Ultrasensitive and portable assay of mercury (II) ions via gas pressure as readout.

It is of the significant importance to achieve facile and on-site detection of heavy metal ions due to the serious harm to environment and human health. Herein, a facile and portable strategy was developed for detection of Hg2+ via portable pressure meter. Biotinylated DNA1 was conjugated on the surface of streptavidin-coated magnetic beads (MBs) to form MBs-DNA1 complex. In the presence of Hg2+, MBs-DNA1 can hybridize with platinum nanoparticles (PtNPs)-functionalized DNA2 (DNA2-PtNPs) via T-Hg2+-T binding. Then, PtNPs effectively catalyzed the decomposition of H2O2 to generate oxygen, leading to an increase in pressure of sealed well of 96-well plate. The gas pressure was linearly related with the concentration of Hg2+ in the range between 10 pM and 100 nM with a detection limit of 2.79 pM, which is more sensitive than most of the previous reports. The specific T-Hg2+-T binding made it easy to selectively detect Hg2+ even when other metal ions co-existed with Hg2+. Therefore, it offers a cost-effective, rapid, facile and portable way to detect Hg2+ by combining gas-generation reaction with T-Hg2+-T binding, which holds great potential for detecting Hg2+ in water sample.