FIGURE 2.

Addition of PLL-g-PEG in H1 buffer to zwitterionic (A) and negatively charged (B) bilayers. Arrows along the time axes indicate injections. The various stages of the experiment are indicated with schematic drawings where possible. (A) Zwitterionic bilayer (DOPC). Frequency decreases and dissipation factor increases upon addition of PLL-g-PEG, indicating copolymer adsorption. However, material is removed from the surface upon both further addition of the polymer and rinsing with H1 buffer (thick arrows). (B) Negatively charged bilayer (DOPC:DOPS 95:5). Initial adsorption of PLL-g-PEG is followed by a spontaneous desorption of material (encircled). For clarity and space reasons, some of the buffer exchange steps have been omitted. *1 and *2 indicate the start and endpoints used to calculate the frequency and dissipation shifts shown in Table 1.