Hi, I am working on the theoretical aspects of phase separation in mixed lipid bilayers. During my PhD, I developped a model to predict quantitatively the phase diagrams of ternary mixtures with two phospholipids and cholesterol.
At this moment I’am interested by budding in lipids symmetric bilayers.
Budding in asymmetric membranes
If you are interested in these matters, I would be glad to further discuss them with you.
Wolff, J., Komura, S., & Andelman, D. (2016). Budding transition of asymmetric two-component lipid domains. Phys. Rev. E, 94(3), 9 pp.
Abstract: We propose a model that accounts for the budding transition of asymmetric two-component lipid domains, where the two monolayers (leaflets) have different average compositions controlled by independent chemical potentials. Assuming a coupling between the local curvature and local lipid composition in each of the leaflets, we discuss the morphology and thermodynamic behavior of asymmetric lipid domains. The membrane free-energy contains three contributions: the bending energy, the line tension, and a Landau free-energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams containing fully budded, dimpled, and flat states as a function of the two leaflet compositions. The global phase behavior is analyzed, and depending on system parameters, the phase diagrams include one-phase, two-phase, and three-phase regions. In particular, we predict various phase coexistence regions between different morphologies of domains, which may be observed in multicomponent membranes or vesicles.
Wolff, J., Komura, S., & Andelman, D. (2015). Budding of domains in mixed bilayer membranes. Physical Review E, 91(1).
Abstract: We propose a model that accounts for the budding behavior of domains in lipid bilayers, where each of the bilayer leaflets has a coupling between its local curvature and the local lipid composition. The compositional asymmetry between the two monolayers leads to an overall spontaneous curvature. The membrane free energy contains three contributions: the bending energy, the line tension, and a Landau free energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams which contain fully budded, dimpled, and flat states. In particular, for some range of membrane parameters, the phase diagrams exhibit a tricritical behavior as well as a three-phase coexistence region. The global phase diagrams can be divided into three types and are analyzed in terms of the curvature-composition coupling parameter and domain size.
Wolff, J., Marques, C. M., & Thalmann, F. (2011). Thermodynamic Approach to Phase Coexistence in Ternary Phospholipid-Cholesterol Mixtures. Physical Review Letters, 106(12).
Abstract: We introduce a simple and predictive model for determining the phase stability of ternary phospholipid-cholesterol mixtures. Assuming that competition between the liquid and gel order of the phospholipids is the main driving force behind lipid segregation, we derive a Gibbs free energy of mixing, based on the thermodynamic properties of the lipids main transition. A numerical approach was devised that enables the fast and efficient determination of the ternary diagrams associated with our Gibbs free energy. The computed phase coexistence diagram of DOPC/DPPC/cholesterol reproduces well-known features for this system at 10 degrees C, as well as its evolution with temperature.