Resonance scattering spectral detection of ultratrace Hg(II) using herring sperm DNA modified nanogold probe as catalyst

Herring sperm DNA (hsDNA) was used to modify 10 nm nanogold to obtain a resonance scattering (RS) probe (AuhsDNA) for detection of Hg(2+). In the presence of salt, Hg(2+) interacts with AuhsDNA to form stable Hg(2+)-hsDNA complexes, and releases nanogold particles to form larger nanogold clusters that can be removed by membrane filtration. The excess AuhsDNA in the filtrate solution exhibits a catalytic effect on the reaction between hydroxylamine (NH(2)OH) and Cu(II). The excess AuhsDNA decreased with the addition of Hg(2+), which led the RS intensity at 602 nm to decrease. The decreased RS intensity (Δl(602 nm)) had a linear response to Hg(2+) concentration in the range of 0.4-400 nM, with a detection limit of 0.2 nM Hg(2+). This RS method was applied for the detection of Hg(2+) in water samples, with sensitivity, selectivity and simplicity.