Leveduras quimicamente modificadas com silsesquioxanos cúbicos: avaliação como biossorvente e sensor eletroquímico
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Data
2019-03-12
Autores
Freitas, Bianca Trama
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A detecção, especiação e remoção de contaminantes orgânicos e inorgânicos é uma das maiores preocupações ambientais atualmente. Assim, a busca por tecnologias eficientes envolvendo materiais de baixo custo para a resolução de tal problema tem aumentado, e se tornou de extrema importância. Dentro deste contexto, o presente trabalho atuou na produção de um novo material nanoestruturado bioinorgânico híbrido com grandes potencialidades na área de nanotecnologia. O objetivo principal consistiu em modificar quimicamente a levedura Saccharomyces cerevisiae com silsesquioxanos cúbicos. Após devidas modificações, o material preparado (LevS) bem como seus precursores, foram caracterizados por técnicas espectroscópicas tais como infravermelho (FTIR) e microscopia eletrônica de varredura (MEV). O material hibrido formado (LevS) foi aplicado como biossorvente de chumbo (Pb) e níquel (Ni), obtendo-se uma capacidade máxima de sorção de 248 mg g-1 e 64,6 mg g-1, respectivamente, e porcentagem de sorção chegando a 100% para 500 ppm de Pb2+ em 250mLg-1 de razão líquido/sólido em pH 4, e 77,7% para 100 ppm de Ni2+ em 100 mLg-1 de razão líquido/sólido em pH 6. Adicionalmente com intuito de avaliar a toxidade neuronal dos metais em questão, foram efetuados testes de toxicidade em fatias de hipocampo de ratos que comprovaram que, uma vez submetidos à concentrações de 1 e 3 μM (0,2 e 0,6 ppm) Pb2+ e 10 e 30 μM (0,5 e 1,5 ppm) de Ni2+, as alterações neuronais causadas são irreversíveis. O material híbrido também foi testado na adsorção do corante catiônico, o azul de metileno, e em seguida o material obtido (LevSA) foi caracterizado por voltametria cíclica empregando um eletrodo de pasta de grafite. Para os testes voltamétricos, a levedura modificada com silsesquioxano foi submetida ao azul de metileno (LevSA), sendo observada alta capacidade de adsorção de tal corante. O novo material foi aplicado em eletrodo de pasta de grafite e suas características eletroquímicas foram avaliadas e descritas.
The detection, speciation and organic and inorganic contaminants removal is one of the biggest environmental concerns today. Thus, the search for efficient technologies involving low-cost materials for solving such a problem has increased, and became extremely important. Within this context, the present work was focused in the production of a new nanostructured hybrid material bioinorganic with great potential in the area of nanotechnology. The main objective was chemically modify the yeast Saccharomyces cerevisiae with cubic silsesquioxane. After appropriate modifications, the prepared material (LevS) as well as its precursors was characterized by spectroscopic techniques such as infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDS) and Diffuse Reflectance UV/Vis. The hybrid material formed (LevS) was applied as biosorbent of lead (Pb) and nickel (Ni), with a maximum capacity of sorption of 248 mg g-1 and 64.6 mg g-1, respectively, and percentage of reaching 100% sorption to 500 ppm of Pb2+ on 250 cm3 g-1 liquid/solid ratio and 4 pH, and 77.7% to 100 ppm of Ni2+ on 100 cm3 g-1 liquid/solid ratio at pH 6. In addition, in order to evaluate the neuronal toxicity of the metals in question, toxicity tests were performed on hippocampal slices of mice that proved that, once submitted to concentrations of 1 and 3 μM (0.2 and 0.6 ppm) Pb2+ and 10 and 30 μM (0.5 and 1.5 ppm) of Ni2+, neuronal changes caused are irreversible. The hybrid material was also tested on adsorption of the cationic dye, methylene blue, and then the material obtained (LevSA) was characterized by cyclic voltammetry using a graphite paste electrode. For the voltammetric tests, the modified yeast with silsesquioxane was subjected to methylene blue (LevSA), being observed adsorption capacity of such a dye. The new material applied in graphite paste electrode and their electrochemical characteristics were evaluated and described.
The detection, speciation and organic and inorganic contaminants removal is one of the biggest environmental concerns today. Thus, the search for efficient technologies involving low-cost materials for solving such a problem has increased, and became extremely important. Within this context, the present work was focused in the production of a new nanostructured hybrid material bioinorganic with great potential in the area of nanotechnology. The main objective was chemically modify the yeast Saccharomyces cerevisiae with cubic silsesquioxane. After appropriate modifications, the prepared material (LevS) as well as its precursors was characterized by spectroscopic techniques such as infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDS) and Diffuse Reflectance UV/Vis. The hybrid material formed (LevS) was applied as biosorbent of lead (Pb) and nickel (Ni), with a maximum capacity of sorption of 248 mg g-1 and 64.6 mg g-1, respectively, and percentage of reaching 100% sorption to 500 ppm of Pb2+ on 250 cm3 g-1 liquid/solid ratio and 4 pH, and 77.7% to 100 ppm of Ni2+ on 100 cm3 g-1 liquid/solid ratio at pH 6. In addition, in order to evaluate the neuronal toxicity of the metals in question, toxicity tests were performed on hippocampal slices of mice that proved that, once submitted to concentrations of 1 and 3 μM (0.2 and 0.6 ppm) Pb2+ and 10 and 30 μM (0.5 and 1.5 ppm) of Ni2+, neuronal changes caused are irreversible. The hybrid material was also tested on adsorption of the cationic dye, methylene blue, and then the material obtained (LevSA) was characterized by cyclic voltammetry using a graphite paste electrode. For the voltammetric tests, the modified yeast with silsesquioxane was subjected to methylene blue (LevSA), being observed adsorption capacity of such a dye. The new material applied in graphite paste electrode and their electrochemical characteristics were evaluated and described.
Descrição
Palavras-chave
Levedura, Silsesquioxano, Chumbo, Níquel, Biossorção, Toxicidade, Voltametria, Yeast, Silsesquioxane, Lead, Nickel, Biosorption, Toxicity, Voltammetry