Hydrophobic Nanoparticles Drives Size-Dependent Remodelling in Asymmetric Bilayers

The interactions between heterogeneous components in a biomimetic bilayer controls its physical properties such as its rigidity, local and bulk curvature and propensity towards phenomena such as membrane fission and fusion. In particular, membrane proteins (MPs) and nanoparticles (NPs) have been subjects of intense interest due to their similar scale to the bilayer width and because of their ability to affect local membrane structure. However, how such NPs interact in the presence of heterogeneous aggregates in the bilayer has been the subject of much debate, especially its effect on raft-like structures. To better understand the effects of hydrophobic integration of nanoscale components on such raft-like structures, we have simulated a series of generic hydrophobic NPs interacting with a phase-separating two-component surfactant bilayer. We find that the hydrophobic NP tends to aggregate at the phase interface, acting as a line tension relaxant i.e. a lineactant on the phase separated interface, which results in differing demixing behavior. In particular, we demonstrate that depending on the size of the NP, the effect of the line tension can drive the a cap/bud formation around the NP, ultimately resulting in the formation of a NP-micelle structure.