1 research outputs found
Surface-Enhanced Infrared Spectroscopy and Neutron Reflectivity Studies of Ubiquinone in Hybrid Bilayer Membranes under Potential Control
Surface-enhanced infrared adsorption
spectroscopy (SEIRAS) and
neutron reflectometry (NR) were employed to characterize ubiquinone
(UQ) containing hybrid bilayer membranes. The biomimetic membrane
was prepared by fusing phospholipid vesicles on a hydrophobic octadecanethiol
monolayer self-assembled on a thin gold film. Using SEIRAS, the assembly
of the membrane is monitored <i>in situ</i>. The presence
of ubiquinone is verified by the characteristic carbonyl peaks from
the quinone ester. A well-ordered distal lipid leaflet results from
fusion of vesicles with and without the addition of ubiquinone. With
applied potential, the hybrid bilayer membrane in the absence of UQ
behaves in the same way as previously reported solid supported phospholipid
membranes. When ubiquinone is incorporated in the membrane, electric
field induced changes in the distal leaflet are suppressed. Changes
in the infrared vibrations of the ubiquinone due to applied potential
indicate the head groups are located in both polar and nonpolar environments.
The spectroscopic data reveal that the isoprenoid unit of the ubiquinone
is likely lying in the midplane of the lipid bilayer while the head
has some freedom to move within the hydrophobic core. The SEIRAS experiments
show redox behavior of UQ incorporated in a model lipid membrane that
are otherwise inaccessible with traditional electrochemistry techniques