Investigation the cytotoxicity and photo-induced toxicity of carbon dot on yeast cell.

Carbon dots (CDs) as a new fluorescent material with excellent water solubility, chemical inertness, and easy surface modification are a good candidate for bioimaging and biosensing due to their low toxicity and good biocompatibility. Although carbon is not an intrinsically toxic substance, carbon nanomaterials such as CDs may cause risks to human health and the potentially hazardous effects of CDs on various living systems must be completely determined. So far, cytotoxicity studies of CDs have focused on human cells and are mainly conducted on limited cell lines. In the present study, toxicity assessment of CDs was evaluated on yeast cells Pichia pastoris as a unicellular eukaryotic model. Results revealed dose-dependent toxicity of CDs on yeast cells and less relative cell growth in 25 mg/ml of CDs as compared to the control group. CDs binding curve confirmed the interaction between CDs and surface of yeast cells. SEM images showed that the CDs caused cell shrinkage and hole formation on the surface of yeast cells and also induced slightly cell deformation. It was demonstrated that CDs could generate the ROS dose-dependently. Finally, results showed the growth inhibition and ROS generation effects of CDs were enhanced at light exposure, as an important environmental factor. These findings could have important implications for applications of CDs.