Lateral electrical conductivity of mica-supported lipid bilayer membranes measured by scanning tunneling microscopy.
Lateral electrical conductivity of mica-supported lipid bilayer membranes measured by scanning tunneling microscopy.
复制标题
通过扫描隧道显微镜测量云母支撑的脂质双层膜的横向电导率。
DOI：
10.1016/s0006-3495(95)79922-2
复制
发表时间：
1995
影响因子：
3.4
通讯作者：
W. Wiegräbe
中科院分区：
文献类型：
--
作者：
M. Heim;G. Cevc;R. Guckenberger;H. Knapp;W. Wiegräbe
利用扫描隧道显微镜（STM）研究了云母支撑的脂质单分子膜和相应的脂质双分子膜的横向电导率。新裂开的云母表面在暴露于潮湿空气中时，被发现是导电的。通过Langmuir-Blodgett技术将脂质单层转移到这样的表面上，该技术使云母表面疏水并在实验可达到的湿度（5-80%）和施加的电压（0-10 V）范围内抑制沿着表面的电流。这对于二棕榈酰磷脂酰乙醇胺（DPPE）以及二棕榈酰磷脂酰胆碱（DPPC）单层是真实的。重复沉积的DPPC层的Langmuir-Blodgett LB技术的装置不会导致形成一个稳定的表面支撑的双层，因为高亲水性的磷脂酰胆碱头基，导致DPPC/DPPC双层剥离的支持表面在样品制备过程中。与此相反，DPPE或DPPC单分子层在DPPE单分子层之上产生了一个相当稳定的云母支撑的双层，可以通过STM进行研究。取决于环境湿度，在35 - 60%的湿度范围内，10 - 100 fA的电流沿着DPPE双层表面流动。DPPC表面更亲水，在可比条件下的导电性高达100倍。因此，异常高的横向电导率取决于，并可能通过，表面吸附的水层。环境湿度和表面亲水性对测得的横向电流的突出表明了这一点。（250字处删节）
Lateral electric conductivity of mica-supported lipid monolayers and of the corresponding lipid bilayers has been studied by means of scanning tunneling microscopy (STM). The surface of freshly cleaved mica itself was found to be conductive when exposed to humid air. Lipid monolayers were transferred onto such a surface by means of the Langmuir-Blodgett technique, which makes the mica surface hydrophobic and suppresses the electric current along the surface in the experimentally accessible humidity (5–80%) and applied voltage (0–10 V) range. This is true for dipalmitoylphosphatidylethanolamine (DPPE) as well as dipalmitoylphosphatidylcholine (DPPC) monolayers. Repeated deposition of DPPC layers by means of the Langmuir-Blodgett LB technique does not lead to the formation of a stable surface-supported bilayer because of the high hydrophilicity of the phosphatidylcholine headgroups that causes DPPC/DPPC bilayers to peel off the supporting surface during the sample preparation. In contrast to this, a DPPE or a DPPC monolayer on top of a DPPE monolayer gives rise to a rather stable mica-supported bilayer that can be studied by STM. Electric currents between 10 and 100 fA, depending on the ambient humidity, flow along the DPPE bilayer surface, in the humidity range between 35 and 60%. The DPPC surface, which is more hydrophilic, is up to 100 times more conductive under comparable conditions. Anomalous high lateral conductivity thus depends on, and probably proceeds via, the surface-adsorbed water layers. The prominence of ambient humidity and surface hydrophilicity on the measured lateral currents suggests this.(ABSTRACT TRUNCATED AT 250 WORDS)