| Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 89 === Cholesterol is one of the major constituents of cellular membranes and is a critical precursor molecule for the synthesis of steroid hormones. It can play a critical role in a person’s health because atypical total cholesterol in serum is an indicator of the abnormality in the lipid metabolism, of arteriosclerosis and hypertension. It’s improtant that all people know what their cholesterol level is and how it affects their risk of developing heart disease.
In this thesis, we develop the cholesterol biosensor by the enzymatic immobilization connecting with the extended gate field effect transistor (EGFET). In this study, we use the EGFET to detect the variation of pH value. The sensing layer was obtained by depositing SnO2 on the conductive ITO glass with the sputtering method. We choose two different biological recognition devices, including the cholesteryl ester hydrolase (CEH) and cholesterol dehydrogenase (CDH). Then we make use of the enzymatic immobilizing technology, including the cross-linking and gel entrapment, to manufacture the enzyme modified field effect transistor (EnFET). The sample solution was prepared by diluting the 200mg/dL cholesterol standard.
The results show that CDH EnFET has much more obvious variation than CEH EnFET which can’t detect the variation of the fatty acid. And the linearity and the stability of the EnFET using gel entrapment technology are better than that of using cross-linking technology. The output voltage and response time could be adjusted by changing the quantity of co-enzyme or the incubating time of CDH and co-enzyme. The cholesterol biosensor has advantages of the minimization and disposability. The cholesterol biosensor can detect cholesterol of lower concentration and its linear range is between 20 and 160mg/dL.
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