A simple and inexpensive methodology was used to develop a new method in order to inspect the DNA damage
due to dopamine and some ionic metals. In addition, the inhibitory and repair effects of some antioxidant such as
glutathione and ascorbic acid were studied and compared with each other using electrochemical impedance
spectroscopy (EIS) and differential pulse voltammetry (DPV). In this work a pencil graphite electrode (PGE)
was modified with multiwall carbon nanotubes (MWCNTs) and chitosan (CHIT), then it was decorated with a
ds-DNA (ds-DNA/CHIT–MWCNTs/PGE). Due to interaction of ds-DNA and the damaging agents
(dopamine + metallic ions), electrochemical and spectroscopy properties of ds-DNA at the surface of the modified
electrode was changed, and these changes are followed with EIS and DPV methods. Our study showed that
dopamine, Cu(II) and Fe(III) alone could not destroy DNA, but dopamine + Cu(II) and dopamine + Fe(III) can
damage DNA. In addition, the ability of dopamine–Cu(II) was greater than dopamine–Fe(III). Moreover, some
antioxidant such as glutathione and ascorbic acid can overcome and/or minimize the influence of these damaging
interactions.