Sphingolipid Monolayers on the Air−Water Interface and Electrochemical Behavior of the Films Transferred onto Glassy Carbon Electrodes

Abstract

In the present paper the packing and dipolar properties of dimirystoylphosphatidylcholine and sphingolipid monolayers were studied at the air−water interface in correlation with the charge-transfer process of the K3Fe(CN)6/ K4Fe(CN)6 redox couple voltammetricaly analyzed on glassy carbon electrodes coated with the transferred monolayers. Lipid molecules having in common the lipophilic chain or the polar group were chosen for the analysis. Different degrees of electrochemical irreversibility in the voltammetric profile were observed depending on the lipid nature. The reversibility of the process was recovered after further addition of calcium chloride to the solution under study, indicating an increase in the monolayer permeability and consequently an increase in the rate of the charge-transfer process. The necessary amount of calcium to produce this effect depended also on the nature of the monolayer, which was evidence of some specific interaction between Ca2+ and each lipid. Surface pressure−area and su...