FIGURE 4.

Time-lapse sequences of false-colored fluorescence images depicting the disruption of supported bilayers on SiO₂ (A–H) and the interaction of PLL-g-PEG in H1 with supported vesicular layers on TiO₂ (I–L). The green color corresponds to the lipids. (A–C) A DOPC bilayer, doped with 1% NBD-PC, before (A), a few seconds after (B), and 30 min after (C) the addition of PLL-g-PEG in H1 buffer. (D) The worms formed during the bilayer disruption were observed to collapse into globular structures (encircled). Two sequential images taken 45 min after PLL-g-PEG addition, 60 s apart, are shown. The collapse is instantaneous. (E–G) A DOPC:DOPS 9:1 bilayer, doped with 1% NBD-PC, before (E), 1 min after (F), and 5 min after (G) PLL-g-PEG addition in H1 buffer. (H) A fluorescence image demonstrating the colocalization of phospholipids (green) and PLL-g-PEG-fluorescein (red) in the worm-like structures and aggregates that form after the disruption of a of DOPC:DOPS 9:1 SPB. The polymer was added in H1 buffer. Some worms appear as double lines (one in green and one in red) in the images (white arrowheads) due to their movement during the time passed between the acquisition of the images in the two channels. Colocalization was also observed in the case of DOPC bilayers (not shown). (I–J) Zwitterionic (DOPC) vesicles adsorbed on the surface of TiO₂ form a supported vesicular layer (I). They are replaced on the surface by the adsorbing PLL-g-PEG (J). (K–L) The copolymer has no effect on the negatively charged (DOPC:DOPS 9:1) vesicles. The average intensity of the images is the same before (K) and after (L) the addition of the polymer. In both cases, the vesicles remain intact. Formation of wormlike structures is not observed. Vesicles were labeled with NBD-PC.