Continuing electrochemical studies of phospholipid monolayers of dioleoyl phosphatidylcholine at the mercury-electrolyte interface
Continuing electrochemical studies of phospholipid monolayers of dioleoyl phosphatidylcholine at the mercury-electrolyte interface
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DOI：
10.1021/la980314o
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发表时间：
1998-10-13
期刊：
影响因子：
3.9
通讯作者：
Nelson, A
中科院分区：
文献类型：
--
作者：
Bizzotto, D;Nelson, A
本文定量地研究了二油酰磷脂酰胆碱(DOPC)从汞表面气/液界面扩散的磷脂单分子膜的电化学性质。这些层表现出多个状态，通过以两个尖锐的电容峰为特征的相变来相互转换。用电势脉冲技术(计时库仑计时法)定量研究了DOPC单分子膜在汞电极上的性质。确定了电荷密度和DOPC在汞/溶液界面扩散所产生的膜压力。结果表明，当负电位超过-1.8V时，脂层从汞表面转移到汞表面。相对于Ag/AgCl2(饱和氯化钾)，脂单分子膜的最大膜压或稳定性的电位估计为-0.4V，脂膜向汞表面转移的零电荷电位漂移为+0.435 V。注意到汞上的DOPC单层性质与单晶金电极上的不溶性表面活性剂单层性质的相似性。利用Tl~+和Cd~(2+)还原进一步表征了扩散的DOPC层，特别是第一相变。从-0.65V到与第一相变相一致的电位，膜对这些金属离子的渗透率随着外加负势的增大而增大。第二个相变代表了一个涉及缺陷生长和结合的过程。
The electrochemical properties of phospholipid monolayers of dioleoyl phosphatidylcholine (DOPC) spread from the gas/solution interface on mercury surfaces are quantitatively investigated in this paper. These layers display multiple states which interconvert through phase transitions characterized by two sharp capacitive peaks. Potential pulse techniques (chronocoulometry) were used to quantitatively investigate the properties of the DOPC monolayer on a mercury electrode. Charge density and the resulting film pressure due to DOPC spreading at the Hg/solution interface were determined. Results indicate that the lipid layers are displaced from the mercury surface at negative potentials in excess of -1.8 V. The potential of maximum film pressure or stability of the lipid monolayer and the shift in the potential of zero charge due to lipid transfer to the mercury surface were estimated as -0.4 and +0.435 V versus Ag/AgCl (saturated KCl), respectively. The similarity of the DOPC monolayer properties on mercury to the insoluble surfactant monolayer properties on single-crystal gold electrodes is noted. The spread DOPC layer and specifically the first phase transition was further characterized utilizing Tl+ and Cd2+ reduction. From potentials of -0.65 V to the potential coincident with the first phase transition, the permeability of the layer to these metal ions increases with an increase in the applied negative potential. The second phase transition represents a process involving the growth and coalescence of defects.