Molecular Dynamics Simulations of Micelle Properties and Behaviors of Sodium Lauryl Ether Sulfate Penetrating Ceramide and Phospholipid Bilayers

Abstract

Molecular dynamics (MD) simulations with the umbrella sampling (US) method were used to investigate the properties of micelles formed by sodium lauryl ether sulfate with two ether groups (SLE2S) and behaviors of corresponding surfactants transferring from micelles to ceramide and DMPC bilayer surfaces. Average micelle radii based on the Einstein–Smoluchowski and Stokes–Einstein relations showed excellent agreement with those measured by dynamic light scattering, while those obtained by evaluating the gyration radius or calculating the distance between the micelle sulfur atoms and center of mass overestimate the radii. As an SLE2S micelle was pulled down to the ceramide bilayer surface in a 400 ns constant-force steered MD (cf-SMD) simulation, the micelle was partially deformed on the bilayer surface, and several SLE2S surfactants easily were partitioned from the micelle into the ceramide bilayer. In contrast, a micelle was not deformed on the DMPC bilayer surface, and SLE2S surfactants were not transferred from the micelle to the DMPC bilayer. Potential of mean force (PMF) calculations revealed that the Gibbs free energy required for an SLE2S surfactant monomer to transfer from a micelle to bulk water can be compensated by decreased Gibbs free energy when an SLE2S monomer transfers into the ceramide bilayer from bulk water. In addition, micelle deformation on the ceramide bilayer surface can reduce the Gibbs free energy barrier required for a surfactant to escape the micelle and help the surfactant partition from the micelle into the ceramide bilayer. An SLE2S surfactant partitioning into the ceramide bilayer is attributed to hydrogen bonding and favorable interactions between the hydrophilic surfactant head and ceramide molecules, which are more dominant than the dehydration penalty during bilayer insertion. Such interactions between surfactant and lipid molecule heads are considerably reduced in DMPC bilayers owing to dielectric screening by water molecules deep inside the head/tail boundary between the DMPC bilayer. This computational work demonstrates the distinct behavior of SLE2S surfactant micelles on ceramide and DMPC bilayer surfaces in terms of variation in Gibbs free energy, which offers insight into designing surfactants used in transdermal drug delivery systems and cosmetics.

Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design

“…Benzene [149,415,417], Hexane [415] Other Lauryl Ether Sulfate [532], Dodecyl Sulfate [533], CyMe4-BTPhen [534], Acetone [420], DMSO [417,420,535], bis-(3-hydroxy-4-pyridinonato) zinc(II) complex [536], calix [4], resorcinarenes [537], dihydropyrimidine analogues [538], Choline carboxylates [539], Synthetic xanthophylls [540], Triton X-100 [541,542], Benzoic acid [284,287,387], Methane [379], Borneol [282,543], Osthole [282,543], Isopulegol [544], Benzylpiperidine [545], Benzimidazole derivatives [546], Aldehydes [547] Inorganic…”

A case of xenon inhalation therapy for respiratory failure and neuropsychiatric disorders associated with COVID-19

“…Moreover, the enthalpy change (ΔH) was +8 kJ/mol. These findings indicate the possibility of spontaneous occurrence of the detected endothermic process (Song et al, 2020[ 32 ]).…”

“…On the other hand, the released Xe atom immediately re-enters the cycle of interaction with the acyl chains of phospholipids in the solid-ordered phase. Moreover, the released xenon atom will interact with the acyl chains of phospholipids only of the solid-ordered phase of surfactant, but not with molecules of a normally functioning surfactant (because ΔG for such a process is greater than zero (Song et al, 2020[ 32 ])) (Figure 3C (Fig. 3) ).…”

Effect of quaternary ammonium surfactants on biomembranes using molecular dynamics simulation

“…Also, molecular dynamics (MD) simulations and the umbrella sampling (US) method was used to investigate the transfer behavior and changes in Gibbs free energy of a sodium lauryl ether sulfate surfactant with two ether groups (SLE2S) as it transitions from a micelle to a ceramide bilayer. 28 The potential of mean force (PMF) profiles generated for the transfer of SLE2S surfactant from a micelle to bulk water and then to a ceramide or DMPC bilayer unveiled attractive interactions between SLE2S monomers and ceramide lipid molecules. These interactions involved head-based electrostatic and hydrogen-bonding interactions, as well as hydrocarbon-tail-based hydrophobic interactions.…”