Development of Colorimetric Sensor Using Gold Nanoparticle and Thymine-Single Stranded DNA for Rapid and Selective Detection of Mercury Ions in Water

Abstract

    In this study, we have developed a colorimetric sensor for rapid and selective detection of mercury ions (Hg²⁺) in water by using the gold nanoparticle solution (AuNPs) and thymine-single stranded DNA (T-ssDNA). AuNPs is used as a sensing element based on their unique surface plasmon resonance properties and the T-ssDNA is selfassembled on gold nanoparticles to produce the AuNPs-T-ssDNA complex. Single-stranded DNA (T-ssDNA) could enhance the AuNPs against NaNO₃-induced aggregation. However, the presence of mercury ions in the complex of AuNPs-T-ssDNA will reduce the stability of AuNPs due to the formation of Hg²⁺ mediated T-Hg²⁺ -T base pairs accompanied with the AuNPs color change from red to purple or even to dark blue. As a result, Hg²⁺ can be detected qualitatively or quantitatively by the naked eye or by UV-vis spectral measurement. The lowest detectable concentration of mercury ions by naked eye and by the UV-vis spectral measurement was 0.06μM and 1nM, respectively.