Polymer interactions with phospholipid monolayers: Understanding formation of polymer-stabilized nanodiscs

Polymer stabilized phospholipid nanodiscs are gaining rapid interest as a detergent free method of extracting membrane proteins from cell membranes and maintaining them in an active state in solution. Although the structure of the discs is established, with the polymer belt wrapping the exposed hydrophobic tails of a ~10nm disc of lipid bilayer, it is not known how this structure forms from the initially intact lipid membrane. Formation speed of the discs depends on monolayer composition but so far our, and similar studies by others have used largely simple phospholipid layers. In this experiment we aim to use the new higher flux on INTER to follow the kinetics of adsorption and/or penetration of polymer to more complex lipid monolayers at the air water interface containing unsaturated and saturated lipids, as well as to characterise the evolving structure of the lipid/polymer layer. We will vary the surface pressure and composition of the lipid membrane to investigate the effects of fluidity and phase separation, and the polymer type and hydrophobic/hydrophilic balance. These experiments will access timescales inaccessible on other neutron reflectometers, to improve our understanding of how polymer-stabilized nanodiscs form, which will improve their future application and uptake in membrane protein biology.