Spectrophotometric Determination of Trace Hg~(2+) with hsDNA-modified Nanosilver Probe

摘要

Herring sperm DNA (hsDNA) was used to modify 5 nm nanosilver to obtain a hsDNA-nanosilver probe (Ag-hsDNA) for (Hg)~(2+). In the presence of (Hg)~(2+), it combined with hsDNA to produce Hg~(2+)-hsDNA complexes and to release nanosilver particles, based on formation of stable T-(Hg)~(2+)-T mismatches. Nanosilver particles aggregated to form larger nanosilver clusters and led the absorption at 412 nm decreased in the pH 6.5 Na_2HPO_4-NaH_2PO_4 buffer solution and 0.05 mol/L NaCl medium. The decreased absorption (△A_(412 nm)) is linear to Hg~(2+) concentration in the range of 1.36-10.86μg/L Hg~(2+), with regress equation of △A=0.0987C_(Hg)~(2+) +0.0624, correlation coefficient of 0.9890, and detection limit of 0.30μg/L (Hg)~(2+). The assay was applied to the analysis of (Hg)~(2+) in wastewater with satisfactory results.