Trypsin-stabilized fluorescent gold nanocluster for sensitive and selective Hg2+ detection.

We report on trypsin-stabilized fluorescent gold nanoclusters (Au NCs) for the sensitive and selective detection of Hg(2+) ions. The Au NCs have an average size of 1 nm and show a red emission at 645 nm. The photostable properties of the trypsin-stabilized Au NCs were examined, and their photochemical stability was found to be similar to that of CdSe quantum dots. The fluorescence was particularly quenched by Hg(2+), and therefore the Au NCs can be used as fluorescent sensors for sensitive and selective Hg(2+) detection to a detection limit of 50 ± 10 nM and the quantitative detection of Hg(2+) in wide and low concentration range of 50-600 nM. 2011 © The Japan Society for Analytical Chemistry