A highly selective nanogold-aptamer catalytic resonance scattering spectral assay for trace Hg 2+ using HAuCl 4-ascorbic acid as indicator reaction

Abstract

Single strand DNA (ssDNA) was used to modify nanogold to obtain a nanogold-aptamer resonance scattering (RS) probe (NGssDNA) for Hg 2+, based on the formation of stable thymine-Hg 2+-thymine (T-Hg 2+-T) mismatches and aggregation of the released nanogold particles. After removing the aggregated particles by filtrate membrane, the excess NGssDNA in the filtration solution exhibit catalytic effect on the gold particle reaction between HAuCl 4 and ascorbic acid (AA) that appear as RS peak at 596 nm. When Hg 2+ concentration increased, the RS intensity at 596 nm decreased. The decreased intensity is linear to Hg 2+ concentration in the range of 0.00008–0.888 ng/mL Hg 2+, with detection limit of 0.000034 ng/mL. The nanogold-aptamer catalytic RS assay was applied to determination of Hg 2+ in water with satisfactory results.