Detection of mercury ions (II) based on non-cross-linking aggregation of double-stranded DNA modified gold nanoparticles by resonance Rayleigh scattering method.

This work describes a sensitive approach utilizing non-cross-linking aggregation of double-stranded DNA modified gold nanoparticles (dsDNA-AuNPs) for the detection of mercury ions (Hg(2+)) by resonance Rayleigh scattering (RRS) method for the first time. The double-stranded DNA contains a mismatched T-T base pair in the chain terminus, resulting in a flexible DNA tail and preventing the AuNPs from aggregation. Thus, a low RRS signal is obtained. However, in the presence of Hg(2+), the non-cross-linking aggregation of dsDNA-AuNPs occurs, due to the Hg(2+)-mediated coordination of T-Hg(2+)-T base pair. The aggregation of nanoparticles generates a high RRS value. Particularly, the solution color and ultraviolet-visible absorption barely changed under the same conditions, while it is capable of detecting by RRS method with a low detection limit (0.4nM), which is 1000-fold lower than that of the colorimetric method. The proposed method was successfully applied to the detection of Hg(2+) in real samples. The sensitive and selective assay might be inspiring for the development of new detectors for other metal ions or biomolecules.