Luminescent Biological Probes Derived from Ruthenium(II) Estradiol Polypyridine Complexes

Apoptosis, autophagy, cell cycle arrest, cell invasion and BSA-binding studies in vitro of ruthenium(ii) polypyridyl complexes

Four new ruthenium(ii) polypyridyl complexes were synthesized and characterized. The anticancer activity was investigated by cytotoxicity in vitro, apoptosis, comet assay, ROS, autophagy, cell invasion and western blot analysis.

The photochemistry of mono- and dinuclear cyclometalated bis(tridentate)ruthenium(ii) complexes: dual excited state deactivation and dual emission

A low-energy ³LL′CT state efficiently depopulates the emissive ³MLCT state in cyclometalated [Ru(dpb-R)(tpy)]⁺ complexes (dpbH = 1,3-di(2-pyridyl)benzene, tpy = 2,2′;6′,2′′-terpyridine).

Luminescent Rhenium(I) and Iridium(III) Polypyridine Complexes as Biological Probes, Imaging Reagents, and Photocytotoxic Agents

Although the interactions of transition metal complexes with biological molecules have been extensively studied, the use of luminescent transition metal complexes as intracellular sensors and bioimaging reagents has not been a focus of research until recently. The main advantages of luminescent transition metal complexes are their high photostability, long-lived phosphorescence that allows time-resolved detection, and large Stokes shifts that can minimize the possible self-quenching effect. Also, by the use of transition metal complexes, the degree of cellular uptake can be readily determined using inductively coupled plasma mass spectrometry. For more than a decade, we have been interested in the development of luminescent transition metal complexes as covalent labels and noncovalent probes for biological molecules. We argue that many transition metal polypyridine complexes display triplet charge transfer ((3)CT) emission that is highly sensitive to the local environment of the complexes. Hence, the biological labeling and binding interactions can be readily reflected by changes in the photophysical properties of the complexes. In this laboratory, we have modified luminescent tricarbonylrhenium(I) and bis-cyclometalated iridium(III) polypyridine complexes of general formula [Re(bpy-R(1))(CO)3(py-R(2))](+) and [Ir(ppy-R(3))2(bpy-R(4))](+), respectively, with reactive functional groups and used them to label the amine and sulfhydryl groups of biomolecules such as oligonucleotides, amino acids, peptides, and proteins. Additionally, using a range of biological substrates such as biotin, estradiol, and indole, we have designed luminescent rhenium(I) and iridium(III) polypyridine complexes as noncovalent probes for biological receptors. The interesting results generated from these studies have prompted us to investigate the possible applications of luminescent transition metal complexes in intracellular systems. Thus, in the past few years, we have developed an interest in the cytotoxic activity, cellular uptake, and bioimaging applications of these complexes. Additionally, we and other research groups have demonstrated that many transition metal complexes have facile cellular uptake and organelle-localization properties and that their cytotoxic activity can be readily controlled. For example, complexes that can target the nucleus, nucleolus, mitochondria, lysosomes, endoplasmic reticulum, and Golgi apparatus have been identified. We anticipate that this selective localization property can be utilized in the development of intracellular sensors and bioimaging reagents. Thus, we have functionalized luminescent rhenium(I) and iridium(III) polypyridine complexes with various pendants, including molecule-binding moieties, sugar molecules, bioorthogonal functional groups, and polymeric chains such as poly(ethylene glycol) and polyethylenimine, and examined their potentials as biological reagents. This Account describes our design of luminescent rhenium(I) and iridium(III) polypyridine complexes and explains how they can serve as a new generation of biological reagents for diagnostic and therapeutic applications.

The biological effect of the nitroimidazole derivative of a polypyridyl ruthenium complex on cancer and endothelial cells

The ruthenium polypyridyl complexes [Ru(dip)2(bpy/bpy-2-nitroIm)](2+) (dip = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2'-bipyridine, bpy-2-nitroIm = 4-[3-(2-nitro-1H-imidazol-1-yl)propyl]) were found to be ca. ten times more cytotoxic against breast cancer (4T1) and human lung adenocarcinoma epithelial cells (A549) than a well-known anticancer drug, cisplatin. Even though the Ru complexes were quite cytotoxic towards FVB mouse lung microvascular endothelial cells (MLuMEC FVB) their efflux from these non transformed cells was much more efficient than from cancer ones. Both Ru complexes accumulated in cells. The cellular uptake of both Ru complexes occurs through passive diffusion while the nitroimidazole derivative is also endocytosed. They arrest cell growth in the S-phase and induce apoptosis. Such cell response can result from activation of oxidative stress by Ru complexes. The modulation of the mRNA expression profile for genes which might be involved in metastasis and angiogenesis processes by Ru complexes was analyzed for both cancer (4T1) and endothelial (MLuMEC FVB) cells. Ru complexes appeared to have a distinct impact on cell adhesion and migration as well as they affect endothelial cell vasculature. They are not only cytotoxic but are also potentially invasive and anti-metastatic agents. This work illustrates the putative future development of polypyridyl ruthenium.

Effects of daidzein in regards to cytotoxicity in vitro, apoptosis, reactive oxygen species level, cell cycle arrest and the expression of caspase and Bcl-2 family proteins

In the present study, the in vitro cytotoxicity of daidzein was evaluated in human BEL-7402, A549, HeLa, HepG-2 and MG-63 cancer cell lines. BEL-7402 cells were sensitive to daidzein treatment, with an IC₅₀ value of 59.7±8.1 µM. Daidzein showed no cytotoxic activity toward A549, HeLa, HepG-2 and MG-63 cells. Daidzein increased the levels of reactive oxygen species (ROS) and induced a decrease in mitochondrial membrane potential. Morphological and comet assays showed that daidzein effectively induced apoptosis in BEL-7402 cells. Additionally, daidzein caused cell cycle arrest at the G2/M phase in the BEL-7402 cell line. Daidzein downregulated the expression of Bcl-2, Bcl-x and Baid proteins and upregulated the levels of Bim protein in the BEL-7402 cells. The results demonstrated that daidzein induced BEL-7402 cell apoptosis through an ROS-mediated mitochondrial dysfunction pathway.

Anticancer activity studies of a ruthenium(II) polypyridyl complex against human hepatocellular (BEL-7402) cells

A Ru(II) polypyridyl complex [Ru(bpy)2(HMSPIP)](ClO4)2 (1) (bpy=2,2'-bipyridine, HMSPIP=2-(4-methylsulfonyl)phenyl-1H-imidazo[4,5-f][1,10] phenanthroline) was synthesized. The IC50 value of the complex against human hepatocellular cell BEL-7402 is 21.6±2.7 μM. The complex shows no cytotoxic activity toward human lung adenocarcinoma cell A549, human osteosarcoma cell MG-63 and human breast cancer cell SK-BR-3 cells. It is easily for complex 1 to be taken up by BEL-7402 cells. The complex can enhance the reactive oxygen species (ROS) levels and induce the decrease in the mitochondrial membrane potential. The complex inhibits the cell growth in BEL-7402 cells at G2/M phase. Complex 1 can regulate the expression of Bcl-2 family proteins. The results show that the complex induces apoptosis of BEL-7402 cells through a ROS-mediated mitochondrial dysfunction pathway.

Effect of radiation on cytotoxicity, apoptosis and cell cycle arrest of human osteosarcoma MG-63 induced by a ruthenium(II) complex

Radiation has large influence on the cytotoxicity, apoptosis and cell cycle arrest. The bioactivity of ruthenium(II) complex [Ru(dmb)2(DBHIP)](ClO4)2 (Ru1) (DBHIP=2-(3,5-dibromo-4-hydroxylphenyl)imidazo[4,5-f][1,10]phenanthroline) was investigated in the absence and presence of radiation. The cytotoxicity of Ru1 against MG-63 cells was evaluated by CCK-8 method. Ru1 shows high cytotoxicity upon radiation. Radiation can enhance the cytotoxicity of Ru1 on MG-63 cells. The apoptosis was studied by Hoechst 33258 staining method and flow cytometry. The reactive oxygen species, mitochondrial membrane potential, cell cycle arrest and western blot analysis were investigated in detail. The complex induces the apoptosis in MG-63 cells through ROS-mediated mitochondrial dysfunction pathway.

DNA interaction, antioxidant activity, and bioactivity studies of two ruthenium(II) complexes

Two new ruthenium(II) polypyridyl complexes [Ru(dmb)2(dcdppz)](ClO4)2 (1) and [Ru(bpy)2(dcdppz)](ClO4)2 (2) were prepared and characterized. The crystal structure of the complex 2 was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P21/n with a=12.9622(14)Å, b=17.1619(19)Å, c=22.7210(3)Å, β=100.930(2)(°), R=0.0536, Rω=0.1111. The DNA-binding constants for complexes 1 and 2 were determined to be 1.92×10(5) (s=1.72) and 2.24×10(5) (s=1.86)M(-1), respectively. The DNA-binding behaviors showed that complexes 1 and 2 interact with DNA by intercalative mode. The antioxidant activities of the ligand and the complexes were performed. Ligand, dcdppz, has no cytotoxicity against the selected cell lines. Complex 1 shows higher cytotoxicity than complex 2, but lower than cisplatin toward selected cell lines. The apoptosis and cell cycle arrest were investigated, and the apoptotic mechanism of BEL-7402 cells was studied by reactive oxygen species (ROS), mitochondrial membrane potential and western blot analysis. Complex 1 induces apoptosis in BEL-7402 cells through ROS-mediated mitochondrial dysfunction pathway and by regulating the expression of Bcl-2 family proteins.

Phosphorescent chemosensor for Hg2+ based on an iridium(iii) complex coordinated with 4-phenylquinazoline and carbazole dithiocarbamate

A colorimetric phosphorescent chemosensor Ir(pqz)2(cdc) showed satisfactory selective, sensitive, naked eye detection and fluorescence change response to Hg²⁺ in MeCN.

Unexpected DNA binding properties with correlated downstream biological applications in mono vs. bis-1,8-naphthalimide Ru(ii)-polypyridyl conjugates

The development of two 1,8-napthalimide-conjugated Ru(ii)-polypyridyl complexes which exhibit different DNA binding and photocleavage behavior is presented.

Cytotoxicity in vitro, cell migration and apoptotic mechanism studies induced by ruthenium(ii) complexes

Four Ru(ii) complexes [Ru(N–N)₂(DHBT)](ClO₄)₂ were synthesized and characterized. The cytotoxicity in vitro, apoptosis, comet assay, cell migration, ROS, mitochondrial membrane potential, cell cycle arrest and expression of proteins were investigated.

Imaging of the nuclei of living tumor cells by novel ruthenium(ii) complexes coordinated with 6-chloro-5-hydroxylpyrido[3,2-a]phenazine

Novel ruthenium(ii) complex 1 can be developed as a low toxicity fluorescence probe for living cell nuclei in future.

A highly selective phosphorescence probe for histidine in living bodies

A heterobimetallic ruthenium(ii)–nickel(ii) complex has been developed for phosphorescence imaging of histidine in live cells and bodies.

Synthesis, characterization, cytotoxicity, a poptosis and cell cycle arrest of dibenzoxanthenes derivatives

Two new dibenzoxanthenes compounds 1 and 2 have been synthesized and characterized by analytical and spectral methods. The crystal structure of compound 2 informs that the five rings of compound are almost planar. The DNA binding properties of two compounds were studied by absorption titration, viscosity measurement and luminescence. These results indicate that two compounds interact with calf thymus DNA through intercalative mode. Agarose gel electrophoresis experiment shows that PBR 322 DNA can be induced to cleave by two compounds under photoactivated condition. Compound 1 exhibits higher cytotoxicity than compound 2 toward MG-63, BEL-7402 and A549 cells. The apoptosis and cellular uptake of MG-63 cells were studied by fluorescence microscopy. Two compounds can also enhance the level of reactive oxygen species (ROS) and decrease the mitochondrial membrane potential. Compound 1 induces cell cycle arrest in G2/M phase and compound 2 induces cell cycle arrest in G0/G1 phase in MG-63.

Luminescent gold surfaces for sensing and imaging: patterning of transition metal probes

Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium(II), RubpySS, osmium(II), OsbpySS, and cyclometalated iridium(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications.

Synthesis, characterization, in vitro cytotoxicity, and apoptosis-inducing properties of ruthenium(II) complexes

Two new Ru(II) complexes, [Ru(bpy)₂(FAMP)](ClO₄)₂1 and 2, are synthesized and characterized by elemental analysis, electrospray mass spectrometry, and ¹H nuclear magnetic resonance. The in vitro cytotoxicities and apoptosis-inducing properties of these complexes are extensively studied. Complexes 1 and 2 exhibit potent antiproliferative activities against a panel of human cancer cell lines. The cell cycle analysis shows that complexes 1 and 2 exhibit effective cell growth inhibition by triggering G0/G1 phase arrest and inducing apoptosis by mitochondrial dysfunction. The in vitro DNA binding properties of the two complexes are investigated by different spectrophotometric methods and viscosity measurements.

2-Nitroimidazole-ruthenium polypyridyl complex as a new conjugate for cancer treatment and visualization

A novel long-lifetime highly luminescent ruthenium polypyridyl complex containing 2-nitroimidazole moiety [Ru(dip)2(bpy-2-nitroIm)]Cl2 (dip=4,7-diphenyl-1,10-phenanthroline, bpy-2-nitroIm=4-[3-(2-nitro-1H-imidazol-1-yl)propyl]-2,2'-bipyridine) has been designed cancer treatment and imaging. The luminescence properties of the synthesized compound strongly depend on the oxygen concentration. Under oxygen-free conditions quantum yield of luminescence and the average lifetime of emission were found to be 0.034 and 1.9 μs, respectively, which is ca. three times higher in comparison to values obtained in air-equilibrated solution. The binding properties of the investigated ruthenium complex to human serum albumin have been studied and the apparent binding constant for the formation of the protein-ruthenium adduct was determined to be 1.1×10(5)M(-1). The quantum yield and the average lifetime of emission are greatly enhanced upon binding of ruthenium compound to the protein. The DNA binding studies revealed two distinguished binding modes which lead to a decrease in luminescence intensity of ruthenium complex up to 60% for [DNA]/[Ru]<2, and enhancement of emission for [DNA]/[Ru]>80. Preliminary biological studies confirmed fast and efficient accumulation of the ruthenium complex inside cells. Furthermore, the ruthenium complex was found to be relatively cytotoxic with LD50 of 12 and 13 μM for A549 and CT26 cell lines, respectively, under normoxic conditions. The retention and cellular uptake of ruthenium complex is enhanced under hypoxic conditions and its LD50 decreases to 8 μM for A549 cell line.

The studies on bioactivity in vitro of ruthenium(ii) polypyridyl complexes towards human lung carcinoma A549 cells

Three complexes were synthesized and characterized. The cytotoxicity, apoptosis, cellular uptake, reactive oxygen species, mitochondrial membrane potential, cell cycle arrest and western blot analysis were investigated.

Modulation of the organelle specificity in Re(i) tetrazolato complexes leads to labeling of lipid droplets

Neutral Re(i) tetrazolato complexes exhibit labeling of lipid droplets with high specificity.

The induction of apoptosis in BEL-7402 cells through the ROS-mediated mitochondrial pathway by a ruthenium(ii) polypyridyl complex

The in vitro cytotoxicity, apoptosis, cellular uptake, cell cycle arrest, ROS, mitochondrial membrane potential, western blot analysis and DNA-binding induced by Ru1 were investigated.

Synthesis, Characterisation, Interaction with DNA, Cytotoxicity, and Apoptotic Studies of Ruthenium(II) Polypyridyl Complexes

We report the synthesis and characterisation of two new ruthenium(ii) polypyridyl complexes containing monodentate ancillary ligands [Ru(L)4(4HEPIP)], where L = 4-aminopyridine (1) or pyridine (2) and 4HEPIP = 2-(4-hydroxy-3-ethoxyphenyl)-1H-imidazo[4,5-f][1,10](phenanthroline). These complexes were characterised by elemental analysis and ultraviolet-visible, infrared, and 1H NMR spectroscopy. The binding properties of the two complexes towards calf thymus (CT)-DNA were investigated with different spectrophotometric methods, viscosity measurements, and salt dependent studies. Experimental results indicated that the complexes interact with CT-DNA base pairs by intercalation. Upon irradiation at 365 nm, these complexes efficiently cleave pBR322 DNA from super coiled form I to nicked form II. Their cytotoxicity on different cancer cell lines such as A549, Du145, and HeLa was investigated. The IC50 values are 39.5, 28.3, and 27.3 μM for complex 1, and 55, 67.9, and 47.9 μM for complex 2 respectively. Cellular uptake and apoptosis induced by these complexes was also studied.

Targeting the endoplasmic reticulum with a membrane-interactive luminescent ruthenium(ii) polypyridyl complex†Electronic supplementary information (ESI) available: Experimental details, characterization of and Fig. S1-S6. See DOI: 10.1039/c3sc51725jClick here for additional data file

The characterization and bioactivity of the dinuclear ruthenium(ii) complex [(Ru(DIP)2)2(tpphz)]4+ (DIP = 4,7-diphenyl-1,10-phenanthroline and tpphz = tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine) is reported. This new complex is found to be luminescent in acetonitrile, where excitation into MLCT (metal-to-ligand charge-transfer) bands in the visible area of the spectrum (λex = 450 nm, ε = 45 000 M-1 cm-1) result in red emission (λem,max = 620 nm, ΦMLCT = 0.017). Aqueous in vitro binding studies indicate that this complex binds to duplex DNA with an affinity of 1.8 × 106 M-1 through a non-classical groove-binding interaction, however, unlike the parent complex [(Ru(phen)2)2(tpphz)]4+ (phen = 1,10-phenanthroline), it also displays an increase in MLCT luminescence on addition of liposomes. Confocal microscopy and TEM studies show that this lipophilic complex targets the endoplasmic reticulum of eukaryotic cells, where it functions as an imaging agent for this organelle, and cytotoxicity studies in human cancer cell lines indicate a comparable potency to the anti-cancer drug cisplatin.

Inhibition of tumor growth and vasculature and fluorescence imaging using functionalized ruthenium-thiol protected selenium nanoparticles

Here we reported the high tumor targeting efficacy of luminescent Ru(II)-thiols protected selenium nanoparticles (Ru-MUA@Se). We have shown that a dual-target inhibitor Ru-MUA@Se directly suppress the tumor growth but also block blood-vessel growth. We also determined that the nanoparticles entered the cells via clathrin-mediated endocytosis pathway. In a xenograft HepG2 tumor model, we found that Ru-MUA@Se effectively inhibited tumor angiogenesis and suppressed tumor growth with low side effects using metronomic chemotherapy with Ru-MUA@Se. In vivo investigation of nanoparticles on nude mice bearing HepG2 cancer xenografts confirmed that Ru-MUA@Se nanoparticles possessed high tumor-targeted fluorescence imaging, exhibited enhanced antitumor efficacy and decreased systemic toxicity. Moreover, Ru-MUA@Se not only significantly induced dose-dependent disruption of mitochondrial membrane potential in HepG2 cells after 24 h treatment, but it also enhanced reactive oxygen species (ROS) generation. Our results suggest that the potential application of these Ru-MUA@Se nanoparticles in targeting cancer imaging and chemotherapy.

Dual topoisomerase I and II poisoning by chiral Ru(II) complexes containing 2-thiophenylimidazo[4,5-f][1,10]phenanthroline derivatives

A series of chiral Ru(II) complexes bearing thiophene ligands were synthesized and characterized. Both Ru(II) complexes Δ/Λ-[Ru(bpy)2(pscl)](2+) (Δ/Λ-1) and Δ/Λ-[Ru(bpy)2(psbr)](2+) (Δ/Λ-2) (bpy=2,2'-bipyridine, pscl=2-(5-chlorothiophen-2-yl)imidazo[4,5-f][1,10]phenanthroline, psbr=2-(5-bromothiophen-2-yl)imidazo[4,5-f][1,10]phenanthroline) showed antitumor activities against A549, HepG2 and BEL-7402 tumor cell lines, especially HeLa tumor cell line. Moreover, Δ enantiomers were more active than Λ enantiomers, accounting for the different cellular uptake. In addition, with the extension of time, these enantiomers could finally accumulate in the nucleus, suggesting that nucleic acids were the cellular target of these enantiomers. The DNA-binding behaviors of complexes were studied using spectroscopic and viscosity measurements. Results suggested that four complexes could bind to DNA in an intercalative mode but no obvious DNA-binding selectivity between the enantiomers was observed. Topoisomerase inhibition and DNA religation assay confirmed that four complexes acted as efficient dual topoisomerase I and II poisons, DNA strand breaks had also been observed from alkaline single cell gel electrophoresis (comet assay). Δ-1 and Δ-2 inhibited the growth of HeLa cells through the induction of apoptotic cell death, as evidenced by the Alexa Fluor® 488 annexin V staining assays and flow cytometry analysis. The results demonstrated that Δ/Λ-1 and Δ/Λ-2 acted as dual topoisomerase I and II poisons and caused DNA damage that could lead to cell cycle arrest by apoptosis.

Development of a ruthenium(II) complex-based luminescent probe for hypochlorous acid in living cells

A novel Ru(II) complex, [Ru(bpy)2(DNPS-bpy)](PF6)2 (bpy: 2,2'-bipyridine, DNPS-bpy: 4-(2,4-dinitrophenylthio)methylene-4'-methyl-2,2'-bipyridine), has been designed and synthesized as a highly sensitive and selective luminescence probe for the recognition and detection of hypochlorous acid (HOCl) in living cells by exploiting a "signaling moiety-recognition linker-quencher" sandwich approach. The complex possesses large stokes shift (170 nm), long emission wavelength (626 nm), and low cytotoxicity. Owing to the effective photoinduced electron transfer (PET) from Ru(II) center to the electron acceptor, 2,4-dinitrophenyl (DNP), the red-emission of bipyridine-Ru(II) complex was completely withheld. In aqueous media, HOCl can trigger an oxidation reaction to cleave the DNP moiety from the Ru(II) complex, which results in the formation of a highly luminescent bipyridine-Ru(II) complex derivative, [Ru(bpy)2(COOH-bpy)](PF6)2 (COOH-bpy: 4'-methyl-2,2'-bipyridyl-4-carboxylic acid), accompanied by a 190-fold luminescence enhancement. Cell imaging experimental results demonstrated that [Ru(bpy)2(DNPS-bpy)](PF6)2 is membrane permeable, and can be applied for capturing and visualizing the exogenous/endogenous HOCl molecules in living cell samples. The development of this Ru(II) complex probe not only provides a useful tool for monitoring HOCl in living systems, but also strengthens the application of transition metal complex-based luminescent probes for bioimaging.

Anticancer activity and DNA binding of a bifunctional Ru(II) arene aqua-complex with the 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine ligand

The synthesis and full characterization of the new aqua-complex [(η(6)-p-cymene)Ru(OH2)(κ(2)-N,N-2-pydaT)](BF4)2, [2](BF4)2, and the nucleobase derivative [(η(6)-p-cymene)Ru(9-MeG)(κ(2)-N,N-2-pydaT)](BF4)2, [4](PF6)2, where 2-pydaT = 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine and 9-MeG = 9-methylguanine, are reported here. The crystal structures of both [4](PF6)2 and the chloro complex [(η(6)-p-cymene)RuCl(κ(2)-N,N-2-pydaT)](PF6), [1](PF6), have been elucidated by X-ray diffraction. The former provided relevant information regarding the interaction of the metallic fragment [(η(6)-p-cymene)Ru(κ(2)-N,N-2-pydaT)](2+) and a simple model of DNA. NMR and kinetic absorbance studies have proven that the aqua-complex [2](BF4)2 binds to the N7 site of guanine in nucleobases, nucleotides, or DNA. A stable bifunctional interaction (covalent and partially intercalated) between the [(η(6)-p-cymene)Ru(κ(2)-N,N-2-pydaT)](2+) fragment and CT-DNA has been corroborated by kinetic, circular dichroism, viscometry, and thermal denaturation experiments. The reaction mechanism entails the very fast formation of the Ru-O-(PO3) linkage prior to the fast intercalation of the 2-pydaT fragment. Then, a Ru-N7-(G) covalent bond is formed at the expense of the Ru-O-(PO3) bond, yielding a bifunctional complex. The dissociation rate of the intercalated fragment is slow, and this confers additional interest to [2](BF4)2 in view of the likely correlation between slow dissociation and biological activity, on the assumption that DNA is the only biotarget. Furthermore, [2](BF4)2 displays notable pH-dependent cytotoxic activity in human ovarian carcinoma cells (A2780, IC50 = 11.0 μM at pH = 7.4; IC50 = 6.58 μM at pH = 6.5). What is more, complex [2](BF4)2 is not cross-resistant with cisplatin, exhibiting a resistance factor, RF(A2780cis), of 0.28, and it shows moderate selectivity toward the cancer cell lines, in particular, A2780cis (IC50 = 3.0 5 ± 0.08 μM), relative to human lung fibroblast cells (MRC-5; IC50 = 24 μM), the model for healthy cells.