Colorimetric sensing of trace UO22+ by using nanogold-seeded nucleation amplification and label-free DNAzyme cleavage reaction

• Published in: Analyst (London) Vol. 137; no. 8; pp. 1866 - 1871
• Main Authors: Luo, Yanghe, Zhang, Yi, Xu, Lili, Wang, Lisheng, Wen, Guiqing, Liang, Aihui, Jiang, Zhiliang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2012
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods; Trace analysis; Chemical analysis; Nucleation; Gallic acid; Color reaction; Colorimetry; Single stranded DNA; Concentration; Buffer solution; Chemical enrichment; Aggregation; Substrate; Gene amplification; Double stranded DNA; Absorption; Adsorption; Detection limit; pH; Cleavage; Peak; Surface plasmon resonance; Uranyl; Silver I
• DOI: 10.1039/c2an00039c
• ISSN: 0003-2654

In pH 4.4 HACNaAC 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 3.672.5 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, 0.0830.67 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 . A new nanogold enhanced spectrophotometric method is proposed for the detection trace UO 2 2+ , with simplicity, rapidity, low-cost, high sensitivity and selectivity.