本研究旨在開發電化學式膽固醇生物感測器,以偵測血液中的膽固醇濃度為主要目的。電極組裝方式是先將聚苯胺(PANI)電沉積於直徑1 mm白金(Pt)電極,白金奈米粒子再電沉積於PANI/Pt,並將膽固醇氧化酶(ChOx)以及牛血清蛋白(BSA)溶液滴附於nano Pt/PANI/Pt電極表面,最後於外層覆蓋一層硫醇基丙基三甲氧基矽烷(MPTMS)溶膠-凝膠溶液;結果顯示,此MPTMS/ChOx-BSA/nano Pt/PANI/Pt感測電極具有良好的操作性能,偵測游離膽固醇之線性範圍為1~13 mM,線性相關係數R值為0.9908,偵測極限與電流密度分別為14.9 M以及20.95 A.cm-2mM-1,就溫度與pH值之探討而言,此生物感測器於pH值7.5以及溫度45 oC會產生最大電流值,就電極製作的再現性而言,電極重複製作5次,每次完成的電極偵測同濃度的膽固醇,所得訊號之相對標準偏差值為4.68 %,顯示電極製作步驟具有很好的再現性。
An amperometric cholesterol biosensor has been developed. The ultimate goal is to apply this biosensor to determine cholesterol level in blood. On a 1-mm platinum (Pt) working electrode, poly-aniline (PANI) was first electro-deposited. The process of platinum nano-particles (nano Pt) deposition followed. A solution containing cholesterol oxidase (ChOx) and bovine serum albumin (BSA) was added onto this nano Pt/PANI/Pt electrode. The final step of fabricating the biosensor was to coat a semi-permeable membrane of 3-mercapto-propyl-trimethoxy-silane (MPTMS). The performance of this MPTMS/BSA-ChOx/nano Pt/PANI/Pt biosensor in sensing cholesterol is excellent. The linear range of detecting free cholesterol was 1~13 mM with a correlation coefficient (R) 0.9908. Its detection limit and sensitivity were 14.9M and 20.95 A.cm-2mM-1, respectively. In the studies of pH and temperature effects, the biosensor showed maximum responses at pH 7.5 and 45 oC. For the study of biosensor fabrication reproducibility, the biosensor preparation processes repeat 5 rounds. The biosensor fabricated in each round was used to detect same concentration of cholesterol. The current responses from the five biosensors in cholesterol detections showed a relative standard deviation of 4.68%. This implies that our fabrication processes are good in terms of biosensor reproducibility.