Application of Poly(3,4-ethylenedioxythiophene)-modified Screen-printed Electrodes in Electroanalysis

[[abstract]] 本論文利用電化學的方法在水溶液環境中製備聚(3,4-乙烯二氧吩)(PEDOT)的修飾電極，我們利用LiClO4為電解質，成功的將PEDOT修飾在網版印刷電極(SPE)上。 我們用SPE/PEDOT修飾電極在pH 2.0 ~ 12.0環境下偵測半胱氨酸(cysteine,CySH)的氧化，發現PEDOT薄膜在酸性到鹼性環境下偵測CySH都有很好的催化效果，而在pH 6.0的環境下催化效果最為明顯。我們用循環伏安法來偵測CySH，在濃度範圍20 ~ 100 μM之間，其濃度校正曲線斜率為0.0237 μA/μM，偵測極限為7.3 μM。利用流動注入分析系統的方法可以提昇偵測的靈敏度及降低偵測極限，在濃度範圍0.05 ~ 200 μM之間，其濃度校正曲線斜率為0.0527 μA/μM，偵測極限為0.03 μM，在濃度為0.5、20及200 μM，其誤差分別為1.44, 1.77, 2.88%。真實樣品實驗中，我們選用黑松沙士、尿液及阿斯匹靈為基質溶液，利用標準添加法在這些真實樣品中分別添加0、5、15及50 μM的CySH，在沙士及阿斯匹靈真實樣品中，偵測CySH的回復率分別為90%及100%以上，而尿液中的成分則有抑制CySH氧化電流的現象。 另外我們發現PEDOT薄膜可以吸附benzoquinone(BQ)及catechol(CA)，我們利用此特性進一步完成SPE/PEDOT/BQ及SPE/PEDOT/CA複合修飾電極，並應用於偵測AA及NADH。[[abstract]]In this study, we prepared a poly(3,4-ethylenedioxythiophene) (PEDOT) modified electrode by the electropolymerization of 0.01 M 3,4-ethylenedioxythiophene at a screen-printed electrode (SPE) in the presence of 0.1 M LiClO4 and 5 mM hydroxypropyl-β-cyclodexdrine. Many bio-interests were selected as test analytes. Electrochemical oxidation of cysteine in various pH buffer solutions (pH 2.0 ~12.0) was conducted at the SPE/PEDOT modified electrodes. Cyclic voltammetric studies showed that the SPE/PEDOT modified electrodes possessed great catalytic activity toward cysteine oxidation, and the best catalytic responses occurred in pH 6.0 buffer solution. Flow injection analysis (FIA) coupled amperometric detection was used in order to decrease detection limit. The FIA conditions were examined and the FIA signals were optimized. A linear calibration plot was obtained for 0.05-200 μM cysteine with a slope of 0.0527 μA/μM. The detection limit (S/N = 3) was 0.03 μM. The relative standard deviation was 1.44, 1.77, 2.88% for 3 continuous injection of 0.5, 20, 200 μM cysteine standards, respectively. Determination of cysteine in real sample was conducted using the same approach. We prepared three real samples, root beer syrup, human urine, and aspirin, as back ground solutions. The recovery of cysteine from real sample was determined using the standard addition method and the mean recovery was 93.5% and 105.0% for root beer syrup and aspirin, respectively. In the human urine real sample, the cysteine oxidation current were decreased. Moreover, we discovered that the PEDOT thin film may adsorb benzoquinone (BQ) and catechol (CA) in solution. The prepared SPE/PEDOT/BQ and SPE/PEDOT/CA modified electrodes can used for electrochemical detections of AA and NADH.[[note]]碩