Solid-phase synthesis of red dual-emissive nitrogen-doped carbon dots for the detection of Cu2+ and glutathione

Red dual-emissive carbon dots (CDs) were prepared by a novel and facile solvent-free carbonization method using O-phenylenediamine (OPD) as precursor and Al(NO 3 ) 3 ·9H 2 O as assistant. The prepared CDs manifesting intriguing dual-emission behavior at 600 nm and 650 nm demonstrate good fluorescence quenching rate (99%) on Cu 2+ , in which the linear range was 6–33 μM and detection limit was 0.145 μM. In addition, the CDs-Cu 2+ system shows excellent glutathione (GSH) turn-on detection in the range of 19–52 μM, where a red-shift to 650 nm and 700 nm was observed and the maximum value of F/F 0 is 5.8. Reasonable quenching mechanism was speculated to be the combination of static and dynamic quenching. Cytotoxicity measurements displayed good biocompatibility of CDs and cell viability was higher than 83% even under the highest concentration of CDs.