The use of DNA self-assembled gold nano-rods for novel analysis of lead and/or mercury in drinking water

Abstract

A novel, uncomplicated method for the analysis of lead (Pb²⁺) and mercury (Hg²⁺) ions has been developed with the use of gold nano-rods (AuNRs), which were combined with ssDNA. The AuNR–ssDNA assembly was stabilized by electrostatic interactions. The ssDNA has a random coil structure, which was changed to G-quartet and hairpin-like structures after binding with Pb²⁺ and Hg²⁺ ions, respectively. The bonding with lead and mercury caused the ssDNA assembled AuNRs (ssDNA–AuNRs) to disperse, and this increased the surface plasmon resonance (SPR) absorption of the AuNRs. Changes in the UV-vis spectral intensities allowed the selective detection of Pb²⁺ and Hg²⁺ ions at concentrations as low as 19.8 nM and 3.2 nM, respectively. Linear correlations were observed between the UV-vis spectra and the Pb²⁺ and Hg²⁺ analytes in the concentration ranges of 25–250 nM (R² = 0.9971) for Pb²⁺ and 4–40 nM (R² = 0.9956) for Hg²⁺, respectively. The literature suggests that the novel method is another example in which the ssDNA–AuNR assembly has been used for trace analysis of Pb²⁺ and Hg²⁺.