TOXIDEZ, DEGRADAÇÃO NO MEIO-AMBIENTE E MÉTODOS ELETROANALÍTICOS DE DETECÇÃO DO PESTICIDA CARBARIL

This work presents a review about the toxicity, degradation in the environment and the determination of carbaryl pesticide residues, one of the most important compound of carbamates class, in different matrices, through electroanalytical methods, including the detection using non-modified electrodes as boron-doped diamond and using biosensors. Due to the toxicity and large utilization of this pesticide in cultures such as pineapple, cotton, banana, potatoes, onion, bean and tomato, it is necessary to known the degradation ways of this compound and known about sensitive methodologies for the detection of residues in foods, natural waters and soils.Este artigo apresenta breve revisão de literatura sobre o inseticida carbaril, muito utilizado na agricultura brasileira. Foram abordados seus efeitos tóxicos em humanos e animais, bem como sua degradação no meio-ambiente. Explorou-se a determinação de seus resíduos por métodos eletroanalíticos, utilizando os eletrodos de platina, mercúrio, diamante dopado com boro e eletrodos modificados, tais como os biossensores. O conhecimento das formas de degradação possibilita a elaboração de processos físicos e químicos visando o tratamento de águas e solos poluídos. Além disso, devido ao uso intenso do carbaril em culturas de frutas e vegetais, também é necessário o desenvolvimento de metodologias sensíveis para a detecção de resíduos nesses alimentos

Estudos da lesão ao DNA por corantes têxteis e da capacidade protetora de flavonóides empregando biossensor eletroquímico: Carolina Venturini Uliana. -

A molécula do DNA pode ser modificada por substâncias eletrofílicas, tanto de origem exógena quanto endógena. As lesões geradas podem ser mutagênicas e contribuir para o processo de carcinogênese. Assim, desvios significativos da estrutura da dupla hélice desempenham um papel importante no metabolismo do DNA. Um biossensor voltamétrico baseado na imobilização de DNA de fita dupla (dsDNA) sobre eletrodos descartáveis foi desenvolvido para aplicação nos estudos de interação entre corantes têxteis e a molécula do DNA, na ausência e na presença de flavonóides em solução. Os eletrodos modificados foram colocados em contato com soluções de corantes têxteis da classe dos dispersos, o Disperso Orange 1 (DO1) e o Disperso Red 1 (DR1), e seus produtos de eletrólise por oxidação e por redução. A variação dos sinais de oxidação das bases guanina e adenina presentes no dsDNA imobilizado, obtidos antes e após cada interação, foi utilizada como parâmetro de análise dos resultados. O tempo para que a interação DNA:corante ocorresse foi avaliado utilizando o biossensor e estabeleceu-se 180 s. A concentração dos corantes foi analisada na faixa de 1,0 x 10-8 a 1,0 x 10-4 mol L-1, sendo que a variação do sinal voltamétrico das bases foi mais intensa para DR1 (sinais da guanina e adenina decresceram 48% e 51% do seu valor original, respectivamente), enquanto que na presença de DO1, as intensidades de corrente da guanina e adenina diminuíram 30% e 10% de seu valor original, respectivamente, quando comparada a mesma concentração dos corantes de 1,0 x 10-6 mol L-1. Além da diminuição da intensidade de corrente das bases guanina e adenina, o aparecimento de novos picos e deslocamentos do potencial de pico das bases foram observados após as interações com produtos de eletrólises. Estudos de interação também...DNA molecule may be modified by electrophilic substances, either from endogenous or exogenous origin. Lesions generated may be mutagenic and contribute to the process of carcinogenesis. In this way, significant deviations on the double helix structure play an important role in the DNA metabolism. A biosensor based on double-stranded DNA (dsDNA) immobilization on disposable electrodes has been developed for application in interaction studies between textile dyes and DNA molecule in the absence and presence of flavonoids in solution. The modified electrodes were placed in solutions of disperse textile dyes, Disperse Orange 1 (DO1) and Disperse Red 1 (DR1), and their products of electrolyses by oxidation and reduction. The variation of the oxidation signals of guanine and adenine bases of the immobilized dsDNA, obtained before and after each interaction, was used as a parameter for analyzing the results. The time for DNA:dye interaction was evaluated using the biosensor and 180 s was established. The concentration of dyes was analyzed in the range from 1.0 x 10-8 to 1.0 x 10-4 mol L-1, and the bases voltammetric signal variation was more intense for DR1 (signals of guanine and adenine decreased 48% and 51% of its original value, respectively), whereas in the presence of DO1, the current intensities of guanine and adenine decreased by 30% and 10% of its original value, respectively, when compared the same dyes concentration of 1.0 x 10-6 mol L-1. Besides adenine and guanine current intensities decrease, the appearance of new peaks and peaks potential shifts were also observed after interactions with electrolysis products. Interaction studies were also performed by means of UV-Vis spectrophotometry in aqueous phase showed different effects of hypochromism and hiperchromism of DNA band after interactions... (Complete abstract click electronic access below

Desenvolvimento de um biosensor amperométrico para a detecção do vírus da Hepatite C

O presente trabalho relata o desenvolvimento de um biossensor amperométrico para detecção do vírus da Hepatite C (HCV) por meio da reação de hibridização do DNA imobilizado na superfície do eletrodo com o DNA complementar proveniente de amostras de soro de pacientes. Neste dispositivo, a reação da enzima peroxidase com o substrato peróxido de hidrogênio e com o mediador de elétrons ácido 5-aminossalicílico é utilizada como marcadora da reação de hibridização. Estudos eletroquímicos e espectrofotométricos foram empregados na investigação do produto da oxidação do mediador pela enzima, sugerindo-se que este seja um complexo formado entre o Fe4+ presente no grupo heme da peroxidase e o grupo NH2 do ácido 5-aminossalicílico. Este complexo sofre redução na superfície do eletrodo resultando na resposta analítica do sistema proposto. Na construção do biossensor, os eletrodos de ouro, obtidos a partir de CDs graváveis denominados CDtrodos, foram modificados com monocamadas auto-organizadas de ácido lipóico 1,0 x 10-3 mol L-1 por 120 minutos. Estudos quimiométricos, por meio do planejamento fatorial completo e fracionado, foram aplicados para obtenção das melhores condições de imobilização das biomoléculas, compreendendo a concentração e o tempo de incubação dos CDtrodos nas soluções da proteína estreptavidina, da sonda de DNA específica para o HCV genótipos 1 e 3, do DNA complementar e do conjugado avidina-peroxidase, marcador da reação de hibridização. O valor de cut-off foi determinado como sendo de –0,599 A e biossensor foi então aplicado em amostras positivas para HCV. Os resultados mostraram que o biossensor desenvolvido é adequado para aplicação em amostras dos genótipos 1 e 3, os quais prevalecem no Brasil.This work presents the development of an amperometric biosensor for the detection of Hepatitis C virus (HCV) through the reaction of hybridization of DNA immobilized on the electrode surface with the complementary DNA (c-DNA) from serum samples of patients. In this device, the reaction of the enzyme peroxidase with the substrate hydrogen peroxide and with the electron mediator 5-aminossalicylic acid is used as hybridization label. Electrochemical and spectrophotometric studies were carried out to investigate the oxidation product of the mediator by the enzyme, suggesting that one is a complex formed between the Fe4+ of heme peroxidase group and NH2 group of 5-aminossalicylic acid. This complex undergoes reduction in the electrode surface resulting in the analytical response of the proposed system. For the construction of the biosensor, the gold electrodes, obtained from recordable CDs namely CDtrodes, were modified with self-assembled monolayers of lipoic acid 1.0 x 10-3 mol L-1 for 120 minutes. Chemometric studies, through the full and fractional factorial design, were applied to obtain the best conditions for the biomolecules immobilization, including the concentration and the incubation time of CDtrodes in the solutions of the protein streptavidin, the DNA probe specific for the HCV genotypes 1 and 3, c-DNA and the avidin-peroxidase conjugate, label of the reaction of hybridization. The cut-off value was determined as -0599 A and the biosensor was applied for HCV positive samples. The results showed that the developed biosensor is suitable for application in samples of genotypes 1 and 3, which are those that prevail in Brazil.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Electrochemical investigations on the capacity of flavonoids to protect DNA against damage caused by textile disperse dyes

In previous work, the interaction of DNA with the textile dyes Disperse Orange 1 (DO1) and Disperse Red 1 (DR1), and their electrolysis products, resulted in significant changes in the characteristic oxidation peaks of the guanine and adenine moieties of immobilized dsDNA, measured using pencil graphite electrodes. In order to evaluate the protective capacity of flavonoids and teas against DNA damage caused by the dyes, studies of the interaction of DNA with DO1 and DR1 were conducted in the presence of the flavonoids myricetin and apigenin. The flavonoids were able to protect adenine and guanine from interaction with the dyes, as shown by smaller decreases in current intensity. Solutions of green tea and chamomile tea also showed protective capacities. Using interaction times of 180 s, the adenine moiety current intensity decreased by 60% of the initial value after interaction with 1.0 x 10(-5) mol L-1 DR1 alone, but by only 8% when the same DR1 concentration was employed in a mixture with 5.0 x 10(-7) mol L-1 myricetin, and by no more than 1% in a mixture with chamomile tea. The results indicated that damage to the DNA molecule could be reduced by the presence of flavonoids as well as green tea and chamomile tea, which are natural sources of the flavonoids myricetin and apigenin, respectively. (C) 2013 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Evaluation of the interactions of DNA with the textile dyes Disperse Orange 1 and Disperse Red 1 and their electrolysis products using an electrochemical biosensor

A disposable pencil graphite electrode modified with dsDNA was used in combination with square wave voltammetry in order to evaluate the interaction of DNA with the textile dyes Disperse Orange 1 (DO1) and Disperse Red 1 (DR1), and with the products of their electrolysis. Significant changes in the characteristic oxidation peaks of the guanine and adenine moieties of immobilized dsDNA were observed after incubation of the modified electrode for 180 s in solutions of the dyes in their original forms. The same was observed using the electrolysis products obtained by oxidation and reduction conversions. The oxidation peak currents of the guanine and adenine moieties decreased when the concentrations of DO1 and DR1 were increased up to 5.0 × 10 -6 and 1.0 × 10-6 mol L-1, respectively; the signal decreases were more pronounced after interaction with the oxidized dyes, compared to the reduced compounds. The interactions between DNA and DO1, DR1, and the electrolyzed dyes were further investigated by UV-vis spectrophotometry in solution, and different effects such as hypochromism and hyperchromism were observed in the resulting DNA spectra. The investigated interactions showed clear evidence of changes in the DNA structure, and suggested a predominant intercalation mode leading to damage in the biomolecule. © 2013 Elsevier B.V

Application of Factorial Design Experiments to the Development of a Disposable Amperometric DNA Biosensor

The development of an amperometric DNA-based biosensor (genosensor) requires the optimization of many experimental parameters in order to maximize sensitivity. If only one parameter is evaluated per experiment, the resultant genosensor is unlikely to be ideal, because several of the parameters could be interdependent. Herein, chemometric experiments employing full and fractional factorial designs were used to develop biosensor for hepatitis. The results demonstrate that the use of chemometric tools enables optimization of experimental conditions using a smaller number of experiments and with reduced requirements for reagents and samples, which is in line with the principles of green chemistry.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

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Immunomodulatory effect of crude leaf extract of <i>Piper fuligineum</i> on LPS-stimulated human monocytes.

<p>The results of the controls (medium and ketoprofin, unstimulated and LPS stimulated) were used in the analyses for all extract evaluated. Data are expressed as median ± SEM (pg/mL). ANOVA with Bonferroni post-test; p < 0.05; *: significantly different from placebo treatment, #: significantly different from ketoprofen treatment.</p

Immunomodulatory effect of crude leaf extract of <i>Piper gaudichaudianum</i> on LPS-stimulated human monocytes.

<p>The results of the controls (medium and ketoprofin, unstimulated and LPS stimulated) were used in the analyses for all extract evaluated. Data are expressed as median ± SEM (pg/mL). ANOVA with Bonferroni post-test; p < 0.05; *: significantly different from placebo treatment, #: significantly different from ketoprofen treatment.</p