(174af) Curvature-Driven Adsorption and Alignment of Cationic Nanoparticles to Phase Boundaries in Multicomponent Lipid Bilayers
In this work, we use coarse-grained molecular dynamics simulations to investigate the effect of lipid phase behavior on the adsorption of 2-6 nm cationic NPs. We first determined the free energy change for adsorbing a NP to one-phase liquid-disordered and liquid-ordered bilayers, composed of saturated and unsaturated phospholipids, respectively. We find that that NP adsorption depends on the competition between favorable NPâlipid interactions and the unfavorable curvature deformation of the bilayer, resulting in more favorable interactions with the liquid-disordered bilayer due to its lower bending modulus. We then measured the free energy change associated with moving a NP across the surface of a phase-separated bilayer and identified a free energy minimum at the phase boundary that is attributed to the thickness gradient between the two phases that enables favorable NPâlipid interactions without necessitating large curvature deformations. Finally, we investigate the effect of NP aspect ratio on the preferential adsorption onto phase-separated bilayers by measuring the free energy associated with rotating the long axis of the NP relative to the phase boundary . The simulation results thus indicate that the intrinsic curvature present at phase boundaries drives preferential interactions with surface-adsorbed NPs, providing new insight into the forces that drive NP behavior at multicomponent, phase-separated lipid bilayers.