Graphene Oxide Modified Glassy Carbon Research Articles

Polycalconcarboxylic acid/electrochemically reduced graphene oxide-modified glassy carbon electrode-based voltammetric sensor for the simultaneous determination of dopamine and tyrosine

polycalconcarboxylic acid/electrochemically reduced graphene oxide-modified glassy carbon electrode-based voltammetric sensor for the simultaneous determination of dopamine and tyrosine

Enhanced sensitivity and selectivity of an electrochemical sensor for real-time propofol monitoring in anesthesia

In this study, an electrochemical sensor for the real-time monitoring of propofol (PPF) in anesthesia was developed using molecularly imprinted polymers and reduced graphene oxide-modified glassy carbon electrodes (MIPs/rGO/GCE). To make the electrode, GO was thermally reduced into rGO, which was then electrodeposited on GCE (rGO/GCE), followed by the electropolymerization of MIPs using LiClO4, pyrrole, and PPF (template) solution on rGO/GCE (MIPs/rGO/GCE). The PPF was then taken out of the pyrrole polymer. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS) examinations of surface composition and morphology revealed that electropolymerization MIP on rGO/GCE and reduction and deposition of rGO on GCE were both successful processes. MIPs/rGO/GCE revealed significant sensitivity and selectivity towards PPF in electrochemical tests utilizing cyclic voltammetry (CV) and amperometry. Results demonstrated a linear range from 0.5 to 250 μM that was steady and wide, with a sensitivity of 1.0776 μA/μM and a detection limit value of 0.08 μM. MIPs/rGO/GCE demonstrated outstanding electrocatalytic activity over a broad linear range and a reasonable detection limit value for PPF concentrations. To assess the method's applicability for the analysis of PPF, it was applied to real biological samples of human plasma and urine.

Imprinted polymer/reduced graphene oxide-modified glassy carbon electrode-based highly sensitive potentiometric sensing module for imidacloprid detection

A sensitive and highly selective potentiometric sensor for imidacloprid detection (IMD) is presented. Reduced graphene oxide (rGO) was used to modify a glassy carbon electrode in the fabrication of this sensor. The rGO is coated with IMD molecularly imprinted polymer (MIP), which serves as a sensing compound for herbicide recognition. Under ideal circumstances, a linear range of 0.5 µM-1.0 mM was measured, with a detection limit of 0.2 µM IMD. The method exhibits great selectivity towards the IMD's determination, according to the examination of the effects of potentially interfering species. For the direct potentiometric detection of IMD in several pesticide formulation samples, the assay method has been validated and shown to be adequate. The obtained recovery ranges from 94.5 to 106.4 % of the nominal or spiked concentration, with a mean relative standard deviation of 1.3 %. The applicability outcomes of using the presented sensor were contrasted with those attained by high-performance liquid chromatography (HPLC). There was no discernible difference between the suggested and HPLC procedures. Due to the sensitive membrane's and the liquid junction's proximity, this module's use permits applications with a small sample volume. The proposed sensor's effectiveness in a complicated matrix points to applications for rapid detection and tests for quality assurance and control in the agro-industry.

An electrochemical biosensor based on graphene oxide for determination of sertraline hydrochloride as an antidepressant drug

This research was done to develop an electrochemical sensor for the determination of the antidepressant drug sertraline hydrochloride (SH) using carboxylated graphene oxide-modified glassy carbon electrodes and silver vanadate nanoparticles (AgVO3/c-GO/GCE). The modified electrode, made of AgVO3/c-GO nanocomposite, was prepared using a hydrothermal technique. Studying the morphology and structure of changed electrodes revealed that AgVO3 nanowires and c-GO nanosheets formed a 3D hybrid matrix with a significant precise surface area and increased porosity. The prepared AgVO3/c-GO/GCE can be anticipated to be an appropriate platform for selective and sensitive SH sensing, according to studies of the electrochemical properties using CV and DPV techniques. With a detection limit and sensitivity of 25 ± 0.5 nM and 0.01901 μA/μM, respectively, the suggested sensor demonstrated a broad linear response range from concentrations of 0 to 1600 μM. Finally, the design sensor's suitability for accurately and precisely determining the SH in pharmaceutical tablets was assessed.

Elucidation of DNA-Eltrombopag Binding: Electrochemical, Spectroscopic and Molecular Docking Techniques.

Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor and nano-biosensor using reduced graphene oxide-modified glassy carbon electrode to detect DNA-eltrombopag binding. The reduction of desoxyguanosine (dGuo) and desoxyadenosine (dAdo) oxidation signals in the presence of the drug demonstrated that a strong interaction could be established between the eltrombopag and dsDNA. The eltrombopag-DNA interaction was further investigated by UV absorption and fluorescence emission spectroscopy to gain more quantitative insight on binding. Viscosity measurements were utilized to characterize the binding mode of the drug. To shed light on the noncovalent interactions and binding mechanism of eltrombopag molecular docking and molecular dynamics (MD), simulations were performed. Through simultaneously carried out experimental and in silico studies, it was established that the eltrombopag binds onto the DNA via intercalation.

An ultrasensitive electrochemical sensor for detecting porcine epidemic diarrhea virus based on a Prussian blue-reduced graphene oxide modified glassy carbon electrode

This study developed a novel, ultrasensitive sandwich-type electrochemical immunosensor for detecting the porcine epidemic diarrhea virus (PEDV). By electrochemical co-deposition of graphene and Prussian blue, a Prussian blue-reduced graphene oxide-modified glassy carbon electrode was made, further modified with PEDV-monoclonal antibodies (mAbs) to create a new PEDV immunosensor using the double antibody sandwich technique. The electrochemical characteristics of several modified electrodes were investigated using cyclic voltammetry (CV). We optimized the pH levels and scan rate. Additionally, we examined specificity, reproducibility, repeatability, accuracy, and stability. The study indicates that the immunosensor has good performance in the concentration range of 1 × 101.88 to 1 × 105.38 TCID50/mL of PEDV, with a detection limit of 1 × 101.93 TCID50/mL at a signal-to-noise ratio of 3σ. The composite membranes produced via co-deposition of graphene and Prussian blue effectively increased electron transport to the glassy carbon electrode, boosted response signals, and increased the sensitivity, specificity, and stability of the immunosensor. The immunosensor could accurately detect PEDV, with results comparable to real-time quantitative PCR. This technique was applied to PEDV detection and served as a model for developing additional immunosensors for detecting hazardous chemicals and pathogenic microbes.

Simultaneous Quantitation of Lead and Cadmium on an EDTA-Reduced Graphene Oxide-Modified Glassy Carbon Electrode.

Cadmium (Cd) and lead (Pb) are classified as category one toxicants. The provisional guideline values, according to the World Health Organization (WHO), for Cd and Pb are 3 and 10 ppb, respectively. An easy, quick, and cheap analytical technique is in demand for the determination of these toxic heavy metals in water. Hence, a novel electrochemical sensing platform is developed by modifying the glassy carbon electrode with ethylenediaminetetraacetic acid (EDTA)-functionalized reduced graphene oxide (ErGO) for the low-cost simultaneous quantitation of toxic heavy-metal ions, lead and cadmium, in real water samples. EDTA is grafted to the surface of graphene oxide, via amine linkage, and the oxygen functionality is reduced by a green agent, tyrosine. Various physical and electrochemical characterizations of the as-prepared electrocatalytic material were performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), ζ-potential, ultraviolet diffuse reflectance spectroscopy (UV-DRS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), etc. The glassy carbon electrode (GCE) is modified with ErGO by a simple drop-casting method for simultaneous metal-ion quantitation by differential pulse voltammetry (DPV). EDTA functionalization of graphene oxide and its further reduction using the green agent enhance the stability and sensitivity of the electrode substrate. The limits of detection for cadmium and lead ions calculated for ErGO/GCE are 1.02 and 2.52 ppb, while the limits of quantification for lead and cadmium ions are 3.41 and 8.4 ppb, and their sensitivities are 0.8 and 0.6 nA/ppb, respectively. Real river water contains 200.2 ± 0.38 ppb of Pb2+ ions (mean ± stdev, n = 3) by the DPV technique, which is validated by ICP-OES analysis.

Fabrication of Sulfur-Doped Reduced Graphene Oxide Modified Glassy Carbon Electrode (S@rGO/GCE) Based Acetaminophen Sensor

In the past few years, the design and fabrication of highly sensitive and selective electrochemical sensors have received enormous attention from electrochemists. Acetaminophen is an important drug that is used as an antipyretic and analgesic drug throughout the world. It is important to monitor the accurate amount of acetaminophen. Herein, we have prepared sulfur-doped reduced graphene oxide (S@rGO) using simple strategies. The morphological feature of the S@rGO was characterized by using scanning electron microscopy whereas phase purity and formation of S@rGO were authenticated by X-ray diffraction. Further, the glassy carbon electrode was modified using S@rGO as an electrode modifier and employed as an acetaminophen sensor (S@rGO/GCE). This modified sensor (S@rGO/GCE) demonstrates a reasonable detection limit of 0.07 µM and a sensitivity of 0.957 µA/µMcm2.

One-step Electrodeposition of CuNi Bimetallic Nanocatalyst Anchored on Reduced Graphene Oxide Modified Glassy Carbon Electrode for Nonenzymatic Sensing of Glucose

One-step Electrodeposition of CuNi Bimetallic Nanocatalyst Anchored on Reduced Graphene Oxide Modified Glassy Carbon Electrode for Nonenzymatic Sensing of Glucose

Novel Electrochemical Sensor for the Determination of Bisphenol A Using a Molybdenum(IV) Sulfide Quantum Dots Polysodium Styrene Sulfonate Functionalized Reduced Graphene Oxide Modified Glassy Carbon Electrode (GCE) by Differential Pulse Voltammetry (DPV)

A sensitive electrochemical platform for the determination of bisphenol A (BPA) was constructed. A hybrid of MoS2 quantum dots decorated poly sodium styrene sulfonate functionalized reduced graphene oxide (MoS2 QDS@PSS-rGO) was prepared by a simple method. The hybrid was cast on a bare glassy carbon electrode (GCE) to form the MoS2 QDs@PSS-rGO/GCE. The electrochemical response of BPA on the MoS2 QDs@PSS-rGO/GCE was significantly enhanced compared to the unmodified electrode, indicating that the nanocomposite possessed an electrocatalytic effect. A novel method was established to determine BPA with a detection limit of 0.008 μM. The applicability of the prepared sensor was demonstrated to determine BPA in real samples with high recoveries.

Electrochemical Dopamine Sensor Based on Gold Nanoparticles Electrodeposited on a Polymer/Reduced Graphene Oxide-Modified Glassy Carbon Electrode

A novel electrochemical dopamine (DA) sensor based on Au nanoparticles (AuNPs) electrochemically loaded on poly([2,2′;5′,2″]-terthiophene-3′-carbaldehyde)/reduced graphene oxide (poly(TTP)/rGO) improved glassy carbon electrode (GCE) was fabricated. The Au@poly(TTP)/rGO/GCE was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), amperometry, and electrochemical impedance spectroscopy (EIS). The optimized Au@poly(TTP)/rGO/GCE sensor had a wide electroactive surface area and exhibited good selectivity. The linear determination range of the sensor was from 0.02 to 232 µM with a sensitivity of 315 µA/mM/cm2. The limit of detection (LOD) was estimated to be 11.5 nM using signal-to-noise (S/N) ratio of 3. Additionally, the sensor displayed excellent selectivity, satisfactory response time from 4.5 to 6 s, replicability with a relative standard deviation (RSD) of 2.31%, reproducibility with a RSD of 3.67%, and storage stability with 92.57% of its initial current response for 37 days. The Au@poly(TTP)/rGO/GCE was employed to estimate DA in injection samples.

Electrochemical Determination of Diclofenac Sodium in Pharmaceutical Sample Using Copper Nanoparticles/Reduced Graphene Oxide Modified Glassy Carbon Electrode

Electrochemical Determination of Diclofenac Sodium in Pharmaceutical Sample Using Copper Nanoparticles/Reduced Graphene Oxide Modified Glassy Carbon Electrode

Simultaneous determination of catechol and hydroquinone with L-cysteine and nickel cobaltite Co-Functionalised Graphene Oxide Modified Glassy Carbon Electrode

ABSTRACT Catechol and Hydroquinone are considered to be main organic pollutants in water, and have a threat to human health and ecology security. It is imperative to establish a detection method of catechol and hydroquinone with high selectivity and sensitivity.In this work, a composite of L-Cysteine and nickel cobaltite co-functionalised graphene oxide was synthesised successfully by a facile hydrothermalmethod.The morphology and structure of the as-prepared composite was characterised by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the final product formed a 3D framework with urchin-like nickel cobaltite nanoparticle tightly packed on the layers of graphene oxide. The electrochemical properties of the composite modified glassy carbon electrode for detecting hydroxybenzeneisomers (hydroquinone and catechol) were tested by cyclic voltammetry and differential pulse voltammetry. The results discovered that the modified electrode exhibited an excellent repeatability and anti-interference towards the detection of catechol and hydroquinonewith linear response in the range of 10–140 μM and 10–200 μM, respectively.

Amino Acid-Functionalized Electrochemically Reduced Graphene Oxide-Modified Glassy Carbon Electrodes for the Efficient Sensing of Nitrite

Amino Acid-Functionalized Electrochemically Reduced Graphene Oxide-Modified Glassy Carbon Electrodes for the Efficient Sensing of Nitrite

Simple and Rapid Determination of Tartrazine Using Poly(l-arginine)/Electrochemically Reduced Graphene Oxide Modified Glassy Carbon Electrode

Simple and Rapid Determination of Tartrazine Using Poly(l-arginine)/Electrochemically Reduced Graphene Oxide Modified Glassy Carbon Electrode

Electrochemical Determination of Hydrogen Peroxide by a Nonenzymatic Catalytically Enhanced Silver-Iron (III) Oxide/Polyoxometalate/Reduced Graphene Oxide Modified Glassy Carbon Electrode

The synergism of phosphomolybdic acid hydrate (POM) decorated with silver-iron (III) oxide (Ag-Fe2O3) nanoparticles and anchored on reduced graphene oxide (RGO) have been demonstrated to be effective as a nonenzymatic H2O2 sensor platform. The assembly of the sensor components and their interactions were probed morphologically, spectroscopically and electrochemically. The Ag-Fe2O3/POM/RGO nanocomposite sensor provided an enhanced electroactive surface area, electrical conductivity and sensitivity for hydrogen peroxide compared to an unmodified glassy carbon electrode (GCE) at –0.55 V versus a saturated calomel electrode. The developed sensor amperometric response was linear across the concentration range from 0.3 mM to 3.3 mM (R2 = 0.992) with a detection limit and sensitivity of 0.2 μM and 271 μA·mM‒1·cm−2 respectively. Concomitantly, a short response time of T90 < 5 sec at a signal-to-noise ratio of 4 was achieved. The sensor was shown to determine hydrogen in the presence of interfering species, and exhibited high selectivity with relative standard deviation values less than 4.2%. The results indicate that the use of RGO to anchor and photochemically reduce POM also improved the reduction properties due to the irregular size distribution and catalytic activity of Ag-Fe2O3 stimulated by its adhesion to the distinctive POM/RGO matrix.

Electrochemical Detection of Alloxan on Reduced Graphene Oxide Modified Glassy Carbon Electrode

AbstractAlloxan is a toxic reagent that strongly induces the diabetes by destroying insulin‐producing β‐cells in the pancreas of living organisms. The reduction product of alloxan is dialuric acid, which is responsible for the intracellular generation of ROS to enhance the stress in living cells to cause kidney disease or diabetic nephropathy. Herein, we studied for the first time the electrochemical properties of alloxan on reduced graphene oxide modified glassy carbon electrode (rGO/GCE) in 0.1 M phosphate buffer solution (PBS) at pH 7. The obtained results were compared with graphene oxide modified GCE (GO/GCE) and bare GCE surfaces. The modified rGO/GCE showed well defined redox couple with 10 fold increase in both reduction as well as oxidation peak current for alloxan than that of GO/GCE and bare GCE. Differential pulse voltammetry (DPV) technique shows the linear increase in both oxidation and reduction peak current of alloxan in the range of 30 μM to 3 mM with LOD of 1.2 μM. An amperometric signal of alloxan is also increases with respect to each addition of 50 μM of alloxan on rGO/GCE at constant potential of −0.05 V. The linear range of alloxan is observed between 50 μM to 750 μM (S/N=3). This kind of rGO/GCE surface is more suitable platform or sensor matrix for estimating unknown concentration of alloxan molecule in the real biological systems.

MnO2 Nanowires-Decorated Reduced Graphene Oxide Modified Glassy Carbon Electrode for Sensitive Determination of Bisphenol A

In this paper, MnO2 nanowires-decorated reduced graphene oxide composite (MnO2 NWs-rGO) was synthesized by physical adsorption and controlled potential reduction. Means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and cyclic voltammetry (CV) were used to characterize this material. Glassy carbon electrode (GCE) modified with MnO2 NWs-rGO composite was fabricated by drop-coating method for the sensitive determination of bisphenol A (BPA). Electrochemical behaviors of BPA at the MnO2 NWs-rGO/GCE were studied using CV and chronocoulometry (CC). Experimental results found that MnO2 NWs-rGO/GCE exhibited excellent electrocatalytic activity, sensitivity, stability, and selectivity towards BPA. Under the optimized experimental conditions, quantitative analysis was carried out using the second derivative linear sweep voltammetry (SDLSV), and the MnO2 NWs-rGO/GCE revealed a good linear response to BPA concentration ranging from 0.02–20 μM and 20–100 μM, and the detection limit was 6.0 nM (S/N = 3). This new method possessed some obvious advantages, such as high determination sensitivity, simple preparation process, rapid response and low cost. The sensing performance of MnO2 NWs-rGO/GCE was demonstrated for the detection of BPA in plastic samples, and satisfactory results have been obtained. Therefore, an efficient determination method for monitoring trace levels of BPA was developed.

Novel electrochemical sensor using a dual-working electrode system for the simultaneous determination of glucose, uric acid and dopamine

Dual working electrodes were constructed for the simultaneous determination of three analytes. A graphene oxide-modified glassy carbon electrode (GO/GCE) was used for adsorptive anodic stripping voltammetry to detect uric acid and dopamine, while a chitosan/glucose oxidase/Prussian blue-graphite modified glassy carbon electrode (Chi/GOx/PB-G/GCE) was used for chronoamperometric glucose detection. The fabrication and operation conditions for both electrodes were optimized. Linearity was obtained in the ranges of 0.10–30 µM and 30–80 µM for dopamine, 0.20–10 µM and 10–30 µM for uric acid and 15–1,500 µM for glucose. The system provided detection limits (LOD = 3σ/S) of 0.080 µM, 0.11 µM, and 5.7 µM for dopamine, uric acid and glucose, respectively. This dual-working electrode system showed good reproducibility and excellent recovery for the simultaneous determination of dopamine, uric acid, and glucose. When used to analyze dopamine, uric acid, and glucose in blood plasma samples, the results agreed well with those from conventional methods (P > 0.05), indicating the potential of this system to simultaneously determine these three analytes in real samples.

Enhanced performance of pyrrolic N-doped reduced graphene oxide-modified glassy carbon electrodes for dopamine sensing

Two different nitrogen-doped reduced graphene oxides (N-rGOs) were used to modify glassy carbon electrodes (GCE/N-rGOs) as electrochemical sensors for the detection of dopamine (DA). For comparison, GCE/rGO was also studied. The N-rGOs were synthesized via hydrothermal treatment of graphene oxide (GO) with the N-dopants amitrole and urea. The resultant graphene materials exhibited distinct types and distributions of nitrogenated functional groups, but they possessed a similar oxygen content, thus avoiding interference from oxygenated groups. Pyridinic nitrogen was introduced into the rGO structure when amitrole was used as the N-dopant, whereas pyrrolic nitrogen was preferentially formed in the reaction with urea. After optimization of several experimental parameters and sensor calibration, the GCE/pyrrolic-N-rGO electrode was found to exhibit superior electrochemical performance compared with the pyridinic-N-rGO one, demonstrating a limit of detection and sensitivity of 335 nM and 3.51 μA μM−1, respectively. This sensor also showed better selectivity in the presence of interfering agents in the forms of ascorbic and uric acids. A significant improvement of sensor parameters can be explained in terms of the contribution of electrons derived from the pyrrolic structure to the delocalized C sp2-conjugated graphene system.