scholarly journals Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)

2020 ◽  
Vol 18 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Ping Tang ◽  
Xiaosheng Tang ◽  
Shiyong Mei ◽  
Yixi Xie ◽  
Liangliang Liu ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Antioxidant Capacity ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Carbon Electrode ◽  
Oxidation Peak ◽  
Modified Glassy Carbon Electrode ◽  
Peak Current ◽  
Oxidation Peak Current ◽  
Antioxidant Capacities

AbstractIn this study, an electrochemical biosensor based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE) was developed and employed for antioxidant screening and antioxidant capacity evaluation. The oxidation peak current of guanine was improved and nearly tripled after modifications of chitosan and MoS2 nanosheet. The immobilized guanine could be damaged by hydroxyl radicals generated in Fenton solution. However, in the presence of antioxidants, the guanine was protected and the oxidation peak current of guanine increased. This process mimics the mechanism of antioxidant protection in human body. The factors affecting preparation of sensor and detection of antioxidant capacity were optimized. At the optimum conditions, the guanine/CS/MoS2/GCE showed wide linear range, low detection limit, satisfactory reproducibility and stability for detection. Ascorbic acid was used as a model antioxidant to evaluate the antioxidant capacity. A good linearity was observed with a correlation coefficient of 0.9959 in the concentrations between 0.5 and 4.0 mg L-1. The antioxidant capacities of three flavonoids were also tested and the rank of antioxidant capacities was ascorbic acid (51.84%), quercetin (45.82%), fisetin (34.39%) and catechin (16.99%). Due to the rapid measurement and low cost, this sensor could provide an available sensing platform for antioxidant screening and evaluation.

scholarly journals Sensitive Voltammetric Sensor for Tryptophan Detection by Using Polyvinylpyrrolidone Functionalized Graphene/GCE

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 125 ◽  
Author(s):  
Quanguo He ◽  
Jun Liu ◽  
Jinxia Feng ◽  
Yiyong Wu ◽  
Yaling Tian ◽  
...  
Keyword(s):  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Oxidation Mechanism ◽  
Carbon Electrode ◽  
Oxidation Peak ◽  
Experimental Conditions ◽  
Peak Current ◽  
Oxidation Peak Current

In this paper, an electrochemical method for the measurement of tryptophan (Trp) was developed based on a glassy carbon electrode modified with polyvinylpyrrolidonefunctionalized graphene (PVP-GR)/glassy carbon electrode (GCE). In 0.1 M phosphate buffer solution (PBS, pH = 2.2), compared with bare GCE, PVP/GCE, and GR/GCE, the oxidation peak current of Trp increased dramatically at PVP-GR/GCE. The oxidation mechanism of Trp on the PVP-GR/GCE was discussed and the experimental conditions were optimized. Under the best experimental conditions, the oxidation peak current of Trp was proportional to its concentration in the range of 0.06 µM–10.0 µM and 10.0–100.0 µM, and the limit of detection (LOD) was 0.01 µM (S/N = 3). The target modified electrode with excellent repeatability, stability and selectivity, was successfully applied to detectTrp in drugs and biological samples.

Electrochemical Sensor for the Detection of Dopamine in the Presence of Ascorbic Acid in Neutral pH on Graphitized Nanoporous Carbon Modified Glassy Carbon Electrode

2012 ◽  
Vol 584 ◽  
pp. 334-338
Author(s):  
Rajendiran Thangaraj ◽  
Muringah Kandy Mufeedah ◽  
Annamalai Senthil Kumar
Keyword(s):  
Ascorbic Acid ◽  
Glassy Carbon Electrode ◽  
Modified Electrode ◽  
Glassy Carbon ◽  
Nanoporous Carbon ◽  
Carbon Electrode ◽  
Oxidation Peak ◽  
Modified Glassy Carbon Electrode ◽  
Buffer Solution ◽  
Neutral Ph

Selective detection of dopamine (DA) in presence of ascorbic (AA) is an important analytical problem, due to its combined existence in the biological system. In the present study, we are reporting an electrochemical detection method for dopamine (DA) in the presence of ascorbic acid (AA) using graphitized nanoporous carbon (NPC) modified glassy carbon electrode (GCE/NPC) in 0.1 M phosphate buffer solution. The modified electrode shows excellent electrocatalytic activities towards the oxidations of DA and AA in neutral pH buffer solution. Compared to unmodified GCE, GCE/NPC shows well separated and enhanced oxidation peak currents. Differential pulse voltammetric technique used as qualitative analytical tool for the detection of DA. The oxidation peak potentials for DA and AA were at -80 and 136 mV vs Ag/AgCl respectively. The modified electrode shows good stability and reproducibility with the relative standard deviation value of 2.6 %. The analytical application of the modified electrode (GCE/NPC) was demonstrated for the individual determination of DA in clinical injection and pharmaceutical tablet by using standard addition method.

Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene

2020 ◽  
Vol 18 (1) ◽  
pp. 1054-1063
Author(s):  
Yafen Fu ◽  
Zongyi You ◽  
Aiping Xiao ◽  
Liangliang Liu ◽  
Weien Zhou
Keyword(s):  
Antioxidant Capacity ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Carbon Electrode ◽  
Oxidation Peak ◽  
Nitrogen Doped ◽  
Oxidation Peak Current ◽  
Capacity Evaluation ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

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.

A Novel Electrochemical Sensor for the Analysis of Salbutamol in Pork Samples by Using NiFe2O4 Nanoparticles Modified Glassy Carbon Electrode

2013 ◽  
Vol 850-851 ◽  
pp. 1279-1282 ◽  
Author(s):  
Su Xing Luo ◽  
Yuan Hui Wu ◽  
Hua Gou ◽  
Yan Liu
Keyword(s):  
Detection Limit ◽  
Electrochemical Sensor ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrochemical Method ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Peak Current ◽  
Anodic Peak Current ◽  
Pork Samples

In this work, a simple and sensitive electrochemical method sensor was developed to determine salbutamol based on magnetic NiFe2O4nanoparticles modified glassy carbon electrode. It was found the anodic peak current of salbutamol was linear with the concentration of salbutamol from 2.0 μM to 60 μM with a detection limit of 1.0 μM (S/N=3). The developed method was successfully applied to determine salbutamol content in pork samples with satisfactory results.

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