Nesta terça-feira (31) a pós-doutoranda pela Universidade Estadual de Campinas (Unicamp) e pesquisadora no Centro de Desenvolvimento de Materiais Funcionais (CDMF), Nádia Guerra Macedo, apresentou a pesquisa “Enhanced bactericide effect of cuboid-like Ag NPs/α-Ag2WO4 induced by fs laser and EB irradiation”, durante a sessão de pôsteres da XIX Brazil MRS Meeting.
O α-Ag2WO4 é um óxido complexo com conhecidas propriedades fotocatalíticas e antimicrobiana. No entanto, essas propriedades são muito dependentes da superfície, e algumas morfologias experimentalmente obtidas quase não apresentam atividades. Entre as novas rotas para o modificação de materiais, laser de femtossegundo (fs) e irradiação de feixe de elétrons (EB) aparecem como ferramentas rápidas e eficazes. Neste estudo, emprega-se, separadamente, esses dois métodos para desenvolver nanopartículas de Ag (NPs) em α-Ag2WO4 semelhante ao modo cubóide, uma morfologia com relativamente baixa atividade antimicrobiana.
Também participaram da autoria do estudo apresentado os pesquisadores Thales Rafael Machado, Roman Alvarez Roca, Marcelo de Assis, Camila Cristina de Foggi, Verónica Puerto-Belda, Gladys Mínguez-Vega, André Rodrigues Pinheiro, Miguel San-Miguel, Eloisa Cordoncillo, Héctor Beltrán Mir, Juan Andrés e Elson Longo.
Confira o resumo do trabalho abaixo:
Resumo
Multimetal oxides attract great interest due to several possible promising applications. For instance, α-Ag2WO4 is a complex oxide with well-known photocatalytic and antimicrobial properties. However, these properties are very surface-dependent, and some experimentally obtained morphologies present almost no activities. Among the new routes to the modification of materials, femtosecond (fs) laser and electron-beam (EB) irradiation appear as green, fast and effective tools. In this study, we employed, separately, these two methods to grow Ag nanoparticles (NPs) on cuboid-like α-Ag2WO4, a morphology with relatively low antimicrobial activity, as showed by our group. [1] We irradiated one sample inside a SEM equipment and another sample with fs laser pulses. The resulting Ag NPs/-α-Ag2WO4 composites were analyzed with FE-SEM, TEM, HR-TEM and EDS technics. Their activities against Methicillin-resistant Staphylococcus aureus (MRSA) were evaluated through minimum bactericidal concentration (MBC) tests, and compared to a non-irradiated cuboid-like α-Ag2WO4 sample. Both tools were able to grow metallic Ag NPs on the surface of pristine α-Ag2WO4, and both composites presented enhanced activities against MRSA. However, the fs laser irradiated sample was 64 times more bactericide when compared to the blank sample, while the EB irradiated sample presented an increase in the activity of only 2 times. The superior effect of the fs laser sample is due to the generation of unexpected metastable hexagonal Ag NPs and to a larger distribution of the laser generated NPs. Although the two methods interact with matter at a quantum level, the fs laser irradiation arouse as a better tool to stabilize unusual phases, leading to superior synergic effects in the composite materials.
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CDMF
O CDMF é um dos Centros de Pesquisa, Inovação e Difusão (Cepids) apoiados pela Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp), e recebe também investimento do Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), a partir do Instituto Nacional de Ciência e Tecnologia dos Materiais em Nanotecnologia (INCTMN).
