Binding Mode and Photo-cleavage of an Azo Dye, Acid Chrome Blue K, to Double-Stranded DNA

The binding of an azo dye, acid chrome blue K (ACBK) with double-stranded DNA was systematically investigated in Britton?CRobinson (B?CR) buffer solutions by spectroscopic and electrochemical methods. Cyclic voltammetry results showed that noteworthy changes took place in the irreversible oxidation peak of ACBK after reacting with double-stranded DNA, while only tiny changes appeared after reacting with single-stranded DNA, suggesting that ACBK can selectively combine with double helix DNA. Furthermore, a?hydrophobic groove-binding mode between ACBK and double-stranded DNA was proposed from UV?CVis analysis. Moreover, binding parameters such as the binding constant (K) and the binding site size (s) between the two species were further determined to be 1.9 (±0.6)×10⁵?L?mol^?1 and 2.1 (±0.1), respectively, using a voltammetric titration method. Agarose gel electrophoresis showed that ACBK can effectively promote the photo-cleavage of supercoiled plasmid pBR322 DNA to the nicking form, indicating the potential genotoxicity of this dye.