Luminescence : the journal of biological and chemical luminescence | 2021
A lable-free ratiometric method to detect Hg2+ based on structure change of DNA.
Abstract
In this work, a simple ratiometric method has been designed to detect Hg2+ based on the structural change between double-stranded DNA (dsDNA) and G-quadruplex structure. When Hg2+ was added, the designed G-quadruplex structure could change into corresponding dsDNA by forming the T-Hg2+ -T mismatch. This kind of variation resulted in the decrease of the fluorescence from G-quadruplex/N-Methyl Mesoporphyrin IX (NMM) complex and the increase of the fluorescence from dsDNA/Sybr Green I (SG I) pair. The secondary excitation wavelength of SG I was employed to excite NMM and SG I simultaneously. The titration experiment indicated that the new method had a linear response within 0.7-2.5 μM Hg2+ with a limit of detection 9.3 nM. Because using the T-Hg2+ -T mismatch to recognize Hg2+ was very specific, the selectivity of the new method was also satisfactory. The recoveries ranging from 92.8% to 110.2% suggested that this new method could achieve a potential application for Hg2+ detection in real environmental samples.