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- Title
Switchable DNA tweezer and G-quadruplex nanostructures for ultrasensitive voltammetric determination of the K-ras gene fragment.
- Authors
Chen, Haohan; Sun, Xiaofan; Cai, Rongfeng; Tian, Yaping; Zhou, Nandi
- Abstract
Voltammetric detection of the K-ras gene fragment was accomplished through the combined application of (a) a switchable DNA nanostructure, (b) the use of hairpin probe and exonuclease III (Exo III)-assisted signal amplification, (c) a split G-quadruplex, and (d) by exploiting the redox activity of DNAzyme. Three assistant oligonucleotides were designed to construct a DNA tweezer on a gold electrode. It is in "open state" in the absence of K-ras DNA. Then, a hairpin probe was introduced, whose stem-loop structure can be opened through hybridization with the K-ras DNA. Exo III is added which hydrolyzes the complementary region of the hairpin sequence to release a single-stranded rest fragment. The ssDNA hybridizes with the DNA tweezer on the electrode which thereby is switched to the "closed state". This leads to the formation of G-quadruplex due to the shortened distance of the split G-quadruplex-forming sequences in the tweezer. The voltammetric signal of the G-quadruplex-hemin complex, with a peak near −0.3 V vs. Ag/AgCl, is used as the signal output. Under the optimal conditions, the current response in differential pulse voltammetry (DPV) increases linearly with the concentration of K-ras DNA in the range of 0.01–1000 pM, and the detection limit is 2.4 fM. The assay can clearly discriminate K-ras DNA from a single-base mutation. The method has excellent selectivity and was applied to the determination of K-ras DNA in (spiked) serum samples.
- Subjects
EXONUCLEASES; DNA; SINGLE-stranded DNA; GOLD electrodes; NANOSTRUCTURES; MICROBIAL exopolysaccharides; DETECTION limit; GENES
- Publication
Microchimica Acta, 2019, Vol 186, Issue 12, p1
- ISSN
0026-3672
- Publication type
Article
- DOI
10.1007/s00604-019-3993-5