One pot synthesis of fluorescent gold nanoclusters from Curcuma longa extract for independent detection of Cd2+, Zn2+ and Cu2+ ions with high sensitivity

The current research describes that the development of a novel fluorescence strategy for the monitoring of metal ions (Cd2+, Zn2+ and Cu2+) from various environments. The fluorescence sensing platform was developed for parallel detection of three divalent ions i.e., Cd2+, Zn2+ and Cu2+ ions from aqueous solution by synthesizing highly orange red-emission gold nanoclusters derived from Curcuma longa root extract (CE) and 11- mercapto undecanoic acid (11-MUA) (CE/11-MUA-AuNCs) as reducing and capping ligands. In order to reduce the interference from co-existing metal ions, different masking agents were used to mask their interference during target metal ion analysis in the presence of other metal ions. Using CE/11-MUA-AuNCs, fluorescence enhancement mechanism was noticed for Cd2+ and Zn2+ ions, whereas fluorescence “turn-off” mechanism was observed for Cu2+ ion. The CE/11-MUA-AuNCs probe exhibited good quantitative response to Cd2+ and Zn2+ ions through fluorescence enhancement (0.01–2.5 and 0.025–5.0 μM for Cd2+ and Zn2+ ions) and to Cu2+ ion via turn-off (0.05–10 μM). Importantly, 0.012, 0.016 and 0.026 μM detection limits represent the better sensitivity among the reported analytical methods for the analysis of Cd2+, Zn2+ and Cu2+ ions. The practical application of the probe was applied to quantitative detection of Cd2+, Zn2+ and Cu2+ ions in real samples (urine, plasma, spinach, and wheat germ), which proves that the probe could be established as one of the routine and reliable analytical platform for parallel sensing of three metal ions (Cd2+, Zn2+ and Cu2+ ions).