A ratiometric electrochemical biosensor for the exosomal microRNAs detection based on bipedal DNA walkers propelled by locked nucleic acid modified toehold mediate strand displacement reaction

Sensitive and selective detection of microRNAs (miRNAs) in cancer cells derived exosomes have attracted rapidly growing interest owing to their potential in diagnostic and prognostic applications. Here, we design a ratiometric electrochemical biosensor based on bipedal DNA walkers for the attomolar...

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Bibliographic Details
Published in:	Biosensors & bioelectronics 2018-04, Vol.102, p.33-40
Main Authors:	Zhang, Jing, Wang, Liang-Liang, Hou, Mei-Feng, Xia, Yao-Kun, He, Wen-Hui, Yan, An, Weng, Yun-Ping, Zeng, Lu-Peng, Chen, Jing-Hua
Format:	Article
Language:	eng
Subjects:	Biosensing Techniques - methods Bipedal DNA walker Breast Neoplasms - blood Breast Neoplasms - genetics Cell Line, Tumor DNA - chemistry DNA - genetics Electrochemical Techniques - methods Exosomal miRNAs Female Humans Limit of Detection Locked nucleic acid MicroRNAs - analysis MicroRNAs - blood MicroRNAs - genetics Nucleic Acid Amplification Techniques - methods Oligonucleotides - chemistry Oligonucleotides - genetics Point-of-Care Systems Ratiometric electrochemical biosensor Reproducibility of Results Toehold mediate strand displacement reaction
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Summary:	Sensitive and selective detection of microRNAs (miRNAs) in cancer cells derived exosomes have attracted rapidly growing interest owing to their potential in diagnostic and prognostic applications. Here, we design a ratiometric electrochemical biosensor based on bipedal DNA walkers for the attomolar detection of exosomal miR-21. In the presence of miR-21, DNA walkers are activated to walk continuously along DNA tracks, resulting in conformational changes as well as considerable increases of the signal ratio produced by target-respond and target-independent reporters. With the signal cascade amplification of DNA walkers, the biosensor exhibits ultrahigh sensitivity with the limit of detection (LOD) down to 67 aM. Furthermore, owing to the background-correcting function of target-independent reporters termed as reference reporters, the biosensor is robust and stable enough to be applied in the detection of exosomal miR-21 extracted from breast cancer cell lines and serums. In addition, because locked nucleic acid (LNA) modified toehold mediate strand displacement reaction (TMSDR) has extraordinary discriminative ability, the biosensor displays excellent selectivity even against the single-base-mismatched target. It is worth mentioning that our sensor is regenerative and stable for at least 5 cycles without diminution in sensitivity. In brief, the high sensitivity, selectivity and reproducibility, together with cheap, make the proposed biosensor a promising approach for exosomal miRNAs detection, in conjunction with early point-of-care testing (POCT) of cancer. •The biosensor combining merits of DNA walker, ratio assay, LNA and TMSDR.•The walker fueled by TMSDR is superior to the burnt bridge mechanism based walker.•The ratiometric biosensor presents extraordinary stability and reproducibility.
ISSN:	0956-5663 1873-4235