When 11:30 AM - 12:30 PM Mar 03, 2009
Where 2150 HH Dow
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Patterns and Transitions in Lipid Membranes


Vernita Gordon, University of Illinois at Urbana Champaign

"Smart" encapsulating systems with functionalizable patterns that have programmed responses to environmental cues would constitute a significant advance on technologies for encapsulation and controlled release, such as drug delivery.  Lipids are natural, biological amphiphiles that, in aqueous solution, self-assemble to form a wide variety of phases, notably bilayer membranes consisting of two opposed monolayer leaflets.  Such lipid membranes are important in a variety of contexts.  In engineering, they serve as as vectors for directed encapsulation and controlled release of active agents such as drugs.  In biology, lipids form the essential structure of the cell membrane and cellular organelles.  In physics, lipid membranes are widely used as model systems for coupled elasticity, entropy, and phase transitions.  For all these cases, patternings and structural transitions are important and can confer new functionalities on membranes.  Understanding such patternings and changes will allow the engineering of "smart", functional lipid-based structures for tailored, responsive application and will yield insight into basic biology that will, in turn, prepare the way for specific design of membrane-active functional agents.  I will discuss several cases of such patternings and transitions: (1) The shapes of domains formed by lateral phase separation in different lipid mixtures;  (2) The promotion and localization of phase separation by membrane adhesion;  (3) Lipid-specific modification of membrane phase and topology by functional peptides.