title: Label-free detection of sub-nanomolar lead(II) ions in aqueous solution using a metal-based luminescent switch-on probe.
abstract: A label-free oligonucleotide-based luminescent switch-on assay has been developed for the selective detection of sub-nanomolar Pb(2+) ions in aqueous solution and real water samples. An iridium(III) complex was employed as a G-quadruplex specific luminescent probe and a guanine rich DNA (PS2.M, 5'-GTG(3)TAG(3)CG(3)T(2)G(2)-3') was employed as recognition unit for Pb(2+) ions. The PS2.M exists in a single-stranded conformation in the absence of Pb(2+) ions, and the weak binding of the iridium(III) probe to ssDNA results in a weak luminescence signal. Upon binding to Pb(2+) ions, the single-stranded DNA sequence (PS2.M) is induced into a G-quadruplex conformation, which greatly enhances the luminescence emission of the iridium(III) probe. The assay can detect Pb(2+) ions in aqueous media with a limit of detection of 600 pM. It also exhibits good selectivity for Pb(2+) ions over other heavy metal ions. Furthermore, the application of the assay for the detection of Pb(2+) ions in spiked river water samples has been demonstrated.
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Hong-Zhang
authors.initials: HZ
authors.lastname: He
authors.forename: Ka-Ho
authors.initials: KH
authors.lastname: Leung
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Daniel Shiu-Hin
authors.initials: DS
authors.lastname: Chan
authors.forename: Chung-Hang
authors.initials: CH
authors.lastname: Leung
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.forename: Anne
authors.initials: A
authors.lastname: Bourdoncle
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mergny
authors.forename: Dik-Lung
authors.initials: DL
authors.lastname: Ma
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007854:Lead / Q000032:analysis*; D008163:Luminescent Measurements / Q000295:instrumentation*; D008832:Microchemistry / Q000295:instrumentation*; D015336:Molecular Probe Techniques / Q000295:instrumentation*; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012996:Solutions; D013194:Staining and Labeling; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; D007854:Lead