Thermal Fluctuations of Oriented Lipid Membranes by Nonspecular Neutron Reflectometry

Abstract

We present a novel method to measure and to analyze lipid bilayer fluctuations based on time-of-flight nonspecular neutron reflectivity (TOF-NSNR). To validate this approach, we compare the results obtained on the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) to NSNR data collected in the conventional monochromatic mode. For the DMPC model system in its fluid L α phase, we determine the fluctuation spectrum of an averaged bilayer in an oriented multilamellar stack and compare the result to the predictions of the linearized smectic free energy functional. In particular, we show how the smectic penetration depth Λ can be determined from the measurements. Furthermore, significant changes in the fluctuation spectrum of DMPC are observed upon the interaction with the antimicrobial peptide magainin 2 and cannot be explained by the smectic model.

Fluctuations and destabilization of single phospholipid bilayers

“…13 and 14͒. In particular, structural information on the variation in chemical composition has been obtained using neutrons 5,[15][16][17] or electron density using x rays. [18][19][20][21][22] Although most of the structural and equilibrium properties of lipid membranes are now well understood, many of their dynamic features still need to be elucidated.…”

Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions

“…Neutron and X-ray diffraction [18], spectroscopy [19], reflectometry [20] and solid-state NMR [21] have also given information on the structure and dynamics of model lipid membranes.…”

Molecular motions in lipid bilayers studied by the neutron backscattering technique

“…Off-specular x-ray and neutron reflectivity from aligned phases presents the additional advantage that the components of the scattering vector Q can be projected onto the symmetry axis of the membrane 8,24,25 . In both examples, the time-averaged elastic scattering is studied, and information on e.g.…”