Propriedades ópticas de membranas à base de polímeros naturais e nanopartículas de carbono
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Data
2016-12-21
Autores
Caetano, Laís Galvão [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A fibroína da seda extraída dos casulos do bicho-da-sêda é um co-polímero particularmente atraente para aplicações em dispositivos fotônicos e opticoeletrônicos devido a sua transparência óptica, biocompatibilidade e propriedades mecânicas. Esta tese apresenta a obtenção de suspensões e filmes iridescentes-luminescentes de fibroína contendo nanopartículas luminescentes de carbono (“carbon dots”) obtidos a partir de carvão vegetal. As nanopartículas luminescentes de carbono apresentam biocompatibilidade, baixa toxicidade, propriedades de fotoluminescência interessantes e possibilidade de modificação da superfície. Redes de difração foram produzidas nestes filmes utilizando como molde um DVD comercial. Os materiais obtidos foram caracterizados por um conjunto de técnicas de análise: Microscopia de Força Atômica (AFM), Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (MET), Espectroscopia de absorção na região do UVVis, Espectrofotometria de absorção molecular na região do infravermelho com transformada de Fourier (FTIR) e Luminescência. Medidas de luminescência mostram que os carbon dots emitem múltiplas cores entre toda a região do visível. Planos cristalinos foram observados nas imagens de MET das nanopartículas, no qual foram asssociadas a estrutura do grafite. Pela análise de UV-Vis dos carbon dots observou-se que a absorção óptica decai gradualmente à medida em que ocorre deslocamento para o vermelho e para os filmes de fibroína observou-se um ombro referente a transição eletrônica da tirosina (aminoácido de sua composição). A partir dos espectros de FTIR observou-se que não houve mudança na estrutura da fibroína após a adição dos carbon dots. As imagens de AFM e MEV comprovam a presença dos micropadrões periódicos na superfície dos filmes. Os resultados mostraram que os filmes de fibroína contendo carbono dots tem um grande potencial para a biomedicina, principalmente devido os seus parâmetros de luminescência se extenderem em toda a região do visível e por apresentar uma matriz sustentável, com excelentes propriedades ópticas e mecânicas.
Silk fibroin extracted from silkworm cocoons is a particularly attractive copolymer for applications in photonics and optoelectronics devices due its optical transparency, biocompatibility and high mechanical strength. This thesis presents the preparation of suspensions and iridescent-luminescent films of silk fibroin containing luminescent carbon nanoparticles (carbon dots) obtained from vegetal coal. Luminescent carbon nanoparticles present high biocompatibility, low toxicity, interesting photoluminescence properties and possibility of surface modification. Diffraction gratings were produced in these films using a commercial DVD as a template. The materials obtained were characterized by a set of analysis techniques: Atomic-Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV-Visible Spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Luminescence. Luminescence measurements show that carbon dots emit light at the entire visible region. Crystalline planes were observed in the TEM images of the nanoparticles, where upon the graphite structure was associated. By analyzing the UV-Vis spectra of the carbon dots it was observed that the optical absorption gradually decreases as the red shift occurs. In the UV-Vis spectra of the silk fibroin films it was observed a shoulder referring to the electronic transition of the tyrosine (amino acid of its composition). From the FTIR spectra it was observed that there was no change in the silk fibroin structure after addition of the carbon dots. The AFM and SEM images confirm the presence of the periodic micro-patterns on the surface of the films. The results showed that the silk fibroin films containing carbon dots have a great potential for biomedicine, mainly due to its luminescence parameters extending throughout the visible region and due to a sustainable platform with excellent optical and mechanical properties.
Silk fibroin extracted from silkworm cocoons is a particularly attractive copolymer for applications in photonics and optoelectronics devices due its optical transparency, biocompatibility and high mechanical strength. This thesis presents the preparation of suspensions and iridescent-luminescent films of silk fibroin containing luminescent carbon nanoparticles (carbon dots) obtained from vegetal coal. Luminescent carbon nanoparticles present high biocompatibility, low toxicity, interesting photoluminescence properties and possibility of surface modification. Diffraction gratings were produced in these films using a commercial DVD as a template. The materials obtained were characterized by a set of analysis techniques: Atomic-Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV-Visible Spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Luminescence. Luminescence measurements show that carbon dots emit light at the entire visible region. Crystalline planes were observed in the TEM images of the nanoparticles, where upon the graphite structure was associated. By analyzing the UV-Vis spectra of the carbon dots it was observed that the optical absorption gradually decreases as the red shift occurs. In the UV-Vis spectra of the silk fibroin films it was observed a shoulder referring to the electronic transition of the tyrosine (amino acid of its composition). From the FTIR spectra it was observed that there was no change in the silk fibroin structure after addition of the carbon dots. The AFM and SEM images confirm the presence of the periodic micro-patterns on the surface of the films. The results showed that the silk fibroin films containing carbon dots have a great potential for biomedicine, mainly due to its luminescence parameters extending throughout the visible region and due to a sustainable platform with excellent optical and mechanical properties.
Descrição
Palavras-chave
Fibroína da seda, Carbon dots, Silk fibroin, Carbon dots