Multi-technique spectroscopic and computational modeling approaches for elucidation of the binding mechanism between two disperse azo dye derivatives and DNA.

Using multi-spectroscopy and molecular docking techniques, the binding mechanism between two azo dyes and the calf thymus (Ct-DNA) was investigated under physiological settings. After the addition of Ct-DNA, each azo dye exhibited a hypochromic effect and slightly increased the wavelength of the maximum absorption. This suggested that the probes and Ct-DNA interacted via a groove binding mode, which was corroborated by the molecular docking data. The thermodynamic parameters, ΔG°, ΔH°, and ΔS°, were determined by calculating the binding constants from the maximum absorption spectra of both azo dyes at different Ct-DNA concentrations at different temperatures. Moreover, fluorescence resonance energy transfer indicates that the interval between the donor (EB-Ct-DNA) and acceptor (azo dye) is suitable for energy transfer. Hydrogen bonds and π electrons on the azo dye's benzene ring are essential for binding the dye to Ct-DNA, according to molecular modeling research. These probes bind to the minor groove of Ct-DNA, and the molecular docking results are in good agreement with the spectroscopic findings.