Effect of ionic strength on Ibuprofenate adsorption on a lipid bilayer of dipalmitoylphosphatidylcholine from molecular dynamics simulations

FRIGINI, EZEQUIEL; PORASSO, RODOLFO D.

Virtual

Congreso; XLIX SAB 2021; 2021

In this work, the free energy change in the process of transferring ibuprofenate from thebulk solution to the center of a model of the dipalmitoylphosphatidylcholine bilayer atdifferent NaCl concentrations was calculated. Two minima were found in the free energyprofile. A local minimum -located in the vicinity of the membrane- and the global freeenergy minimum is found in the tail region. The downward shift of free energy minima,with increasing NaCl concentration, is consistent with the results of previous works.Conversely, the upward shift of the free energy maximum with increasing ionic strength isdue to the competition of sodium ions and lipids molecules to coordinate withibuprofenate and neutralize its charge. In addition, normal molecular dynamicssimulations were performed to study the effects of the ibuprofenate on lipid bilayer and inpresence of a high ibuprofenate concentration. The effect of ionic strength on theproperties of the lipid bilayer and on lipid-drug interactions was analyzed. The area perlipid shrinking with increasing ionic strength, volume of lipids and thickness of the bilayeris consistent with the experimental results. At a very high ibuprofenate concentration, thelipid bilayer dehydrates, and it consequently transforms into the gel phase.