Selective Detection of Hg(II) Over Cd(II) and Pb(II) Ions by DNA Functionalized CNT

This paper describes the selective detection of Hg(II) ions over Cd(II) and Pb(II) ions by DNA functionalized carbon nanotube (DFC) resistive network. The nucleobases, especially adenine and thymine, which are bound to the nanotubes through π-π stacking interactions, have strong affinities for Hg(II) ions and bind to the Hg(II) ions at suitable ligand sites forming a stable chelate complex. The coordinate ligand-Hg(II) bond possesses higher covalent character than either the ligand-Cd(II) or the ligand-Pb(II) bond. The higher the covalent character of the coordinate bonds in the chelate complex formed on the DFC network, more is the e-scattering at the metal-binding sites and thus greater is the reduction in the conductance of the DFC network. The amount of covalent character of the metal-ligand bond is measured by the stability factor of the complex.