title: Nitrogen-doped carbon quantum dots: facile synthesis and application as a "turn-off" fluorescent probe for detection of Hg2+ ions.
abstract: A facile, economical and straightforward hydrothermal strategy is used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) by using folic acid as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 4.5 ± 1.0 nm and exhibit excitation wavelength-dependent fluorescence with the maximum emission and excitation at 390 and 470 nm, respectively. Furthermore, due to the effective quenching effect of Hg(2+) ions, such N-CQDs are found to serve as an effective fluorescent sensing platform for lable-free sensitive detection of Hg(2+) ions with a detection limit of 0.23 μM. The selectivity experiments reveal that the fluorescent sensor is specific for Hg(2+) even with interference by high concentrations of other metal ions. Most importantly, the N-CQDs-based Hg(2+) ions sensor can be successfully applied to the determination of Hg(2+) in tap water and real lake water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for monitoring of Hg(2+) in environmental application.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, China; University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Ruizhong
authors.initials: R
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, China. Electronic address: weichen@ciac.ac.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D002244:Carbon / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000032:analysis / Q000138:chemical synthesis*; D007477:Ions / Q000032:analysis / Q000737:chemistry; D008628:Mercury / Q000032:analysis* / Q000737:chemistry; D015336:Molecular Probe Techniques; D009584:Nitrogen / Q000737:chemistry*; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D007477:Ions; D014874:Water Pollutants, Chemical; D002244:Carbon; D008628:Mercury; D009584:Nitrogen
keywords: Carbon; Fluorescence; Folic acid; Mercury; Quantum dots; Sensor