Advisor: M. Losche.
We have developed a biomimetic tethered lipid
membrane system that enables the structural and
functional characterization of peptide or proteins
interacting with lipid bilayers. In general, tethered
bilayers are prepared by self-assembly of a monomolecular
layer of a thiol-functionalized lipid on a planar
gold surface, followed by the precipitation of
a natural membrane component, typically a phospholipid.
In the final membrane architecture, the thiolipid
is the minority component and acts as a tether,
and the phospholipid is the majority component,
dominating the overall properties of the membrane.
Depending on the details of the preparation protocol,
the bilayer should include a nanometer-thin hydration
layer between the membrane and the gold film which
effectively decouples the surface film from the
inorganic substrate.
The
functional characterization of the resulting bilayer
membranes is performed by electrochemical impedance
spectroscopy (EIS), a technique that determines
the capacitive and resistive properties of the
surface film. For a given phospholipid species,
the insulating properties of the membrane depend
sensitively on parameters such as lipid solution
concentration, temperature, and buffer pH.
This
project consists of a thorough introduction into
the basic preparation technique for tethered bilayers
and a primer of EIS, which will subsequently be
used as the main characterization technique to
optimize the preparation of bilayers with respect
to their electrical performance (resistance to
ion transfer and capacitance) and defect density.
In addition, optical microscopy using fluorescent
markers will be used to assess the in-plane homogeneity
of the resulting membranes. This homogeneity is
important for the intended use of the system as
sensor surfaces in research on the interaction
of misfolded amyloid peptide (exploring the molecular
origin of Alzheimer’s disease), toxin interaction
with membranes, as well as their use to model signalling
events at membrane surfaces. |
