Sprecher
Beschreibung
The self-assembly of amphipathic copolymers with phospholipids in aqueous solution results in the formation of ‘nanodiscs’ containing a planar segment of phospholipid bilayer encapsulated by a polymer belt. Recent studies have reported that lipids rapidly exchange between both nanodiscs in solution and external sources of lipids e.g. [1]. There are, however, outstanding questions regarding precise details of polymer-lipid interactions, the factors influencing lipid exchange and the structural effects of such exchange processes. Here, we structurally investigate the influence of membrane charge on free polymer interaction, and the impact of polymer chemistry on the propensity of nanodiscs undergo lipid exchange [2]. This was performed using two implementations of neutron reflectometry (NR): a traditional structural approach to examine the detailed location and amount of polymer incorporated in the lipid layers in order to understand the structures formed at equilibrium, and a novel compositional, time-resolved approach to investigate the changes in surface excess of both lipid and polymer during the interaction. We show that both free polymer and SMALP (styrene-co-maleic acid lipid particles) nanodiscs are surface active and disassemble when adsorbed to a clean air-water interface. In the presence of a pre-existing monolayer, the polymer embeds throughout the monolayer, the extent of which is governed by the net monolayer charge. Finally, we demonstrate that nanodiscs stabilised by three different polymers will exchange both lipids and polymer with a monolayer. These results demonstrate the dynamic nature of nanodiscs which interact with the local environment and are likely to deposit both lipids and polymer at all stages of use.
References:
[1] S. C. L. Hall, C. Tognoloni, R. A. Campbell, J. Richens, P. O'Shea, A. E. Terry, G. J. Price et al., Journal of Colloid and Interface Science 2022, 625, 220-236
[2] S. C. L. Hall, L. A. Clifton, C. Tognoloni, K. A. Morrison, T. J. Knowles, C. J. Kinane, T. R. Dafforn, K. J. Edler, T. Arnold, Journal of Colloid and Interface Science 2020, 574, 272-284.
