Ultrasensitive SERS detection of mercury based on the assembled gold nanochains.

Mercuric ions (Hg(2+)) mediate the transformation of single-stranded DNA to form double helical DNA by T-Hg(2+)-T interaction between base pairs. With this strategy, DNA modified gold nanoparticles (Au NPs) were assembled into chains which were displayed remarkable surface-enhanced Raman scattering (SERS) signal. Under optimized conditions, the length of gold nanochains was directly proportional to the mercuric ions concentrations over 0.001-0.5 ng mL(-1) and the limit of detection (LOD) in drinking water was as low as 0.45 pg mL(-1). With ultrasensitivity and excellent selectivity, this feasible and simple method is potentially as a promising tool for monitoring of mercury ions in food safety and environmental applications.