| Summary: | 碩士 === 國立交通大學 === 生醫工程研究所 === 107 === Alzheimer’s disease is the most common cause of dementia. There are two major causes of disease. One is the accumulation of beta-amyloid 42 around the cerebral cortex to form plaques, the other is tau protein hyperphosphorylation triggers tau aggregation and nerve fibers entangled, leading to neuronal death. Consequently, the study will investigate whether Tau protein can be dephosphorylated by the method of interaction with human phosphatase. Firstly, we use the electrochemical quartz crystal microbalance (EQCM) to be the sensor that investigate the electrical conductivity of polyaniline polymer film. Polyaniline polymer films immobilized on the gold surface was optimized to observe the current-potential and frequency responses by Potentiostatic technique. The EQCM system is used to cross-linking with glutaraldehyde and immobilize ALP on the polymer film. We use Absorbance principle to measure ALP activity. Finally, we use QCM adsorption principle to measure the weight differ of Tau protein dephosphorylation. As a result of three parts of the experiments, the conductivity of polyaniline film can be triggered by a cathodic potential of -0.8 V could be better and deposited rapidly. The results of SEM pictures indicate PANI-GA modified working electrode to be drawn up in orderly ranks. Compared with before and after of the carbone atom is significantly increased by the EDS content. Then the functional group of GA can immobilize ALP using the covalent bond. ALP catalyzes the hydrolysis of ρ-Nitrophenyl phosphate (pNPP) to ρ-Nitrophenol. PNPP is colorless but ρ-Nitrophenol has a strong absorbance at 405 nm. The rate of increased absorbance at 405 nm is proportional to the enzyme activity.
We want to demonstrate dephosphorylates Tau protein by ALP and we make another experiments. Add the tau protein on the membrane and its phosphorylation by the protein kinase GSK-3β and ATP. The experiments are monitored by frequency responses. And using different concentration of ALP interacts with phosphorylation tau protein to look at whether the phosphate can be removed from the membrane. Finally, ALP concentration is 123Unit on the polymer film which is the best structure and dephosphorylation. This device will be a sensor for the treatment of Alzheimer's patients in the further.
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