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.

作为一种新型荧光材料的碳点（CD）具有优异的水溶性，化学惰性和易于表面修饰的特性，因为它们的低毒性和良好的生物相容性使其成为生物成像和生物传感的理想选择。尽管碳不是本质上有毒的物质，但是碳纳米材料（例如CD）可能会危害人类健康，因此必须完全确定CD对各种生物系统的潜在危害。到目前为止，CD的细胞毒性研究集中在人类细胞上，并且主要在有限的细胞系上进行。在本研究中，对CDs的毒性评估是在酵母毕赤酵母中进行的。作为单细胞真核模型。结果显示与对照组相比，CD对酵母细胞的剂量依赖性毒性和25 mg / ml CD的相对细胞生长较少。CDs结合曲线证实了CDs和酵母细胞表面之间的相互作用。SEM图像表明，CD引起酵母细胞表面的细胞收缩和孔形成，并引起细胞的轻微变形。已经证明CD可以剂量依赖性地产生ROS。最后，结果表明，作为重要的环境因素，CD的生长抑制和ROS生成作用在光照下得到增强。这些发现可能会对CD的应用产生重要影响。