AVS 52nd International Symposium
    Applied Surface Science Monday Sessions
       Session AS+BI+NS-MoM

Paper AS+BI+NS-MoM3
Local Mobility in Membranes: Atomic Force Microscopy and Fluorescence Correlation Spectroscopy

Monday, October 31, 2005, 9:00 am, Room 206

Session: Nanoscale Analysis: Biomaterial and Other Applications
Presenter: A.R. Burns, Sandia National Laboratories
Authors: A.R. Burns, Sandia National Laboratories
D.J. Frankel, Sandia National Laboratories
Correspondent: Click to Email
The lateral organization and dynamics of lipids and proteins in membranes are critical to cellular signaling processes. Fluorescence imaging and atomic force microscopy (AFM) are both effective ways to map the location and structure of membrane components and domains (e.g., lipid rafts) in supported membranes. Since dynamical processes like translational diffusion of lipids and proteins are dependent on the local membrane structure and molecular interactions, it would be advantageous to correlate dynamics with detailed topography mapped out with AFM. We do this by performing fluorescence correlation spectroscopy (FCS) at specific sites imaged by simultaneous AFM and submicron confocal fluorescence microscopy. We have thus examined the relative partitioning and diffusion coefficients for both tail and head labeled GM1 ganglioside, as well as for head and tail labeled phospholipids, in phase separated domains. Our results indicate significant mobility changes in the micron-scale domains due to differences in lipid packing and ordering. We also observe a large reduction in the mobility of GM1 when bound to cholera toxin B fragments. The effects of membrane proteins will be discussed as well. This research was supported in part by the Division of Materials Science and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract DE-AC04-94AL85000.