Unraveling the Role of Monoolein in Fluidity and Dynamical Response of a Mixed Cationic Lipid Bilayer

Abstract

The maintenance of cell membrane fluidity is of critical importance for various cellular functions. At lower temperatures when membrane fluidity decreases, plants and cyanobacteria react by introducing unsaturation in the lipids, so that the membranes return to a more fluidic state. To probe how introduction of unsaturation leads to reduced membrane fluidity, a model cationic lipid dioctadecyldimethylammonium bromide (DODAB) has been chosen, and the effects of an unsaturated lipid monoolein (MO) on the structural dynamics and phase behavior of DODAB have been monitored by quasielastic neutron scattering and time-resolved fluorescence measurements. In the coagel phase, fluidity of the lipid bilayer increases significantly in the presence of MO relative to pure DODAB vesicles and becomes manifest in significantly enhanced dynamics of the constituent lipids along with faster hydration and orientational relaxation dynamics of a fluorophore. On the contrary, MO restricts both lateral and internal motions of the lipid molecules in the fluid phase (>330 K), which is consistent with relatively slow hydration and orientational relaxation dynamics of the fluorophore embedded in the mixed lipid bilayer. The present study illustrates how incorporation of an unsaturated lipid at lower temperatures (below the phase transition) assists the model lipid (DODAB) in regulating fluidity via enhancement of dynamics of the constituent lipids.

A Comparative Study on DMSO-Induced Modulation of the Structural and Dynamical Properties of Model Bilayer Membranes

“… , In this time-resolved measurement, a short pulse is given for the electronic excitation of the fluorophore molecules and the fluorescence spectrum of the optically excited chromophore red shifts in time as the surrounding solvent molecules reorient themselves surrounding the solute probe molecules to establish a new, excited charge distribution state. Therefore, the dynamics of the overall solvent response is described in terms of solvation correlation function [ C ( t )], which serves as a better descriptor of the environmental response due to the coupled dynamics of the lipid molecules and their surrounding water molecules . It is true that C153 does not contain any hydrophobic anchor, but still its hydrophobicity is more compared to the commonly used varieties of other coumarin dyes.…”

Caffeine modulates the dynamics of DODAB membranes: Role of the physical state of the bilayer

“…Dioctadecyldimethylammonium bromide (DODAB) is a double chained cationic lipid (Fig. 1) which forms a lamellar structure in aqueous solution analogous to biological membranes and has been widely investigated due to their membrane mimetic properties [31][32][33][34][35][36]. Various recent studies have shown the usefulness of DODAB membranes for a number of biomedical applications such as antimicrobials [37][38], drug/vaccine delivery [39][40][41], and gene/DNA transfection [42].…”

Enhanced Microscopic Dynamics of a Liver Lipid Membrane in the Presence of an Ionic Liquid

“…These motions occur in a wide range of time scales ranging from vibrations at ∼fs to flip flop motions which take a few hours, and over a wide variety of length scales, from molecular rotations at a few Ås to the macroscopic deformation of the vesicles at the micrometer scale. To investigate these motions, various experimental methods have been used, such as dynamic light scattering (Hassan et al, 2015;Sharma et al, 2020), fluorescence spectroscopy (Machán and Hof, 2010;Singh et al, 2019), electron paramagnetic resonance (McConnell and Kornberg, 1971), nuclear magnetic resonance (Perlo et al, 2011), quasielastic neutron scattering (Busch et al, 2010;Armstrong et al, 2011;Sharma et al, 2015aSharma et al, , 2017aDubey et al, 2018;Sharma and Mukhopadhyay, 2018), neutron spin echo (Boggara et al, 2010;Lee et al, 2010;Woodka et al, 2012;Nickels et al, 2015). Each method has limited accessible temporal and spatial regimes.…”