title: Ultrasensitive electrochemical detection of miRNA-21 by using an iridium(III) complex as catalyst.
abstract: The ultrasensitive electrochemical detection of miRNA-21 was realized by using a novel redox and catalytic "all-in-one" mechanism with an iridium(III) complex as a catalyst. To construct such a sensor, a capture probe (CP) was firstly immobilized onto the gold electrode surface. In the presence of miRNA-21, a sandwiched DNA complex could form between CP and a methylene blue (MB) labeled G-rich detection probe modified onto a gold nanoparticle (AuNP) surface (DP-AuNPs). Upon addition of K(+), the structure of DP changed to a G-quadruplex. Then, the iridium(III) complex could selectively interact with the G-quadruplex, catalyzing the reduction of H2O2, which was accompanied by an electrochemical signal change using MB as an electron mediator. Under optimal conditions, the electrochemical signal of MB reduction peak was proportional to miRNA concentration in the range from 5.0 fM to 1.0 pM, with a detection limit of 1.6 fM. In addition, satisfactory results were obtained for miRNA-21 detection in human serum samples, indicating a potential application of the sensor for bioanalysis.
authors.affiliation: School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China; Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Miao
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Wanhe
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Tianshu
authors.initials: T
authors.lastname: Kang
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Jinbiao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Kwok-Keung
authors.initials: KK
authors.lastname: Shiu
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Chung-Hang
authors.initials: CH
authors.lastname: Leung
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China. Electronic address: edmondma@hkbu.edu.hk.
authors.forename: Dik-Lung
authors.initials: DL
authors.lastname: Ma
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D015342:DNA Probes / Q000737:chemistry; D055664:Electrochemical Techniques / Q000379:methods*; D054856:G-Quadruplexes; D006046:Gold / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D008751:Methylene Blue / Q000737:chemistry; D035683:MicroRNAs / Q000032:analysis / Q000097:blood*; D010084:Oxidation-Reduction
chemical_list: D056831:Coordination Complexes; D015342:DNA Probes; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D007495:Iridium; D006046:Gold; D006861:Hydrogen Peroxide; D008751:Methylene Blue
keywords: Electrochemical biosensor; Iridium(III) complex; miRNA-21