In this study, a microwave-assisted synthesis of fluorescent egg-white-protected gold nanoclusters (ew-AuNCs) for sensing Hg2+ ions and melamine was developed, optimized, and evaluated. By conducting infrared spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we confirmed that clusters consisting of 22 Au atoms were successfully embedded in egg white. Transmission electron microscopy measurements revealed that the ew-AuNCs were well dispersed with an average diameter of 2.7 ± 0.7 nm. The ew-AuNCs exhibited red fluorescence emission (λem 648 nm) with high quantum yield (2.37%). In the presence of Hg2+ ions, the fluorescence of these ew-AuNCs was quenched because of the Hg2+-Au+ interaction. The relative change in fluorescence intensity at 648 nm was dependent on the concentration of Hg2+ ions. Detection of melamine was based on the diminished fluorescence quenching of ew-AuNCs by Hg2+ when melamine was added along with Hg2+. The limit of detection for Hg2+ ions and melamine was 0.89 nM and 0.46 μM, respectively. Determination of Hg2+ ions in a pond water sample and of melamine in milk and dog food samples was performed, and the recoveries from the developed method were >92.9%, confirming its potential for sensor applications.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Chemical Engineering(all)