A difunctional electrochemiluminescence sensor based on Ru-MOFs and strand-displacement-amplification reaction for ultrasensitive detection of Hg2+ and Ag+

A label free difunctional electrochemiluminescence (ECL) sensor for the ultrasensitive detection of mercury ions (Hg2+) and silver ions (Ag+) was constructed based on Ru(bpy)32+-functionalized metal-organic frameworks (Ru-MOFs) and the strand-displacement-amplification (SDA) reaction. Electrodeposited Ru-MOFs not only overcome the disadvantage of poor stability of traditional Ru2+ in aqueous solution, but also serve as an excellent carrier for hairpin DNA H1 during sensor construction. The SDA technology can transform extremely low concentrations of Hg2+ and Ag+ into a large number of the same alternative target DNA (tDNA). By combining SDA with Ru-MOFs, the detection sensitivity of the sensor is further improved. Meanwhile, the generated same alternative target tDNA can realize the detection of Hg2+ and Ag+ ions on this same sensing platform, which is beneficial to solve the common problems of high cost, long time and complicated operation in the detection of metal ion. The detection limits for Hg2+ and Ag+ are as low as 0.00032 pM and 0.00298 pM, respectively. And the corresponding linear detection range (LDR) is 0.001–1000 pM and 0.01–10000 pM, respectively. This ECL sensor has also been successfully used in the determination of Hg2+ and Ag+ in seawater, indicating an ideal platform for the simultaneous detection of trace heavy metal ions.