Facile and rapid detection of toxic heavy metal ions using double-stranded DNA-gold nanoparticle conjugates containing mismatch base pair

通过双链DNA-金纳米粒子（dsDNA-GNP）的非交联聚集和胸腺嘧啶-Hg ^<2+>-胸腺嘧啶（T-Hg^<2 +>-T）复合物的形成实现了汞离子（Hg^<2 +>）的肉眼比色检测。在亚微摩尔浓度的Hg（ClO_4）_2存在下，dsDNA-GNP在室温下于水溶液中1 min内自发聚集，其分散体的颜色由红色变为无色。这种独特的胶体行为可能是由于在dsDNA层和分散介质之间的界面处形成T-Hg^<2+>-T复合物引起的颗粒之间的熵排斥的降低。

Colorimetric detection of mercury ions (Hg^<2+>) with the naked eye was accomplished by a combination of non-crosslinking aggregation of double-stranded DNA-carrying gold nanoparticles (dsDNA-GNP) and complex formation of thymine-Hg^<2+>-thymine (T-Hg^<2+>-T). The dsDNA-GNP having a T-T mismatch site located near the distal end aggregated spontaneously within 1 min in the presence of Hg(ClO_4)_2 at a sub-micromolar concentration in aqueous media at room temperature, resulting in the distinct color change of the particle's dispersion from red to colorless. This unique colloidal behavior was presumably due to the decrease in the entropic repulsion between the particles induced by the T-Hg^<2+>-T complex formation at the interface between the dsDNA layer and the dispersal medium.