Nitrogen and sulfur co-doped carbon dot-based ratiometric fluorescent probe for Zn2+ sensing and imaging in living cells

A near-infrared nitrogen and sulfur co-doped carbon dot (N,S-CD)-based ratiometric fluorescent probe is proposed that is synthesized via hydrothermal approach using glutathione and formamide as precursor for sensing and imaging of Zn 2+ . The prepared N,S-CDs facilitate binding with Zn 2+ owing to N and S atom doping. The ratio (I 650 /I 680 ) of fluorescence intensity at 650 nm and 680 nm increased with the concentrations of Zn 2+ when the excitation wavelength was 415 nm. The linearity range was 0.01 to 1.0 μM Zn 2+ with a detection limit of 5.0 nM Zn 2+ . The proposed probe was applied to label-free monitoring of Zn 2+ in real samples and fluorescent imaging of Zn 2+ in living cells, which confirmed its promising applications. Graphical abstract