title: Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.
abstract: Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.
authors.affiliation: Department of Biomedical Engineering, McGill University, 3775 Rue University, Montreal, QC H3A 2B4, Canada.
authors.forename: Hicham
authors.initials: H
authors.lastname: Chibli
authors.forename: Lina
authors.initials: L
authors.lastname: Carlini
authors.forename: Soonhyang
authors.initials: S
authors.lastname: Park
authors.forename: Nada M
authors.initials: NM
authors.lastname: Dimitrijevic
authors.forename: Jay L
authors.initials: JL
authors.lastname: Nadeau
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry / Q000378:metabolism*; D007204:Indium / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry / Q000494:pharmacology*; D045663:Quantum Dots; D012235:Rhodamines / Q000737:chemistry / Q000494:pharmacology; D013440:Sulfides / Q000737:chemistry / Q000494:pharmacology*; D013481:Superoxides / Q000737:chemistry / Q000378:metabolism*; D017967:Zinc Compounds / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D010720:Phosphines; D012235:Rhodamines; D013440:Sulfides; D017967:Zinc Compounds; D007204:Indium; D013481:Superoxides; C022027:lissamine rhodamine B; D017665:Hydroxyl Radical; C031238:zinc sulfide; C090882:indium phosphide