Two new dinuclear bimetallic complexes, [{PdCl(bipy)}{μ-(pyrazine)}{PtCl(bipy)}]Cl(ClO4) (1) (bipy is 2,2'-bipyridine) and [{PdCl(en)}{μ-(pyrazine)}{PtCl(en)}]Cl(ClO4) (2) (en is ethylenediamine), have been synthesized and characterized by elemental microanalysis, IR, (1)H NMR spectroscopy and MALDI-TOF mass spectrometry. The pKa values of the coordinated water molecules of the diaqua species were determined as well. Substitution reactions of complexes (1) and (2) with thiourea (Tu), l-methionine (l-Met), l-cysteine (l-Cys), l-histidine (l-His) and guanosine-5'-monophosphate (5'-GMP) were studied under the pseudo-first order conditions as a function of nucleophile concentration and temperature. The order of reactivity of nucleophiles was: Tu > l-Met > l-Cys > l-His > 5'-GMP. Substitution reactions with Tu, l-Cys and l-His were followed by decomposition of bimetallic complexes to the corresponding substituted mononuclear complexes [Pd(N-N)(Nu)2] and [Pt(N-N)(Nu)2] (N-N = bipy, en), releasing the bridging ligand. However, the structures of starting bimetallic complexes were preserved during the reactions with l-Met and 5'-GMP. The absorption spectroscopic study of interactions of calf-thymus DNA (CT-DNA) with complexes (1), (2) and [{PdCl(bipy)}{μ-(NH2(CH2)6H2N)} {PtCl(bipy)}]Cl(ClO4) (3), has shown that all the complexes exhibit high intrinsic binding constants (Kb = 10(4)-10(5) M(-1)). DNA-ethidium bromide (DNA-EB) fluorescence was quenched after addition of complexes (1), (2) or (3), indicating displacement of intercalating EB by complexes. All complexes have shown good binding affinity to bovine serum albumin protein (BSA). Chemosensitivity of A375 (human melanoma) and HeLa (human cervical cancer) cell lines toward complexes (1), (2) and (3) was analyzed by SRB assay. Complex (1) displayed significant inhibitory effect on the growth of both cell lines.

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In this study, C-doped TiO 2 nanoparticles (C-TiO 2 ) were prepared and tested as a photosensitizer for visible-light-driven photodynamic therapy against cervical cancer cells (HeLa). X-ray diffraction and Transmission Electron Microscopy confirmed the anatase form of nanoparticles, spherical shape, and size distribution from 5 to 15 nm. Ultraviolet-visible light spectroscopy showed that C doping of TiO 2 enhances the optical absorption in the visible light range caused by a bandgap narrowing. The photo-cytotoxic activity of C-TiO 2 was investigated in vitro against HeLa cells. The lack of dark cytotoxicity indicates good biocompatibility of C-TiO 2 . In contrast, a combination with blue light significantly reduced the survival of HeLa cells: illumination only decreased cell viability by 30% (15 min of illumination, 120 µW power), and 60% when HeLa cells were preincubated with C-TiO 2 . We have also confirmed blue light-induced C-TiO 2 -catalyzed generation of reactive oxygen species in vitro and intracellularly. Oxidative stress triggered by C-TiO 2 /blue light was the leading cause of HeLa cell death. Fluorescent labeling of treated HeLa cells showed distinct morphological changes after the C-TiO 2 /blue light treatment. Unlike blue light illumination, which caused the appearance of large necrotic cells with deformed nuclei, cytoplasm swelling, and membrane blebbing, a combination of C-TiO 2 /blue light leads to controlled cell death, thus providing a better outcome of local anticancer therapy.

Ionizing radiation induces DNA double strand breaks (DSBs) that trigger phosphorylation of the histone protein H2AX (γH2AX). Immunofl uorescent staining visualizes formation of γH2AX foci, allowing their quantifi cation. This method, as opposed to Western blot assay and Flow cytometry, provides more accurate analysis, by showing exact position and intensity of fl uorescent signal in each single cell. In practice there are problems in quantifi cation of γH2AX. This paper is based on two issues: the determination of which technique should be applied concerning the radiation dose, and how to analyze fl uorescent microscopy images obtained by different microscopes. HTB140 melanoma cells were exposed to γ-rays, in the dose range from 1 to 16 Gy. Radiation effects on the DNA level were analyzed at different time intervals after irradiation by Western blot analysis and immunofl uorescence microscopy. Immunochemically stained cells were visualized with two types of microscopes: AxioVision (Zeiss, Germany) microscope, comprising an ApoTome software, and AxioImagerA1 microscope (Zeiss, Germany). Obtained results show that the level of γH2AX is time and dose dependent. Immunofl uorescence microscopy provided better detection of DSBs for lower irradiation doses, while Western blot analysis was more reliable for higher irradiation doses. AxioVision microscope containing ApoTome software was more suitable for the detection of γH2AX foci.

Background: Considering that HTB140 melanoma cells have shown a poor response to either protons or alkylating agents, the effects of a combined use of these agents have been analysed.