Publications

Abstract Thin films composed of oleylamine (OLA) and double-stranded deoxyribonucleic acid (dsDNA from Salmon testes) have been successfully constructed on polycrystalline Au surfaces using the electrostatic adsorption and self-assembly (SA) technique. The formation of the Au/OLA/dsDNA films was followed step-by-step by Quartz Crystal Microbalance with energy dissipation (QCM-D), Atomic Force Microscopy (AFM), and electrochemical techniques such as Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The use of these techniques allowed the characterization and the follow up of the successful construction of the OLA/dsDNA composite film. The main advantages of the proposed methodology are the simplicity of the modification procedure, the stability of the dsDNA self-assembled film, and the potential employment of the dsDNA modified gold electrodes to study the interactions of DNA with target molecules. Copyright

Abstract The electrodeposition of metals using ionic liquids has received considerable attention during the last ten years. Recent developments have taken these novel electrolytes from laboratory to commercial scale. One of the factors limiting the development into practical plating systems is the understanding of how brighteners function. In this study we describe the addition of three polar additives and their effect upon the nucleation mechanism of zinc and the resultant morphology. It is shown that the structure of the zinc deposits is controlled by double layer properties and it is proposed that the brightening effect of ethylene diamine and ammonia are caused by their ability to inhibit the adsorption of chloride at the electrode surface. The deposition of most metals using ionic liquids results in apparently amorphous deposits, which tend to be actually nano-crystalline. The additives used in this study produce macro-crystalline deposits, which resemble those obtained from aqueous solutions.

Abstract The electrodeposition of zinc has been studied in two deep eutectic solvents. Unlike the metals studied to date in these liquids, zinc electrodeposition is not mass transport limited and the morphology of the deposit differs in the two liquids. This study shows that changing the concentration of solute affects the physical properties of the liquid to different extents although this is found to not effect the morphology of the metal deposited. EXAFS was used to show that the speciation of zinc was the same in both liquids. Double layer capacitance studies showed differences between the two liquids and these are proposed to be due to the adsorption of a species on the electrode which is thought to be chloride. The differences in zinc morphology is attributed to blocking of certain crystal faces leading to deposition of small platelet shaped crystals in the glycol based liquid.

Abstract Firefly luciferase is the most studied bioluminescence system, and its catalyzed reactions have been relatively well characterized. However, the color tuning mechanism that leads to firefly multicolor bioluminescence is still unknown, nor is consensual which is the yellow-green and red emitters. Computational studies have been essential in the study of oxyluciferin (OxyLH(2)) chemi- and bioluminescence and are responsible for most of our knowledge of this natural phenomenon. The objective of this manuscript is the analysis of the benefits and the conclusions derived from the theoretical studies of the light emitter, OxyLH(2), and its applications on bioluminescence research.

Abstract In the present work, lipophilic caffeic and ferulic acid derivatives were synthesized, and their cytotoxicity on cultured breast cancer cells was compared. A total of six compounds were initially evaluated: caffeic acid (CA), hexyl caffeate (HC), caffeoylhexylamide (HCA), ferulic acid (FA), hexyl ferulate (HF), and feruloylhexylamide (HFA). Cell proliferation, cell cycle progression, and apoptotic signaling were investigated in three human breast cancer cell lines, including estrogen-sensitive (MCF-7) and insensitive (MDA-MB-231 and HS578T). Furthermore, direct mitochondrial effects of parent and modified compounds were investigated by using isolated liver mitochondria. The results indicated that although the parent compounds presented no cytotoxicity, the new compounds inhibited cell proliferation and induced cell cycle alterations and cell death, with a predominant effect on MCF-7 cells. Interestingly, cell cyle data indicates that effects on nontumor BJ fibroblasts were predominantly cytostatic and not cytotoxic. The parent compounds and derivatives also promoted direct alterations on hepatic mitochondrial bioenergetics, although the most unexpected and never before reported one was that FA induces the mitochondrial permeability transition. The results show that the new caffeic and ferulic acid lipophilic derivatives show increased cytotoxicity toward human breast cancer cell lines, although the magnitude and type of effects appear to be dependent on the cell type. Mitochondrial data had no direct correspondence with effects on intact cells suggesting that this organelle may not be a critical component of the cellular effects observed. The data provide a rational approach to the design of effective cytotoxic lipophilic hydroxycinnamic derivatives that in the future could be profitably applied for chemopreventive and/or chemotherapeutic purposes.

Abstract In the present work, Dempster-Shafer Theory (DST) was employed for the implementation of a combined strategy for classification and/or virtual screening of potential anticoccidial drug candidates, based on the combination of the information provided by multiple QSAR models which are derived from different molecular structure representations. The application of such a strategy lead to a classification performance superior to the individual use of QSAR models, achieving accuracy/sensibility/specificity values over 94%/86%/96% and 86%/75%/89% on training and predicting series, respectively. Parallely, the application of such a strategy lead to values of enrichment metrics significantly superiors to the individual use of QSAR models as virtual screening tools. All these results suggest that the use of DST as the theoretical probabilistic base for the implementation of a combined classification and/or virtual screening strategy can be efficiently employed on the process of discovery and development of novel potential anticoccidial candidates, contributing in this way to overcome the emergence of resistance to current therapies.

Abstract In the last couple of years, carbon dots have emerged as a new novel luminescent particle for applications in fluorescence and microscopy in some ways analogous to quantum dots and silicon nanocrystals/particles. As with any fluorescent label or tag, absolute fluorescence intensity, brightness, and particle photostability are a primary concern. In this communication we subsequently show that similar to classical fluorophores, carbon dots located in the near-field, near to Plasmon supporting materials, show enhanced intensities and improved photostabilities.

Abstract The inhibition mechanisms of the firefly luciferase (Luc) by three of the most important inhibitors of the reactions catalysed by Luc, dehydroluciferyl-coenzyme A (L-CoA), dehydroluciferin (L) and L-luciferin (L-LH(2)) were investigated. Light production in the presence and absence of these inhibitors (0.5 to 2 mu M) has been measured in 50 mM Hepes buffer (pH = 7.5), 10 nM Luc, 250 mu M ATP and D-luciferin (D-LH(2), from 3.75 up to 120 mu M). Nonlinear regression analysis with the appropriate kinetic models (Henri-Michaelis-Menten and William-Morrison equations) reveals that L-CoA is a non-competitive inhibitor of Luc (K(i) = 0.88 +/- 0.03 mu M), L is a tight-binding uncompetitive inhibitor (K(i) = 0.00490 +/- 0.00009 mM) and L-LH2 acts as a mixed-type non-competitive-uncompetitive inhibitor (K(i) = 0.68 +/- 0.14 mMand alpha K(i) = 0.34 +/- 0.16 mu M). The Km values obtained for L-CoA, L and L-LH(2) were 16.1 +/- 1.0, 16.6 +/- 2.3 and 14.4 +/- 0.96 mu M, respectively. L and L-LH(2) are strong inhibitors of Luc, which may indicate an important role for these compounds in Luc characteristic flash profile. L-CoA K(i) supports the conclusion that CoA can stimulate the light emission reaction by provoking the formation of a weaker inhibitor.

Abstract Knudsen mass-loss effusion technique was used for measuring the vapor pressures at different temperatures of the following crystalline compounds: diphenylacetic acid, between 357.27 and 379.08 K; triphenylacetic acid, between 418.98 and 436.97 K; 2,2-diphenylpropanoic acid, between 366.08 and 386.00 K; 3,3-diphenylpropanoic acid, between 366.09 and 386.03 K; 3,3,3-triphenylpropanoic acid, between 402.17 and 420.10 K. From the temperature dependence of the vapor pressure of each crystalline compound, the standard (p (0) = 10(5) Pa) molar enthalpies and Gibbs energies of sublimation, at T = 298.15 K, were derived. The measured thermodynamic properties are compared with literature results for phenylacetic and phenylpropanoic acids and correlations for estimation of the vapor pressures from the enthalpy of sublimation and the temperature of fusion of these and other compounds are presented.

Abstract Microwave irradiation offers a considerable advantage over conventional synthesis with rate enhancements and cleaner reactions. Accordingly, a new microwave-assisted method for the synthesis of functionalized chromones was developed allowing the obtention of a library of chromone carboxamides. The method has been shown to present several advantages including operational simplicity, good performance, significant reduction in reaction time, less formation of by-products, and easier work-up.