Estudo das interações de porfirinas com sistemas de interesse biológico: potencial uso no transporte de fármacos e aplicação fotodinâmica

• Autor(a) principal: Bezerra, Fábio de Castro
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/0013000004m0s
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/12234
• topic: Terapia fotodinâmica; Porfirinas; Biomoléculas; Interação; Photodynamic therapy; Porphyrins; Biomolecules; Interaction; CIENCIAS EXATAS E DA TERRA::FISICA::FISICA GERAL

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