Amplified Fluorescent Detection of Mercuric Ions by Conjugation of the ThT-induced G-Quadruplex Based Hybridization Chain Reaction

• DOI: 10.2116/analsci.33.1333
• Publication Date: 2017-12-09T22:20:51Z
• Authors: Tianxiao Chen; Shuzhen Tan; Wei Li; Yuqing Zhu
• Keywords: G-Quadruplexes; Thiazoles; Spectrometry, Fluorescence; Limit of Detection; Nucleic Acid Hybridization; Benzothiazoles; Mercury; 01 natural sciences; 0104 chemical sciences

A sensitive fluorescent method for the detection of Hg2+ was developed based on triple-helix molecular switch (THMS)-induced hybridization chain reaction (HCR) amplification. THMS was composed of a T-rich mercury-specific probe and an initiator probe, designed by the Watson-Crick and Hoogsteen base pairings and employed as a signal trigger. Two hairpin probes containing the G-quadruplex sequence were used as signal amplification elements. In the presence of Hg2+, the T-Hg2+-T mismatch resulted in disassembling the THMS and releasing the initiator probe. One of the hairpins was opened by the released initiator probe, which triggered a successive cross-opening of two hairpins based the strand displacement principle, resulting in the formation of long-chain DNA with multiple G-quadruplex. When thioflavin T (ThT), a fluorophore, was bound to the G-quadruplex, an obvious fluorescence enhancement would occur. This sensing system enabled the highly sensitive and selective detection of aqueous Hg2+ with a limit-of-detection of 10.2 pM.