title: Label-free electrochemical nucleic acid biosensing by tandem polymerization and cleavage-mediated cascade target recycling and DNAzyme amplification.
abstract: Owing to the intrinsic importance of nucleic acid as bio-targets, the achievement of its simple and sensitive detection with high confidence is very essential for biological studies and diagnostic purposes. Herein, a label-free, isothermal, and ultrasensitive electrochemical detection of target DNA was developed by using a tandem polymerization and cleavage-mediated cascade target recycling and DNAzyme releasing amplification strategy. Upon sensing of the nucleic acid analyte for the assembled hairpin-like probe DNA on the electrode, the DNA polymerase guided the target recycling and simultaneously triggered the lambda exonuclease cleavage, accompanied by the cascade recycling of the released new complementary strand and the amplified liberation of the G-rich sequence of the HRP-mimicking DNAzyme. The electrocatalytic reduction of H2O2 by the generated hemin/G-quadruplex DNAzyme was used for the signal readout and further amplification toward target response. Such tandem functional operation by DNA polymerase, lambda exonuclease and DNAzyme endows the developed biosensor with a high sensitivity and also a high confidence. A low detection limit of 5 fM with an excellent selectivity toward target DNA could be achieved. It also exhibits the distinct advantages of simplicity in probe design and biosensor fabrication, and label-free electrochemical detection, thus may offer a promising avenue for the applications in disease diagnosis and clinical biomedicine.
authors.affiliation: Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, No. 53Rd. Zhengzhou, Qingdao, Shandong 266042, China. Electronic address: sliu@qust.edu.cn.
authors.forename: Shufeng
authors.initials: S
authors.lastname: Liu
authors.affiliation: Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, No. 53Rd. Zhengzhou, Qingdao, Shandong 266042, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Gong
authors.affiliation: Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, No. 53Rd. Zhengzhou, Qingdao, Shandong 266042, China.
authors.forename: Yanqun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, No. 53Rd. Zhengzhou, Qingdao, Shandong 266042, China. Electronic address: wangli@qust.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation; D003217:Conductometry / Q000295:instrumentation*; D004247:DNA / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D021881:DNA, Catalytic / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D021141:Nucleic Acid Amplification Techniques / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA / Q000295:instrumentation*; D013194:Staining and Labeling
chemical_list: D021881:DNA, Catalytic; D004247:DNA
keywords: DNA; DNAzyme; Electrochemical biosensor; Target recycling