A technique for highly sensitive detection of mercury ions using DNA-functionalized gold nanoparticles and resonators based on a resonance frequency shift

Mercury is widely used in various research and industrial areas. However, due to the ionization of mercury to the mercury ion, the influence of this ion on human health and the environment is cause for concern. Gold nanoparticles (AuNPs) are the most widely studied nanomaterial because of their unique optical, chemical, electrical, and catalytic properties and have attracted much interest regarding the applications to detection of toxic metal ions. In this paper, we propose a technique for detection of divalent mercury using AuNPs and Mercury-specific-oligonucleotide–conjugated resonators (MSOIRs). The detection technique is based on the measurement of a resonance frequency shift in the resonators that results from a specific interaction between the thymine–thymine base pair and mercury ion as well as the adsorption of AuNPs that act as a mass amplifier. Our proposed method can quantify mercury ions with the limit of detection of 100 pM, which is 10-fold better than that of the existing assays. Furthermore, MSOIR can detect mercury ions in real tap water. These results imply that the mercury-detecting sensor may be used to enhance drinking-water quality.