Abstract An electrochemical sensor based on guanine-, polythionine-, and nitrogen-doped graphene modified glassy carbon electrode (G/PTH/NG/GCE) was fabricated and applied for antioxidant capacity evaluation of natural compounds and complexes in electrochemical method since natural sources of active compounds exhibited various antioxidant activities. When the antioxidants existed in the system, the generated hydroxyl radicals were scavenged and the damage to guanine immobilized on the electrode was reduced less resulting in the oxidation peak current increased in square wave voltammetry. After the modifications of polythionine- and nitrogen-doped graphene, the oxidation peak current was improved. The effects of pH, incubation time, and concentrations of guanine and Fe2+ ions on the performances of the electrode were investigated and optimized. The G/PTH/NG/GCE showed good linearity, reproducibility, and storage stability for antioxidant capacity evaluation of ascorbic acid at the optimum conditions. The antioxidant capacities of three flavonoids and three plant extracts were measured using the G/PTH/NG/GCE and DPPH methods. Myricetin showed the highest antioxidant capacity in both electrochemical and DPPH methods. The proposed G/PTH/NG/GCE exhibited easy fabrication procedure, rapid detection time, and low cost for the detection of antioxidant activity for various kinds of samples.

中文翻译：

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天然化合物在鸟嘌呤、聚硫氨酸和氮掺杂石墨烯修饰的玻碳电极上的抗氧化能力的电化学评价

摘要 制备了一种基于鸟嘌呤、聚硫氨酸和氮掺杂石墨烯修饰玻碳电极（G/PTH/NG/GCE）的电化学传感器，并将其应用于电化学方法中天然化合物和配合物的抗氧化能力评估。活性化合物表现出各种抗氧化活性。当体系中存在抗氧化剂时，产生的羟基自由基被清除，对固定在电极上的鸟嘌呤的损伤减少，方波伏安法中氧化峰电流增加。经过聚硫氨酸和氮掺杂石墨烯的改性后，氧化峰电流得到改善。研究并优化了pH值、孵育时间、鸟嘌呤和Fe2+离子浓度对电极性能的影响。G/PTH/NG/GCE 在最佳条件下对抗坏血酸的抗氧化能力评价显示出良好的线性、重现性和储存稳定性。使用 G/PTH/NG/GCE 和 DPPH 方法测量了三种黄酮类化合物和三种植物提取物的抗氧化能力。杨梅素在电化学和 DPPH 方法中均显示出最高的抗氧化能力。所提出的 G/PTH/NG/GCE 在检测各种样品的抗氧化活性方面表现出简单的制造过程、快速的检测时间和低成本。杨梅素在电化学和 DPPH 方法中均显示出最高的抗氧化能力。所提出的 G/PTH/NG/GCE 在检测各种样品的抗氧化活性方面表现出简单的制造过程、快速的检测时间和低成本。杨梅素在电化学和 DPPH 方法中均显示出最高的抗氧化能力。所提出的 G/PTH/NG/GCE 在检测各种样品的抗氧化活性方面表现出简单的制造过程、快速的检测时间和低成本。