Colorimetric assay for mercury (II) based on mercury-specific deoxyribonucleic acid-functionalized gold nanoparticles
2011
Wu, Jikui | Li, Lan-ying | Zhu, Dan | He, Pingang | Fang, Yuzhi | Cheng, Guifang
A colorimetric nanoprobe—mercury-specific DNA-functionalized gold nanoparticles (Au–MSD) was developed for sensing Hg²⁺. The new mercury-sensing concept relies on measuring changes in the inhibition of “non-crosslinking” aggregation of Au–MSD-induced by the folding of mercury-specific DNA strand through the thymine–Hg²⁺–thymine (T–Hg²⁺–T) coordination. In the absence of Hg²⁺, a high concentration of MgCl₂ (50mM) results in a rapid aggregation of Au–MSD because of the removal of charge repulsion. When Hg²⁺ is present, the particles remain stable due to the folding of MSD functionalized on the particle surface. The assay enables the colorimetric detection of Hg²⁺ in the concentration range of 0.1–10μM Hg²⁺ ions with a detection limit of 60nM, and allows for the selective discrimination of Hg²⁺ ions from the other competitive metal ions. Toward the goal for practical applications, the sensor was further evaluated by monitoring Hg²⁺ in fish tissue samples.
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