title: Sensitive immobilization-free electrochemical DNA sensor based on isothermal circular strand displacement polymerization reaction.
abstract: A highly sensitive electrochemical DNA sensor that requires no probe immobilization has been developed based on a target recycling mechanism utilizing a DNA polymerase with a strand displacement activity. The electrochemical detection is realized by taking advantage of the difference in diffusivity between a free ferrocene-labeled peptide nucleic acid (Fc-PNA) and a Fc-PNA hybridized with a complementary DNA, while the DNA polymerase-assisted target recycling leads to signal generation and amplification. The hybridization of the target DNA opens up a stem-loop template DNA with the Fc-PNA hybridized to its extruded 5' end and allows a DNA primer to anneal and be extended by the DNA polymerase, which results in sequential displacement of the target DNA and the Fc-PNA from the template DNA. The displaced target DNA will hybridize with another template DNA, triggering another round of primer extension and strand displacement. The released Fc-PNA, due to its neutral backbone, has much higher diffusivity towards a negatively charged electrode, compared to that when it is hybridized with a negatively charged DNA. Therefore, a significantly enhanced signal of Fc can be observed. The outstanding sensitivity and simplicity make this approach a promising candidate for next-generation electrochemical DNA sensing technologies.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
authors.forename: Feng
authors.initials: F
authors.lastname: Xuan
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
authors.forename: Xiaoteng
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong; Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong. Electronic address: kehsing@ust.hk.
authors.forename: I-Ming
authors.initials: IM
authors.lastname: Hsing
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D004247:DNA / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D015342:DNA Probes / Q000737:chemistry; D055664:Electrochemical Techniques; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D020135:Peptide Nucleic Acids / Q000737:chemistry
chemical_list: D015342:DNA Probes; D020135:Peptide Nucleic Acids; D004247:DNA