The impact of metal ions on the phase behavior of phosphatidylcholine (PC) was investigated at the air/water interface by surface pressure-area (pi-A) isotherm measurements. The analysis of the pi-A isotherms showed that with the metal ionic radius decreasing, the concentration of the metal ions C increasing, and the valence of metal ions Q increasing, the amount of the corresponding curves of A0 decreases, the phase transition point would change more apparently, the collapse pressure would become larger subsequently, and the curve would be extended outside. The phenomenon could be approached when the metal ion concentration C became great enough. These experiments were identified with the rules on Langmuir films, by a variety of properties of metal ions (ion radius, ion concentration, ion valence, etc.). Among all the factors, the ionic valence showed the greatest impact on the phase changes, followed by the ion concentration, while the ionic radius influences were less on the phase-change characteristics.
Air ; Ions ; chemistry ; Membranes, Artificial ; Metals ; chemistry ; Phase Transition ; Phosphatidylcholines ; chemistry ; Surface Properties ; Water ; chemistry