Counter-ion adsorption and electrostatic potential in sodium and choline dodecyl sulfate micelles - a molecular dynamics simulation study

Autor(es)

Eliasquevici, Rafaela ; Bernardino, Kalil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Molecular Modeling; v. 30, n. 4, p. 13-pg., 2024-04-01.

Resumo

ContextCholine-based surfactants are interesting both from the practical point of view to obtaining environmental-friendly surfactants as well as from the theoretical side since the interactions between the choline and surfactants can help to understand self-assembly phenomena in deep eutectic solvents. Although no significant change was noticed in the micelle size and shape due to the exchange of the sodium counter-ion by choline in our simulations, the adsorption of the choline cation over the micelle surface is stronger than the adsorption of the sodium, which leads to a reduction of the exposed surface area of the micelle and remarkable effects over the electrostatic potential. The choline neutralizes the surface charge of the surfactant better than sodium; however, this is partially compensated by a stronger water orientation around the SDS micelle. The balance between the contributions from the surfactant, the counter-ion, and water to the electrostatic potential leads to a complex pattern with alternate regions of positive and negative potential at the micelle/water interface which can be important to the incorporation of other charged species at the micelle surface as well as for the interaction between micelles in solution.MethodsTo evaluate the effects of the counter-ion substitution, micelles of sodium dodecyl sulfate (SDS) and choline dodecyl sulfate (ChDS) were studied and compared by means of molecular dynamics simulations in aqueous solution. In both cases, the simulations started from pre-assembled micelles with 60 dodecyl sulfate ions and 240-ns simulations were performed at NPT ensemble at T = 323.15 K and P = 1 bar using the Gromacs software with the OPLS-AA force field to describe dodecyl sulfate and choline, angstrom qvist parameters for sodium, and SPC model for water molecules. (AU)

• Processo FAPESP: 22/15862-7 - Estudo computacional da auto-agregação de surfactantes iônicos em solventes eutéticos profundos.
• Beneficiário: Rafaela Eliasquevici
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 23/09350-6 - Termodinâmica de agregação de nanoestruturas em solventes neotéricos por simulações de dinâmica molecular
• Beneficiário: Kalil Bernardino
• Modalidade de apoio: Auxílio à Pesquisa - Regular