Facile synthesis of phosphorus and nitrogen co-doped carbon dots with excellent fluorescence emission towards cellular imaging.

Fluorescent carbon nanomaterials have attracted increasing attention owing to their unique photoluminescence properties, good biocompatibility and low toxicity in bioimaging as well as biosensing. Heteroatom doping is usually used to improve photoluminescence properties by tuning the functional groups and the particle size domain effect, thus leading to redshifted emission. Here, we report a straightforward strategy for the fabrication of a mixture of fluorescent phosphorus and nitrogen carbon nanodots (P,N-CDs) followed by separating two kinds of fluorescent fractions based on their different negative charges.