Carbon dots-based fluorescent probe for off-on sensing of Hg(II) and I-

Herein, we report a simple, one-step reflux method for synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and diethylenetriamine (DETA) as the surface passivation reagent along with a high quantum yield (82.40%), the fluorescence intensity of the CDs was found to be effectively quenched by Hg(II) ions. Upon addition of I- to the CDs/Hg(II) complex dispersion, the fluorescence intensity of the CDs was significantly recovered. Furthermore, we developed an off-on fluorescence assay for the detection of I- using CDs/Hg(II) as a fluorescence probe. This probe enables the selective detection of Hg(II) with a linear range of 0-80 mu M and a limit of detection is 0.201 mu M and a limit of detection about I- is 0.234 mu M with a linear range of 0-70 mu M. Most importantly, the sensors can be successfully applied to the determination of Hg(II) and I- in real lake water and urine of cattles, the off-on sensor demonstrates high selectivity, repeatability, stability, which offer this CDs-based off-on fluorescent sensor a promising platform for environmental and biological sensing applications. (C) 2015 Elsevier B.V. All rights reserved.