title: Magnified fluorescence detection of silver(I) ion in aqueous solutions by using nano-graphite-DNA hybrid and DNase I.
abstract: This paper describes a novel approach utilizing nano-graphite-DNA hybrid and DNase I for the amplified detection of silver(I) ion in aqueous solutions for the first time. Nano-graphite can effectively quench the fluorescence of dye-labeled cytosine-rich single-stranded DNA due to its strong π-π stacking interactions; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the hairpin structure can be cleaved by DNase I, and in such case Ag(+) is delivered from the complex. The released Ag(+) then binds other dye-labeled single-stranded DNA on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled single-stranded DNA from the nano-graphite, which leads to significant amplification of the signal. The present magnification sensing system exhibits high sensitivity toward Ag(+) with a limit of detection of 0.3nM (S/N=3), which is much lower than the standard for Ag(+) in drinking water recommended by the Environmental Protection Agency (EPA). The selectivity of the sensor for Ag(+) against other biologically and environmentally related metal ions is outstanding due to the high specificity of C-Ag(+)-C formation. Moreover, the sensing system is used for the determination of Ag(+) in river water samples with satisfying results. The proposed assay is simple, cost-effective, and might open the door for the development of new assays for other metal ions or biomolecules.
authors.affiliation: Research Center of Analytical Instrumentation, Analytical & Testing Center, Sichuan University, Chengdu, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Research Center of Analytical Instrumentation, Analytical & Testing Center, Sichuan University, Chengdu, China.
authors.forename: Bianmiao
authors.initials: B
authors.lastname: Li
authors.affiliation: Research Center of Analytical Instrumentation, Analytical & Testing Center, Sichuan University, Chengdu, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Research Center of Analytical Instrumentation, Analytical & Testing Center, Sichuan University, Chengdu, China. Electronic address: yduan@scu.edu.cn.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Duan
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure; D003850:Deoxyribonuclease I / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D007477:Ions; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D012834:Silver / Q000032:analysis*; D012996:Solutions / Q000032:analysis; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D007477:Ions; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; D012834:Silver; D006108:Graphite; D004247:DNA; D003850:Deoxyribonuclease I
keywords: Ag(+) detection; Amplified detection; C–Ag(+)–C; Nano-graphite