Local Dynamics of Model Membrane Systems probed by Neutron Spectroscopy

Topic  26
Main supervisor C.Garvey (christopher.garvey@tum.de)
MLZ institution TUM
Local supervisor 1 Pierre Guillot
Institution Solvay
Local supervisor 2 Daria Noferini
Institution ESS
Local supervisor 3 Dorthe Posselt
Institution Univ. Roskilde
Local supervisor 4
Title Local Dynamics of Model Membrane Systems probed by Neutron Spectroscopy
Description Understanding the dynamics of biological membranes, when they interact with various structurally different molecules, sets the basis for understanding how this interaction is related to many cellular processes including those related to severe diseases. In the present project, the change in lipid dynamics by two classes of molecules exerting mechanical stress on the membrane: (i) simple alcohols and (ii) antimicrobial peptides. The presence of chains with a mismatch in hydrophobic length and the resulting creation of free volume are also expected to influence the dynamics of the lipid matrix. These effects have important implications, for example regarding exploration of the anesthetic effect, and the adaption of membranes for micro-organisms growing in adverse conditions. Likewise, antimicrobial peptides interact with the lipid membrane and increase membrane permeability, however it is unclear to which extent stable pores and holes are formed. Accordingly, it is to be expected that information on changes in the membrane lipid dynamics can shed light on peptide-membrane interactions. The change of the local and collective lipid dynamics will be investigated using a combination of neutron spectroscopic methods, i.e. time-of-flight quasielastic neutron scattering (probing motions in the time domain of 0.01-0.1 ns), neutron backscattering (0.1-5 ns) and neutron spin-echo spectroscopy (time domain 0.1-400 ns) available at FRM II in Garching. The combination of these methods enables investigations over a wide range of time scales of molecular motions. Small- and wide angle x-ray scattering are available at Roskilde University, Denmark, to provide structural characterisation. A longer stay at ESS is planned in collaboration with CSPEC scientists (direct geometry time of flight spectrometer) to prepare for future measurements on this topic at especially CSPEC, when this instrument is in operation in (late) 2025.