Development of Infrared Biosensor for Immunoassays Based on Reflection Absorption Spectroscopy
反射吸收法 ； 生化感測器 ； 傅立葉紅外光光譜儀 ； FT-IR ； Biosensors ； Reflection Absorption
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To eliminate the tedious preparation steps in conventional immunoassays type of methods, infrared sensors based on reflection-absorption mode were developed in this work. Because infrared radiation can interact with any organic molecules, the use of infrared radiation to produce analytical signals can remove the steps in labeling of fluorescencing molecules such as in fluorescence detection method. This new method utilized an immobilizing antibody to absorb its corresponding antigen and in consequence, resulting more intense infrared signal by the absorbed antigen. To study the performance of this proposed method, three pairs of antibody/antigen proteins were used as probe proteins and their infrared absorption bands were carefully examined in order to obtain the best band position for quantitative analyses. To obtain the optimal conditions for detections, the effect of optical system, the stability of immobilized protein, and the selectivity in detection of antibody/antigen pair were investigated. Results in the construction of optical system indicated that with large incident angle of infrared radiation, the signals of absorbed protein were enhanced tremendously. Meanwhile, the size of the aperture in the optical system should be close to the size of the deposited protein to effectively remove the un-interacted radiations. In the immobilization of protein in reflection substrates, three materials including silver, copper, and stainless steel were examined. Results indicated that silver plate is not only providing the highest reflection capability but also strongly interacting with the protein molecules deposited on it. With 2.5 %(v/v) of glutardialdehyde as cross-linking agent, the deposited protein on silver plate was found to be highly stable in buffer solutions. By blocking with suitable materials, such as polyvinyl alcohol or poly allyl amine, nonspecific interactions between proteins can be largely reduced. Using the optimal conditions, the infrared detection of proteins through the principle of immunology was achieved in this work.
理學院 > 化學研究所