[Effect of lipid monolayers on diffusion of oxygen through the air/water interface]

The dependence of the diffusion current on the depth of immersion of the electrode was studied by polarography using an open platinum electrode. As the electrode was brought from the depth of the liquid phase to its surface, an increase in the current under aerobic conditions was observed, due to diffusion of oxygen through the interface. The formation of lipid monolayers of phosphatidylcholine, stearic acid, hexadecanol, octadecanol, eicosanol, and docosanol on the water surface led to a decrease in diffusion current; the effect being most pronounced at a minimal depth of immersion of the electrode. The maximum value of the relative decrease in diffusion current R was obtained for docosanol monolaers. It was shown that the R value increases with increasing surface pressure in monolayers of phosphatidylcholine and stearic acid. It is assumed that the decrease in diffusion flow of O2 in the presence of monolayers is caused by the formation of an energy barrier that prevents the sorption of O2, which is related to the presence of hydrocarbon chains weakly interacting with oxygen.