Abstract:
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Ubiquinone (UQ) is one of the main electron
and proton shuttle molecules in biological systems, and
dipalmitoylphosphatidylcholine (DPPC) is one of the most
used model lipids. Supported planar bilayers (SPBs) are
extensively accepted as biological model membranes. In this
study, SPBs have been deposited on ITO, which is a
semiconductor with good electrical and optical features.
Speci
fi
cally, topographic atomic force microscopy (AFM)
images and force curves have been performed on SPBs with
several DPPC:UQ ratios to study the location and the
interaction of UQ in the SPB. Additionally, cyclic voltammetry
has been used to understand the electrochemical behavior of
DPPC:UQ SPBs. Obtained results show that, in our case, UQ
is placed in two main di
ff
erent positions in SPBs. First,
between the DPPC hydrophobic chains, fact that originates a
decrease in the breakthrough force of the bilayer, and the
second between the two lea
fl
ets that form the SPBs. This
second position occurs when increasing the UQ content, fact
that eventually forms UQ aggregates at high concentrations.
The formation of aggregates produces an expansion of the SPB
average height and a bimodal distribution of the breakthrough
force. The voltammetric response of UQ depends on its
position on the bilayer |