Institute of Biochemistry and Biophysics, University of Tehran, 13145-1384 Tehran, Iran.
Anal Biochem. 2009 May 1;388(1):81-90. doi: 10.1016/j.ab.2009.02.021. Epub 2009 Feb 25.
The electrocatalytic oxidation of five amino acids-glycine, aspartic acid, cysteine, glutamic acid, and tyrosine-on two copper-based electrodes comprising copper microparticle-modified carbon paste electrode (m-CPE) and copper nanoparticle-modified CPE (n-CPE) was investigated. In the voltammograms recorded using m-CPE, a single anodic peak related to the oxidation of amino acids appeared and was related to the electrocatalytic oxidation of the amino acids via the electrogenerated Cu(III) species. Using n-CPE, however, two overlapped anodic peaks in the voltammograms appeared and were related to two fine tunable steps of the oxidation process. The currents of the two peaks were controlled by diffusion and were confirmed by chronoamperometric measurements. The amino acids were oxidized on n-CPE at higher rates and at lower potentials compared with m-CPE. This was attributed to the nanosize of copper nanoparticles. Some primary linear-chain amines and primary branched-chain amines were oxidized on the copper-based electrodes as markers. The catalytic rate constants, the transfer coefficients, and the diffusion coefficients for the amino acids are reported. Simple, sensitive, and time-saving sensing procedures in both batch and flow systems were developed for the analysis of the amino acids, and the corresponding analytical parameters are reported.
本文研究了两种铜基电极（铜微粒修饰碳糊电极（m-CPE）和铜纳米粒子修饰 CPE（n-CPE））上五种氨基酸（甘氨酸、天冬氨酸、半胱氨酸、谷氨酸和酪氨酸）的电催化氧化。在 m-CPE 记录的伏安图中，出现了一个与氨基酸氧化有关的单一阳极峰，这与通过电生成的 Cu(III)物种的氨基酸电催化氧化有关。然而，在 n-CPE 中，伏安图中出现了两个重叠的阳极峰，这与氧化过程的两个微调步骤有关。两个峰的电流由扩散控制，并通过计时安培测量得到证实。与 m-CPE 相比，氨基酸在 n-CPE 上的氧化速率更高，电位更低。这归因于铜纳米粒子的纳米尺寸。一些初级直链胺和初级支链胺在铜基电极上被氧化作为标记物。报道了氨基酸的催化速率常数、传递系数和扩散系数。开发了批处理和流动系统中简单、灵敏和节省时间的传感程序来分析氨基酸，并报道了相应的分析参数。
