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

• Resonance Rayleigh scattering method is used for sensitive detection of Hg2+.
• The sensitivity of the sensing system is better than previous reports.
• The sensor relies on non-crosslinking aggregation of AuNPs.
• The proposed method is successfully applied in real sample assay.

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 (Hg2+) 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 Hg2+, the non-cross-linking aggregation of dsDNA-AuNPs occurs, due to the Hg2+-mediated coordination of T–Hg2+–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 (0.4 nM), which is 1000-fold lower than that of the colorimetric method. The proposed method was successfully applied to the detection of Hg2+ in real samples. The sensitive and selective assay might be inspiring for the development of new detectors for other metal ions or biomolecules.

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