Cytotoxicity and immune response of CdSe/ZnS Quantum dots towards a murine macrophage cell line

The quantum dots (QDs) community has raised great concerns about the exposure and possible cytotoxicity impact of QDs to biological systems since the majority of QDs are made from heavy metals such as cadmium and lead. It is well known that macrophage cells serve as the first line of immune defense against exogenous substances, but the toxicity of QDs on macrophages remains poorly understood to date and some reported literature even have shown inconsistent results. In this study, we aimed at investigating the cytotoxicity and immune response of CdSe/ZnS QDs in mouse macrophage cells. Our confocal images showed that CdSe/ZnS QDs were captured by macrophages and were located in the cytoplasmic region. The flow cytometry assay showed that the uptake efficiency of QDs within cells was as high as 90%. More importantly, the cells treated with QDs showed a decrease in the cell viability and an enhanced gene transcription of cytokines IL-6 and TNF alpha was observed, but no changes were detected in the mechanism of releasing cytokines IL-6 and TNF alpha in the cells. These results suggest that the treatment of CdSe/ZnS QDs is indeed affecting the cell viability of the macrophages but did not cause any obvious immune response changes in the cells.