Complete transformation of ZnO and CuO nanoparticles in culture medium and lymphocyte cells during toxicity testing.
Here, we present evidence on complete transformation of ZnO and CuO nanoparticles, which are among the most heavily studied metal oxide particles, during 24 h in vitro toxicological testing with human T-lymphocytes. Synchrotron radiation-based X-ray absorption near edge structure (XANES) spectroscopy results revealed that Zn speciation profiles of 30 nm and 80 nm ZnO nanoparticles, and ZnSO4- exposed cells were almost identical with the prevailing species being Zn-cysteine. This suggests that ZnO nanoparticles are rapidly transformed during a standard in vitro toxicological assay, and are sequestered intracellularly, analogously to soluble Zn. Complete transformation of ZnO in the test conditions was further supported by almost identical Zn spectra in medium to which ZnO nanoparticles or ZnSO4was added. Likewise, Cu XANES spectra for CuO and CuSO4-exposed cells and cell culture media were similar. These results together with our observation on similar toxicological profiles of ZnO and soluble Zn, and CuO and soluble Cu, underline the importance of dissolution and subsequent transformation of ZnO and CuO nanoparticles during toxicological testing and provide evidence that the nano-specific effect of ZnO and CuO nanoparticles is negligible in this system. We strongly suggest to account for this aspect when interpreting the toxicological results of ZnO and CuO nanoparticles.
a Future Industries Institute, University of South Australia , Mawson Lakes , Australia.
Angela
A
Ivask
b National Risk Management Research Laboratory , US Environmental Protection Agency , Cincinnati , OH , USA.
Kirk G
KG
Scheckel
a Future Industries Institute, University of South Australia , Mawson Lakes , Australia.
Pankaj
P
Kapruwan
c Heriot-Watt University , Edinburgh , UK.
Vicki
V
Stone
d CSIRO Manufacturing , Clayton , Australia.
Hong
H
Yin
a Future Industries Institute, University of South Australia , Mawson Lakes , Australia.
Nicolas H
NH
Voelcker
a Future Industries Institute, University of South Australia , Mawson Lakes , Australia.
Enzo
E
Lombi
D002470:Cell Survival / Q000187:drug effects; D003300:Copper / Q000737:chemistry / Q000633:toxicity*; D003470:Culture Media; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D012995:Solubility; D013499:Surface Properties; D013601:T-Lymphocytes / Q000187:drug effects*; D018675:Toxicity Tests; D056928:X-Ray Absorption Spectroscopy; D015034:Zinc Oxide / Q000737:chemistry / Q000633:toxicity*
D003470:Culture Media; D003300:Copper; D015034:Zinc Oxide; C030973:cupric oxide
Copper oxide; mammalian cells; nanoparticles; speciation; zinc oxide