A multifunctional fluorescent sensor for Ag⁺ and Hg²⁺ detection in seawater

In order to detect Ag⁺ and Hg²⁺ in seawater, we explored a multifunctional fluorescence sensor. A multifunctional Ag⁺ and Hg²⁺ sensor was designed by using gold nanoparticles (AuNPs) as quenching agent, PicoGreen dye as fluorescent probe of base pairing double-stranded deoxyribonucleic acid (DNA), and combining the characteristics of Ag⁺ making C base mismatch and Hg²⁺ making T base mismatch. Meanwhile, the DNA logic gate was constructed by establishing logic circuit, truth table, and logic formula. The relevant performances of the sensor were investigated. The results revealed that the sensor can detect Ag⁺ in the range of 100 to 700 nM with R² = 0.98129, and its detection limit is 16.88 nM (3σ/slope). The detection range of Hg²⁺is 100-900 nM with R² = 0.99725, and the detection limit is 5.59 nM (3σ/slope). An AND-AND-NOR-AND molecular logic gate has been successfully designed. With the characteristics of high sensitivity, multifunction, and low cost, the recommended detection method has the potential to be applied to the detection of Ag⁺ and Hg²⁺ in seawater.