APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010;
Portland, Oregon
Session W19: Focus Session: Synchrotron X-ray and Neutron Techniques in Soft Matter and Biological
11:15 AM–2:15 PM,
Thursday, March 18, 2010
Room: B118-B119
Sponsoring
Units:
DPOLY DBP
Chair: Zhang Jiang, Argonne National Laboratory
Abstract ID: BAPS.2010.MAR.W19.10
Abstract: W19.00010 : Neutron and X-ray Scattering From Single Supported Lipid Bilayers: Reflectometry, Grazing Incidence In-Plane Diffraction and Off-Specular Scattering
1:27 PM–2:03 PM
Preview Abstract
Abstract
Author:
Jaroslaw Majewski
(Los Alamos National Laboratory)
Biological membranes mediate transport and communication between the cell
and its surroundings. They defend the cell against invasive agents, and most
present day drugs interact with membrane components. Complexity of the cell
membranes renders many of their characteristics impenetrable to fundamental
physical studies. As a result, a significant emphasis has been placed on
developing model lipid membranes that facilitate the physical and chemical
characterization of particular membrane features.
X-ray (XR) and neutron reflectivity (NR) and grazing incidence X-ray
diffraction (GIXD) techniques can be utilized to measure the structure of
single, supported lipid bilayers in bulk water. GIXD studies demonstrated
that bilayers formed by vesicle fusion have more disorder in the inner
leaflet compared to structures prepared using the
Langmuir-Blodgett/Schaeffer (LB/S) technique. In both cases, only a modest
water cushion was detected between the bilayer and substrate. Diffraction
from in-plane ordered domains was observed from bilayers prepared by either
technique. In the case of 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC)
bilayers, the ordered domains were coupled across both leaflets, scattering
as one entity. Contrastingly, the ordered domains were uncoupled in
1,2-Dipalmitoyl-sn-Glycero-3-Phosphoethanolamine (DPPE) bilayers.
NR can be effectively used to study polymer-supported single lipid bilayers
in bulk water. Using NR and fluorescence microscopy, we demonstrated that a
hydrated, surface-tethered polymer network capable of five-fold change in
thickness over a 25-37 C temperature range can be a novel support for single
DPPC bilayers in a liquid environment. Moderate temperature change swells
the polymer, lifting the membrane from the substrate, creating a nearly
aqueous cushion. Additionally, as the polymer swells, it promotes both in-
and out-of-plane undulations in the supported membrane. Off-specular neutron
scattering was used to deduce the in-plane correlation length of the
membrane distortions.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.W19.10