Chemiluminescence assay for the sensitive detection of iodide based on extracting Hg~(2+) from a T-Hg~(2+)-T complex

摘要

A simple and sensitive chemiluminescence assay for iodide (I-) detection was reported, which was based on iodide extracting Hg~(2+) from DNA featuring a stem-loop structure containing T-Hg~(2+)-T. Specifically, Hg~(2+) induced random coiled G-rich single-strand DNA to form a stem-loop structure containing T-Hg~(2+)-T. Because the binding of Hg~(2+) and I~- is much stronger than that of Hg ~(2+) and thymine (T), I~- could extract Hg~(2+) from the stem-loop structure, releasing the DNA, which then bound with K~+ and transformed into a K~+-stabilized G-quadruplex (with hemin as a cofactor), which catalyzed the H_2O_2-mediated oxidation of luminol. The produced chemiluminescence as a sensing signal was applied to sensitively and selectively detect iodide with a detection limit of 12 nM. This system exhibited the first DNAzyme-based iodide sensor. Finally, the sensor was successfully applied for iodide detection in real lake water samples.