A Label- and Enzyme-Free Fluorescent Method for the Rapid and Simple Detection of Hg2+ in Cigarettes Using G-Triplexes as the Signal Reporter

Knowledge about the quantity of Hg2+ in tobacco is important for the health of smokers. Thus, a novel G-triplex-based label- and enzyme-free fluorescent method was developed for detecting Hg2+ in tobacco. In this system, the target Hg2+ ions associate with the DNA complex that serves as a probe through formation of specific thymine-Hg2+-thymine (T-Hg2+-T) base pairing, which results in the release of the P2-containing G-triplexes. Subsequently, fluorescence enhancement is achieved by producing G-triplexes, which bind with thioflavine T (ThT). A detection limit of 0.2 nM was achieved within 40 min. The method has been successfully applied to the detection of mercury in tobacco. At this time, the application for detecting Hg2+ in tap and river water samples also indicates that further applications are anticipated.