A dual-color fluorescent biosensing platform based on WS2 nanosheet for detection of Hg2+ and Ag+

In this work, an effective dual-color fluorescent biosensing platform based on WS2 nanosheets was developed for homogeneous detection of Hg2+ and Ag+. This sensing platform was constituted by exploiting the fluorescence quenching ability of WS2 nanosheets and the interactions between WS2 nanosheets and DNA molecules. In the absence of additional any masking agents, the biosensor could achieve detection of Hg2+ and Ag+ in the same solution by monitoring fluorescence intensity changes at 525 nm and 583 nm, respectively. Hg2+ and Ag+ were selectively detected in the concentration range from 6.0-650.0 nM and 5.0-1000.0 nM, respectively, with the detection limit of 3.3 nM and 1.2 nM, respectively. It was also demonstrated that the WS2 nanosheet-based sensing platform was suitable for the simultaneous detection of Hg2+ and Ag+ in drinking water, serum and cell lysate samples. Moreover, the possible mechanism of fluorescence quenching by WS2 nanosheets was revealed to be related to static quenching, dynamic quenching, and Fo¨rster resonant energy transfer (FRET). This work extended the application of WS2 nanosheets to environmental monitoring and medical diagnosis.