title: Colorimetric sensing of trace UO2(2+) by using nanogold-seeded nucleation amplification and label-free DNAzyme cleavage reaction.
abstract: In pH 4.4 HAC-NaAC buffer solution at 80 °C, nanogold particles (NG) strongly enhanced the slow, colored reaction of Ag(i)-gallic acid to form nanosilver particles, which exhibited a strong surface plasmon resonance (SPR) absorption peak at 460 nm, but the aggregated nanogold particles (ANG) exhibited a weak enhancement. The increased absorption value at 460 nm was linear to the NG concentration in the range of 3.6-72.5 ng mL(-1) Au. In pH 5.5 MES buffer solution at 80 °C, single-stranded substrate DNA and DNAzyme hybridize to form double-stranded DNA (dsDNA). The presence of uranyl (UO(2)(2+)) resulted in cleavage of the substrate DNA of dsDNA, releasing a short, single-stranded DNA that can be adsorbed onto the NG and protect them from aggregation; those un-adsorbed NG were aggregated to ANG. As the UO(2)(2+) concentration increased, more short, single-stranded DNA were released, and more NG were protected by the cleavage of substrate single-strand DNA, so the colored particle reaction and the absorption value at 460 nm enhanced linearly. On those grounds, 0.083-0.67 nmol L(-1) UO(2)(2+) can be detected rapidly by this colorimetric sensing assay, with a detection limit of 0.04 nmol L(-1).
authors.affiliation: Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection of the Ministry of Education, Guangxi Normal University, Guilin 541004, China.
authors.forename: Yanghe
authors.initials: Y
authors.lastname: Luo
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lili
authors.initials: L
authors.lastname: Xu
authors.forename: Lisheng
authors.initials: L
authors.lastname: Wang
authors.forename: Guiqing
authors.initials: G
authors.lastname: Wen
authors.forename: Aihui
authors.initials: A
authors.lastname: Liang
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D003124:Colorimetry / Q000379:methods*; D004247:DNA / Q000737:chemistry; D021881:DNA, Catalytic / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles; D009693:Nucleic Acid Hybridization; D020349:Surface Plasmon Resonance; D017974:Uranium Compounds / Q000032:analysis*
chemical_list: D021881:DNA, Catalytic; D004277:DNA, Single-Stranded; D017974:Uranium Compounds; D006046:Gold; D004247:DNA; C047385:uranium oxide