title: Photosensitization of CdSe/ZnS QDs and reliability of assays for reactive oxygen species production.
abstract: CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that can act as electron donors are said to be "photosensitized": that is, they are able to oxidize or reduce molecules whose redox potential lies inside their band edges, in particular molecular oxygen and water. This leads to the formation of reactive oxygen species (ROS) and phototoxicity. In this work, we quantify the generation of different forms of ROS from as-synthesized QDs in toluene; water-solubilized, unconjugated QDs; QDs conjugated to the neurotransmitter dopamine; and dopamine alone. Results of indirect fluorescent ROS assays, both in solution and inside cells, are compared with those of spin-trap electron paramagnetic resonance spectroscopy (EPR). The effect of these particles on the metabolism of mammalian cells is shown to be dependent upon light exposure and proportional to the amount of ROS generated.
authors.affiliation: Department of Biomedical Engineering, McGill University, 3775 Rue University, Montreal, QC, Canada. daniel.cooper@mail.mcgill.ca
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Cooper
authors.forename: Nada M
authors.initials: NM
authors.lastname: Dimitrijevic
authors.forename: Jay L
authors.initials: JL
authors.lastname: Nadeau
mesh_terms: D000818:Animals; D017209:Apoptosis; D019187:Cadmium Compounds / Q000737:chemistry*; D045744:Cell Line, Tumor; D004298:Dopamine / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D045663:Quantum Dots; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018036:Selenium Compounds / Q000737:chemistry*; D026082:Singlet Oxygen / Q000378:metabolism; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D017382:Reactive Oxygen Species; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D026082:Singlet Oxygen; C058667:cadmium selenide; C031238:zinc sulfide; D004298:Dopamine