Single Step Synthesis of Gold Nanoparticles Decorated Graphene Oxide Using Aniline as Reducing Agent and Study its Application on Elecrocatalytic Detection of Tryptophan

2014 ◽  
Vol 938 ◽  
pp. 182-191
Author(s):  
P. Divya ◽  
A. Sudarvizhi ◽  
K. Pandian
Keyword(s):  
Gold Nanoparticles ◽  
Cyclic Voltammetry ◽  
Graphene Oxide ◽  
Modified Electrodes ◽  
Differential Pulse ◽  
Calibration Graph ◽  
Single Step ◽  
Reducing Agent ◽  
Step Method ◽  
Experimental Conditions

A single step method for the synthesis of gold nanoparticles decorated graphene oxide nanocomposite using aniline as reducing agent has been developed. The composite was characterized using FE-SEM, UV-Vis and FT-IR and XRD analysis. The electron transfer behavior of the modified electrodes was investigated in a redox probe using cyclic voltammetry. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical properties of AuNPs/GO/GCE towards the electrochemical oxidation of tryptophan. A calibration graph was constructed by plotting the concentration of tryptophan against the peak current. Under the optimum experimental conditions, the oxidation peak currents were measured by varying the tryptophan concentrations. The resulting sensor displays an excellent repeatability and long-term stability.

Solar Exfoliated Graphene Oxide: A Platform for Electrochemical Sensing of Epinephrine

2020 ◽  
Vol 16 (4) ◽  
pp. 393-403 ◽  
Author(s):  
Renjini Sadhana ◽  
Pinky Abraham ◽  
Anithakumary Vidyadharan
Keyword(s):  
Cyclic Voltammetry ◽  
Graphene Oxide ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Simultaneous Detection ◽  
Differential Pulse ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Reduced Graphene ◽  
Pulse Voltammetry

Introduction: In this study, solar exfoliated graphite oxide modified glassy carbon electrode was used for the anodic oxidation of epinephrine in a phosphate buffer medium at pH7. The modified electrode showed fast response and sensitivity towards Epinephrine Molecule (EP). The electrode was characterized electrochemically through Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). Area of the electrode enhanced three times during modification and studies reveal that the oxidation process of EP occurs by an adsorption controlled process involving two electrons. The results showed a detection limit of 0.50 ± 0.01μM with a linear range up to 100 μM. The rate constant calculated for the electron transfer reaction is 1.35 s-1. The electrode was effective for simultaneous detection of EP in the presence of Ascorbic Acid (AA) and Uric Acid (UA) with well-resolved signals. The sensitivity, selectivity and stability of the sensor were also confirmed. Methods: Glassy carbon electrode modified by reduced graphene oxide was used for the detection and quantification of epinephrine using cyclic voltammetry and differential pulse voltammetry. Results: The results showed an enhancement in the electrocatalytic oxidation of epinephrine due to the increase in the effective surface area of the modified electrode. The anodic transfer coefficient, detection limit and electron transfer rate constant of the reaction were also calculated. Conclusion: The paper reports the determination of epinephrine using reduced graphene oxide modified glassy carbon electrode through CV and DPV. The sensor exhibited excellent reproducibility and repeatability for the detection of epinephrine and also its simultaneous detection of ascorbic acid and uric acid, which coexist in the biological system.

scholarly journals Suitability of the Cyclic Voltammetry Measurements and DPPH• Spectrophotometric Assay to Determine the Antioxidant Capacity of Food-Grade Oenological Tannins

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2925 ◽  
Author(s):  
Arianna Ricci ◽  
Giuseppina Paola Parpinello ◽  
Nemanja Teslić ◽  
Paul Andrew Kilmartin ◽  
Andrea Versari
Keyword(s):  
Cyclic Voltammetry ◽  
Colorimetric Assay ◽  
Radical Scavenging ◽  
Calibration Graph ◽  
Spectrophotometric Assay ◽  
Experimental Conditions ◽  
Fast Analysis ◽  
Cv Measurements ◽  
And Control ◽  
Analytical Approaches

Twenty commercially available oenological tannins (including hydrolysable and condensed) were assessed for their antiradical/reducing activity, comparing two analytical approaches: The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging spectrophotometric assay and the cyclic voltammetry (CV) electrochemical method. Electrochemical measurements were performed over a −200 mV–500 mV scan range, and integrated anodic currents to 500 mV were used to build a calibration graph with (+)-catechin as a reference standard (linear range: From 0.0078 to 1 mM, R2 = 0.9887). The CV results were compared with the DPPH• assay (expressed as % of radical scavenged in time), showing high correlation due to the similarity of the chemical mechanisms underlying both methods involving polyphenolic compounds as reductants. Improved correlation was observed by increasing the incubation time with DPPH• to 24 h (R2 = 0.925), demonstrating that the spectrophotometric method requires a long-term incubation to complete the scavenging reaction when high-molecular weight tannins are involved; this constraint has been overcome by using instant CV measurements. We concluded that the CV represents a valid alternative to the DPPH• colorimetric assay, taking advantage of fast analysis and control on the experimental conditions and, because of these properties, it can assist the quality control along the supply chain.

scholarly journals Novel Electrochemical Sensor Fabricated for Individual and Simultaneous Ultrasensitive Determination of Olaquindox and Carbadox Based on MWCNT-OH/CMK-8 Hybrid Nanocomposite Film

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3041 ◽  
Author(s):  
Yanqing Liu ◽  
Gengxin Hu ◽  
Hongwu Wang ◽  
Su Yao ◽  
Yinjian Ye
Keyword(s):  
Electrochemical Sensor ◽  
Simultaneous Determination ◽  
Modified Electrode ◽  
Electrochemical Impedance ◽  
Modified Electrodes ◽  
Differential Pulse ◽  
Hybrid Nanocomposite ◽  
Experimental Conditions ◽  
Linear Relationships

A hybrid nanocomposite consisting of hydroxylated multi-walled carbon nanotubes (MWCNTs−OH) and cube mesoporous carbon (CMK−8) was applied in this study to construct an MWCNT−OH/CMK−8/gold electrode (GE) electrochemical sensor and simultaneously perform the electro-reduction of olaquindox (OLA) and carbadox (CBX). The respective peak currents of CBX and OLA on the modified electrode increased by 720- and 595-fold relative to the peak current of GE. The performances of the modified electrode were investigated with electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry. Then, the modified electrodes were used for the individual and simultaneous determination of OLA and CBX. The fabricated sensor demonstrated a linear response at 0.2–500 nmol/L in optimum experimental conditions, and the detection limits were 104.1 and 62.9 pmol/L for the simultaneous determination of OLA and CBX, respectively. As for individual determination, wide linear relationships were obtained for the detected OLA with levels of 0.05–500 nmol/L with LOD of 20.7 pmol/L and the detected CBX with levels of 0.10–500 nmol/L with LOD of 50.2 pmol/L. The fabricated sensor was successfully used in the independent and simultaneous determination of OLA and CBX in spiked pork samples.

Polyazulenes Based Materials for Heavy Metal Ions Detection

2017 ◽  
Vol 68 (10) ◽  
pp. 2215-2218
Author(s):  
Alexandra Oprisanu ◽  
Ioana Georgiana Lazar ◽  
Maria Daniela Pop ◽  
Eleonora Mihaela Ungureanu ◽  
Raluca Isopescu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Polymerization ◽  
Modified Electrodes ◽  
Functional Materials ◽  
Rotating Disk ◽  
Differential Pulse ◽  
Membered Ring ◽  
Rotating Disk Electrode ◽  
Rotating Disk Electrode Voltammetry ◽  
Metal Ions Detection

Azulene is a special monomer used to functionalize electrodes due to its high polarizability, because it makes possible spontaneous electron drift from the five-membered ring to the seven-membered ring. Our study concerns the electrochemical characterization by cyclic voltammetry, differential pulse-voltammetry and rotating disk electrode voltammetry of a new azulene monomer, 4-(5-isopropyl-3,8-dimethylazulen-1-yl)-2,6-bis((E)-2-(thiophen-2-yl)vinyl) pyridine (L). It has been used to obtain complexing modified electrodes by electrochemical polymerization. PolyL films modified electrodes have been characterized by cyclic voltammetry in ferrocene probe solution. The complexing properties of polyL based functional materials have been investigated towards heavy metals (Pb, Cd Hg, Cu) by preconcentration � anodic stripping technique.

Zero waste, single step methods of fabrication of reduced graphene oxide decorated with gold nanoparticles

2022 ◽  
pp. e00387
Author(s):  
Marek Wojnicki ◽  
Beata Michorczyk ◽  
Konrad Wojtaszek ◽  
Dawid Kutyła ◽  
Karolina Kołczyk-Siedlecka ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Single Step ◽  
Zero Waste ◽  
Reduced Graphene

scholarly journals Influence of Experimental Conditions on Deposition of Silver Nanoparticles Onto Surface of Graphene Oxide / Wpływ Warunków Eksperymentalnych Na Proces Osadzania Nanocząstek Srebra Na Powierzchni Tlenku Grafenu

2015 ◽  
Vol 60 (4) ◽  
pp. 2631-2636
Author(s):  
M. Wojnicki ◽  
I. Mania ◽  
M. Marzec ◽  
M. Gajewska ◽  
K. Mech
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Alkaline Solution ◽  
Acidic Solution ◽  
Deposition Process ◽  
Reducing Agent ◽  
Experimental Conditions ◽  
Initial Concentration ◽  
The Impact

Present work describes the influence of silver nanoparticles precursor form as well as the impact of graphene oxide initial concentration on deposition of the silver nanoparticles onto graphene oxide. Borane dimethylamine complex (DMAB) was used as the reducing agent. It was observed that application of silver ammonia complexes as the silver nanoparticles precursor as well as alkaline solution effect in higher quantity of deposited AgNPs in comparison to deposition process with the use of silver(I) nitrate in acidic solution.

scholarly journals Controlled Reduction of Graphene Oxide Using Sulfuric Acid

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 59
Author(s):  
Ana Cecilia Reynosa-Martínez ◽  
Erika Gómez-Chayres ◽  
Rafael Villaurrutia ◽  
Eddie López-Honorato
Keyword(s):  
Graphene Oxide ◽  
Sulfuric Acid ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Single Step ◽  
Reducing Agent ◽  
H2so4 Concentration ◽  
Sulfur Doping ◽  
Domain Structures ◽  
Diffraction Patterns

Sulfuric acid under different concentrations and with the addition of SO3 (fuming sulfuric acid) was studied as a reducing agent for the production of reduced graphene oxide (RGO). Three concentrations of sulfuric acid (1.5, 5, and 12 M), as well as 12 M with 30% SO3, were used. The reduction of graphene oxide increased with H2SO4 concentration as observed by Fourier-transformed infrared spectroscopy and X-ray photoelectron spectroscopy. It was observed that GO lost primarily epoxide functional groups from 40.4 to 9.7% and obtaining 69.8% carbon when using 12 M H2SO4, without leaving sulfur doping. Additionally, the appearance of hexagonal domain structures observed in transmission electron microscopy and analyzed by selected area electron diffraction patterns confirmed the improvement in graphitization. Although the addition of SO3 in H2SO4 improved the GO reduction with 74% carbon, as measured by XPS, the use of SO3 introduced sulfur doping of 1.3%. RGO produced with sulfuric acid was compared with a sample obtained via ultraviolet (UV) irradiation, a very common reduction route, by observing that the RGO produced with sulfuric acid had a higher C/O ratio than the material reduced by UV irradiation. This work showed that sulfuric acid can be used as a single-step reducing agent for RGO without sulfur contamination.

scholarly journals Enhancement of graphene oxide through β-cyclodextrin composite to sensitive analysis of an antidepressant: Sulpiride

2021 ◽  
Vol 19 (1) ◽  
pp. 228-236
Author(s):  
Ayca Urcuk ◽  
Leyla Karadurmus ◽  
Nurgul K. Bakirhan ◽  
Sibel A. Ozkan
Keyword(s):  
Graphene Oxide ◽  
Urine Analysis ◽  
Limit Of Detection ◽  
Pyrolytic Graphite ◽  
Differential Pulse ◽  
Electrochemical Analysis ◽  
Calibration Plot ◽  
Experimental Conditions ◽  
Accumulation Time ◽  
Square Wave

Abstract In this study, the electrochemical behavior of sulpiride (SUL) was examined deeply by using pyrolytic graphite electrode modified with graphene oxide (GO) and β-cyclodextrin (β-CD). The developed nanosensor indicated considerable impact by significantly increasing the signal of SUL compared with the bare electrode. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) methods were utilized to investigate the SUL electrochemical analysis in aqueous solutions. Under optimum experimental conditions, calibration plot for SUL with a limit of detection of 2.83 × 10−9 M was obtained at accumulation time of the 30 s using square wave adsorptive stripping voltammetric technique (AdSSWV) in the range of 1.0 × 10−7 to 5.0 × 10−5 M. The effects of accumulation potential, accumulation time, pH, scan rate, electrolyte, and interfering agents were studied to obtain the intensive peak signal of the analyte. The presented method is validated and successfully performed for the determination of the SUL tablet and capsule. The fabricated nanosensor was carried out for the detection of SUL in the urine. Excellent recoveries among 104.37, 103.82, and 101.95% were obtained for tablet and capsule forms and urine analysis.

scholarly journals Novel Competitive Voltammetric Aptasensor Based on Electrospun Carbon Nanofibers-Gold Nanoparticles Modified Graphite Electrode for Salmonella enterica serovar Detection

2020 ◽  
Vol 11 (2) ◽  
pp. 8702-8715
Keyword(s):  
Gold Nanoparticles ◽  
Carbon Nanofibers ◽  
Electrochemical Detection ◽  
Salmonella Enterica ◽  
Electrochemical Impedance ◽  
Graphite Electrode ◽  
Limit Of Detection ◽  
Differential Pulse ◽  
Pencil Graphite Electrode ◽  
Experimental Conditions

Salmonella enterica is considered one of the most common bacterial agent causes of acute gastroenteritis and foodborne illness in humans worldwide. Antibiotic-resistant is considered as a major problem in Salmonella enterica Serovar. This study introduces a new simple and sensitive aptasensor based on chitosan (Chi)-electrospun carbon nanofibers (CNF) /gold nanoparticles (GNPs) decorated pencil graphite electrode (GE) as a novel platform for electrochemical detection of Salmonella enterica Serovar. A Salmonella-specific recognition aptamer ssDNA sequence was used in the development of this voltammetric biosensor. Electrochemical behaviors of electrodes; unmodified GE, CNF-Chi/GE, GNPs/CNF-Chi/GE, GNPs/CNF-Chi/GEs linked with the aptamer were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). After the optimization of experimental conditions (e.g., CNF concentration, pH, and incubation time), electrochemical detection of Salmonella was performed via differential pulse voltammetry (DPV) in methylene blue solution. The designed aptasensor exhibited a linear range of 10 to 105 (CFU/mL) with the limit of detection (LOD) 1.223 (Cfu/mL) for Salmonella. This aptasensor displayed excellent selectivity and remarkable sensitivity in terms of the detection of Salmonella enterica even in the real samples as compared to the polymerase chain reaction (PCR) technique. The constructed aptasensor is a highly sensitive sensor for the detection of Salmonella enterica and also can be tailored for various other targets.

Facile Synthesis and Characterizations of Silver Nanoparticles-Reduced Graphene Oxide Hybrid

2021 ◽  
Vol 317 ◽  
pp. 208-213
Author(s):  
Nurul Izrini Ikhsan ◽  
Nurul Ain Mohamed Zamri
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Large Scale ◽  
Average Particle Size ◽  
Modified Electrodes ◽  
Reducing Agent ◽  
Average Particle ◽  
Reduced Graphene

Here, we report the synthesis of silver nanoparticles-reduced graphene oxide (AgNPs-rGO) hybrid for simple and eco-friendly method. Silver nanoparticles (AgNPs) were successfully deposited on reduced graphene oxide (rGO) sheets to form (AgNPs-rGO) hybrid using lemon extract as a reducing and stabilizing agent. The products form a stable aqueous solution without any surfactant stabilizers and this makes it possible to produce (AgNPs-rGO) hybrid on a large scale using low-cost solution processing technique. The synthesis of nanohybrid was examed at different ratio of reducing agent (1:1, 1:2, 1:4) and characterized using UV-Visible (UV-Vis) absorption spectrum, X-ray diffraction (XRD), Raman spectroscopy analyses and transmission electron microscopy (TEM) analyses. From UV-Vis absorption spectrum, the (AgNPs-rGO) (1:1) hybrid result shows the sharp peak at 433 nm indicating the accomplishment formation of AgNPs on the surface of rGO sheets. Crystalline and spherical AgNPs with an average particle size of 21 nm were found in the (AgNPs-rGO) hybrid with the assistance of 1:1 reducing agent. Furthermore, (AgNPs-rGO) (1:1) hybrid exhibit fast electron-transfer kinetics for electrochemical reaction of Fe (CN)63-/4- redox couple compared to other controlled modified electrodes, suggesting the potential applications for electrocatalysis and electrochemical sensor.

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