A single-stranded DNA-based and terbium (III) fluorescent probe for facile and rapid detection of mercury (II)

Hg2+, as a highly dangerous pollutant, seriously affects public health and food safety. In this work, a biosensor based on single-stranded DNA and Tb3+ fluorescent probe was constructed for facile and rapid detection of Hg2+. The detection method only needs one DNA strand, which consists of two parts: the G-rich sequence is the Tb3+ luminescent antenna ligand and the T-rich sequence is the Hg2+ recognition probe. Free mercury-specific DNA (MSD) in an aqueous solution could significantly enhance Tb3+ luminescence. Upon the addition of Hg2+, the conformation of MSD will switch from the free random coil structure to the hairpin structure. Thus, Tb3+ was released and the fluorescence of Tb3+ was decreased. After condition optimization, the change of fluorescence intensity was proportional to the logarithmic concentration of Hg2+ from 0.01 to 10 μM with a detection limit of 1.9 nM. In addition, the detection results of Hg2+ in real samples were satisfactory. The designed fluorescent probe has great advantages in simplicity and functionality and has great development potential in food safety and environmental pollution.