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A rolling circle amplification-assisted DNA walker triggered by multiple DNAzyme cores for highly sensitive electrochemical biosensing.

Sina WangYuhang JiHaomin FuHuangxian JuJianping Lei
Published in: The Analyst (2018)
DNA walkers from monopodial to multipedal types have usually one cleavage site to power the walking system along with the track. Herein, a multipedal DNA walker (m-DNA walker) with multiple DNAzyme cores was constructed with the assistance of rolling circle amplification (RCA) for highly sensitive electrochemical biosensing. Firstly, a three-component DNA complex as a swing strand was prepared by integrating a padlock, an RCA primer and a block DNA as a recognition element in the DNA walker system. After ferrocene-labeled track DNA (trDNA) and capture DNA were fixed on a gold electrode, the three-component DNA complex was imported onto the electrode as a swing arm to form a m-DNA walker. In the presence of target DNA and a RCA kit, the block was displaced from the complex and RCA was initiated to form multiple DNAzyme strands. Upon hybridization with trDNA, the m-DNA walker was motivated by the cleavage of multiple DNAzyme cores in the presence of manganese ions to free signal molecules. Under the optimal circumstances, the electrochemical m-DNA walker showed a linear range from 1.0 fM to 1.0 nM with a detection limit of 0.28 fM. Moreover, the m-DNA walker demonstrated a rapid cleavage rate and a low ratio of the swing strand to the track, which is more excellent than a single foot walker and a bipedal DNA walker. The practicality of the proposed strategy was also confirmed by detecting target DNA in 10% human serum, showing promising applications in clinical diagnosis.
Keyphrases
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  • cell free
  • single molecule
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  • sensitive detection
  • aqueous solution