Cyclic voltammetry (CV) and single-step chronocoulometry were used to study the interaction of [Ru(phen)2dppz]2+ (phen=1,10-phenanthroline; dppz=dipyrido[3,2-a:2′,3′-c]phen- azine) with herring sperm DNA. The addition of DNA caused a diminution in the peak current and a positive shift in the peak potential of the complex of [Ru(phen)2dppz]2+. The 12 mV positive shift in the peak potential of [Ru(phen)2dppz]2+ indicates that [Ru(phen)2dppz]2+ binds 2.6 times more strongly to DNA than its reductive form. In addition, by using fluorimetric and UV-spectrophotometric methods and studies of denatured DNA and the effect of NaCl solution, it was also found that the binding mode was intercalation. The decrease of peak current is proportional to the concentration of DNA, which can be applied to estimate DNA concentration.
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