Toward selective, sensitive, and discriminative detection of Hg(2+) and Cd(2+)via pH-modulated surface chemistry of glutathione-capped gold nanoclusters.
Heavy metal pollution can exert severe effects on the environment and human health. Simple, selective, and sensitive detection of heavy metal ions, especially two or more, using a single probe, is thereby of great importance. In this study, we report a new and facile strategy for discriminative detection of Hg(2+) and Cd(2+) with high selectivity and sensitivity via pH-modulated surface chemistry of the glutathione-capped gold NCs (GSH-Au NCs). By simply adjusting pH values of the colloidal solution of the NCs, Hg(2+) could specifically turn off the fluorescence under acidic pH, however, Cd(2+) could exclusively turn on the fluorescence under alkaline pH. This enables the NCs to serve as a dual fluorescent sensor for Hg(2+) and Cd(2+). We demonstrate that these two opposing sensing modes are presumably due to different interaction mechanisms: Hg(2+) induces aggregation by dissociating GSH from the Au surface via robust coordination and, Cd(2+) could passivate the Au surface by forming a Cd-GSH complex with a compact structure. Finally, the present strategy is successfully exploited to separately determine Hg(2+) and Cd(2+) in environmental water samples.
College of Chemistry, Nanchang University, Nanchang 330031, China. pchuang@ncu.edu.cn fywu@ncu.edu.cn.
Pengcheng
P
Huang
Sha
S
Li
Nan
N
Gao
Fangying
F
Wu
D001667:Binding, Competitive; D002104:Cadmium / Q000032:analysis* / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D005978:Glutathione / Q000737:chemistry* / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008628:Mercury / Q000032:analysis* / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence / Q000379:methods; D055095:Optics and Photonics; D013050:Spectrometry, Fluorescence / Q000379:methods; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis
D003102:Colloids; D004785:Environmental Pollutants; D005456:Fluorescent Dyes; D007477:Ions; D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D002104:Cadmium; D006046:Gold; D008628:Mercury; D005978:Glutathione