- 學位論文
金、鉑、玻璃碳電極在生物性緩衝溶液中之背景電流及電化學視窗之研究
Background Signals and the Electrochemical Windows of Au, Pt, and GC Electrodes in Biological Buffers
摘要
對電化學的實驗而言，許多實驗因素如緩衝液種類、酸鹼值、離子種類、電極材料等等，都會影響電化學的表現。而當我們在進行電化學相關的實驗時，真實的信號常常會受到背景電流的影響，兩者混在一起，導致我們不易去解讀出真正的信號在哪裡。這些背景電流的來源，常常會是來自於緩衝溶液與其中的電解質，抑或是受電極材料的影響而有所不同，然而，這些資訊卻鮮少被系統性的整合以及研究。為了因應在相關領域快速發展中的生物電極、生物感測器等儀器之需求，我們在此進行一系列有系統性的實驗，來研究有關背景信號值以及電化學視窗的關係，特別著重在金、玻璃石墨、白金電極在三羥甲基氨基甲烷、4-羟乙基哌嗪乙磺酸、磷酸緩衝液這三種常見的生物緩衝液的表現，此處的實驗皆有加入100 mM的過氯酸鋰作為電解質。我們透過鹽酸、硫酸及氫氧化鈉，去調控這幾種緩衝溶液的酸鹼度從6.0到9.0，並從中觀察酸鹼度造成的效應。此外，在控制酸鹼度的實驗中，我們也藉由加入鹽酸與硫酸的不同，比較出了氯離子與硫酸根離子在金屬表面有著不同的反應。這些反應同時也表現出明顯的氧化還原峰，讓人能知道進行循環伏安法時，哪一些會是背景電流值的信號，例如在電極施加高電位時，表面會氧化形成水合層，且造成在循環伏安法有明顯的氧化還原峰。此外，我們也透過原子力顯微鏡，去觀測實驗時循環伏安法施加在樣品上時的表面起伏變化，這也幫助我們對於電極表面有更深的理解，用以幫助我們去翻譯在生物緩衝溶液中電化學圖譜的結果。這項實驗提供較全方面的電化學資訊，相信對於生物電極的材料或是生物感測器的發展能有良好的影響。
並列摘要
For electrochemical experiments involving biological buffers, pH values, ions, and electrode materials play major roles in the electrochemical diagram of the measurements. As we are conducting electrochemical experiments, background signals are sometimes mixed with true signals, easily leading to a wrong interpretation of the data. These background signals are easily induced by the reactions between buffers and electrode materials. However, these background signals have rarely been studied systematically. In response to rapid developments in the field and application of bioelectrodes, we conducted a much-needed systematic study of these background signals and the electrochemical windows in buffers—specifically, of the electrochemical windows gold, glassy carbon, and platinum in three most commonly used biological buffers, namely, Tris, HEPES, and phosphate. We examined the pH effect using HCl, H2SO4, and NaOH to modulate the pH values from 6.0 to 9.0 in the three buffers. Furthermore, through comparison of HCl and H2SO4, we were able to illustrate the reaction between Cl− ions and the metallic electrode. This reaction also led to clear redox peaks as background signals in cyclic voltammograms. When a high potential was applied, the formation of hydroxide was evident on the metallic electrode, which led to a clear reduction peak in cyclic voltammograms. In addition, we used an atomic force microscope to monitor the morphology of the electrode surface when a cyclic potential was applied. All tests were conducted in the presence of 100 mM LiClO4, which was used as the electrolytes. These characterization results yield critical insights into electrode surface reactions, insights which are crucial for precisely interpreting electrochemical results measured in biological buffers. This fundamental study provides comprehensive information, which is especially helpful for the development of bioelectrode materials and bioelectronics applications.