Modification of mechanical properties of model membranes by some bifunctional surfactants

The interaction of two series of new surfactants with an incorporated anti-oxidant functional group, with erythrocytes and planar lipid membranes was stu-died. The surfactants were synthesized to be potentially used as common bio-cides or as agents protecting biological and/or model membranes against lipid peroxidation. Both applications need the use of such bifunctional surfactants in significantly different concentrations. The aim of this work was to find the concentration range in which the surfactants studied could be used as biocides. Two different models were chosen; pig erythrocyte and asolectin planar membranes. The studied parameters of these models were hemolysis of red blood cells and the stability of BLM in the presence of the compounds studied, i.e., the parameters describing the mechanical properties of the model membranes used. Additionally, the role of counterions in the interaction of bifunctional surfactants with model membranes was studied. It was found that both homologous series of the surfactants influence model membranes to different degrees, depending on the length of their hydrophobic part and the kind of counterion. In the latter case it seems that the differences in the hydrated radii of bromide and chloride ions, and hence the differences in their ability to modify electrostatic interaction between the lipid polar heads and compounds studied, are responsible for the effects observed.