title: Novel cellulose polyampholyte-gold nanoparticle-based colorimetric competition assay for the detection of cysteine and mercury(II).
abstract: We provide a highly sensitive and selective assay to detect cysteine (Cys) and Hg(2+) in aqueous solutions using Au nanoparticles (NPs) stabilized by carboxylethyl quaternized cellulose (CEQC). This method is based on the thiophilicity of Hg(2+) and Au NPs as well as the unique optical properties of CEQC-stabilized Au NPs. CEQC chains are good stabilizing agents for Au NPs even in a high-salt solution. The addition of Cys results in the aggregation of CEQC-stabilized Au NPs, which induces the visible color change and obvious redshift in UV-visible absorption spectra. On the other hand, Hg(2+) is more apt to interact with thiols than Au NPs; thus, it can remove the Cys and trigger Au NP aggregate redispersion again. By taking advantage of this mechanism, a novel off-on colorimetric sensor has been established for Cys and Hg(2+) detection. This new assay could selectively detect Cys and Hg(2+) with the detection limits as low as 20 and 40 nM in aqueous solutions, respectively.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Jun
authors.initials: J
authors.lastname: You
authors.forename: Haoze
authors.initials: H
authors.lastname: Hu
authors.forename: Jinping
authors.initials: J
authors.lastname: Zhou
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
authors.forename: Yaping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kondo
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry*; D003545:Cysteine / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D053758:Nanoparticles / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D006046:Gold; D008628:Mercury; D002266:Carboxymethylcellulose Sodium; D003545:Cysteine