Abstract |
Several studies suggested that the cytotoxic effects of quantum dots (QDs) may be mediated by cadmium ions (Cd2+) released from the QDs cores. The objective of this work was to assess the intracellular Cd2+ concentration in human breast cancer MCF-7 cells treated with cadmium telluride (CdTe) and core/shell cadmium selenide/ zinc sulfide (CdSe/ZnS) nanoparticles capped with mercaptopropionic acid (MPA), cysteamine (Cys), or N-acetylcysteine (NAC) conjugated to cysteamine. The Cd2+ concentration determined by a Cd2+-specific cellular assay was below the assay detection limit (<5 nM) in cells treated with CdSe/ZnS QDs, while in cells incubated with CdTe QDs, it ranged from approximately 30 to 150 nM, depending on the capping molecule. A cell viability assay revealed that CdSe/ZnS QDs were nontoxic, whereas the CdTe QDs were cytotoxic. However, for the various CdTe QD samples, there was no dose-dependent correlation between cell viability and intracellular [Cd2+], implying that their cytotoxicity cannot be attributed solely to the toxic effect of free Cd2+. Confocal laser scanning microscopy of CdTe QDs-treated cells imaged with organelle-specific dyes revealed significant lysosomal damage attributable to the presence of Cd2+ and of reactive oxygen species (ROS), which can be formed via Cd2+-specific cellular pathways and/or via CdTe-triggered photoxidative processes involving singlet oxygen or electron transfer from excited QDs to oxygen. In summary, CdTe QDs induce cell death via mechanisms involving both Cd2+ and ROS accompanied by lysosomal enlargement and intracellular redistribution.
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Authors | Sung Ju Cho, Dusica Maysinger, Manasi Jain, Beate Röder, Steffen Hackbarth, Françoise M Winnik |
Journal | Langmuir : the ACS journal of surfaces and colloids
(Langmuir)
Vol. 23
Issue 4
Pg. 1974-80
(Feb 13 2007)
ISSN: 0743-7463 [Print] United States |
PMID | 17279683
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Cadmium Compounds
- Cations, Divalent
- Reactive Oxygen Species
- Cadmium
- Tellurium
- cadmium telluride
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Topics |
- Cadmium
(chemistry, pharmacology)
- Cadmium Compounds
(chemistry, toxicity)
- Cations, Divalent
(chemistry)
- Cell Survival
(drug effects)
- Humans
- Nanoparticles
(chemistry)
- Quantum Dots
- Reactive Oxygen Species
(metabolism)
- Signal Transduction
- Tellurium
(chemistry, toxicity)
- Time Factors
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