Desenvolvimento de materiais híbridos baseados em nanopartículas de sílica densa decoradas com grupos carboxilatos e complexos luminescentes de európio
Data
2019-03-01
Autores
Santos, João Antonio Oliveira
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Biomarcadores luminescentes a base de íons lantanídeos tivalentes (Ln3+) vêm sendo aplicados como sondas luminescentes em imageamento celular e marcação biológica devido às suas excelentes propriedades óticas. Sua obtenção pode ser feita pela funcionalização da superfície de nanopartículas de sílica com complexos de lantanídeos, assim um novo material híbrido é formado unindo as propriedades luminescentes do complexo com a alta estabilidade e baixa toxicidade da matriz de sílica. Este trabalho teve como objetivo principal a caracterização morfológica, estrutural e espectroscópica de novos híbridos luminescentes obtidos através da decoração da superfície de nanopartículas de sílica com grupos ácidos carboxílicos responsáveis por intermediar a formação de complexos de Eu3+ utilizando o ligante dicetonato, Hdbm (dibenzoilmetano). Desta forma, esses híbridos luminescentes foram sintetizados através de uma sequência de cinco etapas reacionais. Primeiramente, nanopartículas de sílica esféricas/esferoidais foram sintetizadas via metodologia sol-gel e através de medidas de MEV-FEG foram estimados diâmetros médios entre 32 e 80 nm. As posteriores etapas de modificação de superfície foram avaliadas principalmente pelas técnicas de MEV-FEG, EDS, RMN-29Si, Termogravimetria, Potencial Zeta, FTIR, Raman/SERS e Fotoluminescência. As propriedades luminescentes dos híbridos foram avaliadas e observou-se que os grupos carboxilatos superficiais não sensibilizam os íons Eu3+ por efeito antena, servindo apenas de sítios quelantes para o íon. Os híbridos luminescentes formados após a coordenação dos ligantes dbm ao íon Eu3+ apresentaram forte luminescência na região do vermelho e tiveram seus parâmetros de intensidade avaliados, eles ainda apresentaram elevada pureza de cor e alto tempo de vida de estado excitado, fazendo destes materiais excelentes candidatos a atuarem como futuros biomarcadores.
Luminescent biomarkers based on trivalent lanthanoide (IUPAC recommendation) ions (Ln3+) have been applied as luminescent probes in cellular imaging and biological labeling due to their excellent optical properties. They can be obtained by the surface functionalization of silica nanoparticles with lanthanoide complexes, thus a novel hybrid material is formed by joining the luminescent properties of the complex with the high stability and low toxicity of the silica matrix. The main aim of this work was the morphological, structural and spectroscopic characterization of new luminescent hybrids obtained through the decoration of the silica nanoparticles with carboxylic acid groups responsible for intermediating the formation of Eu3+ complexes using the β-diketone ligand, Hdbm (dibenzoilmetano). In this way, these luminescent hybrids were synthesized through a sequence of five reactional steps. First, spherical / spheroidal silica nanoparticles were synthesized via the sol-gel methodology and diameters between 32 and 80 nm were estimated were estimated by through SEM-FEG. Subsequent surface modification steps were evaluated mainly by SEM-FEG, EDS, 29Si NMR, Thermogravimetry, Zeta Potential, FTIR, Raman / SERS and Photoluminescence techniques. The luminescent properties of the hybrids were evaluated and it was observed that surface carboxylate groups do not sensitize Eu3+ ions by antenna effect, serving only as chelating sites . The luminescent hybrids formed only after the Eu3+ ion coordination with dbm ligands e showed strong luminescence in the red region, their intensity parameters were evaluated, and they presented high color purity and high-excited state lifetime, and they, making these materials excellent candidates to act as future biomarkers.
Luminescent biomarkers based on trivalent lanthanoide (IUPAC recommendation) ions (Ln3+) have been applied as luminescent probes in cellular imaging and biological labeling due to their excellent optical properties. They can be obtained by the surface functionalization of silica nanoparticles with lanthanoide complexes, thus a novel hybrid material is formed by joining the luminescent properties of the complex with the high stability and low toxicity of the silica matrix. The main aim of this work was the morphological, structural and spectroscopic characterization of new luminescent hybrids obtained through the decoration of the silica nanoparticles with carboxylic acid groups responsible for intermediating the formation of Eu3+ complexes using the β-diketone ligand, Hdbm (dibenzoilmetano). In this way, these luminescent hybrids were synthesized through a sequence of five reactional steps. First, spherical / spheroidal silica nanoparticles were synthesized via the sol-gel methodology and diameters between 32 and 80 nm were estimated were estimated by through SEM-FEG. Subsequent surface modification steps were evaluated mainly by SEM-FEG, EDS, 29Si NMR, Thermogravimetry, Zeta Potential, FTIR, Raman / SERS and Photoluminescence techniques. The luminescent properties of the hybrids were evaluated and it was observed that surface carboxylate groups do not sensitize Eu3+ ions by antenna effect, serving only as chelating sites . The luminescent hybrids formed only after the Eu3+ ion coordination with dbm ligands e showed strong luminescence in the red region, their intensity parameters were evaluated, and they presented high color purity and high-excited state lifetime, and they, making these materials excellent candidates to act as future biomarkers.
Descrição
Palavras-chave
SiO2, Processo sol-gel, Luminescência, Lantanídeo, Ácido carboxílico, Sol-gel process, Luminescence, Lanthanoids, Carboxylic acid