| Abstract
| - DNA interacts with insoluble monolayers made of cationic amphiphiles as well as with monolayers ofzwitterionic lipids in the presence of divalent ions. Binding to dioctadecyldimethylammonium bromide(DODAB) or distearoyl-sn-glycero-3-phosphocholine (DSPC) monolayers in the presence of calcium isaccompanied by monolayer expansion. For the positively charged DODAB monolayer, this causes a decreaseof surface potential, while an increase is observed for the DSPC monolayers. Binding to dipalmitoyl-sn-glycero-3-phosphocholine preserves most of the liquid expanded−liquid condensed coexistence region. Theliquid condensed domains adopt an elongated morphology in the presence of DNA, especially in the presenceof calcium. The interaction of DNA with phospholipid monolayers is ion specific: the presence of calciumleads to a stronger interaction than magnesium and barium. These results were confirmed by bulkcomplexation studies.
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