Ultrasensitive Mercury Ion Detection Using DNA-Functionalized Molybdenum Disulfide Nanosheet/Gold Nanoparticle Hybrid Field-Effect Transistor Device

Mercury, one of the most harmful pollutants in water, has a significant negative impact on human health. The molybdenum disulfide (MoS 2 ) nanosheet, due to its unique electronic properties, is a promising candidate for high-performance sensing materials. Here, we report a DNA-functionalized MoS 2 nanosheet/gold nanoparticle hybrid field-effect transistor (FET) sensor for the ultrasensitive detection of Hg 2+ in an aqueous environment. Specific DNA was used in the hybrid structure as the capture probe for the label-free detection. By monitoring the electrical characteristics of the FET device, the performance of the sensor was investigated. Our sensor shows a rapid response (1–2 s) to Hg 2+ and an ultralow detection limit of 0.1 nM, which is much lower than the maximum contaminant level (MCL) for Hg 2+ in drinking water (9.9 nM) recommended by the U.S. Environmental Protection Agency (EPA). In addition, the sensor shows a high selectivity to Hg 2+ compared with other interfering metal ions, e.g., As 5+, Cd 2+, Pb 2+, and so forth. This rapid and ultrasensitive method for Hg 2+ detection can either be potentially developed into stand-alone hand-held sensors or be integrated into existing water equipment for continuously monitoring the water quality.