A fluorescence turn-on CDs-AgNPs composites for highly sensitive and selective detection of Hg2+

In this paper, a simple and effective fluorescence turn-on approach for highly sensitive and selective monitoring Hg2+ ions was designed by using carbon dots (CDs) and silver nanoparticles (AgNPs). It reveals that the fluorescence of CDs solution can be quenched in the presence of AgNPs through inner filter effect (IFE) and the quenched CDs-AgNPs system is turned on after addition of Hg2+ ions, which is due to higher affinity of Hg2+ and AgNPs than that of CDs and AgNPs, thus resulting the disappearance of AgNPs from the CDs-AgNPs composites and leading to the fluorescence turn-on of CDs. The developed fluorescence turn-on approach exhibited high selectivity and sensitivity for detection of Hg2+. Under the optimum experimental conditions, good linearity was achieved over the range of 100-160 μM and the limit of detection (LOD) was estimated to be 2.22×10-8 M for Hg2+. The recoveries of Hg2+ spiked in real samples ranged from 98.4% to 101.6%. Results of this study suggest that the fluorescence turn-on approach can be used to the detection of Hg2+ in real water samples.