title: A novel electrochemical aptasensor for thrombin detection based on the hybridization chain reaction with hemin/G-quadruplex DNAzyme-signal amplification.
abstract: In this work, a novel signal amplification electrochemical aptasensor for the sensitive and selective detection of thrombin was successfully fabricated. The amplification method was based on the hybridization chain reaction (HCR) and a pseudobienzyme electrocatalytic system. HCR-based double-stranded DNA (dsDNA) polymers not only constructed an effective carrier for anchoring larger amounts of electron mediator methylene blue (MB) into the DNA duplexes to produce a strong differential pulse voltammetry (DPV) signal, but also resulted in the formation of hemin/G-quadruplex DNAzymes nanowires by intercalating hemin into two induced single-stranded DNA (ssDNA). With the addition of NADH into the electrolytic cell, the hemin/G-quadruplex acting as an NADH oxidase and HRP-mimicking DNAzyme for the pseudobienzyme amplifying system could in situ biocatalyze the formation of H₂O₂ with local concentrations and low transfer loss resulting in dramatic signal enhancements. The binding event can be detected by a decrease in the integrated charge of MB which electrostatically absorbed onto dsDNA polymers. In the presence of thrombin, the dsDNA polymers associated with MB and hemin/G-quadruplex structures were removed from the electrode surface, leading to a significant decrease of redox current. DPV signals of MB provided quantitative measures of the concentrations of thrombin, with a linear calibration range of 0.01-50 nM and a detection limit of 2 pM. Moreover, the resulting aptasensor also exhibited good specificity, acceptable reproducibility and stability, indicating that the present strategy was promising for broad potential application in clinic assay and various protein analyses.
authors.affiliation: Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Yali
authors.initials: Y
authors.lastname: Yuan
authors.forename: Lijuan
authors.initials: L
authors.lastname: Bai
authors.forename: Shunbi
authors.initials: S
authors.lastname: Xie
authors.forename: Liping
authors.initials: L
authors.lastname: Jiang
mesh_terms: D052157:Aptamers, Nucleotide / Q000032:analysis; D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods*; D054856:G-Quadruplexes; D006427:Hemin / Q000032:analysis*; D006801:Humans; D009693:Nucleic Acid Hybridization; D013917:Thrombin / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D021881:DNA, Catalytic; D006427:Hemin; D013917:Thrombin