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Complexos do tipo cis-[Ru(L-phen)2(apy)2]2+ com interesse no tratamento de Mal de Alzheimer: propriedades físico-químicas e estudos de inibição da Acetilcolina Esterase
(Universidade Federal de São Carlos, 2011-04-15) Chinini, Guilherme Luiz; Carlos, Rose Maria; https://lattes.cnpq.br/1589143355309943; https://lattes.cnpq.br/8779203176912828
The photochemical and photophysical properties of the cis-[Ru(phen)2(4apy)2]2+ complex where 4apy= 4-aminopyridine are reported. In this work the complexes are thermically stable throughout the course of many hours in non-aqueous and aqueous solution and highly colored (red solution in the most of solvents). The absorption is characterized by two broad shoulders and an intense emission is found at 640 nm. Upon photolysis in aqueous solution, accompanied by spectroscopic techniques (UVvis, luminescence, 1H NMR, HPLC) cis-[Ru(phen)2(4apy)2]2+ complex loses the 4apy ligand to give the aquo complexes: cis-[Ru(phen)2(4apy)(H2O)]2+, cis- [Ru(phen)2(H2O)2]2+ and trans-[Ru(phen)2(H2O)2]2+. The aquo complexes have been synthesized and characterized using 1H NMR, FTIR and UV-vis spectroscopy. The photochemical mechanism is confirmed by TD-DFT calculations. Considering the role of acetylcholinesterase inhibitors in the Alzheimer disease treatments, the prepared complexes were tested for AChE inhibition using the Ellman and fluorimetric methods. In these studies Tacrine (hydrochloride-1,2,3,4-tetrahydroacridin-9-amine) was used for comparison purposes. The complexes were also evaluated for their toxicity towards to 3T3 and NG97 cells. The cis-complex binds with micromolar affinity to AChE and display an IC50 of 1.38. The cis-complex is a reversible competitive inhibitor while Tacrine gives mixed and uncompetitive inhibition with acetylcholine as the substrate. Citotoxicity studies showed that the cis complex presents a higher citoxicity against NG97 cells (IC50= 39.84 μmol.mL-1) and a lower citotoxicity toward 3T3 cell. We evaluated the in situ emissive activity of the complex cis-[Ru(phen)2(4apy)2]2+ through confocal microscopy, obtaining the expected contrast as well as the emissive loss resulting from the photolysis process. Overall, these results are of particular interest for designing intelligent metallodrugs based on photochemical and photophysical processes and offer promising potentials for the treatment of Alzheimer diseases.
Novas ligas formadoras de fase amorfa do sistema Ni-Nb-Zr e seu comportamento mecânico
(Universidade Federal de São Carlos, 2011-04-15) Santos, Fabricio Simão dos; Kiminami, Claudio Shyinti; https://lattes.cnpq.br/5443002033733395; https://lattes.cnpq.br/2720282515226804
Ni-based amorphizable alloys in the bulk form show a good combination of properties, with high mechanical strength and hardness, good ductility and excellent corrosion resistance. These alloys have been used in recent technological applications, for example, in pressure sensors and micro-geared motors. Particularly, Ni-Nb-Zr alloys with amorphous structure show, in addition to good mechanical properties, excellent corrosion resistance in acid medium due to the formation of a Nb- and Zr-rich passive film. In this context, the purpose of this project is to develop Ni-Nb-Zr alloys with high glass-forming ability (GFA) by using the topological λ criterion combined with the average electronegativity difference, Δe , and to carry out its mechanical characterization by nanoindentation. Ni45.5Nb23Zr31.5, Ni50Nb28Zr22, Ni57Nb17.5Zr25.5 and Ni79Nb8.5Zr12.5 alloys were selected and produced in the form of melt-spun ribbons and copper mold cast wedges. The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and nanoindentation. Results from the processing of wedge samples revealed the highest GFA for the Ni50Nb28Zr22 alloy, which presented 60% of amorphous fraction for a thickness of 200 μm and 23% for thickness of 320-480 μm. The alloy Ni45.5Nb23Zr31.5 showed the second highest GFA, making possible to obtain 14% of amorphous fraction for a thickness of 240 μm. The hardness and reduced elastic modulus of the ribbon samples increased in the following order: Ni45.5Nb23Zr31.5 < Ni50Nb28Zr22 < Ni57Nb17.5Zr25.5. For the Ni50Nb28Zr22 alloy, it was attained higher hardness and elastic modulus and lower plastic energy for the wedge compared to the ribbon, which can be ascribed to the higher amount of free volume in the structure of the amorphous ribbon. The compressive yield stress (σy,C) of this alloy was estimated to be 2.5 and 3.2 GPa for ribbon and wedge, respectively. viii