Carbon Quantum Dots: In vitro and in vivo Studies on Biocompatibility and Biointeractions for Optical Imaging

Xiumei Tian1 ,* Ao Zeng1 ,* Ziying Liu,1 Cunjing Zheng,2 Yuezi Wei,1 Peiheng Yang,1 Minru Zhang,1 Fanwen Yang,1 Fukang Xie1 1School of Basic Medical Sciences, Affiliated Stomatology Hospital, Guangzhou Medical University, Guangzhou 510182, People’s Republic of China; 2Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fukang Xie Tel +86 20 136 4231 6682Email 378141679@qq.comFanwen Yang Tel +86 20 135 0308 0690Fax +86 20 3710 3509Email yangfanwen@163.comBackground: Understanding the biocompatibility and biointeractions of nano-carbon quantum dots (nano-CQDs) in vitro and in vivo is important for assessing their potential risk to human health. In the previous research, the physical properties of CQDs synthesized by the laser ablation in liquid (LAL) method were analyzed in detail; however, possible bioapplications were not considered.Materials and Methods: CQDs were prepared by LAL and characterized by atomic force microscopy, fluorescence lifetime, absorption spectrum, Fourier-transform infrared spectroscopy, and dynamic light scattering. Their biocompatibility was evaluated in vitro using assays for cytotoxicity, apoptosis, and biodistribution and in vivo using immunotoxicity and the relative expression of genes. Cells were measured in vitro using fluorescence-lifetime imaging microscopy to analyze the biointeractions between CQDs and intracellular proteins.Results: There were no significant differences in biocompatibility between the CQDs and the negative control. The intracellular interactions had no impact on the optical imaging of CQDs upon intake by cells. Optical imaging of zebrafish showed the green fluorescence was well dispersed.Conclusion: We have demonstrated that the CQDs have an excellent biocompatibility and can be used as efficient optical nanoprobes for cell tracking and biomedical labeling except for L929 and PC-3M cells.Keywords: nanoprobe, immunotoxicity, biodistribution, biointeraction, optical imaging