An ultrasensitive and specific electrochemical biosensor for DNA detection based on T7 exonuclease-assisted regulatory strand displacement amplification

• Published in: Analytica chimica acta 2021-10, Vol.1183, p.338988-338988, Article 338988
• Main Authors: Li, Shengqiang, Fu, Zhengxiang, Wang, Chao, Shang, Xipeng, Zhao, Yan, Liu, Cuiying, pei, Ming
• Format: Article
• Language: English
• Subjects: DNA detection; Electrochemical biosensor; Regulatory strand displacement; T7 exonuclease
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2021.338988

An electrochemical biosensor for determination of DNA is developed based on T7 exonuclease-assisted regulatory strand displacement dual recycling signal amplification strategy. First, the hairpin probe recognized and bound the target DNA to form a double strand nucleotide structure, and then the T7 exonuclease was introduced. After be digested by T7 exonuclease, the target DNA was released and entered the next cycle of T7 exonuclease-assisted recycle amplification, while accompanied by a large number of mimic targets (output DNAs) into another cycle. Second, the mimic target reacted with double-chain substrated DNA (CP) by a regulated toehold exchange mechanism, yielding the product complex of detection probes with the help of assisted DNA (S). Finally, after many cycles, a large number of detection probes were produced for binding numerous streptavidin-alkaline phosphatases. The electrochemical biosensor showed very high sensitivity and selectivity with a dynamic response ranged from 0.1 fM to 10 pM with a detection limit of 31.6 aM. Furthermore, this proposed biosensor was successfully applied to the detection of target DNA in 20% diluted serum. The developed strategy has been demonstrated to have the potential for application in molecular diagnostics. [Display omitted] •An ultrasensitive and specific electrochemical biosensor was proposed for the detection of DNA.•The strategy was based on T7 exonuclease-assisted regulatory strand displacement to realize dual signal amplification.•The designed biosensor was proved to rapid response, admirable stability and precision.•This sensing method was successfully applied to detect DNA in 20% diluted human serum samples.