Interaction of Ru(phen)₃Cl₂ with graphene oxide and its application for DNA detection both in vitro and in vivo

The fluorescence of Ru(phen)₃Cl₂ (tris(1,10-phenanthroline)ruthenium(ii) dichloride) can be effectively quenched with the addition of graphene oxide in aqueous solution, due to the formation of a GO-Ru hybrid. A fluorescence enhancement of approximately 50 times can be observed after the addition of a certain amount of DNA into the above-mentioned solution. The fluorescence increase is linearly proportional to the amount of DNA added in the concentration range of 0-70 μM and the DNA detection limit is down to 3.3 × 10^-8 M. Meanwhile, it is found that the GO-Ru hybrid can enter into the nuclei and stain the DNA of living human breast cancer cells MCF-7, while Ru(phen)₃Cl₂ alone cannot cross the cellular membrane in the control experiment. This method can be employed to detect DNA both in vitro and in vivo.