Selective treatment and monitoring of disseminated cancer micrometastases in vivo using dual-function, activatable immunoconjugates.

Drug-resistant micrometastases that escape standard therapies often go undetected until the emergence of lethal recurrent disease. Here, we show that it is possible to treat microscopic tumors selectively using an activatable immunoconjugate. The immunoconjugate is composed of self-quenching, near-infrared chromophores loaded onto a cancer cell-targeting antibody. Chromophore phototoxicity and fluorescence are activated by lysosomal proteolysis, and light, after cancer cell internalization, enabling tumor-confined photocytotoxicity and resolution of individual micrometastases. This unique approach not only introduces a therapeutic strategy to help destroy residual drug-resistant cells but also provides a sensitive imaging method to monitor micrometastatic disease in common sites of recurrence. Using fluorescence microendoscopy to monitor immunoconjugate activation and micrometastatic disease, we demonstrate these concepts of "tumor-targeted, activatable photoimmunotherapy" in a mouse model of peritoneal carcinomatosis. By introducing targeted activation to enhance tumor selectively in complex anatomical sites, this study offers prospects for catching early recurrent micrometastases and for treating occult disease.

Cytotoxicity of cyclometallated ruthenium complexes: the role of ligand exchange on the activity.

The cyclometallated Ru(II) complexes cis-[Ru(phpy)(phen)(CH3CN)2](PF6) (1; phpy(-)=deprotonated 2-phenylpyridine, phen=1,10-phenanthroline) and cis-[Ru(phpy)(bpy)(CH3CN)2](PF6) (2; bpy=2,2'-bipyridine) were investigated as potential agents for photodynamic therapy. The presence of phpy(-) in the coordination sphere results in a red-shift of the Ru→phen and Ru→bpy metal-to-ligand charge transfer of 1 and 2, respectively, thus improving the tissue penetration of light while maintaining the efficient photo-induced ligand exchange required for DNA binding. The 14-fold enhancement of OVCAR-5 cell death that occurs upon irradiation with 690 nm light can be attributed to photo-aquation. The role of glutathione (GSH) on the toxicity of the complex was also explored. Complexes 1 and 2 undergo ligand substitution in the presence of GSH in the dark, such that the metal may covalently bind to biomolecules. The combination of photo-induced ligand exchange and GSH-facilitated ligand exchange may explain the observed cytotoxicity.

Photoinduced ligand exchange and DNA binding of cis-[Ru(phpy)(phen)(CH3CN)2]+ with long wavelength visible light.

The complex cis-[Ru(phpy)(phen)(CH3CN)2](+) (phpy=2-phenylpyridine, phen=1,10-phenanthroline) was investigated as a potential photodynamic therapy (PDT) agent. This complex presents desirable photochemical characteristics including a low energy absorption tail extending into the PDT window (600-850nm) and photoinduced exchange of the CH3CN ligands, generating a species analogous to the chemotherapy drug cisplatin. Furthermore, photochemical reactivity can be controlled through selective irradiation into the Ru-phen singlet metal-to-ligand charge transfer ((1)MLCT) band (λirr=500 nm) of [Ru(phpy)(phen)(CH3CN)2](+) in the presence of excess t-butylammonium chloride (TBACl) resulting in efficient photoinduced production of [Ru(phpy)(phen)(CH3CN)Cl] (Φ=0.25). This lower energy irradiation resulted in greater quantum yield of photosubstitution when compared to direct irradiation into the Ru-phpy (1)MLCT peak (λirr=450 nm; Φ=0.08) in CH2Cl2. It was found that the lower quantum yield observed for irradiation into the Ru→phpy(-)(1)MLCT band results from significant orbital mixing of the phpy(-) ligand with the t2g-type filled set in the metal, giving this state significant ligand-centered character. Lastly, this complex produced a decrease in the mobility of linearized ds-DNA when irradiated with λirr≥420nm, indicative of covalent binding by the transition metal complex similar to that observed for cisplatin. No change in mobility was found for the same samples kept in the dark indicating, unlike cisplatin, DNA binding of cis-[Ru(phpy)(phen)(CH3CN)2](+) only occurs with the activation of light. These observations support the use of cis-[Ru(phpy)(phen)(CH3CN)2](+) as a potential PDT agent by the photoinduced generation of a cisplatin analog.

Electronic tuning of ruthenium complexes by 8-quinolate ligands.

A series of Ru(II) complexes were synthesized with the deprotonated forms of the ligands 8-hydroxyquinoline (quo(-)) and 5-NO(2)-8-hydroxyquinoline (5-NO(2)-quo(-)) as analogs to the prototypical complex [Ru(bpy)(3)](2+) (bpy = 2,2'-bipyridine). Electrochemistry, spectroscopy and density functional theory calculations were utilized to investigate the electronic tuning of the occupied t(2g)-type orbitals of the metal center with variation in the ligation sphere. The maximum of the lowest energy absorption of complexes containing one, two and three 8-quinolate ligands progressively redshifts from 452 nm in [Ru(bpy)(3)](2+) to 510 nm in [Ru(bpy)(2)(quo)](+), 515 nm in [Ru(bpy)(quo)(2)] and 540 nm in [Ru(quo)(3)](-) in water. This bathochromic shift results from the increase in energy of the occupied t(2g)-type orbital across the series afforded by coordination of each subsequent quo(-) ligand to the Ru(II) center. Time-dependent density functional theory calculations along with electrochemical analysis reveals that the lowest energy transition has contributions in the highest occupied molecular orbital from both the quo(-) ligand and the metal, such that the lowest energy transition is not from an orbital that is purely metal-centered in character as in [Ru(bpy)(3)](2+).

A general synthesis of tris-indole derivatives as potential iron chelators.

The development of a novel route for the synthesis of a new class of compounds is described. The first tripodal, tris-indole amines are prepared by straightforward routes.