Effects of TiO crystal structure on the luminescence quenching of [Ru(bpy)(dppz)]-intercalated into DNA.

The intercalation of [Ru(bpy)(dppz)] labeled as Ru(II) (bpy=2,2'-bipyridine and dppz=dipyrido[3,2,-a:2',3'-c]phenazine) into herring sperm DNA leads to the formation of emissive Ru(II)-DNA dyads, which can be quenched by TiO nanoparticles (NPs) and sol-gel silica matrices at heterogeneous interfaces. The calcinations temperature exhibits a remarkable influence on the luminescence quenching of the Ru(II)-DNA dyads by TiO NPs. With increasing calcinations temperature in the range from 200 to 850°C, the anatase-to-rutile TiO crystal structure transformation increases the average particle size and hydrodynamic diameter of TiO and DNA@TiO. The anatase TiO has the stronger ability to unbind the Ru(II)-DNA dyads than the rutile TiO at room temperature. The TiO NPs and sol-gel silica matrices can quench the luminescence of the Ru(II) complex intercalated into DNA by selectively capturing the negatively DNA and positively charged Ru(II) complex to unbind the dyads, respectively. This present results provide new insights into the luminescence quenching and competitive binding of dye-labeled DNA dyads by inorganic NPs.