Figure 2. CdSe/ZnS QDs exhibited toxicity to NRK cells. (A) Cell viability of NRK cells treated with different doses of CdSe/ZnS QDs at 24 and 48 h using MTT assay. (B) Cell apoptosis of NRK cells treated with different doses of CdSe/ZnS QDs at 24 and 48 h using TUNEL staining. *P < 0.05 vs. 10 nM group or control group.