Interaction of a fluorescent cationic surfactant bearing a coumarin derivative with DNA

A fluorescent cationic surfactant with a coumarin derivative (Br-Mac-12) has been designed, synthesized and characterized. The critical association concentration (CAC) and critical micelle concentration (CMC) of Br-Mac-12 was 1.0 × 10−4 and 1.6 × 10−3 mol/L, respectively. The interaction between Br-Mac-12 and DNA has been investigated using UV–vis and fluorescence spectroscopy as well as gel electrophoresis and atomic force microscopy (AFM). Both linear and plasmid DNA were condensed to nanoparticles by Br-Mac-12 at a concentration of 320 μM with incubation at 37 °C for 4 h. Br-Mac-12 has a more efficient binding capacity with DNA than the corresponding DTAB without the fluorophore. The groove binding between the coumarin derivative and DNA plays an important role in addition to the electrostatic and hydrophobic interaction for effective DNA condensation inductions. In addition, the condensation process was reversible, and the residual fluorescence of Br-Mac-12 upon binding with DNA remains at 37.5% of the initial value. The results suggest that Br-Mac-12 combined with a fluorophore has the potential for applications in tracing membrane transport in gene delivery and transfection due to its excellent fluorescence property and DNA binding affinity.