A cytotoxicity study of fluorescent carbon nanodots using human bronchial epithelial cells.

The labeling of living cells with carbon nanoparticles has been increasingly studied both in vivo and in vitro, but concerns about the potential cytotoxicity of these nanoprobes are also increasing. In this study, the fluorescent carbon dots (CDs) without surface modification was synthesized and evaluated for its cytotoxicity. Indicators including cell viability, total reactive oxygen species (ROS), glutathione, malondialdehyde and lactate dehydrogenase were assessed using human bronchial epithelial (16HBE) cell line. Our results showed that CDs preferred to locate on the surface of cells, which significantly increased the membrane permeability of 16HBE cells. CDs exposure could further induce oxidative stress, exhaust the antioxidant defenses of cells and finally lead to decreased cell viability. Therefore, surface modification of CDs is needed to minimize its cytotoxicity. The present work is useful for the development of new strategies towards the in vitro and in vivo applications of CDs for optical imaging and drug delivery.