A reversible metal ion fueled DNA three-way junction molecular device for "turn-on and -off" fluorescence detection of mercury ions (II) and biothiols respectively with high selectivity and sensitivity.

We constructed a reversible molecular device in the nanoscale based on a DNA three-way junction (3WJ) fueled by Hg(2+) binding and sequestration. It is highly responsive to external stimuli, which brings about optically detectable global structural changes. Such a DNA device can serve as a novel "turn-on and -off" fluorescent sensor for Hg(2+) and biothiol detection with high selectivity and sensitivity.