- 學位論文
修飾電極應用於電化學法檢測大腸桿菌
Application of Modified Electrode in Electrochemical Detection of Escherichia coli
摘要
本研究探討了以碳黑（Carbon Black, CB）修飾玻璃碳電極（Glassy Carbon, GC）應用於循環伏安法（Cyclic Voltammetry, CV）與定電位法（Amperometric i-t Curve, i-t）檢測大腸桿菌（Escherichia coli, E. coli）的可行性。修飾方法為在GC表面滴加碳黑墨水（CB ink），並與bare GC進行比較，進一步分析其電化學特性。同時以酵素呈色塗抹法作為E. coli濃度的定量依據。 CV觀察結果顯示，在E = 0.75 V（vs. Ag/AgCl）時，出現明顯的電流訊號，且隨著E. coli濃度的增加，觀察到的氧化峰電流值也呈顯著增加，表明峰電流值與E. coli濃度呈正比關係。此外，CB修飾後的電極在比較中顯示出較大的峰電流值，並能有效提升檢測的靈敏度。推測原因是CB增加了與E. coli接觸的表面積，促進了電子傳遞，從而產生更大的電流訊號。 在該系統中，i-t相較於CV產生了更大的電流訊號。然而，隨著CB濃度的增加，檢測到的訊號也得到提升。將Nafion覆蓋在CB上可有效防止CB脫落於GC上，進一步改善檢測效果。斜率從21.795 μA/(CFU/mL)提高至36.491 μA/(CFU/mL)，線性範圍從7.193"×" 105~108 CFU/mL改為1.728"×" 102~108 CFU/mL，檢測極限（Limit of Detection, LOD）從2.5"×" 105 CFU/mL降低至700 CFU/mL。
並列摘要
This study investigated the feasibility of using carbon black (CB)-modified glassy carbon electrode (GC) for the electrochemical detection of Escherichia coli (E. coli) using cyclic voltammetry (CV) and amperometric i-t curve (i-t) techniques. The modification was performed by depositing carbon black ink (CB ink) onto the surface of GC and comparing it with the bare GC, followed by analysis of its electrochemical characteristics. An enzymatic colorimetric assay was employed for quantitative determination of E. coli concentration. CV observations revealed a significant current signal at E = 0.75 V (vs. Ag/AgCl), and the observed oxidation peak current increased noticeably with the increase in E. coli concentration, indicating a proportional relationship between the peak current and E. coli concentration. Furthermore, the CB-modified electrode exhibited higher peak current values compared to the bare GC, resulting in improved detection sensitivity. This enhancement can be attributed to the increased surface area for interaction between CB and E. coli, facilitating electron transfer and generating larger current signals. In this system, i-t curve generated larger current signals compared to CV. Moreover, the detected signals were further enhanced with increasing CB concentration. The coverage of Nafion on CB effectively prevented CB detachment from the GC surface, thereby improving the detection performance. The slope increased from 21.795 μA/(CFU/mL) to 36.491 μA/(CFU/mL), the linear range expanded from 7.193"×" 105~108 CFU/mL to 1.728"×" 102~108 CFU/mL, and the limit of detection (LOD) decreased from 2.5"×" 105 CFU/mL to 700 CFU/mL.