Cytidine-stabilized copper nanoclusters as a fluorescent probe for sensing of copper ions and hemin

We reported a sensitive and selective fluorescence “turn on–off” strategy for detection of Cu(2+) and hemin, respectively. The fluorescence “turn on” sensor for Cu(2+) detection had a wide linear range of 0.05–2.0 μM with a limit of detection (LOD) of 0.032 μM, and the fluorescence “turn off” sensor for hemin detection possessed a wide linear range of 0.05–4.0 μM with an LOD of 0.045 μM. The sensor for Cu(2+) or hemin exhibited high selectivity over other possible substances. In addition, it was demonstrated by using various analytical characterization techniques that the fluorescence “turn on” sensor for Cu(2+) was constructed on the basis of the formation of water-soluble fluorescent copper nanoclusters (CuNCs), and the fabrication of the fluorescence “turn off” sensor for hemin was predominately based on the inner filter effect of hemin on the fluorescence of the CuNCs. Finally, the proposed fluorescence “turn on–off” sensor system was successfully applied for detection of Cu(2+) in lake water samples and hemin in duck blood samples.