- 學位論文
奈米金屬顆粒結合碳材料及導電高分子之複合薄膜修飾電極並應用於生物感測器
Electrochemical Fabrication of Carbon Materials Combine Metal and Conducting Polymer Composite Film Modified Electrode for Determination of Biomolecules
摘要
本研究第一部分，主要探討還原石墨烯氧化物和鈀奈米複合薄膜 (RGO/Pd) 來偵測多巴胺的感測器，此修飾薄膜在 pH 3的溶液、電位 -1.1 V、循環300秒的條件下，利用電化學的方式將GO/Pd2+ 還原製備，並於掃描式電子顯微鏡（Scanning electron microscope, SEM）、能量散佈分析儀 (Energy dispersive spectroscopy, EDS) 和電化學阻抗頻譜 (Electrochemical impendence spectroscopy, EIS) ，來了解其薄膜特性及表面結構，同時也探討不同修飾薄膜電極偵測多巴胺 (Dopamine, DA) 的電催化氧化反應，我們觀察到此修飾薄膜電極對多巴胺的偵測，與文獻中其他修飾電極相較之下，有較低的氧化波峰電位，並且該修飾電極對多巴胺的電催化氧化電流反應呈一線性關係，偵測範圍從1-150μM和偵測極限為0.233 μM，由數據可以推斷出感測器對於多巴胺具有高度靈敏的檢測，最後，我們提出的感測器在實際樣品中上也具有實用性的發展潛力。 第二部分研究循環伏安法將二苯胺單體 (Diphenylamine, DPA) 電聚合在胺基-官能基化的多層奈米碳管 (Amino functionalization of multi-walled carbon nanotube, AFCNT) 複合薄膜修飾電極上，並使用掃描式電子顯微鏡來觀察PDPA-AFCNT複合膜的表面結構和電化學阻抗頻譜來了解修飾電極表面的電子傳遞現象。PDPA-AFCNT修飾電極可以做為一個多元偵測的感測器，對於兒茶酚 (Catechol)、半胱氨酸 (L-cysteine) 和過氧化氫 (Hydrogen peroxide) 都有良好的電化學催化反應。我們分析PDPA-AFCNT修飾電極並利用旋轉碟電極的方法(Rotating disk electrode, RDE) 測得兒茶酚和半胱氨酸的靈敏度分別為1.36 和1.06 mA mM-1 cm-2，偵測極限為0.01 和 0.05 mM. 和計時安培法偵測過氧化氫得到線性範圍從10 到 800 μM，靈敏度487.1??A mM-1 cm-2 和偵測極限 1 ?M，這些結果都表示，奈米複合薄膜修飾電極可以發展為一個多功能偵測的感測器。 第三部分為電化學預氧化處理的石墨和Nafion複合修飾網版印刷碳電極 (Screen printed carbon electrode, SPCE) 對多巴胺的電化學特性和電催化研究，我們使用簡單的製備方式將石墨以電化學的方式預氧化處理後形成石墨和Nafion複合物，並使用掃描式電子顯微鏡觀察其複合物的表面型態，由SEM圖中，可以清楚看到石墨邊緣的產生缺陷破損而形成石墨奈米片，複合薄膜修飾電極對多巴胺的催化與其他電化學預氧化處理的石墨或Nafion SPCE比較起來，表現出較為出色的電化學活性，而此複合薄膜修飾電極對DA的催化不僅具有良好的線性範圍在0.5 – 70 μM和偵測極限0.023 μM，更有絕佳的選擇性、穩定性和靈敏度，除此之外，複合薄膜修飾電極在真實樣品中偵測多巴胺的結果也是符合我們的期望值。
並列摘要
Part I：A novel and sensitive dopamine (DA) electrochemical sensor was fabricated based on electrochemically prepared reduced graphene oxide (RGO)/palladium (Pd) nanocomposite. RGO/Pd nanocomposite was electrochemically prepared by the reduction of GO/Pd2+ in the pH 3 solution at the constant applied potential of -1.1 V for 300 seconds. The fabricated composite was characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and electrochemical impendence spectroscopy (EIS). The proposed electrode has showed well oxidation behavior for DA than RGO and Pd modified electrodes. Furthermore, the detection of DA at nanocomposite modified electrode has found at lower oxidation potential than other modified electrodes. The electrochemical oxidation of DA at the nanocomposite modified electrode has exhibited a linear relationship in the range from 1 – 150 μM with the detection limit of 0.233 μM. Moreover, the sensor is highly sensitive towards DA detection with good sensitivity. In addition, the fabricated sensor has showed good practicality towards the commercial DA injection reveling it could be used for the detection DA at various pharmaceutical applications. Part II：Diphenylamine (DPA) monomer have been electro-polymerization on the amino functionalization of multi-walled carbon nanotube (AFCNT) composite film modified glassy carbon electrode (GCE) by cyclic voltammetry (CV). The surface morphology of PDPA-AFCNT was studied using field-emission scanning electron microscope (FE-SEM). The interfacial electron transfer phenomenon at the modified electrode was studied using electrochemical impedance spectroscopy (EIS). The PDPA-AFCNT/GCE is act a multiple biosensor and show a good electrocatalytic behavior towards the oxidation of catechol, L-cysteine and the reduction of hydrogen peroxide. Rotating-disk electrode technique was employed to detect catechol and L-cysteine and show the sensitivity of 1.36 and 1.06 mA mM-1 cm-2, detection limit of 0.01 and 0.05 mM. Amperometric determination of hydrogen peroxide at PDPA-AFCNT film modified electrode show linear range from 10 to 800 μM, sensitivity of 487.1 ?A mM-1 cm-2 and detection limit of 1 ?M. This results show that the proposed nano-composite film modified electrode can be utilized to develop a multifunctional biosensor. Part III：Herein, we report a highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite-nafion composite modified screen printed carbon (SPC) electrode. Electrochemical pretreated graphite-nafion composite was prepared by using simple electrochemical method. Scanning electron microscope (SEM) was used characterize the surface morphology of the fabricated composite electrode. The SEM results revealed that graphitic sheets edge planes were totally disturbed and leads to the formation of graphite nanosheets. The composite modified electrode showed enhanced electrocatalytic activity towards the oxidation of DA, when compared with either electrochemically pretreated graphite or nafion SPC electrodes. The fabricated composite electrode exhibits good electrocatalytic oxidation towards DA in the linear response range from 0.5 – 70 μM with the detection limit of 0.023 μM. The proposed sensor also exhibits very good selectivity and stability, with appreciable sensitivity. In addition, the proposed sensor showed satisfactory results towards the pharmaceutical DA samples.