A. Structure of the DMPC Lipid Bilayer. The atomic
density profiles for the hydrated DMPC bilayer are shown in
Figure 2. More relevant to the interaction of a C
fullerene
with the lipid bilayer is the Lennard-Jones energy profile also
shown in Figure 2. This energy profile was obtained by
positioning one fullerene in one of the two leaflets along the
normal of the lipid bilayer at various positions and determining
the (potential) energy of interaction of the fullerene with the
bilayer. The high density of atoms on the C
surface results in
strong dispersion (London) interactions with the surrounding
media. For example, our previous simulation studies revealed
that the dispersion interaction of a C
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fullerene with water is
about four times stronger than for an oil droplet of the same
diameter as the fullerene.
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We therefore anticipate that fullerenes
will exhibit a tendency to position themselves in regions of high
atomic density in anisotropic environments such as lipid bilayers,
as discussed below.