title: An "on-off-on" fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot.
abstract: Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an "on-off" fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an "off-on" fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5-30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0-200 μmol/L and 1.35 μmol/L, respectively. The as-constructed "on-off-on" PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results.
authors.affiliation: Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China. Electronic address: gxj1124@sxu.edu.cn.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Gong
authors.affiliation: Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Shaomin
authors.initials: S
authors.lastname: Shuang
authors.affiliation: Faculty of Science, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China. Electronic address: dc@sxu.edu.cn.
authors.forename: Chuan
authors.initials: C
authors.lastname: Dong
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis*; D002244:Carbon; D002857:Chromium; D005453:Fluorescence; D005638:Fruit / Q000737:chemistry; D000067030:Fruit and Vegetable Juices / Q000032:analysis; D009584:Nitrogen; D010758:Phosphorus; D045663:Quantum Dots
chemical_list: D002857:Chromium; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen; D001205:Ascorbic Acid
keywords: Ascorbic acid; Carbon quantum dot nanoprobe; Chromium(VI); Inner filter effect; Phosphorus/nitrogen dual-doped