DNA binding to fluorescent ruthenium species released from calcium phosphate/nanoporous silicon structures

This work centers on an analysis of calf thymus DNA binding to emissive Ru complexes which diffuse from biocompatible calcium phosphate/nanoporous silicon films. These nanostructures were characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray analysis, and infrared vibrational spectroscopy. In terms of polynucleotide binding, three different systems were analyzed: (1) an aqueous solution of Ru(phen)(3)2+ (a control); (2) surface-adsorbed Ru(phen)(3)2+ onto undoped calcium phosphate/porous Si/Si in aqueous solution; (3) as-prepared and annealed Ru(phen)3(2+)-doped calcium phosphate/porous Si structures in water. For films with fluorescent Ru originally embedded throughout the film, biphasic diffusion character is found; such behavior is attributed to DNA binding to both surface-bound Ru(phen)(3)2+ and species which originate from deeper regions of the film.