Aptamer functionalized gold nanoparticles based fluorescent probe for the detection of mercury (II) ion in aqueous solution.

A method is proposed for the detection of Hg(2+) using Hg(2+) specific DNA (MSD) functionalized gold nanoparticles (AuNPs) based on the formation of T-Hg(2+)-T complex and the excellent quenching fluorescence property of AuNPs. The MSD is rich in thymine (T) and readily forms T-Hg(2+)-T configuration in the presence of Hg(2+). The MSD which is labeled with a fluorescein (FAM) at the 3'-end and a thiol at the 5'-end is bounded to the AuNPs through Au-S covalent bonds to form the probes (AuNPs-MSD). Hg(2+) detection can be easily realized by monitoring the change of fluorescence signal of AuNPs-MSD probes. Hg(2+) can be detected in a range of 0.02-1.0 µM with a detection limit of 16 nM. Besides, the assay shows excellent selectivity for Hg(2+) over other metal cations such as Fe(3+), Ca(2+), Mg(2+), Mn(2+), Cr(3+), Ni(2+), Cu(2+), Co(2+) and Pb(2+). The major advantages of this Hg(2+) assay are its water-solubility, simplicity, low cost and high sensitivity. Moreover, this method provides a potentially useful method for the Hg(2+) detection in aqueous solution.