4.8 Article

A novel label-free electrochemical impedance aptasensor for highly sensitive detection of human interferon-gamma based on target-induced exonuclease inhibition

Journal

BIOSENSORS & BIOELECTRONICS
Volume 142, Issue -, Pages -

Publisher

ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2019.111532

Keywords

Tuberculosis; Human interferon gamma; Electrochemical impedance aptasensor; Target-induced exonuclease inhibition

Funding

  1. National Natural Science Foundation of China [21405035]
  2. General Project Program of the Natural Science Foundation of Hubei Province [2017CFB529]

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In this paper, a novel label-free electrochemical impedance aptasensor for highly sensitive detection of IFN-gamma based on target-induced exonuclease inhibition was constructed. For this purpose, we designed a DNA hairpin modified on the gold electrode whose loop was the aptamer of the IFN-gamma, and the stem was 5'-thiol-modified. In the absence of IFN-gamma, Exonuclease III (Exo III) and Exonuclease I (Exo I) digested the double-stranded and single-stranded strands of the hairpin DNA, respectively, causing smaller impedance value on the surface of the electrode. In the presence of IFN-gamma, the function of Exo III was greatly inhibited by the binding of the aptamer with the target, and it stopped after cutting three bases of the hairpin DNA. Forming a major target-bound aptamer digestion product, it could not be digested by Exo I, so there was larger impedance on the electrode surface. The calibration curve for IFN-gamma was linear in the range of 1 pM-50 nM with the detection limit (LOD) of 0.7 pM. The proposed aptasensor proved good selectivity and reproducibility, and low cost. In addition, the biosensor was able to detect IFN-gamma in serum samples successfully, which is expected to provide an efficient method for TB diagnosis at early stages.

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