Publications

Abstract Atmospheric gaseous pollutants can induce qualitative and quantitative changes in airborne pollen characteristics. In this work, it was investigated the effects of carbon dioxide (CO2) on Acer negundo pollen fertility, protein content, allergenic properties, and carbohydrates. Pollen was collected directly from the anthers and in vitro exposed to three CO2 levels (500, 1000, and 3000 ppm) for 6 and 24 h in an environmental chamber. Pollen fertility was determined using viability and germination assays, total soluble protein was determined with Coomassie Protein Assay Reagent, and the antigenic and allergenic properties were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunological techniques using patients' sera. Also, pollen fructose, sucrose, and glucose values were determined. Carbon dioxide exposure affected negatively pollen fertility, total soluble protein content, and fructose content. The patient sera revealed increased IgE reactivity to proteins of A. negundo pollen exposed to increasing levels of the pollutant. No changes were detected in the SDS-PAGE protein profiles and in sucrose and glucose levels. Our results indicate that increase in atmospheric CO2 concentrations can have a negative influence of some features of A. negundo airborne pollen that can influence the reproductive processes as well as respiratory pollen allergies in the future.

Abstract Conducting polymers directly grown on a supporting substrate through electrochemical methods present improved electrical contact and adherence compared to those deposited from solution. This paper explores different potentiostatic approaches for the electropolymerization of triphenylamine and the prospects of application of the resulting films as inexpensive cathodes for solid-state solar cells. To this end, solid films of the monomer were deposited onto transparent conducting glass and electrochemically cross-linked to different extents. The polymer films were characterized by CV, in situ UV-Vis Spectroscopy, in situ Electrochemical Quartz Crystal Microbalance, and, then, tested as cathodes in an all-solid-state hybrid mesoscopic solar cell based on TiO2 sensitized with CdSe quantum dots. The results indicate that, through the control of the doping state of the p-semiconductor, the Fermi level of the cathode can be tuned to raise the open-circuit voltage of the cells up to values near +0.8 V.

Abstract We describe here a voltammetric method based on the ion transfer at a water/oil interface for the electrochemical study of the interaction between high molecular weight dsDNA and two molecules of biological interest: the anthracycline drug daunorubicin (DNR) and the neurotransmitter dopamine (DA). The binding constants of the complexes were determined by performing an amperometric titration, following the decrease of ion transfer currents upon addition of dsDNA, using differential pulse voltammetry (DPV) technique. Binding constants were interpreted in terms of the main interaction mode of the molecules with DNA. A binding constant of 1.7 x 10(4) M-1 was obtained for the intercalation complex of DNR into DNA base pairs (bp), while a binding constant of 1.8 x 10(3) M-1 was obtained for the electrostatic interaction between positively charged DA and negatively charged dsDNA, using a non-linear binding model. The binding site size, in terms of base pairs, for the interaction between the two molecules and DNA was also estimated using non-linear regression analysis. Two binding site models were tested and compared in this work.

Abstract The present review deals with the sol-gel imprinting of both drug and non-drug templates of medical relevance, namely neurotransmitters, biomarkers, hormones, proteins and cells. Nearly a hundred recent works, either developmental or applied in a medical-related context, were critically analyzed. It may be concluded that, although research is still at an early stage, the potential of these sol-gel materials was well demonstrated in a few applications of critical interest for medicinal/biomedical science. The vast room left for expansion and improvement envisages a continuously growing interest by researchers in the future, eventually resulting in important medical applications able to enter the professional and consumer medical markets.

Abstract This is the first report of a computational study of the color tuning mechanism of firefly bioluminescence, using the oxidative conformation of luciferase. The results of these calculations demonstrated that the electrostatic field generated by luciferase is fundamental both for the emission shift and efficiency. Further calculations indicated that a shift in emission is achieved by modulating the energy, at different degrees, of the emissive and ground states. These differences in energy modulation will then lead to changes in the energy gap between the states.

Abstract Avobenzone is one of the most common UVA-filters in sunscreens, and is known to be photounstable. Some of the strategies used to stabilize this filter present some drawbacks like photosensitization reactions. Antioxidants are widely used as cosmetic ingredients that prevent photoageing and complement the photoprotection offered by the UV-filters preventing or reducing photogenerated reactive species. The purpose of this work was to study the effect of antioxidants in the photostabilization of avobenzone. The filter dissolved in dimethyl sulfoxide or incorporated in a sunscreen formulation was irradiated with simulated solar radiation (750 W/m(2)). The tested antioxidants were vitamin C, vitamin E, and ubiquinone. The area under the curve of the absorption spectrum for UVA range and the sun protection factor (SPF) were calculated. Vitamin E (1:2), vitamin C (1:0.5) and ubiquinone (1:0.5) were the more effective concentrations increasing the photostability of avobenzone. In sunscreen formulations, the most effective photostabilizer was ubiquinone which also promoted an increase in SPF. This knowledge is important to improve effectiveness of sunscreen formulation. Antioxidants can be valuable ingredients for sunscreens with a triple activity of filter stabilization, SPF boosting and photoageing prevention.