Colorimetric and turn-on fluorescence determination of mercury (II) by using carbon dots and gold nanoparticles.

A colorimetric and turn-on fluorometric assay with high sensitivity and selectivity is described for the optical detection of mercury (II) ions (Hg), based on carbon dots with -SH (SN-CDs) and gold nanoparticles (AuNPs). On addition of Hg, the color of the system (SN-CDs/AuNPs) changes from red to blue. A new absorption peak appears at 700 nm, and its absorbance increases with the concentration of Hg, while at 530 nm, the absorbance of AuNPs decreases.