Comment on the: Molecular mechanism of CAT and SOD activity change under MPA-CdTe quantum dots induced oxidative stress in the mouse primary hepatocytes (Spectrochim Acta A Mol Biomol Spectrosc. 2019 Sep 5; 220:117104).

The paper by the authors Hau and Liu (Spectrochim Acta A Mol Biomol Spectrosc. 2019 Sep 5;220:117104) showed the effects of mercaptopropionic acid- CdTe quantum dots to the antioxidant enzymes catalase and superoxide dismutase molecules and then demonstrates the subsequent quantum dots toxic effects at a cellular level, and they proposed a mechanism of QD induced apoptosis and cell death involving oxidative stress, revealing their potential risk in the biomedical applications. QD concentrations were not determined according to the Cd concentrations in the QD that could be measured via ICP-MS. In conclusion, since cell viability above 80% as non-toxic based on ISO 10993-5, CdTe QDs cannot be considered as toxic. Also, according to the literature only CAT and SOD enzyme activities are not enough to claim oxidative stress formation.