INFLUÊNCIA DO TRATAMENTO TÉRMICO NO NANOCOMPÓSITO FOTOCATALISADOR ZnO/TiO2

ZnO/TiO2 nanocomposites were prepared by impregnating zinc acetate dihydrate on the surface of titanium dioxide P25, followed by thermal treatment at 350, 600, 750, and 900 °C, in order to investigate the TiO2 phase and titanate formation and the role of the latter in the photocatalytic activity of the nanocomposite. In the nanocomposites, the anatase-to-rutile transition is favored due to the presence of Zn2+, and the conversion is nearly complete at 750 °C. The presence of zinc metatitanate in the sample heated at 600 °C had no significant effect on the nanocomposite photocatalytic activity.

NANOPARTÍCULAS DE PROTEÍNA ISOLADA DE SOJA EM ÁGUA: EFEITO DA FORÇA IÔNICA E DAS CONCENTRAÇÕES DE PROTEÍNA E SURFACTANTE

Soft nanoparticles of size 200-400 nm were obtained from soybean protein isolate (SPI). The particles were formed and suspended in water by the coacervation of aqueous suspensions of SPI in hostile buffered aqueous solutions in the presence of surfactants. We investigate the effect of storage, ionic strength, and concentrations of SPI and surfactant on nanoparticle size and zeta potential. Transmission electron microscopy images and scattering techniques (SLS/ DLS) revealed that the particles are spherical, with hydrophilic chains at the surface.

SÍNTESE E CARACTERIZAÇÃO DE COMPÓSITOS ORGÂNICO-INORGÂNICOS MACROPOROSOS PARA O SENSORIAMENTO DE H2O2

Electrodes modified with poly(5-amino-1-naphthol)/Prussian blue (poly(5-NH2-1-NAP)/PB) hybrid films are able to electrochemically reduce H2O2 in medium containing an excess of Na+ cations. This is an important advantage for biosensing applications over electrodes in which only conventionally (electro) deposited Prussian blue is present. Consequently, the aim of this work was to examine the application of templates of ordered arrays of colloidal poly(styrene) spheres (800, 450 and 100 nm in diameter) to produce inverse opal structures of poly(5-NH2-1-NAP)/PB hybrid platforms, in an effort to study the influence of the increase in surface area/volume ratio and higher exposition of the mediator active sites on material performance during H2O2 determination employing the different sized porous structures. Moreover, since the accentuated hydrophilic character of poly(5-NH2-1-NAP)/PB also allows H2O2 electrochemical reduction in inner active sites, issues concerning the amount of mediator electrodeposited on the electrode were also reflected in the observed results.

CARACTERIZAÇÃO E AVALIAÇÃO IN VITRO DE NANOCOMPÓSITOS DE POLI (L-ÁCIDO LÁTICO) E NANOTUBOS DE CARBONO DE PAREDES MÚLTIPLAS PURIFICADOS

Carbon nanotubes (CNT) have been studied for biomedical applications due to their unique properties. However, pristine CNT have structural features and impurities that can cause toxicity to biological systems. In this work, we describe a method to purify multiwalled carbon nanotubes (MWCNT) by chemical modification and subsequent attachment of hydroxyl and carboxyl groups to improve dispersion and to decrease toxic effects. Nanocomposites from poly (L-lactic acid) (PLLA) and nanotubes were produced by the solvent casting method and characterized and evaluated for cytocompatibility with Vero cells. The nanocomposite interactions with Vero cells demonstrated that the cells were able to adhere and sustain proliferation and showed favorable cytocompatibility. In vitro studies also revealed an increase in fibroblast cell viability in the nanocomposites, compared with neat PLLA.

Ultrastructural and biochemical detection of biotin and biotinylated polypeptides in Schistosoma mansoni

Biotinylation is proposed for the identification of surface proteins in Schistosoma mansoni using the streptavidin-HRP conjugate for the detection of labeled polypeptides. However, control samples also showed several endogenous biotinylated polypeptides. In an attempt to determine the possibility of nonspecific binding between the streptavidin-HRP conjugate and polypeptides from S. mansoni, the conjugate was blocked with biotinamidecaproate-N-hydroxysuccinimide ester (BcapNHS) before biotin-streptavidin blotting. No bands were detected on the nitrocellulose sheet, demonstrating the specific recognition of biotin by the streptavidin present in the conjugate. Whole cercariae and cercarial bodies and tails showed several endogenous biotinylated polypeptides. The biotin concentration was 13 µg/190,000 cercariae. Adult worms presented less endogenous biotinylated polypeptides than cercariae. These results may be due to changes in the environment from aerobic to anaerobic conditions when cercarial bodies (schistosomula) are transformed into adult worms and a decrease in CO2 production may occur. Cercariae, cercarial bodies and adult male worms were examined by transmission electron microscopy employing an avidin-colloidal gold conjugate for the detection of endogenous biotin. Gold particles were distributed mainly on the muscle fibers, but dispersed granules were observed in the tegument, mitochondria and cytosol. The discovery of endogenous biotin in S. mansoni should be investigated in order to clarify the function of this vitamin in the parasite