| Summary: | 碩士 === 國立陽明大學 === 放射醫學科學研究所 === 91 === A large variety of conventional methods have been used for characterizing and quantifying bio-macromolecules interactions, including dye, fluorophores and radio-tracers labeling. These methods all need complex pre-experiment preparations, and cannot reflect the protein interactions immediately. Some labeling materials even interfere the protein binding.
SPR (surface plasmon resonance) biosensor has shown a great potential for affinity, allowing real-time analysis of biospecific interactions without the use of labeled molecules. It is also immunosensor with high sensitivity and without the need of auxiliary chemicals. In the prior experiments, the optical heterodyne SPR biosensor has shown a sensitivity of 5ng/ml. However, the sensitivity cannot approach the real physiological concentration of clinical usage. Therefore, noise suppression is considered to achieve a higher sensitivity.
In this thesis, the way to suppress excess noise is conducted. Based on the noise generation mechanisms, the excess noise is suppressed by use of the optical heterodyne technique and signal processing. The lock-in amplifier and band-pass filter are adopted to get a higher central frequency to bandwidth ratio (high Q value).
By reducing the excess-noise, the influence of laser fluctuation is lowered significantly and the signal-to-noise ratio is enhanced obviously. Therefore, the sensitivity of the system has been improved to arrive at 100pg/ml in both of the original and the calibrated data.
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