title: Sensitive signal-on fluorescent sensing for copper ions based on the polyethyleneimine-capped silver nanoclusters-cysteine system.
abstract: In this work, we present a label-free sensor for copper ions. This sensor is composed of silver nanoclusters and cysteine. The fluorescence of the silver nanoclusters was quenched by cysteine, which was recovered in the presence of copper ions. This binding of silver nanoclusters to cysteine promoted agglomeration of silver nanoclusters to yield larger non-fluorescent silver nanoparticles. The presence of copper ions resulted in the oxidation of cysteine to form a disulfide compound, leading to recovery of fluorescence of the silver nanoclusters. The fluorescence of the silver nanoclusters in the presence of cysteine increased with increasing concentration of copper ions in the range of 10-200 nM. The detection limit of this sensor for copper ions was 2.3 nM. The silver nanoclusters-cysteine sensor provides a simple, cost-effective, and sensitive platform for the detection of copper ions.
authors.affiliation: Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.forename: Fei
authors.initials: F
authors.lastname: Qu
authors.forename: Hong Qun
authors.initials: HQ
authors.lastname: Luo
authors.forename: Nian Bing
authors.initials: NB
authors.lastname: Li
mesh_terms: D003300:Copper / Q000032:analysis*; D003545:Cysteine / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D057230:Limit of Detection; D049329:Nanostructures; D011094:Polyethyleneimine / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D012834:Silver; D003300:Copper; D011094:Polyethyleneimine; D003545:Cysteine
keywords: Copper ions; Cysteine; Polyethyleneimine; Silver nanoclusters