title: Exonuclease III-assisted cascade signal amplification strategy for label-free and ultrasensitive electrochemical detection of nucleic acids.
abstract: In this work, a simple, signal-on and label-free electrochemical biosensor for ultrasensitive DNA detection is reported on the basis of an autocatalytic and exonuclease III (Exo III)-assisted cascade signal amplification strategy. In the presence of target DNA (T-DNA), the hybridization between the 3'-protruding DNA fragment of hairpin DNA probe (HP1) and T-DNA triggered the Exo III cleavage process, accompanied by the releasing of T-DNA and autonomous generation of new DNA fragment which was used for the successive hybridization with the another hairpin DNA (HP2) on the electrode. After the Exo III cleavage process, numerous quadruplex-forming oligomers which caged in HP2 were liberated on the electrode surface and folded into G-quadruplex-hemin complexes with the help of K+and hemin to give a remarkable electrochemical response. As a result, a low detection limit of 4.83fM with an excellent selectivity toward T-DNA was achieved. The developed electrochemical biosensor should be further extended for the detection of a wide spectrum of analytes and has great potential for the development of ultrasensitive biosensing platform for early diagnosis in gene-related diseases.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Erhu
authors.initials: E
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China. Electronic address: mickyxie@hnu.edu.cn.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors.forename: Jiawan
authors.initials: J
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China. Electronic address: chenjinhua@hnu.edu.cn.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Chen
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis*; D015342:DNA Probes / Q000737:chemistry; D055664:Electrochemical Techniques / Q000379:methods; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D009693:Nucleic Acid Hybridization / Q000379:methods
chemical_list: D015342:DNA Probes; D006427:Hemin; D004247:DNA; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III
keywords: DNA biosensor; Electrochemistry; Exonuclease III; Signal amplification strategy