Sensitive Detection of Hg2+ with Switchable Electrochemiluminescence Luminophore and Disposable Bipolar Electrode

A novel paper-based bipolar electrode-electrochemiluminescence (pBPE-ECL) switch system was used for the rapid, label-free, and sensitive detection of Hg2+. In the proposed approach, Hg2+ selectively mediates two thymine-enriched single-stranded DNA probes to form double-stranded DNA (dsDNA). In the presence of Hg2+, the "light-switch" molecule [Ru(phen)(2) dppz](2+) can freely intercalate into the base pairs of the dsDNA, resulting in intense ECL emission. The assay takes advantage of the wireless pBPE-ECL platform to yield a low-cost, disposable, and sensitive analysis. The system has a limit of 0.1 nM for Hg2+ detection. We also showed that the system can be used to distinguish Hg2+ over other metal ions, including Pb2+, Zn2+, Cu2+, Ba2+, Co2+, Cd2+, Fe3+, Mn2+, and Li+. Moreover, the proposed approach was rapid, low-cost, and label-free for effective sensing of Hg2+ in drinking and lake water.