Dynamics of Phospholipid Membranes Beyond Thermal Undulations
Sudipta Gupta, Judith U. De Mel, Rasangi M. Perera, Piotr Zolnierczuk, Markus Bleuel, Antonio Faraone, Gerald J. Schneider
We investigated the molecular dynamics of unilamellar lipsomes by neutron spin echo spectroscopy. We report the first experimental evidence of a short-range motion at the length-scale of the size of the head group of a lipid. The associated mean square displacement shows a t0.26 dependence in the pico-to nanosecond region that indicates another process beyond the predictions of the Zilman-Granek (ZG) model (t0.66) and translational diffusion (t1). A comparison with molecular dynamics simulations shows that the observed low exponent is associated with a non-Gaussian transient trapping of lipid molecules. This discovery is in quantitative agreement with continuous random walk models, which assume a lateral motion of lipids that are trapped in a local area. The analysis of the mean square displacement leads to the important conclusion that the friction at the interface between water and liposomes plays a minor role. Center of mass diffusion of liposomes and transient trapping of lipids define the range in which the ZG model can be applied to analyze membrane fluctuations.
, De Mel, J.
, Perera, R.
, Zolnierczuk, P.
, Bleuel, M.
, Faraone, A.
and Schneider, G.
Dynamics of Phospholipid Membranes Beyond Thermal Undulations, Journal of Physical Chemistry Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925724
(Accessed December 6, 2023)