Pedersen, Brian Wett5; Sinks, Louise E.3; Breitenbach, Thomas6; Schack, Nickolass Bitsch1; Vinogradov, Sergei A.3; Ogilby, Peter Remsen6
1 Department of Chemistry, Faculty of Science, Aarhus University, Aarhus University2 Department of Biomedicine - Forskning og uddannelse, Syd, Department of Biomedicine, Health, Aarhus University3 University of Pennsylvania4 Department of Chemistry, Science and Technology, Aarhus University5 Department of Biomedicine - Forskning og uddannelse, Syd, Department of Biomedicine, Health, Aarhus University6 Department of Chemistry, Science and Technology, Aarhus University
The response of individual HeLa cells to extracellularly produced singlet oxygen was examined. The spatial domain of singlet oxygen production was controlled using the combination of a membrane-impermeable Pd porphyrin-dendrimer, which served as a photosensitizer, and a focused laser, which served to localize the sensitized production of singlet oxygen. Cells in close proximity to the domain of singlet oxygen production showed morphological changes commonly associated with necrotic cell death. The elapsed post-irradiation “waiting period” before necrosis became apparent depended on (a) the distance between the cell membrane and the domain irradiated, (b) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced, and (c) the lifetime of singlet oxygen. The data imply that singlet oxygen plays a key role in this process of light-induced cell death. The approach of using extracellularly-generated singlet oxygen to induce cell death can provide a solution to a problem that often limits mechanistic studies of intracellularly photosensitized cell death: it can be difficult to quantify the effective light dose, and hence singlet oxygen concentration, when using an intracellular photosensitizer.
Photochemistry and Photobiology, 2011, Vol 87, p. 1077-1091