| Abstract
| - Addition of a weak polyelectrolyte, poly(methacrylic acid) (PMA), to a supported phospholipid bilayermade from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) depresses the melting temperature andalters the morphology of the bilayer in the gel phase. Ellipsometry measurements show that PMA adsorptionlowers the phase transition temperature by 2.4 °C. Atomic force microscopy (AFM) showed no visiblecontrast in the fluid phase (above the melting temperature) but a rich morphology in the gel phase. In thegel phase, adsorption leads to formation of significantly less mobile phospholipid islands and other defects.One consequence of this lower mobility is a decrease in the implied cooperativity number of the phasetransition, N, when polymer is added. Additionally, AFM images of the gel-phase bilayer show a highlydefected structure that anneals significantly more slowly than in the absence of adsorbed polymer.Tentatively, we suggest that PMA preferentially decorates island and defect edges of the DMPC bilayer.
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