• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Master's Dissertation
DOI
10.11606/D.75.2009.tde-25082009-163731
Document
Author
Full name
Rafael Frederice
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2009
Supervisor
Committee
Gehlen, Marcelo Henrique (President)
Fertonani, Iêda Aparecida Pastre
Rodembusch, Fabiano Severo
Title in Portuguese
Fluorescência molecular em nanopartículas de sílica marcadas com quercetina e rodamina B
Keywords in Portuguese
espectroscopia de fluorescência
fluoróforos
hidrólise alcalina
nanopartículas de sílica
Abstract in Portuguese
Nanoesferas de sílica contendo fluoróforos encapsulados (o complexo quercetina- Al+3 e o corante rodamina B) foram preparadas com alto controle de tamanho e morfologia, utilizando catálise ácida e básica do tetraetilortossilicato (TEOS). As nanopartículas obtidas apresentaram diâmetro da ordem de 200-300 nm, possuindo maior regularidade quando preparadas em meio alcalino. Nas preparações foram utilizados o método de Stöber e o método caroço-casca. Devido à hidrólise da quercetina em meio básico, as partículas funcionalizadas com o flavonóide ou com o complexo quercetina-Al+3, apresentaram maior intensidade de emissão sob catálise ácida. No caso da catálise básica, as partículas apresentaram emissão significativa quando preparadas utilizando um sol de alumina, porém foram obtidos paralelepípedos nanométricos. Os decaimentos de fluorescência para o sistema quercetina-alumina são biexponenciais, em concordância com os dois complexos quercetina-Al+3 formados no interior da nanopartícula de sílica. No caso da rodamina B, foram realizadas medidas de espectroscopia de correlação de fluorescência, que mostraram uma relação entre relaxação difusional com tamanho e autoagregação das partículas.
Title in English
Molecular fluorescence in silica nanoparticles doped with quercetin and rhodamine B
Keywords in English
alkaline hydrolysis
fluorescence spectroscopy
fluorophores
silica nanoparticles
Abstract in English
Silica nanospheres doped with quercetin-Al+3 and rhodamine B were synthesized with high size control and morphology, using acid and basic catalysis of tetraethylorthosilicate (TEOS). The nanoparticle diameter obtained was about 200- 300 nm, with higher regularity when synthesized in alkaline media. The Stöber's and core-shell methods were used as preparation methods. Because the alkaline hydrolysis of quercetin, the flavonoid or the quercetin-Al+3 complex doped nanoparticles showed higher emission intensity when acid catalysis was used. When basic catalysis was performed, the particles prepared with an alumina-sol showed expressive emission intensity, but nanometric parallelepipeds were obtained. The quercetin-alumina fluorescence decays are biexponential, agreeing with the two types of quercetin-Al+3 complexes formed in the nanoparticles domain. In the case of rhodamine B, fluorescence correlation spectroscopy (FCS) measurements were performed, showing a relation between diffusion relaxation with size and aggregation behavior.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
RafaelFrederice.pdf (2.73 Mbytes)
Publishing Date
2009-08-26
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.