Gold Nanoparticle-Based Colorimetric and "Turn-On" Fluorescent Probe for Mercury(II) Ions in Aqueous Solution

作者：Wang Hao; Wang Yongxiang; Jin Jianyu; Yang Ronghua^*

来源：Analytical Chemistry, 2008, 80(23): 9021-9028.

DOI：10.1021/ac801382k

An approach for visual and fluorescent sensing of Hg(2+) in aqueous solution is presented. This method is based on the Hg(2+)-induced conformational change of a thymine (T)-rich single-stranded DNA (ssDNA) and the difference in electrostatic affinity between ssDNA and double-stranded (dsDNA) with gold nanoparticles. The dye-tagged ssDNA containing T-T mismatched sequences was chosen as Hg(2+) acceptor. At high ionic strength, introduction of the ssDNA to a colloidal solution of the aggregates of gold nanoparticles results in color change, from blue-gray to red of the solution, and the fluorescence quenching of the dye. Binding of Hg(2+) with the ssDNA forms the double-stranded structure. This formation of dsDNA reduces the capability to stabilize bare nanoparticles against salt-induced aggregation, remaining a blue-gray in the color of the solution, but fluorescence signal enhancement compared with that without Hg(2+). With the optimum conditions described, the system exhibits a dynamic response range for Hg(2+) from 9.6 x 10(-8) to 6.4 x 10(-6) M with a detection limit of 4.0 x 10(-8) M. Both the color and fluorescence changes of the system are extremely specific for Hg(2+) even in the presence of high concentrations of other heavy and transition metal ions, which meet the selective requirements for biomedical and environmental application. ne combined data from transmission electron microscopy, fluorescence anisotropy measurements, and dialysis experiments indicate that both the color and the fluorescence emission changes of the DNA-functioned gold nanoparticles generated by Hg(2+) are the results of the metal-induced formation of dsDNA and subsequent formation of nanoparticle aggregates.

• 出版日期2008-12-1
• 单位北京大学