title: Catalytic gold nanoparticles for fluorescent detection of mercury(II) and lead(II) ions.
abstract: In this study, we developed a fluorescence assay for the highly sensitive and selective detection of Hg(2+) and Pb(2+) ions using a gold nanoparticle (Au NP)-based probe. The Hg-Au and Pb-Au alloys that formed on the Au NP surfaces allowed the Au NPs to exhibit peroxidase-mimicking catalytic activity in the H(2)O(2)-mediated oxidation of Amplex UltraRed (AUR). The fluorescence of the AUR oxidation product increased upon increasing the concentration of either Hg(2+) or Pb(2+) ions. By controlling the pH values of 5mM tris-acetate buffers at 7.0 and 9.0, this H(2)O(2)-AUR-Au NP probe detected Hg(2+) and Pb(2+) ions, respectively, both with limits of detection (signal-to-noise ratio: 3) of 4.0 nM. The fluorescence intensity of the AUR oxidation product was proportional to the concentrations of Hg(2+) and Pb(2+) ions over ranges 0.05-1 μM (R(2)=0.993) and 0.05-5 μM (R(2)=0.996), respectively. The H(2)O(2)-AUR-Au NP probe was highly selective for Hg(2+) (>100-fold) and Pb(2+) (>300-fold) ions in the presence of other tested metal ions. We validated the practicality of this simple, selective, and sensitive H(2)O(2)-AUR-Au NP probe through determination of the concentrations of Hg(2+) and Pb(2+) ions in a lake water sample and of Pb(2+) ions in a blood sample. To the best of our knowledge, this system is the first example of Au NPs being used as enzyme-mimics for the fluorescence detection of Hg(2+) and Pb(2+) ions.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Chen-I
authors.initials: CI
authors.lastname: Wang
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Huang
authors.forename: Yang-Wei
authors.initials: YW
authors.lastname: Lin
authors.forename: Wen-Tsen
authors.initials: WT
authors.lastname: Chen
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
mesh_terms: D002384:Catalysis; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D060106:Lakes; D007854:Lead / Q000032:analysis* / Q000097:blood; D008628:Mercury / Q000032:analysis* / Q000097:blood; D053768:Metal Nanoparticles / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D007477:Ions; D010078:Oxazines; D014867:Water; C470430:Amplex Red; D007854:Lead; D006046:Gold; D006861:Hydrogen Peroxide; D008628:Mercury