Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Catalysis. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Synthesis, spectral and redox properties of tetraammine dioxolene ruthenium complexes

Abstract: A series of species [RuIII(NH3)4(Cat-R)]n+ have been synthesized where Cat-R is a catecholate dianion having the substituent R = CO2−, CO2H, OMe or H. These so-called parent species were characterized by their electronic spectra, FTIR, mass spectrum, cyclic voltammetry and EPR. Controlled potential reduction yields [RuII(NH3)4(Cat-R)](n − 1)+ while controlled potential oxidation yields [RuII(NH3)4(Q-R)](n + 1)+ (Q-R = substituted quinone). Density Functional Theory (DFT) was primarily used to explore the electronic structures of these complexes. Application of the INDO semi-empirical model proved less useful. Time dependent density functional response theory was used to calculate the electronic spectra of the species with R = H. The electronic spectra of the closed shell species are well reproduced by the calculations. The physical properties of these complexes indicate a charge delocalized system reminiscent of a delocalized organic molecule. The simple valence descriptions noted above are convenient to use but do not reflect the actual electronic structure. The electronic spectra of the parent species are temperature dependent. The visible region charge transfer band shifts by about 1500 cm−1 to higher energy in acidic media at liquid nitrogen temperature. This is interpreted in terms of solvent effects rather than valence tautomerism. The electrochemical properties of [RuIII(NH3)4(Cat-R)], in aqueous solution, reveal the first example of a reversible and stable Ru–quinone species in that medium. The pKa values for several dioxolene species, with R = CO2−, are derived from a Pourbaix diagram.

Cell toxicity studies of albumin-based nanosized magnetic beads.

Abstract: The aim of this study was to prepare bovine serum albumin-based beads containing maghemite nanoparticles incorporated via ionic magnetic fluid and to evaluate the cell toxicity of this biocompatible system using the J774-A1 cell line. Transmission electron micrographs obtained from the magnetic fluid sample were used to estimate the average particle diameter around 7.6 nm and diameter dispersion of 0.22. The BSA-based magnetic beads were prepared using the heat protein denaturation route. The nanoparticle concentration in the magnetic fluid sample used for the synthesis of the magnetic beads was in the range of 1.2 x 10(16) to 2.3 x 10(17) particle/ml. The methodology used to investigate the cell toxicity of the magnetic beads was the classical MTT assay. Our observation showed that the toxicity against the J774-A1 cell line depends upon the amount of magnetic material incorporated into the magnetic nanobeads and was found to be 14, 11, 9, 5, and 3% for 2.3 x 10(17), 1.2 x 10(17), 4.6 x 10(16), 2.3 x 10(16), and 1.2 x 10(16) particle/ml, respectively.

Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani.

Abstract: The search for alternatives to control microorganisms is necessary both in clinical and agricultural areas. Antimicrobial photodynamic treatment (APDT) is a promising light-based approach that can be used to control both human and plant pathogenic fungi. In the present study, we evaluated the effects of photodynamic treatment with red light and four phenothiazinium photosensitizers (PS): methylene blue (MB), toluidine blue O (TBO), new methylene blue N (NMBN) and the phenothiazinium derivative S137 on ungerminated and germinated microconidia of Fusarium oxysporum, F. moniliforme, and F. solani. APDT with each PS killed efficiently both the quiescent ungerminated microconidia and metabolically active germinated microconidia of the three Fusarium species. Washing away the unbound PS from the microconidia (both ungerminated and germinated) before red light exposure reduced but did not prevent the effect of APDT. Subcelullar localization of PS in ungerminated and germinated microconidia and the effects of photodynamic treatment on cell membranes were also evaluated in the three Fusarium species. APDT with MB, TBO, NMBN or S137 increased the membrane permeability in microconidia and APDT with NMBN or S137 increased the lipids peroxidation in microconidia of the three Fusarium species. These findings expand the understanding of photodynamic inactivation of filamentous fungi with phenothiazinium PS.