Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India.
Talanta. 2011 Oct 15;85(5):2626-31. doi: 10.1016/j.talanta.2011.08.031. Epub 2011 Aug 22.
The effect of surface modification of indium tin oxide (ITO) by multi wall carbon nanotube (MWNT) and gold nanoparticles attached multi wall carbon nanotube (AuNP-MWNT) has been studied to determine tryptophan, an important and essential amino acid for humans and herbivores. A detailed comparison has been made among the voltammetric response of bare ITO, MWNT/ITO and AuNP-MWNT/ITO in respects of several essential analytical parameters viz. sensitivity, detection limit, peak current and peak potential of tryptophan. The AuNP-MWNT/ITO exhibited a well defined anodic peak at pH 7.2 at a potential of ∼ 669 mV for the oxidation of tryptophan as compared to 760 mV at MWNT/ITO electrode. Under optimum conditions linear calibration curve was obtained over tryptophan concentration range 0.5-90.0 μM in phosphate buffer solution of pH 7.2 with detection limit and sensitivity of 0.025 μM and 0.12 μA μM(-1), respectively. The oxidation of tryptophan occurred in a pH dependent, 2e(-) and 2H(+) process and the electrode reaction followed adsorption controlled pathway. The method has been found selective and successfully implemented for the determination of tryptophan in human urine and plasma samples using standard addition method. The electrode exhibited an efficient catalytic response with good reproducibility and stability.
已研究了通过多壁碳纳米管 (MWNT) 和附着金纳米粒子的多壁碳纳米管 (AuNP-MWNT) 对氧化铟锡 (ITO) 的表面修饰的效果，以确定色氨酸，这是人类和食草动物的重要必需氨基酸。在几个基本分析参数方面，如色氨酸的灵敏度、检测限、峰电流和峰电位，对裸 ITO、MWNT/ITO 和 AuNP-MWNT/ITO 的伏安响应进行了详细比较。与 MWNT/ITO 电极相比，AuNP-MWNT/ITO 在 pH 7.2 时在约 669 mV 处显示出色氨酸氧化的明确定义的阳极峰。在最佳条件下，在 pH 7.2 的磷酸盐缓冲溶液中，色氨酸浓度范围为 0.5-90.0 μM 时，获得了线性校准曲线，检测限和灵敏度分别为 0.025 μM 和 0.12 μA μM(-1)。色氨酸的氧化是依赖 pH 的、2e(-) 和 2H(+) 过程，电极反应遵循吸附控制途径。该方法已被发现具有选择性，并使用标准添加法成功用于测定人尿和血浆样品中的色氨酸。该电极表现出高效的催化响应，具有良好的重现性和稳定性。
