title: Colorimetric sensing of copper(II) based on catalytic etching of gold nanoparticles.
abstract: Based on the catalytic etching of gold nanoparticles (AuNPs), a label-free colorimetric probe was developed for the detection of Cu(2+) in aqueous solutions. AuNPs were first stabilized by hexadecyltrimethylammonium bromide in NH3-NH4Cl (0.6M/0.1M) solutions. Then thiosulfate (S2O3(2-)) ions were introduced and AuNPs were gradually dissolved by dissolved oxygen. With the further addition of Cu(2+), Cu(NH3)4(2+) oxidized AuNPs to produce Au(S2O3)2(3-) and Cu(S2O3)3(5-), while the later was oxid-ized to Cu(NH3)4(2+) again by dissolved oxygen. The dissolving rate of AuNPs was thereby remarkably promoted and Cu(2+) acted as the catalyst. The process went on due to the sufficient supply of dissolved oxygen and AuNPs were rapidly etched. Meanwhile, a visible color change from red to colorless was observed. Subsequent tests confirmed such a non-aggregation-based method as a sensitive (LOD=5.0 nM or 0.32 ppb) and selective (at least 100-fold over other metal ions except for Pb(2+) and Mn(2+)) way for the detection of Cu(2+) (linear range, 10-80 nM). Moreover, our results show that the color change induced by 40 nM Cu(2+) can be easily observed by naked eyes, which is particularly applicable to fast on-site investigations.
authors.affiliation: School of Environment and Materials Engineering, Yantai University, Yantai 264003, PR China.
authors.forename: Ruili
authors.initials: R
authors.lastname: Liu
authors.forename: Zhaopeng
authors.initials: Z
authors.lastname: Chen
authors.forename: Shasha
authors.initials: S
authors.lastname: Wang
authors.forename: Chengli
authors.initials: C
authors.lastname: Qu
authors.forename: Lingxin
authors.initials: L
authors.lastname: Chen
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D002384:Catalysis; D003124:Colorimetry / Q000379:methods; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D060766:Drinking Water / Q000032:analysis; D005506:Food Contamination / Q000032:analysis; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D012758:Shellfish; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D006046:Gold; D003300:Copper