探討表面修飾網版印刷碳膠電極在電化學特性影響

Abstract

網版印刷碳膠電極為廣泛應用於電化學生物感測器上。由於它具有低成本、製程簡單、易圖案化等優點，因而可用於可拋棄式感測系統上。本研究中，針對三種修飾網版印刷碳膠電極方式進行研究。 利用單層奈米碳管溶於Nafion覆蓋於網版印刷碳膠電極上，與利用四種溶液 (0.1% 鹽酸，50 mM 磷酸緩衝溶液，1 M碳酸氫鈉與飽和的碳酸鈉水溶液)對網版印刷碳膠電極進行循環伏安法修飾，此兩種方法均可提升對過氧化氫的氧化電流。有趣的是，當利用非離子界面活性劑 (Triton X-100與Tween 20) 可明顯有效提升對過氧化氫反應與輕微降低抗壞血酸反應，且其連續性使用再現性良好 (Triton X-100, R.S.D = 2.88%; Tween 20, R.S.D = 6.9%, n = 20)，利用此修飾電極方式便宜且容易製程應用。利用Tween 20修飾之電極對於過氧化氫偵測電流較利用Triton X-100修飾方式為佳。接著將葡萄糖氧化酶固定於利用非離子界面活性劑修飾之電極表面上，進行葡萄糖感測，發覺可提升反應電流。顯示修飾後電極應用在以氧化酶為主的電化學生物感測器的潛力上。 由電子顯微鏡圖顯示網版印刷碳膠電極在經由非離子型界面活性劑修飾後，其將在電極表面形成平滑薄膜覆蓋。而利用Tween 20 在電極表面薄膜結構將比Triton X-100來的均勻一致。而利用水滴量測電極表面接觸角可顯示以非離子型界面活性劑修飾，表面化學特性，將由疏水性轉為親水性，可利用此改變性質應用於固定化技術上。

Screen-printed carbon paste electrodes (SPCE) are most commonly used in the fabrication of electrochemical biosensors. SPCE exhibits a great potential in the generation of disposable sensing system because of its economic, easily mass-production, and easily patterned. In this study, the surface of SPCE, which was modified by three methods, was investigated. Both of the surface modifications of SPCE by SWNT (single-walled carbon nanotube)/Nafion coating and surface treatment by cyclic voltammograms (CVs) with 4 types of solutions, including 0.1 % HCl , 50 mM phosphate buffer, 1 M NaHCO3 ,and saturated Na2CO3, performed in this study. The response of pre-treated SPCE exhibited an improved oxidative current of hydrogen peroxide. Interestingly, SPCE modified with nonionic surfactants, e.g. Triton X-100 and Tween 20, showed greatly increased response for hydrogen peroxide, and slightly decreased in response for ascorbic acid. It had a good reproducibility in duplicate test (Triton X-100, R.S.D=2.88%; Tween 20, R.S.D=6.9%, n=20), and it was inexpensive and easy to prepare. Tween 20-modified SPCE response to hydrogen peroxide was better than Triton X-100-modified SPCE. The glucose biosensor was fabricated using nonionic surfactants-modified SPCE exhibited increasing response for sensing glucose. These result indicated that nonionic surfactants-modified SPCE has potential for enhancing the reaction current of oxidase-based electrochemical biosensor. Microscopic images of SPCE under the scanning electron micrograph (SEM) revealed that coated on nonionic surfactants the surface of SPCE forming a smooth film, and Tween 20 coating membrane on the surface of SPCE was more uniform than Triton X-100 coating, and measuring the water contact angles at the nonionic surfactants-modified SPCE surfaces showed the chemical properties on SPCE surface from hydropholicity to hydrophilicity, and can use in immobilization technology.