Exonuclease III–assisted cascade signal amplification strategy for label-free and ultrasensitive electrochemical detection of nucleic acids

• Published in: Biosensors & bioelectronics 2017-01, Vol.87, p.732-736
• Main Authors: Xiong, Erhu, Yan, Xiaoxia, Zhang, Xiaohua, Liu, Yunqing, Zhou, Jiawan, Chen, Jinhua
• Format: Article
• Language: English
• Subjects: Amplification; Biosensing Techniques - methods; Biosensors; Cascades; Cleavage; Deoxyribonucleic acid; DNA - analysis; DNA biosensor; DNA Probes - chemistry; Electrochemical Techniques - methods; Electrochemistry; Electrodes; Exodeoxyribonucleases - chemistry; Exonuclease III; Fragmentation; G-Quadruplexes; Hemin - chemistry; Humans; Limit of Detection; Nucleic Acid Amplification Techniques - methods; Nucleic Acid Hybridization - methods; Signal amplification strategy; Strategy
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2016.09.036

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. •Label-free and sensitive electrochemical detection of nucleic acids.•Exonuclease III–assisted signal amplification strategy for DNA assay.•The developed method shows excellent analytical performance for target DNA.