Preparation of Ru(ii)@oligonucleotide nanosized polymers as potential tumor-imaging luminescent probes.

The development of Ru(ii) complexes as luminescent probes has attracted increasing attention in recent decades. In this study, the nanosized polymers of two Ru(ii) complexes Ru(phen)(dppz) (1, phen = 1,10-phenanthrolin; dppz = dipyrido[3,2-:2',3'-]phenazine) and Ru(phen)(Br-dppz) (2, Br-dppz = 11-bromodipyrido[3,2-:2',3'-]phenazine) with oligonucleotides were prepared and investigated as potential tumor-imaging probes. The formation of the nanosized polymers, which had an average width of 125-438 nm and an average height of 3-6 nm, for 1 and 2@oligonucleotides were observed through atomic force microscopy. The emission spectra indicated that the luminescence of 1 and 2 markedly increased after binding to oligonucleotides and double-strand DNA (calf thymus DNA), respectively. Moreover, further studies indicated that 1@oligonucleotides and 2@oligonucleotides can easily enter into tumor cells and selectively highlight the tumor area in the zebrafish bear xenograft tumor (MDA-MB-231). In summary, this study demonstrated that 1@oligonucleotides and 2@oligonucleotides could be developed as potential tumor-imaging luminescent probes for clinical diagnosis and therapy.