Sphingolipid monolayers on the air-water interface and electrochemical behavior of the films transferred onto glassy carbon electrodes

N. WILKE, ; A.M.BARUZZI; B. MAGGIO.

LANGMUIR

AMER CHEMICAL SOC

Año: 2001 vol. 17 p. 3980 - 3986

0743-7463

In the present paper the packinganddipolar properties of dimirystoylphosphatidylcholineandsphingolipidmonolayers were studied at the air-water interface in correlation with the charge-transfer process of theK3Fe(CN)6/ K4Fe(CN)6 redox couple voltammetricaly analyzed on glassy carbon electrodes coated with thetransferred monolayers. Lipid molecules having in common the lipophilic chain or the polar group werechosen for the analysis. Different degrees of electrochemical irreversibility in the voltammetric profilewere observed depending on the lipid nature. The reversibility of the process was recovered after furtheraddition of calcium chloride to the solution under study, indicating an increase in the monolayer permeabilityand consequently an increase in the rate of the charge-transfer process. The necessary amount of calciumto produce this effect depended also on the nature of the monolayer, which was evidence of some specificinteraction between Ca2+ and each lipid. Surface pressure-area and surface potential-area compressionisotherms at the air-water interface under different subphase composition were performed to get a betterinsight of this behavior. Interactions between the lipids and the ions were also observed, and a correlationbetween these results and the electrochemical response was found.