Sequence-specific detection of nucleic acids utilizing isothermal enrichment of G-quadruplex DNAzymes

G-quadruplex DNAzymes are peroxidase-like complexes formed by nucleic acid G-quadruplexes and hemin. Various chemical sensors and biosensors have been developed, based on such DNAzymes. Here we report a novel, specific nucleic acid detection method utilizing the isothermal amplification strategy of G-quadruplex DNAzymes. In this method, an unlabeled oligonucleotide probe was used. The probing sequence of the oligonucleotide was in the form of a stem-loop structure. A G-rich sequence, containing three GGG repeats, was linked to the 5′-end of the stem-loop structure. In the presence of target, the probing sequence hybridized to the target, and a Gn (n ≥ 2) repeat was extended from its 3′-end. This Gn repeat, together with the three GGG repeats at the 5′-end, folded into a G-quadruplex, and displayed enhanced peroxidase acitivity upon hemin binding. Utilizing the dynamic binding interaction between the probe and its target, the enrichment of G-quadruplex DNAzymes was achieved. Using this method, simple, rapid and cost-effective nucleic acid detection could be achieved. This method displayed high target-length tolerance and good detection specificity; one-base mismatch could be judged easily, even by visual inspection. This method may be used as an auxiliary tool for amplified detection of specific DNA targets in some situations, in which isothermal detection is desirable.

A novel, specific nucleic acid detection method was reported based on an isothermal amplification strategy of G-quadruplex DNAzymes. Using this method, simple, rapid and cost-effective nucleic acid detection could be achieved. This method displayed high target length tolerance and good detection specificity, one-base mismatch could be easily judged, even by visually. This method may be used as an auxiliary tool for amplified detection of specific DNA targets in some situations, in which isothermal detection is desirable.Figure optionsDownload as PowerPoint slideHighlights
► A novel, specific nucleic acid detection method was designed.
► This method utilized a target-mediated isothermal amplification of G-quadruplex DNAzymes.
► This method provides a new way for single-nucleotide polymorphism detection.
► This nucleic acid detection method displayed high target length tolerance.
► This method needs no labeled oligonucleotides, and only simple colorimetric detection was required.