A coarse-grained model of dimethyl sulfoxide for molecular dynamics simulations with lipid membranes

Abstract

Enhanced permeability of biomembranes upon the application of small amphiphiles is of vital importance to biologists and pharmacists, as their physiochemical interactions open new pathways for transdermal drug transportation and administration. Amphiphilic dimethyl sulfoxide (DMSO) is known to alter biomembrane permeability. Atomistic simulation-based studies to explore the impact of amphiphilic molecules on the model lipid membranes are of immense importance. These studies provide molecular details on how the membrane physical properties, such as fluidity and thickness, are modulated by amphiphile-lipid interactions. However, such approaches are usually limited to short simulation time and length scales. To circumvent such limitations, the use of coarse-grained (CG) models is a current computational strategy. In this article, we have presented a new CG force-field for DMSO for molecular dynamics (MD) simulations. The model is designed to reproduce experimental bulk properties of DMSO and its aqueous mixtures, molecular-level structure of liquid DMSO, and the phase transfer energy of a single DMSO molecule from the aqueous phase to the lipid bilayer hydrophobic interior. The current CG DMSO model successfully mimics the structural variation in phospholipid bilayer systems (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine) including alteration in bilayer thickness, lipid tail ordering, lipid lateral packing, and electron density profiles at various DMSO concentrations when compared to those obtained from parallel atomistic simulations.