decreasing the recycling rate, increasing the mobility of the exchanged component, and the mixture is quenched deeper. We expect this outcome to be of applicability in raft phenomenology in plasmatic cell membranes.

Nanodomains in Biomembranes with Recycling

“…Alternative recycling schemes have been discussed elsewhere [25,26,29,30,32]. However, we have argued that the chosen recycling scheme is realistic.…”

“…For example, the observation of nano-domains of rhodopsin (a GPCR) in cadavers' retina cells [8], very similar to those observed in fixed cells or membrane sheets, suggests that active processes are not essential. Alternatively, some other works propose that out-of-equilibrium mechanisms are necessarily at play, driven by active membrane recycling [25,29,14,30,31,26,32]. We explored whether both approaches could be discriminated from an experimental perspective.…”

“…This membrane recycling breaks too large assemblies into smaller pieces. The growth of the condensed phase is thus stopped at a given typical size [15,25,29,30,31,32]. A simple dynamic scaling argument has for instance been proposed in Ref.…”

Equilibrium microphase separation in the two-leaflet model of lipid membranes

“…In nonequilibrium systems, an analog of the microphase separation can be observed when energetically activated reactions between two components are included [5,6]. The nonequilibrium scenario has inspired a variety of proposals in the context of the cell membrane [7][8][9][10][11][12].Equilibrium microphase separation in two-component lipid membranes was found in two-leaflet models with different lipid composition in each leaflet [13][14][15][16]. In these models, coupling between the local membrane curvature and the difference of local lipid compositions in two layers could give rise to an instability at finite wave numbers.…”

“…In nonequilibrium systems, an analog of the microphase separation can be observed when energetically activated reactions between two components are included [5,6]. The nonequilibrium scenario has inspired a variety of proposals in the context of the cell membrane [7][8][9][10][11][12].…”