Cholesterol affects C60 translocation across lipid bilayers

Cholesterol plays an important role in regulating the structural properties of phospholipid membranes and further influences the permeability of molecules and nanoparticles. However, nanoparticles' translocation across phospholipid membranes in the presence of cholesterol on the molecular scale is rarely studied. Here, we performed coarse-grained molecular dynamics simulations to probe the translocation of C-60, one of the most popular nanoparticles, across dipalmitoylphosphatidylcholine bilayers with different concentrations of cholesterol molecules (0-50 mol%). The results reveal that the presence of cholesterol molecules induces lower area per lipid, larger bilayer thickness, and more ordered orientation of lipid tails. The higher the concentration of cholesterol molecules, the more significant is the condensing effect of lipid bilayer as just mentioned. Besides, dynamic processes, free energy profiles and permeability coefficients further indicate that the permeability of C-60 decreases with increasing cholesterol concentration, which can be explained by the condensation effect and reduced free volume. Our researches provide an explicit description of the impact of cholesterol on C-60 translocation across lipid bilayers.