We studied a ternary solutes aqueous solution of NaOH, iron (III)-ethylenediamine-N,N,N′,N′-tetraacetic acid complex (Fe-edta), and 1,2-diheptanoyl-sn-glycero-3-phosphatidylcholine (DHPC)/air interface system to clarify the interactions between iron complexes and lipids with a phosphatidylcholine head group. The solution surface tension and pH were measured as functions of the total molality of NaOH, Fe-edta and DHPC, and the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-edta and DHPC were taken into consideration, and applied to experimental data to obtain phase diagram of adsorption. It was found that (1) adsorption of Fe-edta at the solution/air interface with a DHPC monolayer was about 50–130 times higher than that without a DHPC monolayer and (2) when the bulk mole fraction of NaOH was high, Fe-edta tended to be expelled from the adsorbed film. The last finding suggests that the ambient pH significantly affects passive transport of the iron complex through a phospholipid-containing membrane into the cell interior.

我们研究了NaOH，铁（III）-乙二胺-N，N，N '，N'-四乙酸络合物（Fe-edta）和1,2-二庚酰基-sn的三元溶质水溶液-甘油-3-磷脂酰胆碱（DHPC）/空气界面系统，以阐明铁配合物与脂质与磷脂酰胆碱首基之间的相互作用。测量溶液的表面张力和pH值，作为NaOH，Fe-EDTA和DHPC的总摩尔浓度以及NaOH和DHPC的摩尔分数的函数。推导了严格的热力学方程，其中考虑了Fe-edta和DHPC的整体质子离解平衡，并将其应用于实验数据以获得吸附相图。发现（1）具有DHPC单层的溶液/空气界面上的Fe-edta吸附比没有DHPC单层的溶液高约50-130倍；（2）当NaOH的总摩尔分数高时，Fe -edta倾向于从吸附膜上排出。