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Single Cell Responses to Spatially Controlled Photosensitized Production of Extracellular Singlet Oxygen
Author(s) -
Pedersen Brian W.,
Sinks Louise E.,
Breitenbach Thomas,
Schack Nickolass B.,
Vinogradov Sergei A.,
Ogilby Peter R.
Publication year - 2011
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2011.00951.x
Subject(s) - singlet oxygen , photosensitizer , photochemistry , photodynamic therapy , hela , oxygen , chemistry , biophysics , intracellular , programmed cell death , singlet state , cell , apoptosis , biochemistry , biology , excited state , organic chemistry , physics , nuclear physics
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 postirradiation “waiting period” before necrosis became apparent depended on: (1) the distance between the cell membrane and the domain irradiated, (2) the incident laser fluence and, as such, the initial concentration of singlet oxygen produced and (3) 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.