Synthesis of Yellow-Fluorescent Carbon Nano-dots by Microplasma for Imaging and Photocatalytic Inactivation of Cancer Cells

In recent years, multifunctional nanoparticles with combined diagnostic and therapeutic functions show great promise in nanomedicine. In this study, we report the environmentally friendly synthesis of fluorescent carbon nano-dots such as carbon quantum dots (CQDs) by microplasma using o-phenylenediamine. The produced CQDs exhibited a wide absorption peaks at 380–500 nm and emitted bright yellow fluorescence with a peak at 550 nm. The CQDs were rapidly taken up by HeLa cancer cells. When excited under blue light, a bright yellow fluorescence signal and intense reactive oxygen species (ROS) were efficiently produced, enabling simultaneous fluorescent cancer cell imaging and photodynamic inactivation, with a 40% decrease in relative cell viability. Furthermore, about 98% cells were active after the incubation with 400 μg mL−1 CQDs in the dark, which revealed the excellent biocompatibility of CQDs. Hence, the newly prepared CQDs are thus demonstrated to be materials which might be effective and safe to use for in vivo bioimaging and imaging-guided cancer therapy.