Detection of Interferon-gamma based-on Integration of Conductive Linker and Electrochemical Impedance Spectroscopy
Date Issued
2014
Date
2014
Author(s)
Lee, Guan-Wei
Abstract
Tuberculosis (TB) is an ancient disease constituted a long-term menace to public health. According to World Health Organization (WHO), mycobacterium tuberculosis (MTB) infected nearly a third of people of the world. There is about one new TB occurrence every second worldwide today. Interferon-gamma (IFN-γ) is associated with susceptibility to TB, and interferon-gamma release assays (IGRA) is considered to be the best alternative of tuberculin skin test (TST) for diagnosis of latent tuberculosis infection (LTBI). Although significant progress has been made with regard to the design of enzyme immunoassays for IFN-γ, adopting this assay is still labor-intensive and time-consuming. To alleviate these drawbacks, we used IFN-γ antibody to facilitate the detection of IFN-γ. Our team chose IFN-γ as the target protein and expected to pursue a label-free, high-precision, and rapid detection technique. We chose electrochemical method as the development foundation of the biosensor and adopted conductive linker to form a self-assembled monolayer (SAM). Through the impedance measurement, we can understand the interaction of IFN-γ antibody and IFN-γantigen.
In the thesis, cyclic voltammetry and electrochemical impedance spectroscopy are used to measure the conductive characteristics of three kinds of conductive linkers. From the experimental results, it can be found that conductivity is associated with the number of methylene chain. As the number of methylene chain decreased, the conductivity increased. Through the conductivity enhancement, we can obtain a higher signal/noise ratio such that the detection limit is improved. Fluorescence microscopy was used to verify that the conductive linkers have capability to bind with gold. Finally, we used the electrochemical methods to observe the interaction of IFN-γ antibody and IFN-γ antigen. The results show that for the range from 10 pM to 50 nM, the impedance would increase along with the rising of IFN-γ concentration. When the concentration exceeded this range, the impedance would decrease along with the rising of IFN-γ concentration. It is our conjecture that these two trends can be attributed to the competition between steric hindrance and electrostatic force.
Subjects
電化學阻抗頻譜分析
導電連結分子
丙型干擾素
生物感測器
肺結核
SDGs
Type
thesis
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