Sensitive dual DNAzymes-based sensors designed by grafting self-blocked G-quadruplex DNAzymes to the substrates of metal ion-triggered DNA/RNA-cleaving DNAzymes.
A universal label-free metal ion sensor design strategy was developed on the basis of a metal ion-specific DNA/RNA-cleaving DNAzyme and a G-quadruplex DNAzyme. In this strategy, the substrate strand of the DNA/RNA-cleaving DNAzyme was designed as an intramolecular stem-loop structure, and a G-rich sequence was caged in the double-stranded stem and could not form catalytically active G-quadruplex DNAzyme. The metal ion-triggered cleavage of the substrate strand could result in the release of the G-rich sequence and subsequent formation of a catalytic G-quadruplex DNAzyme. The self-blocking mechanism of the G-quadruplex DNAzyme provided the sensing system with a low background signal. The signal amplifications of both the DNA/RNA-cleaving DNAzyme and the G-quadruplex DNAzyme provided the sensing system with a high level of sensitivity. This sensor design strategy can be used for metal ions with reported specific DNA/RNA-cleaving DNAzymes and extended for metal ions with unique properties. As examples, dual DNAzymes-based Cu(2+), Pb(2+) and Hg(2+) sensors were designed. These "turn-on" colorimetric sensors can simply detect Cu(2+), Pb(2+) and Hg(2+) with high levels of sensitivity and selectivity, with detection limits of 4 nM, 14 nM and 4 nM, respectively.
State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, PR China.
Qi
Q
Zhang
Yang
Y
Cai
Hui
H
Li
De-Ming
DM
Kong
Han-Xi
HX
Shen
D001483:Base Sequence; D003124:Colorimetry / Q000379:methods*; D003300:Copper / Q000032:analysis* / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D054856:G-Quadruplexes; D007477:Ions / Q000032:analysis / Q000378:metabolism; D007854:Lead / Q000032:analysis* / Q000378:metabolism; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D008969:Molecular Sequence Data; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods
D021881:DNA, Catalytic; D007477:Ions; D007854:Lead; D012313:RNA; D003300:Copper; D004247:DNA; D008628:Mercury