Modification of Mechanical Properties of Model Membranes by Some Bifunctional Surfactants

Interaction of two series of new surfactants with an incorporated antioxidant functional group with erythrocytes and planar lipid membranes was studied. Surfactants were synthesized in order 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 surfactants studied could be used as biocides. Two different models were chosen in order to do it; pig erythrocyte and asolectin planar membranes. The studied parameters of these models were hemolysis of red blood cells and stability of BLM in the presence of the compounds studied, i. e., the parameters describing mechanical properties of model membranes used. Additionally, the role of the 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 degree 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 o bserved.