Understanding and Controlling Curvature and Intermolecular Interactions in Biomimetic Membranes

Monique M. Lapinski 1Angelines Castro-Forero 3Aaron Greiner 3Robert Y. Ofoli 3Paweł G. Krysiński 2Gary J. Blanchard 1

1. Michigan State University, Department of Chemistry (MSU), East Lansing, MI 48824, United States
2. Warsaw University, Faculty of Chemistry, Pasteura 1, Warszawa 02-093, Poland
3. Michigan State University, Department of Chemical Engineering and Materials Science (MSU-CHEMS), East Lansing, MI 48824, United States

Abstract

Our research group is interested in creating sensing devices that utilize biomolecules such as enzymes and trans-membrane proteins as the chemically selective agents. In order to locate such molecules in close proximity to a transducing element (e.g. electrode surface, optical window), the interface in which they reside must function as a biomimetic membrane. We discuss in this talk our recent work in creating lipid bilayer systems that may function as biomimetic interfaces. We are interested in both the physical morphology of the bilayers and their fluidity because it is these factors that will determine to a significant extent their utility for our intended application. We consider three aspects of lipid bilayer morphology and dynamics. There are a number of ways to form a lipid bilayer, and among the most widely used methods is the formation of vesicles and their subsequent fusion to a planar substrate. The composition of the vesicles will determine the properties of any resulting planar bilayer, and it is critical to understand whether or not the means by which the vesicles are formed has any bearing on the molecular-scale properties and/or composition of the lipid bilayer. We have studied the translational and rotational motion of chromophores imbedded in bilayers, where the bilayers were formed either by sonication or by extrusion. Our data point to the similarity of the molecular scale environments of the two types of liposomes despite their different morphology. We have also investigated the dynamics of bilayer components, present either in the head group region, or in the acyl chain region. We find that for polar species present in the headgroup region that there can be significant aggregation, a process that leads to molecular-scale heterogeneity in bilayer structures. This finding may have implications on phase segregation phenomena in multi-component lipid bilayer systems. For chromophores imbedded in the nonpolar acyl chain region, our data point to the curvature of the bilayer mediating the local environment of the chromophore, with a sharp break in the organization of the bilayer acyl chain region for vesicles of ca. 1 µm diameter. These results point to the importance of curvature in mediating bilayer dynamics and thus their ability to accommodate different species.

 

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Presentation: Tutorial lecture at SMCBS'2007 International Workshop, by Gary J. Blanchard
See On-line Journal of SMCBS'2007 International Workshop

Submitted: 2007-08-31 19:50
Revised:   2009-06-07 00:44