title: Kinetics of singlet oxygen photosensitization in human skin fibroblasts.
abstract: The roles played by singlet oxygen ((1)O(2)) in photodynamic therapy are not fully understood yet. In particular, the mobility of (1)O(2) within cells has been a subject of debate for the last two decades. In this work, we report on the kinetics of (1)O(2) formation, diffusion, and decay in human skin fibroblasts. (1)O(2) has been photosensitized by two water-soluble porphyrins targeting different subcellular organelles, namely the nucleus and lysosomes, respectively. By recording the time-resolved near-IR phosphorescence of (1)O(2) and that of its precursor the photosensitizer's triplet state, we find that the kinetics of singlet oxygen formation and decay are strongly dependent on the site of generation. (1)O(2) photosensitized in the nucleus is able to escape out of the cells while (1)O(2) photosensitized in the lysosomes is not. Despite showing a lifetime in the microsecond time domain, (1)O(2) decay is largely governed by interactions with the biomolecules within the organelle where it is produced. This observation may reconcile earlier views that singlet oxygen-induced photodamage is highly localized, while its lifetime is long enough to diffuse over long distances within the cells.
authors: Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain.
authors: Ana
authors: A
authors: Jiménez-Banzo
authors: M Luisa
authors: ML
authors: Sagristà
authors: Margarita
authors: M
authors: Mora
authors: Santi
authors: S
authors: Nonell
mesh_terms: D049109:Cell Proliferation; D002478:Cells, Cultured; D003624:Darkness; D005347:Fibroblasts / Q000187:drug effects / Q000528:radiation effects*; D006801:Humans; D007700:Kinetics; D008027:Light; D008858:Microscopy, Phase-Contrast; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011166:Porphyrins / Q000494:pharmacology; D026082:Singlet Oxygen / Q000494:pharmacology*; D012867:Skin / Q000187:drug effects / Q000528:radiation effects*; D013347:Subcellular Fractions
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D026082:Singlet Oxygen; C016136:tetraphenylporphine sulfonate; C021096:tetra(4-N-methylpyridyl)porphine