Nanosensors Based on Structural Memory Carbon Nanodots for Ag Fluorescence Determination.

Ag pollution is of great harm to the human body and environmental biology. Therefore, there is an urgent need to develop inexpensive and accurate detection methods. Herein, lignin-derived structural memory carbon nanodots (C-dots) with outstanding fluorescence properties were fabricated via a green method. The mild preparation process allowed the C-dots to remain plentiful phenol, hydroxyl, and methoxy groups, which have a specific interaction with Ag through the reduction of silver ions. Further, the sulfur atoms doped on C-dots provided more active sites on their surface and the strong interaction with Ag nanoparticles. The C-dots can specifically bind Ag, accompanied by a remarkable fluorescence quenching response. This "turn-off" fluorescence behavior was used for Ag determination in a linear range of 5-290 μM with the detection limit as low as 500 nM. Furthermore, findings showed that this sensing nano-platform was successfully used for Ag determination in real samples and intracellular imaging, showing great potential in biological and environmental monitoring applications.