Synthesis, characterization, cytotoxic activity and crystal structures of tri- and di-organotin(IV) complexes constructed from the β-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}propionate and β-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}propionate skeletons

Reactions of potassium β-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}propionates (L¹HK-L³HK) and potassium β-{[(2Z)-(3-hydroxy-1-methyl-2- butenylidene)]amino}propionate (L⁴HK) with R₃SnCl (R = Ph and ⁿBu) and ⁿBu₂SnCl₂ yielded complexes of composition Ph₃SnL¹H (1), Ph₃SnL²H (2), Ph₃SnL⁴H (3), ⁿBu₃SnL¹H (4), and {[ⁿBu₂Sn(L²H)]₂O}₂ (5) and {[ⁿBu₂Sn(L³H)]₂O}₂ (6), respectively. These complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of 1, 4, 5 and 6 were determined. In the solid state, compound 1 is a one-dimensional polymer built from SnPh₃ moieties bridged by single carboxylate ligands, but two alternating modes of bridging are present along the polymeric chain. Compound 4 is also a one-dimensional polymer built from SnBu₃ moieties bridged by the two carboxylate O-atoms of a single ligand, but only one mode of bridging is present. Di-n-butyltin compounds 5 and 6 are centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes containing a planar Sn₄O₂ core in which two μ₃-oxo O-atoms connect an Sn₂O₂ ring to two exocyclic Sn-atoms. The four carboxylate ligands display two different modes of coordination where both modes involve bridging of two Sn-atoms. The solution structures were predicted by ¹¹⁹Sn NMR spectroscopy. The in vitro cytotoxic activity of compound 5 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumor cell lines is reported.     

Optimization of photodynamic therapy response by survivin gene knockdown in human metastatic breast cancer T47D cells

Photodynamic therapy (PDT) leads to the generation of cytotoxic oxygen species that appears to stimulate several different signaling pathways, some of which lead to cell death, whereas others mediate cell survival. In this context, we observed that PDT mediated by methyl-5-aminolevulinic acid as the photosensitizer resulted in over-expression of survivin, a member of the inhibitor of apoptosis (IAP) family that correlates inversely with patient prognosis. The role of survivin in resistance to anti-cancer therapies has become an area of intensive investigation. In this study, we demonstrate a specific role for survivin in modulating PDT-mediated apoptotic response. In our experimental system, we use a DNA vector-based siRNA, which targets exon-1 of the human survivin mRNA (pSil_1) to silence survivin expression. Metastatic T47D cells treated with both pSil_1 and PDT exhibited increased apoptotic indexes and cytotoxicity when compared to single-agent treated cells. The treatment resulted in increased PARP and caspase-3 cleavage, a decrease in the Bcl-2/Bak ratio and no participation of heat shock proteins. In contrast, the overexpression of survivin by a survivin-expressed vector increased cell viability and reduced cell death in breast cancer cells treated with PDT. Therefore, our data suggest that combining PDT with a survivin inhibitor may attribute to a more favorable clinical outcome than the use of single-modality PDT.     

Photoreduction of Ru(bpy)(3)2+ by amines in aqueous solution. Kinetics characterization of a long-lived nonemitting excited state

The photochemistry of Ru(bpy)(3)+2 in the presence of amines was investigated in water by laser flash photolysis. N,N'-Dimethylaniline and p-phenylenediamine quench the luminescent metal to ligand charge transfer (MLCT) excited state of the complex by an electron transfer reaction that produces the semireduced form Ru(bpy)3+ in relatively high yields. On the other hand, triethylamine (TEA) and aniline do not quench the MLCT. Nevertheless, when laser flash irradiation at 532 nm is carried out in the presence of these amines, the formation of Ru(bpy)3+ is clearly detected by its transient absorption at 510 nm. These results are interpreted by an electron transfer reaction with the participation of a nonemitting excited state of the complex, formed independently of the MLCT from the Franck-Condon or the relaxed singlet excited state. The rate constants for the quenching of this state by TEA and aniline and the quantum yields for Ru(bpy)(3)+ were determined. The new state is formed in a very fast process and has a lifetime of ca 4 micros in water.     

Synthesis and characterization of tribenzyltin(IV) and dibenzyltin(IV) complexes of 2-{[(2Z)-3-hydroxy-1-methyl- 2-butenylidene]amino}acetic acid: Crystal structure of tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene] amino}acetato}tin(IV)

Reactions of equimolar quantities of potassium 2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetate, with R _n SnX_4?n (R: benzyl– and n=2 or 3) in methanol yielded products of compositions LHSn(PhCH₂)₃ and LSn(PhCH₂)₂, respectively. The complexes were characterized by microanalysis, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ^119mSn Mössbauer spectroscopy. A full characterization of the structure of the complex, tribenzyl{2-{[(2Z)-3-hydroxy-1-methyl-2-butenylidene]amino}acetato}tin(IV), was carried out by single crystal X-ray crystallography. The compound exists as centrosymmetric dimers in which two ligand molecules bridge the two tin centres. Each of the tin atoms in the dimeric unit is five coordinate in an approximately trigonal bipyramidal configuration, with carbon atoms in the equatorial positions and oxygen atoms arranged axially.     

Control of cell growth direction by direct fabrication of periodic micro‐ and submicrometer arrays on polymers

In this work, we describe a laser‐assisted microstructuring technique called Direct Laser Interference Patterning to produce topographical cues for tumor cells in a one‐step process. Line‐like patterns with spatial periods ranging from 500 nm to 10 μm are fabricated on polyimide (PI) films. The resulting structures exhibit a well‐defined shape and quality even for patterns with small periodic distances. Subsequently, the behavior of mouse mammary adenocarcinoma cells over those structures is evaluated. The results show that cell growth is well aligned to the direction of the patterns (over 60% lying within 0° to 15° to either side of the surface lines) for all evaluated structure sizes. Moreover, cells grown on patterns with 500 nm spatial period are the most narrowly aligned (up to 80% found between 0° and 15°), showing the potential of the technique. The fabrication process of the PI patterns is supported by a mathematical model of the underlying photo‐chemical ablation process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Complexes of Organometallic Compounds. XXVII. Studies on Diorganolead (IV) Moieties Six-coordinated by ONNO Tetradentate Ligands

New complexes R₂PbL, where L^2? are the dianions in the “planar” SCHIFF base form, of the tetradentate ONNO ligands α, α′ (ethylenedinitrilo)dicresol and 2,2′ bis-benzoxazoline, were synthesized. Their configuration was investigated at the solid state by infrared spectroscopy, and in solution phase mainly by electronic and PMR spectroscopy. An octahedral type structure with linear CPbC moieties, and the ONNO ligand atoms chelating Pb^IV in a square plane, was advanced.     

Neolithic ceramic findings from western Sicily. Chemical-physical and mineralogical characterization

This paper presents the results of a study that is part of a wider research program regarding the knowledge of the initial living phases of Sicilian agricultural and pastoral societies. Three ceramic samples attributed to the medium initial Neolithic (NEO1 and NEO2) and to the first neolithic (NEO3), recovered in two different archaeological sites of the western Sicily, have been analysed. Chemical, mineralogical and spectroscopic data point out a similarity between NEO1 and NEO3 samples; compositional and morphological differences instead have been observed in the NEO2 sample. The firing temperatures of the samples have been estimated by M?ssbauer spectroscopy; they are lower than 500 degrees C for the samples NEO1 and NEO3, and about 700 degrees C for NEO2.