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Figure 4.9
Freeze-Fracture transmission electron micrographs of LLC structures
formed by phosphatidylethanolamine lipids (Verkleij, 1984).
Freeze-fracture electron microscopy (FFEM) has been extensively applied
to the study hydrated lipid phases (Andersson et al., 1995; Larsson, 1989;
Verkleij, 1984). In this technique, frozen samples are cleaved under vacuum.
The fracture plane typically follows the interior (hydrophobic) domains of
membrane-like structures. A thin layer of electron conductive material (e.g.,
carbon or platinum) is then deposited obliquely on the exposed surface to
form a replica that is imaged in the TEM. Here, image contrast results
from variations in thickness of the deposited conductive layer due to shadow-
ing effects during deposition as shown in Figure 4.9 (Severs, 2007; Verkleij,
1984 ).
A key limitation of conventional EM techniques is the necessity to expose
samples to a vacuum, which is required to minimize scattering of the incident
electron beam due to molecules of any gases present. This presents a particular
problem for the study of LLCs since their phase behavior is intrinsically
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