Nanoscale Departures: Excess Lipid Leaving the Surface
during Supported Lipid Bilayer Formation
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Abstract
The behavior of small liposomes on
surfaces of inorganic oxides remains enigmatic. Under appropriate
conditions it results in the formation of supported lipid bilayers
(SLBs). During this process, some lipids leave the surface (desorb).
We were able to visualize this by a combination of time-resolved fluorescence
microscopy and fluorescence recovery after photobleaching studies.
Our observations also allowed us to analyze the kinetics of bilayer
patch growth during the late stages of SLB formation. We found that
it entails a balance between desorption of excess lipids and further
adsorption of liposomes from solution. These studies were performed
with liposomes containing zwitterionic phospholipids (dioleoylphosphatidylcholine
alone or a mixture of dioleoylphosphatidylcholine, dipalmitoylphosphatidylcholine,
and cholesterol) on TiO<sub>2</sub> in the presence of Ca<sup>2+</sup> but in the absence of other salts