Pc. Pandey et Hh. Weetall, APPLICATION OF PHOTOCHEMICAL-REACTION IN ELECTROCHEMICAL DETECTION OFDNA INTERCALATION, Analytical chemistry, 66(8), 1994, pp. 1236-1241
A flow injection analysis (FIA) system for the detection of the compou
nds that intercalate within DNA is reported. A derivative of 9,10-anth
raquinone has been used as the reference compound for photoelectrochem
ical detection. The sodium salts of 9,10-anthraquinone-2,6-disulfonic
acid and 9,10-anthraquinone-2-sulfonic acid are photochemically activa
ted and then reduced in the presence of an electron donor (glucose). T
he electrochemical signal is based on the measurement of the anodic cu
rrent resulting from the oxidation of the reduced form of 9,10-anthraq
uinone. The reduced form of the 9,10-anthraquinone is oxidized through
a mediated mechanism at the surface of a tetracyanoquinodimethane-(TC
NQ)-modified graphite paste electrode covered by a Nucleopore membrane
. TCNQ acts as an efficient mediator for the oxidation of reduced 9,10
-anthraquinone. Cyclic voltammetry, photocyclic voltammetry, and the p
hotoelectrochemical FIA response of 9,10-anthraquinone are reported, E
xperimental results show that these anthraquinones can be intercalated
within the helix of double-stranded calf thymus DNA. The anthraquinon
e molecules that are intercalated within DNA cannot be oxidized due to
their limited transport to the modified electrode surface. This resul
ts in a decrease in the anodic current at a constant concentration of
anthraquinone after intercalation. There is a linear relation between
the decrease in electrochemical response and the DNA concentration at
a constant concentration of anthraquinone. The intercalated anthraquin
one molecules can be completely replaced by another intercalating agen
t (i.e., ethidium bromide) that is more strongly intercalated within D
NA, thereby regenerating the electrochemical response. The calibration
curve for the analysis of this compound is reported.