Effects of Alkali Cations and Halide Anions on the Self-Assembly of Phosphatidylcholine in Oilsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 12 января 2017 г.
Аннотация:ABSTRACT: The interactions between ions and phospholi-
pids are closely associated with the structures and functions of
cell membrane. Instead of conventional aqueous systems, we
systematically investigated the effects of inorganic ions on the
self-assembly of lecithin, a zwitterionic phosphatidylcholine, in
cyclohexane. Previous studies have shown that addition of
inorganic salts with specific divalent and trivalent cations can
transform lecithin organosols into organogels. In this study, we
focused on the effect of monovalent alkali halides. Fourier
transform infrared spectroscopy was used to demonstrate that
the binding strength of the alkali cations with the phosphate of lecithin is in the order Li+ > Na+ > K+. More importantly, the cation−phosphate interaction is affected by the paired halide anions, and the effect follows the series I− > Br− > Cl−. The salts of stronger interactions with lecithin, including LiCl, LiBr, LiI, and NaI, were found to induce cylindrical micelles sufficiently long to form organogels, while others remain organosols. A mechanism based on the charge density of ions and the enthalpy change of the ion exchange between alkali halides and lecithin headgroup is provided to explain the contrasting interactions and the effectiveness of the salts to induce organogelation.