Exploring Fullerenol-C60(OH)24 interactions with lipid bilayers: Molecular dynamics study of agglomeration and surface deposition

Abstract

In this work, the physical–chemical properties of lipid membranes interacting with Fullerenol-C60(OH)24 molecules immersed in an aqueous solution were studied using Molecular Dynamics (MD) simulations. In order to analyze the role played by the concentration of Fullerene-C60(OH)24 in the interaction with lipid membranes, we carried out simulations with variations in the number (n = 1, 2, 4, 8, 12, 16 or 20) of Fullerene-C60(OH)24 molecules present in the solution in which the lipid membrane was immersed. The lipid membrane simulated was composed of DOPC (dipalmitoylphosphatidylcholine) with 30% of cholesterol molecules (DOPC/CHOL(30%)). The average behavior of the Coulomb and vdW interaction energy shows that as the Fullerenol-C60(OH)24 molecules concentration increases, insertion of Fullerenol in the lipid bilayer becomes energetically unfavorable since they tend to interact with each other, leading to the formation of clusters. From the mass density, we confirmed that there is a decrease in the insertion of Fullerenol-C60(OH)24 molecules in the bilayer as n increases. We noticed that Fullerenol molecules get closer to each other and are deposited on the surface of the lipid bilayers but do not penetrate them. The diffusion coefficient (MSD) reveals a decrease in the mobility of Fullerenol molecules as n increases. This observation confirms the agglomeration of Fullerenol on the lipid membrane’s surface. A detailed analysis of hydrogen bonds (HB) involving Fullerenol–Fullerenol, Fullerenol–DOPC, and Fullerenol–Water pairs provides insight into this phenomenon. While the average number of HBs in the Fullerenol–Water pair remains relatively constant as n increases, there is a significant increase in HB interactions for the Fullerenol–Fullerenol pair. In contrast, the Fullerenol–DOPC pair experiences a decrease in HBs, underscoring the preference of Fullerenol to agglomerate and deposit onto the lipid membrane's surface.