AFM TIP
D = 11 nm
AFM TIP
LIPID BILAYER
LlPlD BILAYER
Surface electrostatics
relatively unaffected by
AFM tip
AFM tip is close
enough to perturb the
surface
Figure 3.4: (Left) The finite element model is solved with a constant charge density
boundary condition from D = 40 nm to D = 11 nm as in Chapter 2. Note that these values
of D are for the data shown in Figure 3.2. For other data sets, the D values will be
different. For D = 11 nm and less, we vary the lipids surface charge density according to
the law governing the phenomenon being addressed (i.e. whether it is counterion binding
or mobile lipid charge regulation).
Figure 3.5: Do is chosen as the point where the AFM data starts deviating significantly
from the electrostatic simulation of Chapter 2. For the above sample, Dq = 11 nm. The
AFM data and the electrostatic simulation shown here is the same as in Figure 3.2.
32