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.