Rapid one-pot synthesis of MMTA protected fluorescent gold nanoclusters for selective and sensitive detection of ferric ion.

Herein, we demonstrate a straightforward synthesis of fluorescent gold nanoclusters (AuNCs), employing 2-Mercapto-4-methyl-5-thiazoleacetic acid (MMTA) as a reducing and protecting agent by a rapid one-pot synthesis method with a short time of 20min. The as-synthesized MMTA-AuNCs exhibited bright blue emission with a strong peak centered at 430nm and the quantum yield (QY) was evaluated to be 4.0%. Based on the fluorescence quenching mechanism of a surface chelating reaction between MMTA and ferric ion (Fe3+), the MMTA-AuNCs were exploited as a fluorescence sensor for sensitive and selective detection of Fe3+. Two linear ranges of 9.9-3000.0nM and 3.0-1100μM with a detection limit of 3.0nM were obtained. The detection limit was lower than the maximum level (0.3mgL-1, equivalent to 5.4μM) of Fe3+ permitted in drinking water by the U.S. Environmental Protection Agency. Furthermore, the proposed fluorescent sensing system was successfully applied to the analysis of Fe3+ in real samples such as water and human serum samples with satisfactory recoveries. These results indicated that the as-prepared MMTA-AuNCs could pave an avenue for the development of sensing probes for detection of Fe3+ in environmental and biomedical applications.