RESUMO
The ability to manipulate the structure and function of promising systems via external stimuli is emerging with the development of reconfigurable and programmable multifunctional materials. Increasing antifungal and antitumor activity requires novel, effective treatments to be diligently sought. In this work, the synthesis, characterization, and in vitro biological screening of pure α-Ag2WO4, irradiated with electrons and with non-focused and focused femtosecond laser beams are reported. We demonstrate, for the first time, that Ag nanoparticles/α-Ag2WO4 composite displays potent antifungal and antitumor activity. This composite had an extreme low inhibition concentration against Candida albicans, cause the modulation of α-Ag2WO4 perform the fungicidal activity more efficient. For tumor activity, it was found that the composite showed a high selectivity against the cancer cells (MB49), thus depleting the populations of cancer cells by necrosis and apoptosis, without the healthy cells (BALB/3T3) being affected.
Assuntos
Antifúngicos/farmacologia , Antineoplásicos/farmacologia , Candida albicans/efeitos dos fármacos , Elétrons , Nanopartículas Metálicas/química , Óxidos/química , Prata/química , Tungstênio/química , Neoplasias da Bexiga Urinária/tratamento farmacológico , Animais , Apoptose , Células 3T3 BALB , Proliferação de Células , Humanos , Nanopartículas Metálicas/administração & dosagem , Nanopartículas Metálicas/efeitos da radiação , Camundongos , Óxidos/efeitos da radiação , Prata/efeitos da radiação , Células Tumorais Cultivadas , Tungstênio/efeitos da radiação , Neoplasias da Bexiga Urinária/patologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: The aim of this study was to develop an efficient method for cholesterol oxide product (COP) determination in irradiated and non-irradiated ready-to-eat foods with high water content by gas chromatography-flame ionisation detector after accelerated solvent extraction (ASE), and derivatisation with a silylating reagent. RESULTS: The ASE solvent was an 85:15 v/v petroleum ether/chloroform mixture at 40 °C and 1500 psi followed by solid phase extraction. The ASE method was compared with the established lixiviation method, proving an advantageous alternative which reduces analysis time by a factor of 15 and solvent volume by 50%, and minimises the use of chlorinated solvents. COP derivative structures were identified by gas chromatography coupled with mass spectrometry. Analytical characteristics were determined from standards and recoveries were 63-95%, establishing the validity of the method. CONCLUSION: The results obtained and their analysis by chemometric techniques established COP formation in food samples after e-beam irradiation. Increase in COP concentration depended on both irradiation doses and food composition, mainly water and fat content, although linear correlations among variables were not found. © 2016 Society of Chemical Industry.
Assuntos
Colesterol/análise , Colesterol/efeitos da radiação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Óxidos/análise , Óxidos/efeitos da radiação , Animais , Queijo/análise , Queijo/efeitos da radiação , Colesterol/biossíntese , Colesterol/metabolismo , Cromatografia Gasosa/métodos , Elétrons , Gorduras/análise , Carne/análise , Carne/efeitos da radiação , Óxidos/metabolismo , Carne Vermelha/análise , Carne Vermelha/efeitos da radiação , Salmão/anatomia & histologia , Extração em Fase Sólida/métodos , Solventes/química , Água/análiseRESUMO
AIM: To evaluate the influence of radiation on root canal sealer push-out bond strength to dentine and sealer/dentine interface in teeth filled with AH Plus (Dentsply Ind. Com. Ltda, Petrópolis, RJ, Brazil) and MTA Fillapex (Angelus Ind. Prod. Odontológicos S/A, Londrina, PR, Brazil). METHODOLOGY: Thirty-two maxillary canines were selected and randomly assigned to 2 groups (n = 16): one group was not irradiated, and the other was subjected to a cumulative radiation dose of 60 Gy. Root canals were prepared with the Reciproc system (VDW GmbH, Munich, Germany), and each group was divided into 2 subgroups (n = 8) according to the sealer - AH Plus or MTA Fillapex - using the single-cone filling technique. Then, 1-mm-thick dentine slices were obtained from each root third for the push-out test to evaluate sealer bond strength to dentine and for scanning electron microscopy (SEM) to examine the sealer/dentine interface. Failure mode after debonding was determined with a stereomicroscope at ×25 magnification. Bond strength data were analysed by two-way anova with a split-plot design and post hoc Tukey's test (α = 0.05). RESULTS: Significantly lower bond strength (P < 0.0001) was obtained after irradiation (0.71 ± 0.20 versus 0.97 ± 0.29 MPa) and in specimens filled with MTA Fillapex (0.70 ± 0.18 MPa) compared with AH Plus (1.00 ± 0.27 MPa). Percentage of adhesive failures increased after radiation in all root thirds in the teeth filled with AH Plus. SEM revealed more gap-containing regions and fewer tags at the sealer/dentine interface in irradiated specimens, with more tag formation and fewer gaps with AH Plus sealer. CONCLUSIONS: Radiation was associated with a decrease in the push-out bond strength of sealers to intraradicular dentine and formation of more gaps and fewer tags at the sealer/dentine interface regardless of the sealer.
Assuntos
Compostos de Alumínio/efeitos da radiação , Compostos de Cálcio/efeitos da radiação , Dentina/efeitos da radiação , Resinas Epóxi/efeitos da radiação , Óxidos/efeitos da radiação , Materiais Restauradores do Canal Radicular/efeitos da radiação , Silicatos/efeitos da radiação , Dente Canino , Colagem Dentária , Falha de Restauração Dentária , Análise do Estresse Dentário , Fracionamento da Dose de Radiação , Combinação de Medicamentos , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Teste de Materiais , MaxilaRESUMO
Nanocomposites of graphene oxide (GO) and silver nanoparticles (AgNPs) were synthetized using a practical photochemical silver functionalization. Their photocatalytic activities were evaluated with two dyes, Rhodamine B and Indigo Carmine, under visible-light irradiation. The prepared nanocomposites were characterized by HRTEM, FESEM, XRD, Raman, FTIR and UV-vis absorption spectroscopy. These nanocomposites present new defect domains of sp(3) type in combination with several graphitic functional groups that act as nucleation sites for anchoring AgNPs, while the sp(2)-sp(3) edge defects domains of GO generate the photoactivity. Furthermore, their photocatalytic performances are governed by their large adsorption capacity, and strong interaction with dye chromophores. A comprehensive photocatalytic way underlying the importance of adsorption is suggested to explain the low visible-light responsive photoactivity of the AgNPs-GO nanocomposites and the possible binding-site saturation. Then, the usage of H2SO4 allows the production of ionic species and helps to confirm the strong adsorption of both dyes. The ability to synthesize AgNPs-GO nanocomposites with extensive adsorptive capacity is certainly of interest for the efficient removal of hazardous materials.
Assuntos
Grafite/efeitos da radiação , Índigo Carmim/química , Nanocompostos/efeitos da radiação , Óxidos/efeitos da radiação , Rodaminas/química , Prata/efeitos da radiação , Adsorção , Corantes/química , Grafite/química , Luz , Microscopia Eletroquímica de Varredura , Nanocompostos/química , Nanocompostos/ultraestrutura , Óxidos/química , Fotólise , Prata/química , Ácidos Sulfúricos/químicaRESUMO
This study aimed to evaluate the photocatalytic activity of ZnO and Nb2O5 catalysts, both supported on NaX zeolite and activated charcoal (AC). The synergistic effect between oxide and support and the influence of solution pH (3, 7 and 9) on photocatalytic degradation of reactive blue 5G (C.I. 222) were analyzed. The catalysts Nb2O5/NaX, Nb2O5/AC and ZnO/NaX, ZnO/AC with 5 and 10% (wt%) were prepared by wet impregnation. The results showed that the catalysts exhibit quite different structural and textural properties. The synergic effect between ZnO and NaX support was higher than that with the activated charcoal, showing that these catalysts were more efficient. The most photoactive catalyst was 10% ZnO/NaX which showed 100% discoloration of the dye solution at pH 3, 7 and 9 after 0.5, 5 and 2h of irradiation, respectively. The hydrolytic nature of zeolite favored the formation of surface hydroxyl radicals, which increased the activity of the photocatalyst. Thus, catalysts supported on NaX zeolite are promising for use in photocatalysis.
Assuntos
Compostos Azo/química , Carvão Vegetal/química , Corantes/química , Nióbio/efeitos da radiação , Óxidos/efeitos da radiação , Zeolitas/química , Óxido de Zinco/efeitos da radiação , Catálise , Nióbio/química , Óxidos/química , Fotólise , Raios Ultravioleta , Óxido de Zinco/químicaRESUMO
In this letter, we report, for the first time, the real-time in situ nucleation and growth of Ag filaments on α-Ag2WO4 crystals driven by an accelerated electron beam from an electronic microscope under high vacuum. We employed several techniques to characterise the material in depth. By using these techniques combined with first-principles modelling based on density functional theory, a mechanism for the Ag filament formation followed by a subsequent growth process from the nano- to micro-scale was proposed. In general, we have shown that an accelerated electron beam from an electronic microscope under high vacuum enables in situ visualisation of Ag filaments with subnanometer resolution and offers great potential for addressing many fundamental issues in materials science, chemistry, physics and other fields of science.
Assuntos
Cristalização/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Óxidos/química , Prata/química , Tungstênio/química , Elétrons , Nanopartículas/efeitos da radiação , Óxidos/efeitos da radiação , Tamanho da Partícula , Prata/efeitos da radiação , Resultado do Tratamento , Tungstênio/efeitos da radiaçãoRESUMO
Hafnium oxide (HfO(2)) films were deposited by the ultrasonic spray pyrolysis process. The films were synthesized from hafnium chloride as raw material in deionized water as solvent and were deposited on corning glass substrates at temperatures from 300 to 600 degrees C. For substrate temperatures lower than 400 degrees C the deposited films were amorphous, while for substrate temperatures higher than 450 degrees C, the monoclinic phase of HfO(2) appeared. Scanning electron microscopy showed that the film's surface resulted rough with semi-spherical promontories. The films showed a chemical composition close to HfO(2), with an Hf/O ratio of about 0.5. UV radiation was used in order to achieve the thermoluminescent characterization of the films; the 240 nm wavelength induced the best response. In addition, preliminary photoluminescence spectra, as a function of the deposition temperatures, are shown.