Blue and cyan fluorescent carbon dots: one-pot synthesis, selective cell imaging and their antiviral activity

Carbon dots (CDs) have demonstrated attractive potential in cell imaging and tracking. However, one of the most challenge problems is the selective entrance of CDs into the cytoplasm or cell nucleus. Here, a facile strategy was developed to prepare two types of CDs capable of selective entrance into cytoplasm and the whole cell without further surface modification. The surface charge of CDs changes from negative to neutral after the addition of urea in the hydrothermal process, and the as-prepared CDs exhibit different fluorescent colors. The blue-fluorescent CDs (b-CDs) can only enter the cytoplasm, while the cyan fluorescent CDs (c-CDs) can distribute over the whole cell, including the nucleus. Additionally, the antiviral activity of the two CDs against pseudorabies virus (PRV) was studied and b-CDs were shown to have better antiviral activity. This study has provided a facile and novel strategy for the fabrication of CDs used in selective cell imaging, which may facilitate the application of CDs in nanomedicine.