Abstract: | Metal cations can be selectively detected by restoring and quenching the fluorescent intensity of an “ON–OFF” gold nanocluster (Au NC ) sensor. The fluorescent intensity of Au NCs with metal cations can be restored by chelating with ethylenediaminetetraacetic acid except for Hg2+ ions. A highly selective detection of Hg2+ ion is also achieved under the coexistence of Fe3+ or Cr3+ ions. This assay was applied successfully for detecting Hg2+ in a water sample. The dynamic range of the system was 1 ppm to 25 ppb, and the limit of detection was 25 ppb. |