Coarse-Grained Model of Oxidized Membranes and Their Interactions with Nanoparticles of Various Degrees of Hydrophobicity

We investigate the consequences of lipid peroxidation on the permeation properties of membranes comprising unsaturated lipid molecules by means of coarse-grained molecular simulations. After discussion on the impact of peroxidation on the properties of lipid bilayers such as stretching modulus, area per lipid, water permeation, and the distributions of various lipid components across the membrane, we focus in particular on the effect of peroxidation on the passive translocation of small nanoparticles of varying hydrophobicity across lipid bilayers. We consider two types of oxidized lipid bilayers which differ in their degree of peroxidation using a schematic model for the oxidized beads. Consistently with our previous work for nonoxidized lipid bilayers, we find a narrow window of translocation of the nanoparticles when their hydrophobicity is varied. Our studies suggest that oxidized lipid bilayers feature a more hydrophilic environment and strongly enhance the translocation rate of small nanoparticles without the formation of pores. Furthermore, an optimal permeation rate is found for peroxidized membranes, associated with more hydrophilic nanoparticles than that in the case of nonoxidized lipid bilayers. Strategies for targeting peroxidized lipid membranes in a more specific way are discussed in the light of our findings.