Avaliação da atividade antimicrobiana de nanopartículas de cobre, prata e bimetálicas cobre/prata incorporadas em quitosana
Data
2022-11-21
Autores
Videira, Vanessa de Cassia Gomes 
Orientadores
Diogo, Pellosi Silva
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
As infecções microbianas tem sido um problema recorrente mesmo na era moderna dos antibióticos. Neste sentido, o uso de nanomateriais, em especial nanopartículas metálicas como prata e cobre têm sido avaliadas. Estes metais quando na forma nanoestruturada possuem elevada atividade antimicrobiana, porém sua aplicação pode ser limitada devido ao alto custo da prata ou baixa estabilidade frente a oxidação do cobre. Assim, no presente trabalho utilizou-se de duas estratégias para melhorar as propriedades destes nanomateriais: (i) sintetizar nanopartículas bimetálicas do tipo prata/cobre e (ii) pelo uso do biopolímero quitosana como matriz para a síntese e estabilização destas nanopartículas. Busca-se assim uma ação sinérgica entre o polímero e os nanometais de forma a aumentar a capacidade antimicrobiana e estabilidade cinética do compósito em relação aos componentes separados. A síntese utilizando um método hidrotérmico em refluxo (120 °C) e meio básico (pH ≈ 10) permitiu a obtenção de nanopartículas de Ag, Ag/Cu e Cu com boa dispersão, geometria aproximadamente esférica, tamanho nanométrico (<100 nm) e alta estabilidade em fase aquosa como demonstrado por análises UV-Vis, espalhamento dinâmico de luz e microscopia eletrônica de transmissão. Analises de difração de raios X e infravermelho confirmaram a natureza cristalina das nanopartículas e a ausência de óxidos de cobre na estrutura. As nanopartículas, em especial a de cobre, apresentaram elevada atividade de inibição das bactérias E. Coli e S. Aureus. Além disso, foi demonstrada a possibilidade de formação de filmes finos de quitosana/nanopartículas. Estes resultados promissores abrem grandes oportunidades para o desenvolvimento de materiais antimicrobianos a partir de nanopartículas metálicas incorporadas ao biopolímero quitosana.
Microbial infections have been a recurring problem even in the modern era of antibiotics. In this scenario, the use of nanomaterials, especially metallic nanoparticles such as silver and copper has been evaluated. These metals present a very effective antimicrobial activity when nanostructured, but their application may be limited due to the high cost of silver or low stability against oxidation by copper. Therefore, in the present work, two strategies were used in order to improve the properties of these nanomaterials: (i) synthesize silver/copper nanoalloys and (ii) by the use of chitosan biopolymer as a matrix for the synthesis and stability of these nanoparticles. Therefore, we aimed a synergistic action between the polymer and the nanometals/nanoalloys that increase the antimicrobial capacity and kinetic stability of the composite in relation to the separate components. The synthesis using a hydrothermal method at reflux temperature (120 °C) and basic medium (pH ≈ 10) allowed obtaining Ag, Ag/Cu and Cu nanoparticles with good dispersion, approximately spherical geometry, nanometric size (<100 nm) and high stability in the aqueous phase, as demonstrated by UV-Vis analyses, dynamic light scattering and transmission electron microscopy. X-ray diffraction and infrared analyses confirmed the crystalline nature of the nanoparticles and the absence of copper oxides in the structure. The nanoparticles, especially copper ones, showed high inhibition activity against E. Coli and S. Aureus bacteria. In addition, the possibility of forming thin films of chitosan/nanoparticles was also demonstrated. These promising results demonstrated great opportunities for the development of antimicrobial materials based on metallic nanoparticles incorporated into the chitosan biopolymer.
Microbial infections have been a recurring problem even in the modern era of antibiotics. In this scenario, the use of nanomaterials, especially metallic nanoparticles such as silver and copper has been evaluated. These metals present a very effective antimicrobial activity when nanostructured, but their application may be limited due to the high cost of silver or low stability against oxidation by copper. Therefore, in the present work, two strategies were used in order to improve the properties of these nanomaterials: (i) synthesize silver/copper nanoalloys and (ii) by the use of chitosan biopolymer as a matrix for the synthesis and stability of these nanoparticles. Therefore, we aimed a synergistic action between the polymer and the nanometals/nanoalloys that increase the antimicrobial capacity and kinetic stability of the composite in relation to the separate components. The synthesis using a hydrothermal method at reflux temperature (120 °C) and basic medium (pH ≈ 10) allowed obtaining Ag, Ag/Cu and Cu nanoparticles with good dispersion, approximately spherical geometry, nanometric size (<100 nm) and high stability in the aqueous phase, as demonstrated by UV-Vis analyses, dynamic light scattering and transmission electron microscopy. X-ray diffraction and infrared analyses confirmed the crystalline nature of the nanoparticles and the absence of copper oxides in the structure. The nanoparticles, especially copper ones, showed high inhibition activity against E. Coli and S. Aureus bacteria. In addition, the possibility of forming thin films of chitosan/nanoparticles was also demonstrated. These promising results demonstrated great opportunities for the development of antimicrobial materials based on metallic nanoparticles incorporated into the chitosan biopolymer.