title: Singlet-oxygen-mediated cell death using spatially-localized two-photon excitation of an extracellular sensitizer.
abstract: Controlling and quantifying the photosensitized production of singlet oxygen are key aspects in mechanistic studies of oxygen-dependent photoinitiated cell death. In this regard, the commonly accepted practice of using intracellular photosensitizers is, unfortunately, plagued by problems that include the inability to accurately (1) quantify the sensitizer concentration in the irradiated domain and (2) control the local environment that influences light delivery and sensitizer photophysics. However, capitalizing on the fact that singlet oxygen produced outside a cell is also cytotoxic, many of these problems can be avoided with the use of an extracellular sensitizer. For the present study, a hydrophilic dendrimer-encased membrane-impermeable sensitizer was used to generate an extracellular population of singlet oxygen upon spatially localized two-photon irradiation. Through the use of this sensitizer and this approach, it is now possible to better control the singlet oxygen dose in microscope-based time- and space-resolved single cell experiments. Thus, we provide a solution to a limiting problem in mechanistic studies of singlet-oxygen-mediated cell death.
authors.affiliation: Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University , Aarhus 8000, Denmark.
authors.forename: Frederico M
authors.initials: FM
authors.lastname: Pimenta
authors.forename: Rasmus L
authors.initials: RL
authors.lastname: Jensen
authors.forename: Lotte
authors.initials: L
authors.lastname: Holmegaard
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Esipova
authors.forename: Michael
authors.initials: M
authors.lastname: Westberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Breitenbach
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ogilby
mesh_terms: D016923:Cell Death / Q000187:drug effects; D050091:Dendrimers / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017785:Photons; D017319:Photosensitizing Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D026082:Singlet Oxygen / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D050091:Dendrimers; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D026082:Singlet Oxygen