Highly fluorescent carbon dots as selective and visual probes for sensing copper ions in living cells via an electron transfer process.

As an integral part of many important enzymes, Cu is involved in a number of vital biological processes, which is linked to the oxidative damage and environmental contamination when Cu is excessive. In this work, Cu can be captured by the amino groups of carbon dots (CDs) to form complexes, resulting in a strong fluorescence quenching of CDs via a nonradiative electron transfer process, which offered a rapid, visual, and selective methodology for Cu detection. The probe exhibited a wide response concentration range (0.01-2μM) to Cu with a detection limit of 6.7nM. Significantly, the CDs presented excellent biocompatibility and high photostability, which were applicable for the visualization of Cu dynamic invasion into living cells and Tilapia mossambica. Furthermore, the toxicity of Cu ions to living cells could be inhibited with CDs by the formation of complexes.