Effects of silver sulfide quantum dots coated with 2-mercaptopropionic acid on genotoxic and apoptotic pathways in vitro

Quantum dots (QDs) are highly promising nanomaterials in bioimaging system because of their bright fluorescence, broad UV excitation, narrow emission band, and high photostability. Recently, there is a great activity on Ag2S quantum dots for both imaging and drug/gene delivery due to the potential of having a better cytocompatability and near infrared luminescence. 2-Mercaptopropionic acid (2 MP A)-coated silver sulfide (Ag2S) QDs were reported as the most luminescent, stable, anionic Ag2S QDs in the literature. In this study, we aim to determine the cytotoxicity of 2 MP A/Ag2S in Chinese hamster lung fibroblast (V79) cells. The genotoxic and apoptotic effects of 2 MP A/Ag2S QDs were assessed by the alkaline single cell electrophoresis assay and real time polymerase chain reaction techniques, respectively. The cell viability decreased above 200 μg/ml and 800 μg/ml for MTT tetrazolium and neural red uptake assays, respectively. DNA damage was not observed by 2 MP A/Ag2S QDs at the studied concentration levels (5-2000 μg/ml). The levels of mRNA expression of p53, caspase 3, caspase 9, bax, bcl-2, survivin were not changed by 2 MP A/Ag2S QDs below IC50 (around 1000 μg/ml). Hence, 2 MP A/Ag2S QDs did not show any cytotoxic or genotoxic effects in V79 cells at lower doses. We conclude that the biocompatibility of 2 MP A/Ag2SODs makes them suitable for cell labeling applications.