A Dual-emission Carbon Dots/gold Nanoclusters Fluorescent Probe for Ratiometric and Colorimetric Detection of Pb and Hg

A novel fluorescent probe, carbon dots/gold nanoclusters (CDs/AuNCs), was prepared for ratiometric and colorimetric detection of Pb and Hg simultaneously. The as-prepared probe exhibited two distinct emission peaks at 445 nm and 610 nm. During the detection process, Pb could quench blue fluorescence due to the formation of the CDs-Pb complex and does not affect orange fluorescence. Conversely, Hg could quench the orange fluorescence greatly due to the Hg-Au metallophilic interaction and keep blue fluorescence unaffected. Accordingly, ratiometric fluorescence sensing approaches of Pb and Hg are achieved and dramatic color changes from pink to orange/blue can be observed under UV illumination upon the addition of Pb/Hg. Furthermore, good linear relationships between the fluorescence intensity ratio (/) and Pb/Hg concentration were demonstrated in ranges of 0-130 nM for Pb and 0 to 280 nM for Hg, with detection limits of 6.5 nM for Pb and 3.7 nM for Hg, respectively. The probe showed excellent selectivity and the mutual interference problem of coexistence of Pb and Hg could be effectively solved by introducing masking agents. In addition, the application of CDs/AuNCs proved successful in detecting Pb and Hg in actual water samples, yielding satisfactory recovery rates. These results indicated that the probe provides a new approach for visualizing and semi-quantitatively detecting Pb and Hg, making it highly promising for monitoring environmental water samples.