Ion transfer across a phospholipid monolayer adsorbed at the water∣1,2-dichloroethane interface under surface pressure control (original) (raw)
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Journal of Electroanalytical Chemistry, 2004
The transfer of K þ facilitated by dibenzo-18-crown-6 was examined voltammetrically at an interface between water containing La 3þ , Eu 3þ or Yb 3þ and 1,2-dichloroethane (DCE) containing distearoyl L L -a-phosphatidylcholine (DSPC). The reversible wave for the transfer of K þ from water to DCE vanished owing to the formation of a compact layer at the interface, which was caused by the complex formation of lanthanide ion with a DSPC monolayer. The blocking effect was enhanced in the order of La 3þ < Eu 3þ < Yb 3þ . The complex formation constants were evaluated approximately based on the decrease of voltammetric current. The inhibition of the reversible wave was accompanied by the appearance of a new voltammetric peak at more positive potentials for the restoration of K þ transfer corresponding to the destruction of the compact layer. The peak potential of the new wave shifts positively with an increase of pH and the concentration of lanthanide ion. The blocking effect on transfers of tetraethylammonium ion, bis(tributylammonium)propane ion, ClO À 4 or 1,5-naphthalenedisulfonate ion was also examined.
Study of ion transfer across phospholipid monolayers adsorbed at micropipette ITIES
Journal of Electroanalytical Chemistry, 1997
The transfer of tetraethylammonium cations across phospholipid monolayers deposited at a micropipette ITIES (interface between two immiscible electrolyte solutions) was studied using short potential step techniques. The observed current transients consisted of a capacitive and a faradaic current component, which were separated using a non-linear fit to a model function. Fits were very good. From the capacitive component, the surface c~verage of lipids was calculated by applying a simple model for the monolayer configuration. It appeared that the coverage varied between 80 and 99%. The rate of ion transfer was increased slightly after the lipid addition, but no significant variations between different lipids were found. The transfer mechanism is discussed briefly.