Towards tuning PDT relevant photosensitizer properties: comparative study for the free and Zn2+ coordinated meso-tetrakis[2,6-difluoro-5-(N-methylsulfamylo)phenyl]porphyrin |
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Authors: | Janusz M Dąbrowski Barbara Pucelik Mariette M Pereira Luis G Arnaut |
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Institution: | 1. Faculty of Chemistry, Jagiellonian University, Kraków, Polandjdabrows@chemia.uj.edu.pl;3. Faculty of Chemistry, Jagiellonian University, Kraków, Poland;4. Chemistry Department, University of Coimbra, Coimbra, Portugal;5. Luzitin SA, Coimbra, Portugal |
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Abstract: | The spectroscopic, photochemical, and biological studies of 5,10,15,20-tetrakis2,6-difluoro-5(N-methylsulfamylo)phenyl]porphyrinate Zn(II) (ZnF2PMet) were carried out including absorption and fluorescence spectra, fluorescence quantum yields, triplet absorption spectra, triplet lifetimes, singlet oxygen quantum yield, and reactive oxygen species (ROS) detection under biological conditions and compared with its free-base analog (F2PMet). Zinc coordination into the porphyrin ring results in decrease of hydrophobicity and in higher cellular uptake. F2PMet localized specifically in endoplasmic reticulum and mitochondria while the ZnF2PMet is more diffused all over the cell, bonded to membrane proteins, as assessed by fluorescence microscopy. Zn-porphyrin exhibits greater singlet oxygen quantum yield than its free-base analog. Studies with fluorescent probes confirm that the ZnF2PMet produces mostly singlet oxygen, whereas F2PMet generates more hydroxyl radicals as the ROS. F2PMet is a more effective photosensitizer in vitro than its zinc complex, thus, the final photodynamic effect depends more on the nature of ROS than on the higher cellular uptake. |
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Keywords: | Metalloporphyrins Zn(II) complexes Photodynamic therapy Singlet oxygen Hydroxyl radicals |
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