Influence of Lipid Bilayer Head Group Polarity on Micelle Behavior and Surfactant Transfer: A Molecular Dynamics Simulation Study

Abstract

Molecular dynamics simulations with umbrella sampling were conducted to investigate the behavior of micelles on polar and non-polar lipid bilayer surfaces and surfactant transfer from the SLE2S micelle to the bilayers. Two-dimensional potential of mean force (PMF) profiles reveal that the micelle avoids interaction with the polar 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayer, maintaining its spherical shape. In contrast, it adheres tightly to the non-polar CER NS 24:0 ceramide (Cer240) bilayer, exhibiting an upper hemispherical shape. Electrostatic interactions govern the micelle behavior at the DMPC bilayer whereas both electrostatic and van der Waals interactions influence the shape and adhesion to the Cer240 bilayer. One-dimensional PMF curves suggest that surfactant transfer is unlikely in the DMPC bilayer at either 313.15 K or 350.15 K due to an energy barrier induced by interfacial water. However, transfer can occur in the Cer240 bilayer at 350.15 K, facilitated by the loose packing of head groups.