Arginine-modified carbon dots probe for live cell imaging and sensing by increasing cellular uptake efficiency.

As a new family of nanomaterials, carbon dots (CDs) have been reported to enable to penetrate plasma membrane and show fluorescence in cells due to their small sizes and fluorescent properties. However, development of CDs as effective cellular imaging probes still remains a challenge, since they have relatively low efficiency of cell permeability which is difficult to be detected by a commonly used fluorescence microscope. Here we introduce arginine-modified carbon dots (Arg-CDs) with strong luminescence that could be used for cell imaging under common fluorescence microscope because of the high cellular uptake efficiency. More interestingly, the cellular luminescence showed red-shifting when the Arg-CDs entered cells, and the red luminescence emission ability depended on the cell lines, including NIH 3T3, HEK 293, Hela and MCF-7 cells. This finding opens up a new application field that the Arg-CDs could be used for cell imaging and sensing simultaneously as a fluorescent probe.