Cellular Toxicity of Zinc Quantum Dots in a Mammalian Model (CHO Cells)

The production of quantum dots (QDs) has increased due to their wide variety of commercial products and applications. QDs can be dangerous in the environment because their small size can encourage their incorporation into living systems. In this project, ZnS and ZnSSe were synthesized under microwave irradiation, generating a water-stable nanomaterial. The bandgap energies calculated using the UV-Vis spectra were 3.81 and 3.86 eV for ZnS and ZnSSe QDs, respectively, indicating that the selenium worked as a dopant agent. The photoluminescence analysis shows narrow emission peaks, confirming a low size distribution, and the selenium doping generated a blue shift. The crystal size of both nanomaterials was around 7 nm. The cellular toxicity of these nanomaterials was evaluated using Chinese Hamster Ovary (CHO) Cells (a standard mammalian cell model). The results suggest that ZnS and ZnSSe QDs slightly affect the viability of CHO Cells, but Zn2+ decreases the viability at concentrations higher than 20 mg/L. The content of zinc inside cells (by ICP-OES) suggested that QDs can enter cells more easily than Zn2+. Therefore, the decrease in cell viability caused by Zn2+ outside the cells is likely due to its effect on cell membrane integrity, suggesting that these nanomaterials are less toxic than bulk materials.