Photophysical and thermodynamic landscape of interaction of a styryl-based dye with DNA duplex: effect of medium ionic strength and live cell imaging.

A red-emitting excited-state intramolecular charge transfer pyridinium dye, [4-((1E,3E)-4-(4-(dimethylamino)phenyl)buta-1,3-dien-1-yl)-1-methylpyridin-1-ium] (DAPBMP), was synthesized and characterized using NMR and ESIMS studies. Binding interaction between dye DAPBMP and genomic DNA were investigated using steady-state and time-resolved spectroscopic methods. The thermodynamics of the interaction process were characterized using isothermal titration calorimetry (ITC) which reveals the key role of the hydrophobic effect and electrostatic interaction between the positive charged dye and the negatively charged polyphosphate of DNA backbone.