Tucumã (Astrocaryum aculeatum) pulp presents a large number of secondary metabolites that can mediate the synthesis of metallic nanoparticles through a greener and more sustainable synthetic route than traditional ones. This study investigated the production of silver nanoparticles (AgNPs) mediated by aqueous extracts of tucumã pulp assessing different parameters, such as temperature, concentration of extract, and pH values of the reaction media. The alkaline reaction media produced the most intense and well-defined bands around 400 nm in the electronic spectra, indicating the formation of AgNPs in the three concentrations of tucumã pulp evaluated. The increase in the temperature of the reaction media also enhanced the surface plasmon resonance band of AgNPs but it increased the polydispersivity of produced nanoparticles according to the dynamic light scattering (DLS) and transmission electron microscopy (TEM) data. Zeta potential results indicated moderate stability of the AgNPs (close to -30 mV). Antimicrobial assessment of the colloidal metal particles indicated microbicide activity against the Gram-negative Escherichia coli bacterium.

The photocatalytic degradation of methylene blue dye and ibuprofen drug was studied in the presence of zinc oxide, synthetized by the protein sol-gel route. The catalyst, calcined at 1000 ºC, presented a tendentious morphology to filaments characteristic of ZnO crystalline, characterized by X-ray diffraction (XRD) and confirmed by the presence of Zn energy band in X-ray photoelectron spectrometer (XPS). The result of ultraviolet (UV) light photodegradation of this work is comparable to others that made use of more complex routes, considering the degradation of 97% of methylene blue dye solution and the solution of the ibuprofen drug reached 60% of degradation after 1 h of light incidence. In this research, it is possible to report good degradation results, and the research differential is a material made with a simple and less aggressive route, capable of generating a stable and efficient material.

Carbon-supported platinum-iridium nanowire-shape electrocatalysts containing 20% of metallic loading were synthesized by chemical reduction method using formic acid as a reducing agent and tested towards the oxidation of ethanol in acidic medium. The developed electrocatalysts were synthesized with the following compositions: Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C, Pt0.6Ir0.4/C and Pt0.5Ir0.5/C using for comparison the commercial Pt/C Alfa Aesar catalyst. Physico-chemical characterization was performed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray fluorescence (XRF, for chemical composition) techniques. All the nanowires present a face-centered cubic crystalline structure of the platinum with modifications in the lattice parameter due to the inclusion of iridium. The XRF analyzes show that the theoretical compositions of the synthesized catalysts are very close to the experimental nominal values. TEM analyses showed the formation of nanowires by the synthesis method used. The electrochemical results on the oxidation of ethanol show that the addition of a second metal to the platinum in the composition of the nanowires increases the catalytic activity of the electrode. The nanowire catalysts with low Ir content (Pt0.9Ir0.1/C, Pt0.8Ir0.2/C, Pt0.7Ir0.3/C) present the best outcomes under the analyzed conditions and are promising for application as anodes in direct ethanol fuel cells.

A new nanocomposite based on ZnCdTe semiconductor nanocrystals (NCs) synthesized in situ on reduced graphene oxide (rGO) was obtained. The heterostructure was characterized using UV-Vis emission and absorption spectroscopies, which provided evidences of the growth of the nanocrystals onto the rGO matrix. To evaluate the electrochemical performance, carbon paste electrodes modified with the nanocomposite (QD-rGO/CPE) were prepared, showing high sensitivity in the electroanalytical detection of the pesticide carbendazim. Under optimal operational conditions a calibration curve was constructed with a linear behavior in the range of 9.98 × 10-8 to 1.18 × 10-5 mol L-1, with a correlation coefficient of 0.997. The limit of detection (LOD) and the limit of quantification (LOQ) for carbendazim were 9.16 × 10-8 and 2.78 × 10-7 mol L-1, respectively. The electrode is successfully applied for the determination of carbendazim in orange juice samples.

ABSTRACT The objective of this work was to study the reduction in the capsaicin toxicity by encapsulation in liposomes. Capsaicin was extracted from peppers and characterized with high performance liquid chromatography (HPLC). We determined the zeta potential, polydispersivity index (PdI) and vesicle size of liposomes. Wistar rats were submitted to intravesical instillation of liposomes (LIP), capsaicin (CAP) or liposomes with capsaicin (CAPLIP). After 24 hours, bladders were removed for histological analysis. Vesicle size ranged from 68 to 105 nm with PdI smaller than 0.2 and zeta potential around -30 mV. The vesicles maintained stability over the 14-day study. The histological analysis of the CAP group showed intense inflammation in almost all bladder layers, as well as ulcer formation. Conversely, the CAPLIP group showed a smooth inflammatory reaction and hyperemia. In conclusion, the liposomes effectively protected the bladder against the irritative action of capsaicin.