Dong Shuqing, Zhang Shan, Chi Langzhu, He Pingang, Wang Qingjiang, Fang Yuzhi
Department of Chemistry, East China Normal University, Shanghai 200062, China.
Anal Biochem. 2008 Oct 15;381(2):199-204. doi: 10.1016/j.ab.2008.05.011. Epub 2008 May 17.
A carbon paste electrode modified with multiwall carbon nanotubes and copper(I) oxide (MWCNT-Cu(2)O CPME) was fabricated, and the electrochemical behaviors of 19 kinds of natural amino acids at this modified electrode were studied. The experimental results showed that the various kinds of amino acids without any derivatization displayed obvious oxidation current responses at the modified electrode. It was also found that the current response values of amino acids were dependent mainly on pH values of buffer solutions. The phenomenon could be explained by the fact that the amino acids suffered complexation or electrocatalytic oxidation processes under different pH values. Six kinds of amino acids (arginine, tryptophan, histidine, threonine, serine, and tyrosine), which performed high-oxidation current responses in alkaline buffers, were selected to be detected simultaneously by capillary zone electrophoresis coupled with amperometric detection (CZE-AD). These amino acids could be perfectly separated within 20 min, and their detection limits were as low as 10(-7) or 10(-8)mol L(-1) magnitude (signal/noise ratio=3). The above results demonstrated that MWCNT-Cu(2)O CPME could be successfully employed as an electrochemical sensor for amino acids with some advantages of convenient preparation, high sensitivity, and good repeatability.
制备了一种用多壁碳纳米管和氧化亚铜（MWCNT-Cu₂O CPME）修饰的碳糊电极，并研究了19种天然氨基酸在该修饰电极上的电化学行为。实验结果表明，未经任何衍生化处理的各种氨基酸在修饰电极上均表现出明显的氧化电流响应。还发现氨基酸的电流响应值主要取决于缓冲溶液的pH值。这种现象可以用以下事实来解释：氨基酸在不同pH值下经历了络合或电催化氧化过程。选择了六种在碱性缓冲液中表现出高氧化电流响应的氨基酸（精氨酸、色氨酸、组氨酸、苏氨酸、丝氨酸和酪氨酸），通过毛细管区带电泳-安培检测（CZE-AD）进行同时检测。这些氨基酸可以在20分钟内完美分离，其检测限低至10⁻⁷或10⁻⁸mol L⁻¹量级（信噪比 = 3）。上述结果表明，MWCNT-Cu₂O CPME可以成功用作氨基酸的电化学传感器，具有制备方便、灵敏度高和重复性好等优点。
