Nanoligas bimetálicas Ag/Cu: avaliação estrutural, morfológica e atividade antimicrobiana
Data
2023-05-24
Autores
Harada, Bruna Naemi 
Orientadores
Pellosi, Diogo Silva
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O desenvolvimento de cepas microbianas multirresistentes a antibióticos tem gerado preocupações globais na área da saúde. Neste contexto, nanopartículas metálicas como as nanopartículas de prata (AgNP) e cobre (CuNP) vêm sendo avaliadas como alternativa aos antibióticos comerciais. Ambos os metais possuem atividade antimicrobiana, mas enquanto as CuNP apresentam baixo custo, mas baixa estabilidade, as AgNP apresentam ótima estabilidade, porém custo mais elevado. Assim, neste trabalho o foco foi a produção de nanoligas do tipo Ag/Cu em busca de propriedades sinérgicas entre os metais. O sucesso da síntese das NPs e nanoligas via redução química em solução aquosa contendo polivinilpirrolidona (PVP) dependeu da metodologia aplicada. Por exemplo, o ácido ascórbico (redutor fraco) não foi eficiente, já o boroidreto de sódio (redutor forte) produziu os nanomateriais, mas as partículas com cobre tiveram baixa estabilidade. Por fim, optou-se pela síntese de NPs do tipo core@shell (Ag/Cu@Ag), otimizando o processo de produção via a ferramenta estatística de planejamento fatorial. A camada externa (shell) de prata assegurou a estabilidade das nanoligas produzidas, sendo estas então caracterizadas por espectrofotometria no UV-Vis, por espalhamento dinâmico de luz a fim de obter as medidas de tamanho e potencial zeta, e por microscopia eletrônica de transmissão, confirmando a formação de partículas esféricas nanométricas bem como sua morfologia core@shell. As nanoligas Ag/Cu@AgNPs apresentaram forte atividade biocida contra bactérias Gram-positvas e Gram-negativas, mas não apresentaram atividade antifúngica. Assim, o trabalho mostra que nanoligas do tipo Ag/Cu@AgNPs são materiais promissores no tratamento de infecções bacterianas.
The development of antibiotic-resistant microbial strains it’s a growing concern worldwide. In this scenario, metallic nanoparticles such as silver (AgNP) and copper (CuNP) nanoparticles have been evaluated as alternatives for commercial antibiotics. Both metals have antimicrobial activity but, while CuNP have low cost but low kinetic stability, AgNP have excellent stability, but a higher cost. Thus, the focus of this work was the production of Ag/Cu nanoalloys aiming synergistic effect between the evaluated metals. The success of the synthesis of NPs and nanoalloys via chemical reduction in aqueous solution containing polyvinylpyrrolidone (PVP) depended on the applied methodology. For example, ascorbic acid (weak reducer) was not efficient, while sodium borohydride (strong reducer) produced nanomaterials, but the nanoparticles with high copper content presented low stability. On the other hand, the synthesis of a core@shell (Ag/Cu@Ag) NPs optimized via the factorial design statistical tool produced best results since the Ag outer layer ensures the kinetic stability of the produced nanostructures. These core@shell NPs were then characterized by UV-Vis spectrophotometry, measurements of size and zeta potential and transmission electron microscopy, confirming the formation of spherical nanometric particles as well as their core@shell morphology. The Ag/Cu@AgNPs nanoalloys showed strong biocidal activity against both Gram-positive and Gram-negative bacteria, but did not show antifungal activity. Thus, the work shows that nanoalloys of the Ag/Cu@AgNPs type are promising materials in the treatment of bacterial infections.
The development of antibiotic-resistant microbial strains it’s a growing concern worldwide. In this scenario, metallic nanoparticles such as silver (AgNP) and copper (CuNP) nanoparticles have been evaluated as alternatives for commercial antibiotics. Both metals have antimicrobial activity but, while CuNP have low cost but low kinetic stability, AgNP have excellent stability, but a higher cost. Thus, the focus of this work was the production of Ag/Cu nanoalloys aiming synergistic effect between the evaluated metals. The success of the synthesis of NPs and nanoalloys via chemical reduction in aqueous solution containing polyvinylpyrrolidone (PVP) depended on the applied methodology. For example, ascorbic acid (weak reducer) was not efficient, while sodium borohydride (strong reducer) produced nanomaterials, but the nanoparticles with high copper content presented low stability. On the other hand, the synthesis of a core@shell (Ag/Cu@Ag) NPs optimized via the factorial design statistical tool produced best results since the Ag outer layer ensures the kinetic stability of the produced nanostructures. These core@shell NPs were then characterized by UV-Vis spectrophotometry, measurements of size and zeta potential and transmission electron microscopy, confirming the formation of spherical nanometric particles as well as their core@shell morphology. The Ag/Cu@AgNPs nanoalloys showed strong biocidal activity against both Gram-positive and Gram-negative bacteria, but did not show antifungal activity. Thus, the work shows that nanoalloys of the Ag/Cu@AgNPs type are promising materials in the treatment of bacterial infections.