Abstract
AbstractAn 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.
Highlights
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
These results illustrated that the determination of antioxidant capacity using G/PTH/NG/GCE was effective with good linearity and high accuracy
The antioxidant capacities of ascorbic acid and galangin would be verified in the following study. This comparison showed that the determination of antioxidant capacity using G/PTH/NG/ GCE has a good selectivity of antioxidants and showed a certain anti-interference ability
Summary
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. An electroactive and conductive PTH membrane could be accomplished on the surface of the electrode using electrochemical polymerization This kind of fabrication showed advantages in the thickness of the film, response time, and charge transfer rate than the suspension coating method [18,19]. The proposed G/PTH/NG/GCE showed higher oxidation peak current, which meant higher sensitivity for evaluation It could be directly used in the determination of antioxidant capacity for compounds and mixture without extra processes and reagents. This modified electrode could provide a fast and cheap sensor for the analysis of antioxidants with promising prospects in the food and chemical industries. The observations were completed by a JSM 6610Lv scanning electron microscopy (JEOL, Tokyo, Japan) operated at 25 kV and a JEM-2100 electron microscope (JEOL, Akishima, Japan)
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