Spectroscopic investigations of interactions between Hematoxylin–Ag+ complex and Herring-sperm DNA with the aid of the acridine orange probe

Investigations of the interaction between deoxyribonucleic acid (DNA) and other molecules have captivated scientists over the past years because it is fundamental for many intracellular processes and biotechnological relevance. In this study, Hematoxylin (HE)–Ag+ complex was synthesized, and it was characterized by IR, UV–vis spectroscopy. The binding constant for the HE–Ag+ complex and hsDNA is obtained by double reciprocal method at 303 K and 310 K, respectively, and the corresponding thermodynamic parameters shown the interaction process is driven mainly by entropy. The subsequent experiments indicate that the binding mode between HE–Ag+ complex and hsDNA is a mixed binding which contains partial intercalation and electrostatic binding. Study on the influence of basic group to the complex suggests that the binding interaction has high selectivity. The intercalation mainly occurs between A:T base pair.

► We calculate the binding constant between Hematoxylin–Ag+ complex and hsDNA and thermodynamic parameters.
► From the Scatchard and ionic strength experiment we know that there exists electrostatic binding besides intercalate binding.
► The Hematoxylin–Ag+ complex can partial intercalate into hsDNA and induce bend of the DNA secondary structure.
► The Hematoxylin–Ag+ complex mainly interact with A:T base pairs.