title: Ultrasensitive and selective signal-on electrochemical DNA detection via exonuclease III catalysis and hybridization chain reaction amplification.
abstract: This work reported a novel, ultrasensitive, and selective platform for electrochemical detection of DNA, employing an integration of exonuclease III (Exo-III) assisted target recycling and hybridization chain reaction (HCR) for the dual signal amplification strategy. The hairpin capture probe DNA (C-DNA) with an Exo-III 3' overhang end was self-assembled on a gold electrode. In the presence of target DNA (T-DNA), C-DNA hybridized with the T-DNA to form a duplex region, exposing its 5' complementary sequence (initiator). Exo-III was applied to selectively digest duplex region from its 3-hydroxyl termini until the duplex was fully consumed, leaving the remnant initiator. The intact T-DNA spontaneously dissociated from the structure and then initiated the next hybridization process as a result of catalysis of the Exo-III. HCR event was triggered by the initiator and two hairpin helper signal probes labeled with methylene blue, facilitating the polymerization of oligonucleotides into a long nicked dsDNA molecule. The numerous exposed remnant initiators can trigger more HCR events. Because of integration of dual signal amplification and the specific HCR process reaction, the resultant sensor showed a high sensitivity for the detection of the target DNA in a linear range from 1.0 fM to 1.0 nM, and a detection limit as low as 0.2 fM. The proposed dual signal amplification strategy provides a powerful tool for detecting different sequences of target DNA by changing the sequence of capture probe and signal probes, holding a great potential for early diagnosis in gene-related diseases.
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China; College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000, PR China.
authors.forename: Wang
authors.initials: W
authors.lastname: Ren
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
authors.forename: Zhong Feng
authors.initials: ZF
authors.lastname: Gao
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. Electronic address: linb@swu.edu.cn.
authors.forename: Nian Bing
authors.initials: NB
authors.lastname: Li
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. Electronic address: luohq@swu.edu.cn.
authors.forename: Hong Qun
authors.initials: HQ
authors.lastname: Luo
mesh_terms: D002384:Catalysis; D003217:Conductometry / Q000295:instrumentation*; D004269:DNA, Bacterial / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D017403:In Situ Hybridization / Q000295:instrumentation*; D021141:Nucleic Acid Amplification Techniques / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA / Q000295:instrumentation*
chemical_list: D004269:DNA, Bacterial; C036483:T-DNA; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III
keywords: DNA; Dual amplification; Exonuclease III; Hybridization chain reaction