Molecular Dynamics simulation of the sodium octanoate micelle in aqueous solution: comparison of force field parameters and molecular topology effects on the micellar structure

Abstract

We have performed a series of 10 ns Molecular Dynamics simulations of the sodium octanoate micelle in aqueous solution in the constant NpT ensemble, at p = 1 bar and T = 300 K. Two molecular topologies were studied, one with all internal degrees of freedom and the other constraining bond stretching and angle bending degrees of freedom. Two Lennard-Jones parameters for sodium ions, namely the OPLS andÅqvistand˚andÅqvist parameters, were used. The results show an artificial enhancement of stable sodium bridges between octanoate anions when the OPLS parameters for sodium are used. TheÅqvistThe˚TheÅqvist parameters give a micellar structure in good agreement with experimental and thermodynamical evidences. It is also observed that the aggregation of monomers is strongly dependent on the molecular topology. When theÅqvistthe˚theÅqvist parameters were employed, the model system without constraining geometry had one dissociated monomer after 10 ns, while the model system with bond length and bond angle constraining had five dissociated monomers after a 10 ns trajectory.

Investigating the spontaneous formation of SDS micelle in aqueous solution using a coarse-grained force field

“…In the last two decades, Molecular Dynamic (MD) simulations have become a preferential tool in the investigation of micellar systems. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] MD simulations can provide insight into structural and dynamical features of assembled molecules but the inherent complexity of the systems and an accurate description of structural and dynamic features require elaborate modeling and adequate system size. Otherwise, the long relaxation times involved in self-assembling impose some limitations on the detailed study of aggregation processes using this methodology.…”

Molecular dynamics characterization of n-octyl-β-d-glucopyranoside micelle structure in aqueous solution

“…Early MD simulations were very limited and used bead models to describe the system [16][17][18], and until recently, high end MD simulations with full atomistic models were applied to investigate the properties of the ionic surfactants, such as sodium octanoate [19][20][21][22][23][24], dodecylphosphocholine [25,26], and sodium dodecyl sulphate [27][28][29] molecules in the aqueous solution phase. Early reports on OG stated that aggregates of above 10 monomers were more stable and remain intact during the course of the simulation [30].…”

Self-assembly formation of palm-based esters nano-emulsion: A molecular dynamics study

“…PACKMOL [16] was used to randomly place 24 molecules of POEs and 60 molecules of Span20 surfactant into the simulation box to avoid the strong repulsive contacts of the molecules [9] with no position-restriction applied to the chain of the molecules. All the molecules were inserted into a 10 nm cubic simulation box which made up a 1000 nm 3 of volume.…”

“…Molecular dynamics simulation is a powerful tool to study the molecular arrangement of biomolecules systems [9]. Two important factors in performing molecular dynamics simulation for nano-emulsion system are the box size and the time scale.…”