Biology Reference
In-Depth Information
pound obtained from probe(ssDNA)-modified or hybrid(dsDNA)-
modified electrodes after their interaction with DNA. After the
calculations, if it is seen that a higher value with ssDNA-modified
transducerisobtainedthantheonewithdsDNA-modifiedelectrode,
the related molecule is accepted to show a high a
nity to single-
strand DNA structure. In other words, the compound partitions
more into the ssDNA microenvironment than the one of dsDNA as
a result of these calculations.
Carter
et al.
[76] showed important calculations by using
voltammetric methods for the detection of interaction (electrostatic
or intercalative) of metal complexes with calf thymus DNA. In that
report, binding constant (
K
n
+
) and binding region size(s) were
detected from voltammetric data, that is, shifts in potential and
changes in limitingcurrent withthe addition of DNA.
The shift in
E
1
/
2
value can be used to estimate the ratio of
equilibrium constants for the binding of the oxidized and reduced
forms of ions to DNA molecule. Similarly, for the detection of small
molecules and micelles interactionsthisvalue was used [81].
Considering the Nernstian electron-transfer rate for the
reversible redox reactions of the free and bound forms of com-
pounds and the corresponding equilibrium constants for binding of
each oxidation state to DNA yields, for a 1-e
−
redox process,
E
o
E
o
−
=
.
059log(
K
red
/
K
ox
)
E
o
f
and
E
o
b
are the formal potentials of the oxidized and
reduced forms of a compound couple, in the free and bound forms,
respectively.
K
ox
and
K
red
are the corresponding binding constants
for the oxidizedand reduced species to DNA.
As a result, according to limiting shift the ratio of
K
red
/
K
ox
is
calculated and which form of a compound binds to DNA strongly is
determined.
0
b
f
12.7 Conclusions
Electrochemical DNA biosensors (genosensors) developing for the
detection of compound-DNA interactions are very competitive
devices for the aim of detection time and cost, with the possibility
