Implantação das técnicas espectroscópicas de Laser FlashFotólise e de fosforescência para estudos fotofísicos de sistemas porfirínicos e suas interações com biomoléculas e nanoestruturas
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2023-12-14
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Universidade Federal de Goiás
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The photophysical characterization allows the assessment of processes
following the phenomenon of light absorption, which is of interest for various
applications, both in the field of materials chemistry and in photomedicine. This
work aimed at the photophysical characterization of potential porphyrinic
photosensitizers and their interaction with biomolecular systems and
nanostructures. To achieve this, the spectroscopic techniques of Transient
Absorption (or Laser Flash-Photolysis) and a Spectrophosphorimeter were
implemented, and their usage protocols were established. With these techniques
in operation, an alternative method for determining the triplet state formation
yield and obtaining the singlet oxygen formation yield was proposed,
fundamental properties for the characterization of photosensitizers. It was
possible to investigate the interaction of water-soluble porphyrins with bovine
serum albumin and verify that this interaction affects the triplet states lifetimes
and singlet oxygen yields. These parameters were strongly influenced by the
presence of oxygen and the porphyrin's location at the interaction sites in the
protein structure. Another study conducted was the interaction of cationic
porphyrins with manganese ferrite (FeMn2O4) anionic ferrofluids in which the
interaction leads to the suppression of fluorescence and singlet oxygen (1O2)
generation of the photosensitizers. Interestingly, this interaction is not
predominantly governed by electrostatic interactions but mainly through
chemsorptives and physisorptives interactions. Additionally, it was
demonstrated that photothermal heating breaks the interaction with the
nanostructure, restoring the photophysical properties of the photosensitizer,
making this system a multifunctional nanostructure with luminescent and
theranostics properties.
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ALVES JR., E. S. Implantação das técnicas espectroscópicas de Laser FlashFotólise e de fosforescência para estudos fotofísicos de sistemas porfirínicos e suas interações com biomoléculas e nanoestruturas. 2024. 211 f. Tese (Doutorado em Química) - Instituto de Química, Universidade Federal de Goiás, Goiânia, 2023.