resumo
Surface-Enhanced Raman Scattering (SERS) using colloidal metal (Ag, Au) nanoparticles has been regarded as a powerful method for detecting organic pollutants at vestigial levels. Although less investigated, the controlled synthesis of binary nanostructures comprising two metals provides an alternative route to SERS platforms with tuned surface plasmon resonances. Here, we demonstrate that the use of dendrimers allows the formation of distinct combinations of Ag:Au nanostructures that are composed of smaller metal nanocrystals. Our research highlights the role of the dendrimer macromolecules as a multipurpose ligand in the generation of such hybrid nanostructure, including as a reducing agent, an effective long-term colloidal stabilizer and as a molecular glue for interconnecting the primary metal nanocrystals. Noteworthy, the dendrimer-based Ag:Au hybrid nanostructures are more SERS sensitive as compared to the corresponding colloidal blends or to the single-phase metals, as revealed by using molecular pesticides as analytes in spiked water samples. We suggest that the high SERS sensitivity of the hybrid nanostructures is due to interparticle plasmonic coupling occurring between the primary metal nanoparticle aggregates, whose arrangement is templated by the presence of the dendrimer macromolecules. (C) 2021 Elsevier B.V. All rights reserved.
palavras-chave
ENHANCED RAMAN-SPECTROSCOPY; AU-AG ALLOY; PLASMONIC NANOPARTICLES; ASSEMBLIES; SCATTERING; NANOSPHERES; PESTICIDES; HYBRID
categoria
Chemistry, Physical; Physics, Atomic, Molecular & Chemical
autores
Fernandes, T; Fateixa, S; Ferro, M; Nogueira, HIS; Daniel-da-Silva, AL; Trindade, T
nossos autores
Ana Luísa Daniel da Silva
Investigador Principal
Helena Isabel Seguro Nogueira
Professor Auxiliar com Agregação
João Tiago Moniz Fernandes
Estudante de doutoramento
Marta Ascenção Carmona Ferro
Técnico de Laboratório
Sara Fateixa
Bolseiro de pós-Doutoramento
Tito Trindade
Professor Catedráticoagradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UIDB/50011/2020 & UIDP/50011/2020. Tiago Fernandes thanks the Fundacao para a Ciencia e Tecnologia (FCT) for the PhD grant SFRH/BD/130934/2017. The costs resulting from the FCT hirings is funded by national funds (OE), through FCT, I.P. in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29. Ana L. Daniel-da-Silva acknowledges FCT for the research contract under the Program 'Investigador FCT' 2014.