A rapid and sensitive fluorescence biosensor for Hg2+ detection in environmental samples

As a significant environmental pollutant, Hg2+ has gained widespread concern around the world. In our work, a rapid and elegant fluorescence method based on SYBR GREEN I (SGI) and mercury-specific oligonucleotide (MSO) has been developed for detection of Hg2+. Utilizing the T-Hg2+-T mismatch principle, MSO forms a double-stranded hairpin structure, which can readily embed SGI and produce strong fluorescence. Under optimized conditions including MSO concentration, dye/MSO base ratio, pH value, ionic strength, reaction time and incubation time, a wide linear range (10-100 nM) and a low limit of detection (0.68 nM) were demonstrated. Almost no statistically significant interference for Hg2+ detection was observed among the possible coexisting substances in the water samples, including 15 factors. The recoveries of the three environmental water samples were in the range of 82.8% to 101.8%, indicating that the method was only weakly affected by the environmental matrix and could be applied to the detection of Hg2+ in environmental water samples. This method features potentially low cost, rapid processing, and convenient operation, which indicates considerable promise in practical Hg2+ monitoring.