8 research outputs found
DNA-Based Biosensor for Comparative Study of Catalytic Effect of Transition Metals on Autoxidation of Sulfite
The transition metal-catalyzed oxidation of sulfur(IV)
oxides has
been known for more than 100 years. However, to the best of the authors’
knowledge, no electrochemical quantitative study has yet been carried
out to determine its nature. In view of the transition metal catalyzed
oxidation of sulfur(IV) oxides, a series of radicals are involved
in the overall reaction process whereby the sulfite, in the presence
of transition metals, may cause damages to DNA through the generation
of these highly reactive species. In the present work, {MWCNTs–PDDA/DNA}<sub>2</sub> layer-by-layer (LBL) films were prepared to detect DNA damage
induced by radicals generated from sulfite autoxidation using cyclic
voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
The change in the peak potential separation (Δ<i>E</i><sub>p</sub>) and charge transfer resistance (<i>R</i><sub>p</sub>) after incubation of the DNA biosensor in the damaging solution
for a certain time was used as indicators of DNA damage. It was found
that sulfite in the presence of Co(II), Cu(II), Cr(VI), Fe(III), and
Mn(II) caused damage to DNA while neither sulfite alone nor metal
ions alone did have the same effect. The results suggest that sulfite
is rapidly autoxidized in the presence of Co(II), Cu(II), Cr(VI),
Fe(III), and Mn(II), producing radicals that cause the DNA damage.
These radicals can be ranked in a descending order of their ability
to induce DNA damage with sulfite as follows: Fe(III) > Co(II)
> Cu(II)
> Cr(VI) > Mn(II). The DNA damage induced by sulfite plus Co(II),
Cr(VI), and Fe(III) was inhibited by primary alcohols, but they were
not when superoxide dismutase (SOD) and <i>tert</i>-butyl
alcohol were used. Comparison of methods used to determine the minimum
concentration of a transition metal for sulfite induced DNA damage
revealed that electrochemical impedance spectroscopy and cyclic voltammetry
outperformed the quantitative comparison of different reagents