Spectroscopic and electrochemical approaches for the analysis of interaction between textile dye 231 and salmon sperm DNA

DNA is one of the most critical targets for many artificial agents listed as carcinogens. Most of them irreversibly bind to the DNA and induce genome mutation; therefore, it is vital to study the nature of binding of these molecules to anticipate their toxicity. The interaction between the textile dye reactive red 231 and salmon sperm double-stranded DNA (ss-dsDNA) was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and ultraviolet-visible spectroscopy (UV-vis spectroscopy). Changes in the anodic current signals of the dye were observed in the presence and absence of ss-dsDNA at a glassy carbon electrode (GCE) using CV. The diffusion coefficient (D) was found to be 2.2 x 10(-7) and 9.5 x 10(-8) cM(2) s(-1) from the CV data for the free dye and dye-DNA complex, respectively. Electrochemical and UV-vis spectroscopy indicated 1:1 complex formation of the dye with DNA. The binding constant (k(b)) between the dye and DNA was calculated to be 5.4 x 10(5) M-1 and 4.9 x 10(5) M-1 at pH 4.0 using CV and UV-vis spectroscopy, respectively. Overall, these results suggest that the dye binds to DNA through the combined effect of intercalation and electrostatic interactions. DNA damage was also detected through changes in the voltammetric behaviour of the dye.