Francesca Stephenson with Tim Atherton

Modeling of multicomponent lipid membranes using energy minimization techniques

(started in fall 2009 and will be resumed and completed in spring 2011)

Lipid molecules, such as those found in cell membranes, can form membranes that form surfaces that are closed, can interact to form closed topologically spherical bodies, called vesicles. If a vesicle contains more than one type of lipid, phase separation of the lipids can occur. The domainslipids in a multi-component vesicle system may have different elastic properties and different shapes can form; in extreme cases domains can possibly separate into new vesicles. PLipid properties such as bulk elasticity and line tension between phases dictate the behavior and shape of the vesicle system. Cylindrically symmetric vesicles have been well studied, and the equations that minimize the energy have been solved. The non-cylindrically symmetric case is more complex, and numerical methods are required to solve the governing equations. We plan to use the Surface Evolver program to model the possible vesicle configurations of the non-cylindrically symmetric case with three domains. In particular, we will calculate the interaction energy due to elasticity as two domains are forced to approach one another.