Estudo das interações de porfirinas com sistemas de interesse biológico: potencial uso no transporte de fármacos e aplicação fotodinâmica
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2019-08-23
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Universidade Federal de Goiás
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The purpose of this work was to study the interactions of porphyrins in systems of
biological interest aiming at drug transport and photodynamic applications. Interactions of
anionic meso-tetrakis(p-sulphonatephenyl) porphyrin (TPPS4) and cationic meso-tetrakis (4-
methyl-pyridyl) porphyrin (TMPyP) porphyrins with bovine serum albumin (BSA), antibodies,
DNA and biocompatible nanoparticles of maghemite were evaluated. To obtain the binding
constants and thermodynamic parameters, spectroscopic UV/Vis absorption and fluorescence
techniques were used. Binding constants indicate a higher affinity of porphyrin TPPS4 for
proteins compared to TMPyP. Thermodynamic parameters showed that electrostatic and
hydrophobic interactions mediated the BSA interactions with the porphyrins TPPS4 and
TMPyP, respectively. On the other hand, the nature of porphyrin-antibody interactions shows
a behavior opposite to that observed for BSA (electrostatic for TMPyP and hydrophobic for
TPPS4), indicating that the binding site of porphyrin TMPyP in the antibodies is likely to have
a net negative charge. In the porphyrin TPPS4 interaction with maghemite nanoparticles,
besides obtaining the binding parameters of the interaction, it was possible to estimate the
number of 21 porphyrins coupled in each nanoparticle. Regarding the interaction of DNA with
the porphyrins TPPS4, TMPyP and its complexes with zinc, it was observed that ZnTMPyP has
higher affinity for DNA than TMPyP, whereas TPPS4 and ZnTPPS4 do not bind to DNA, which
explains the results of photodegradation of DNA by these porphyrins.
Keywords: Photodynamic
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BEZERRA, F. C. Estudo das interações de porfirinas com sistemas de interesse biológico: potencial uso no transporte de fármacos e aplicação fotodinâmica. 2019. 71 f. Tese (Doutorado em Fisica) - Universidade Federal de Goiás, Goiânia, 2019.