title: Layer-by-layer self-assembly xylenol orange functionalized CdSe/CdS quantum dots as a turn-on fluorescence lead ion sensor.
abstract: A new turn-on fluorescence sensor based on xylenol orange (XO) functionalized CdSe/CdS quantum dots (QDs) is developed for the determination of lead ion. CdSe/CdS QDs were first modified by mercaptoacetic acid (MAA). The MAA-modified QDs were then capped with the natural biopolymer chitosan and the negatively charged XO. The XO-functionalized QDs were formed via the layer-by-layer self-assembly reaction. The fluorescence of the QDs was quenched by electron transfer mechanism after XO was bound to the QDs. Upon the addition of Pb(2+), a dramatic enhancement of the fluorescence intensity was observed, which resulted from the coordination between Pb(2+) and XO on QDs surface and the disruption of the electron transfer mechanism. Hence the fluorescence of the QDs was recovered. The recovery of the fluorescence intensity showed a good linear relationship with the concentration of Pb(2+) added from 0.05 to 6 μmol L(-1). A detection limit of 0.02 μmol L(-1) was achieved. This method was successfully applied to the determination of lead in real samples with satisfactory results.
authors: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu 215123, China.
authors: Qin
authors: Q
authors: Zhao
authors: Xiaolong
authors: X
authors: Rong
authors: Li
authors: L
authors: Chen
authors: Hongbing
authors: H
authors: Ma
authors: Guanhong
authors: G
authors: Tao
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D060766:Drinking Water / Q000032:analysis; D004784:Environmental Monitoring; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D007854:Lead / Q000032:analysis* / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D045663:Quantum Dots; D045483:Rivers / Q000737:chemistry; D018036:Selenium Compounds / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D013454:Sulfoxides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D060766:Drinking Water; D005456:Fluorescent Dyes; D010636:Phenols; D018036:Selenium Compounds; D012989:Soil Pollutants; D013440:Sulfides; D013454:Sulfoxides; D014874:Water Pollutants, Chemical; C034939:cadmium sulfide; D007854:Lead; C058667:cadmium selenide; C016833:xylenol orange
keywords: Chitosan; Lead determination; Quantum dots; Turn-on fluorescence sensor; Xylenol orange