Interactions of poly(amidoamine) dendrimers with Survanta lung surfactant: the importance of lipid domains.

The interaction of generation 5 (G5) and 7 (G7) poly(amidoamine) (PAMAM) dendrimers with mica-supported Survanta bilayers is studied with atomic force microscopy (AFM). In these experiments, Survanta forms distinct gel and fluid domains with differing lipid composition. Nanoscale defects are induced by the PAMAM dendrimers. The positively charged dendrimers remove lipid from the fluid domains at a significantly greater rate than for the gel domains. Dendrimer accumulation on lipid edges and terraces preceding lipid removal has been directly imaged. Immediately following lipid removal, the mica surface is clean, indicating that lipid defects are not induced by dendrimers binding to the mica substrate and displacing the lipid.