Biology Reference
In-Depth Information
phosphatebackboneallowspre-concentrationofthecomplexinthe
double-stranded DNA layer at the electrode surface and enables
detection of the hybridization event voltammetrically. In another
example, Barton examined a number of intercalators and groove
binders (see Scheme 7.1) as probes for the detection of mismatches
within DNA films [32].
Scheme 7.1.
Chemical structures of the intercalators: [Ir(bpy)(phen)
(phi)]
3
+
, daunomycin (DM), methylene blue (MB); and groove binders:
[Ru(NH
3
)
5
Cl]
2
+
and [Fe(CN)
6
]
4
−
. S.O. Kelly, E.M. Boon, J.K. Barton, N.M.
Jackson, M.G. Hill, Single-base mismatch detection based on charge
transduction through DNA, Nucleic Acids Research, 1999, Vol.
27
, No. 24,
4830-4837, by permission of Oxford University Press.
It was found that probes that intercalate into the DNA base stack
appear to be necessary for mismatch detection. In contrast, probes
thatassociatewithDNApurelythroughelectrostaticinteractionsdo
not yield measurable differences in the electrochemical response
in the presence of base mismatches. The signals obtained from
the intercalators DM, MB and [Ir(bpy)(phen)(phi)]
3
+
are affected
by the presence of a mismatch. However, the response for groove
binding agent was found almost identical for fully matched and
mismatched films. It is possible that the reduction of the ruthenium
complex (Scheme 7.1) proceeds through the facilitated diffusion
of the complex along the double helix, while the intercalated
species participate in electron transfer mediated by the stacked
bases.Experimentalevidenceindicatesthatthebulkierintercalators
exhibited smaller CA/TA charge ratios. Nevertheless, the detection
ofbasemismatcheswasaccomplishedusingdirectelectrochemistry
of molecules bound to DNA films. Subsequently, Yamashita and
coworkers employed ferrocenyl naphthalene diimide (FND) as
