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

Abstract

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 0–80μM and a limit of detection is 0.201µM and a limit of detection about I− is 0.234µM with a linear range of 0–70μM. 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.