Location: Fields Institute

February 18, 2011 - 3:30 p.m.
Dr. Christoph Haselwandter, Applied Physics & Materials Science, Caltech
Symmetry of membrane polyhedra

A mechanistic understanding of biological cell membranes in terms of coarse-grained physical theories requires information about the molecular properties of membranes. It has been proposed that polyhedral bilayer vesicles-symmetrical, hollow vesicles which, as observed in recent experiments, are formed spontaneously by certain amphiphilic molecules-may offer a route towards a more detailed understanding of the structure of membrane components and the energetics of their interactions. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. Allowing for segregation of excess amphiphiles with large spontaneous curvature along the ridges of bilayer polyhedra, we find that polyhedral bilayer vesicles can indeed have lower bending energies than spherical bilayer vesicles. However, our analysis also implies that, contrary to what has been suggested on the basis of experiments, the snub dodecahedron and the snub cube, rather than the icosahedron, generally represent the energetically favorable shapes of bilayer polyhedra.

Biography:
Christoph A. Haselwandter studied physics and mathematics at Imperial College London and Cambridge University, and received his PhD from Imperial College London under the supervision of Prof. Dimitri D. Vvedensky on the multiscale analysis of epitaxial semiconductor surfaces. From 2007 to 2009, Dr. Haselwandter held an Erwin Schrödinger Fellowship in the Department of Physics at Massachusetts Institute of Technology, working with Prof. Mehran Kardar on the nonequilibrium statistical physics of synaptic receptor domains and on mathematical oncology. Since 2009, Dr. Haselwandter has been a member of the Physical Biology of the Cell Group led by Prof. Rob Phillips at California Institute of Technology, where his research focuses on the connection between physical and biological properties of cell membranes.

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