Nanocomposite Modified Carbon Paste Electrode Research Articles

Facile electrochemical determination of 5-fluorouracil as an important anti-cancer drug using CeO2–CuO nanocomposite modified carbon paste electrode

In this study, a carbon paste electrode was modified with a composite material of CeO2–CuO to fabricate an electrochemical sensor. The fabricated sensor was then employed for the analysis of 5-fluorouracil (5-FU), an important anticancer drug, in a phosphate buffer solution (PBS) with pH 7.0, using cyclic voltammetry (CV) and differential potential voltammetry (DPV) techniques. The effect of critical parameters such as catalyst loading, scan rate, type, and pH of the supporting electrolyte on the electrochemical responses of the modified electrode was assessed and optimized. The electrochemical response of the fabricated sensor towards 5-FU remained unaffected in the presence of various potent interfering compounds, indicating its anti-interference capability. The DPV responses of the prepared sensor was linear with the concentration of 5-FU in the range of 0.1–1.0 μmol L−1 and 1.0–40.0 μmol L−1 under optimal experimental conditions, with a detection limit of 0.01 μmol L−1. The electrochemical sensor developed in this study was employed to determine 5-FU in human urine samples with the acceptable recovery. The fabricated sensor demonstrated favorable characteristics such as high sensitivity, repeatability, reproducibility, and stability.

New Au/chitosan nanocomposite modified carbon paste sensor for voltammetric detection of nicotine

A profoundly touchy voltammetric sensor for detection of nicotine (NIC) in urine and tobacco specimens has been developed in light of the boosted electrochemical response of NIC at gold and chitosan nanocomposite modified carbon paste electrode (ACMCPE). Material characterization techniques Scanning Electron Microscope and Energy Dispersive X-ray (SEM & EDX) were utilized to describe the ACMCPE surface material. The impedance spectroscopy technique (EIS), cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) were employed to explore the electrochemical sensing of NIC at ACMCPE. The created sensor exhibits an exceptional electrochemical sensitivity to NIC in a universal Britton–Robinson (B-R) buffer solution with a pH range of 2.0 to 8.0. The sensor shows a linear response over NIC concentration ranges of 4.0–320.0 µM, with the detection limit (LOD) of 7.6 µM. The prepared sensor has been shown to be exceptionally viable in detecting NIC with amazing selectivity and reproducibility. We suggest it as a trustworthy and useful electrochemical sensor for NIC location.

An efficient electrochemical sensor based on ZnO/Co3O4 nanocomposite modified carbon paste electrode for the sensitive detection of hydroquinone and resorcinol

An efficient electrochemical sensor based on ZnO/Co3O4 nanocomposite modified carbon paste electrode for the sensitive detection of hydroquinone and resorcinol

Fabrication non-enzymatic electrochemical sensor based on methyl red and graphene oxide nanocomposite modified carbon paste electrode for determination of nitrite in food samples

The purpose of this work was to create a non-enzymatic electrochemical sensor based on methyl red and modified carbon paste electrodes (MR/GO/CPE) that can measure nitrite in food samples. FE-SEM images showed that the assembly of MR on the surface of GO nanosheets caused the combination of GO nanosheets and MR particles to form a MR/GO nanocomposite with a high density of holes and crevasses. Amperometry, CV, and DPV techniques were used to study the electrochemical responses of MR/GO/CPE to the determination of nitrite. The results revealed that the MR/GO/CPE demonstrated sensitive, selective, and stable responses to determination nitrite. According to amplitude studies, the proposed nitrite sensor should have a sensitivity value of 0.12735 μA/μM, a large linear range of 0–7000 μM, and a low detection limit value of 0.011 μM. In the current study, the accuracy and applicability of the proposed nitrite electrochemical sensor for the determination of nitrite in prepared meat specimens were examined. The results showed good recovery values (more than 96.00 %) and appropriate precision (RSD less than 5.10 %), as well as good agreement between the amperometric measurements and the Test Kit for Nitrate assays. These findings demonstrated that MR/GO/CPE can be used as trustworthy nitrite sensors for tracking nitrite levels in food specimens.

MnCr2O4 nanocomposite modified carbon paste electrode based electrochemical sensor for determination of Norepinephrine: A cyclic voltammetry study

A novel MnCr2O4 nanocomposite modified carbon paste electrode (MnCr2O4/MCPE) based sensor were developed and validated by electrochemical detection of norepinephrine (NE). The MnCr2O4 nanocomposite was synthesized by hydrothermal method. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Infra Red (IR) spectroscopy techniques. To identify the redox properties of the MnCr2O4/MCPE were examined by cyclic voltammetry studies. The investigation of modified electrode has high electroactive surface area, the oxidation and reduction peak occurred at pH7.4 the supporting electrolyte was 0.2 M phosphate buffer solution. MnCr2O4/MCPE as very low detection limit (LOD) is 0.034 µM, high sensitivity, wide linear range (0.0003 mM to 0.0045 mM), applied to the injection sample analysis and the obtained results are satisfactory, good reproducibility exhibits great potential in practical applications.

Modification of Carbon Paste Electrode Using Calyx[6]Arene-TiO2 Nanocomposite for Determination of Cu2+ ion Based on Cyclic Voltammetry

In the present study, an electrochemical sensor for the determination of Cu(II) ions in aqueous solutions was introduced. This study proposes an electrochemical method using the calyx [6]arene-TiO2 nanocomposite modified carbon paste electrode (calyx[6]arene-TiO2/CPE) for the determination of metal Cu2+ ion. Calyx[6]arene-TiO2 were synthesized using the hydrolysis method as the Cu-binding ionophore. The electrode surface was studied by scanning electron microscopy (SEM), and the reduction and oxidation processes were studied by cyclic voltammetry (CV) techniques. The effect of modifier composition, scan rate, variation concentration, repeatability, and type of supporting electrolyte on the determination of metal ions was investigated. The best composition was 0.005 g calyx[6]arene-TiO2 in the carbon paste electrode with a scan rate of 0.5 V/s. The modified electrodes showed good performance for Cu2+ ion detection. Under optimum experimental conditions, a linear range for metal Cu(II) ions was from 0.1, 0.3, 0.5, 0.8, and 1.0 ppm with respective currents of 500, 550, 600, 700, and 800 µA. The limit of detection (LOD) for metal Cu2+ ions is found to be 0.022 ppm with a relative standard deviation (%RSD) of 0.011%.

Ultrahigh specific capacitance of α-Fe2O3 nanorods-incorporated defect-free graphene nanolayers

The development of hybrid materials with high pseudocapacitance and electrical double layer capacitance is an urge for the fabrication of efficient supercapacitor electrodes. Herein, a highly effective, easily performable, high-yielding, and economical method is demonstrated for the preparation of α-Fe2O3 nanorods incorporated defect-free graphene nanosheets that showed excellent supercapacitor performance. α-Fe2O3/graphene nanocomposite has been synthesized by an interlayer catalytic exfoliation of α-Fe2O3 intercalated graphite which showed high conductivity of 3.1 × 106 S/cm. α-Fe2O3/graphene nanocomposite modified carbon paste electrode exhibited ultrahigh specific capacitance values of 1135 mF/cm2 at a scan rate of 5 mV/s and 815 mF/cm2 at a current density of 0.5 mA/cm2. The fast ionic diffusion with no charge transfer resistance of the electrode material was revealed from the electrochemical impedance spectroscopic analysis. α-Fe2O3/graphene nanocomposite showed 100 folds of increase in the specific capacitance compared to α-Fe2O3 and graphene, suggesting their synergistic effect in the nanocomposite leading to a drastic increase in the specific capacitance. The composite displayed good cyclic stability of 79.9% retention of the initial capacitance after 1500 cycles and 54.9% after 10,000 repeated cycles.

ZnO@MnO2 nanocomposite modified carbon paste electrode for electrochemical detection of dopamine

In this study, we have compared the performance of a bare carbon paste electrode (BCPE) against the ZnO@MnO2 nanocomposite modified carbon paste electrode (MCPE) in the electrochemical determination of dopamine (DA). Chemical and structural features of the ZnO@MnO2 nanocomposites were characterized using scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), transmission electron microscopy (TEM), X-Ray diffraction (XRD), thermo-gravimetric analysis (TGA) with differential thermal Analysis (DTA) and Brunauer-Emmet-Teller (BET) surface area analysis. The cyclic voltammetry (CV) measurement of the ZnO@MnO2 nanocomposite MCPE showed better oxidative catalytic activity (3.6 μA) towards the DA than BCPE with higher efficiency (44.50%) in sensing the dopamine, making MCPE suitable for developing biosensors. The electrochemical studies were carried out in 5 × 10−5 M DA and obtained results were measured in the potential range of −0.2 to 0.6 V vs. saturated calomel electrode (SCE). The electrochemical performance of electrochemical impedance spectroscopy (EIS) and Tafel technique were measured for the BCPE and MCPE using 0.2 M phosphate buffer to maintain pH 7.2 with the scan rate of 50 mV/s. The redox peak current for MCPE Vs scan rate had good linearity with correlation coefficients of R2 = 0.9996, which represents the diffusion controlled process was under controlled electron transfer reaction. It is expected that the good electrocatalytic behavior of MCPE can be utilized for the fabrication of biosensors.

Determination of Riboflavin by Nanocomposite Modified Carbon Paste Electrode in Biological Fluids Using Fast Fourier Transform Square Wave Voltammetry

Herein, fast Fourier transformation square-wave voltammetry (FFT-SWV) as a novel electrochemical determination technique was used to investigate the electrochemical behavior and determination of Riboflavin at the surface of a nanocomposite modified carbon paste electrode. The carbon paste electrode was modified by nanocomposite containing Samarium oxide (Sm2O3)/reduced graphene oxide (RGO) (2:1) to improve detection sensitivity of Riboflavin under optimal experimental conditions. Furthermore, the signal-to-noise ratio was significantly increased by application of discrete fast Fourier transformation analysis, background subtraction and two-dimensional integration of the electrode response over the selected potential range and the time window. Obtained cyclic voltammograms demonstrated a diffusion-controlled reversible electron transfer reaction for Riboflavin in phosphate buffer solution (pH=7.2). The peak potential values were pH-dependent, involving the same numbers of protons and electrons. To obtain the maximum sensitivity, some effective parameters such as scan rate (10 mV/s), accumulation time (0.2 s) and potential (+400 mV), frequency (1420 Hz) and amplitude (20 mV) were optimized. As a result, determination of Riboflavin using FFT-SWV showed a linear range of response from 10 to 400 nM (R2=0.9993), with limit of detection of 0.86 nM. An acceptable recovery percent was also obtained for Riboflavin in human plasma samples as criteria of measurement applicability of the proposed modified electrode.

Zeolitic imidazolate frameworks and cobalt-tannic acid nanocomposite modified carbon paste electrode for simultaneous determination of dopamine, uric acid, acetaminophen and tryptophan: Investigation of kinetic parameters of surface electrode and its analytical performance

In this study, we have created a particularly selective electrochemical sensor cobalt-tannic acid nanocomposite (ZIF-8@Co-TA) and a familiar metal organic framework (ZIF-8), which was then used to simultaneously determine acetaminophen (AC), dopamine (DA), tryptophan (Trp), and uric acid (UA) with wide linear ranges and low detection limits (LOD). In addition, we have applied chronoamperometry, differential pulse voltammetry (DPV), electrochemical impedance spectroscopy, and cyclic voltammetry so that the electrochemical features of the fabricated electrode could be assessed. The eminent catalytic activity and high-level conductivity of ZIF-8@Co-TA has led to perfectly separated peaks, and to improved peak currents of DA, UA, AC, and Trp. According to the results, the ΔEp of 130, 120, 310 mV vs. SCE were reported as the level of separation of anodic peak potentials for DA-UA, UA-AC, and AC-Trp, respectively. With LOD of 3.4, 1.2, 5.1 and 6.7 nM, the maximum currents linearly depended on DA, UA, AC and Trp concentrations in the ranges of 0.02–0.44 μM (Sbk/m = 3). Good repeatability and stability were observed after determining DA, UA, AC, and Trp, which was carried out through successfully challenging the chemically modified electrode with some interfering compounds and evaluating it in real samples. Therefore, it seems that fabricated sensor can be properly exploited for clinical experiments and pharmaceutical applications.

An advanced and Facile Synthesized Graphene/Magnetic Fe3O4 Nanoparticles Platform for Subnanomolar Voltammetric Determination of Antipsychotic Olanzapine Drug in Human Plasma

Magnetite nanoparticles (Fe3O4 NPs) hold a promising performance towards sensing applications. Fe3O4 NPs were synthesized by economically viable method and characterized using different techniques. X-ray diffraction (XRD) pattern of Fe3O4 NPs matched consistently with the database in JCPDS card (19–0629) for magnetite. Their average size was around 16 nm. The values of saturation magnetization and pH at point of zero charge (pHzpc) of the NPs were found to be 61.50 emu g−1 and 7.4, respectively. A novel magnetite-graphene nanocomposite (Fe3O4-GR) was then synthesized based on ex situ approach (in which pre-synthesized Fe3O4 NPs were used to anchor the graphene nanosheets). Transmission electronic microscopy (TEM) and Scanning electronic microscopy (SEM) images indicate that GR nanosheets are decorated by Fe3O4 NPs. Further, Fe3O4-GR nanocomposite modified carbon paste electrode (Fe3O4-GR/CPE) was fabricated. Its effective surface area and surface morphology were studied using cyclic voltammetry and SEM techniqes, respectively. Among Fe3O4-GR/CPE, GR/CPE and Fe3O4/CPE, the electrochemical properties of Fe3O4-GR nanocomposite were superior to the individual GR and Fe3O4. Fe3O4-GR/CPE was utilized for determination of Olanzapine drug in its formulation and it exhibited also very low detection limit (LOD = 7.29 × 10−11 M) and good selectivity towards sensing of Olanzapine in human plasma.

Sonochemical synthesis of ErVO4/MnWO4 heterostructures: Application as a novel nanostructured surface for electrochemical determination of tyrosine in biological samples

Present strategy introduces a novel method established for the synthesis of spherical shape ErVO4/MnWO4 heterostructures by a sonochemical method. This heterostructures with optima morphology can be synthesized by changing power and time ultrasound irradiation without any capping agent. BET analysis revealed that ErVO4/MnWO4 prepared in the presence of ultrasonic procedure has 75 times specific surface area as much as that of those was produced in the absence of ultrasonic rays. A variety of analyses (i.e., BET, XRD, TEM, EDS, FT-IR, and SEM) were applied for characterization of the ErVO4/MnWO4. Next, a selective and sensitive nanostructured sensor based on ErVO4/MnWO4 nanocomposite modified carbon paste electrode (ErVO4/MnWO4/CPE) was constructed for electrochemical detection of tyrosine (Tyr). The electrochemical characterizations were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Compared with the unmodified CPE, the oxidation peak current was significantly enhanced for Tyr. The impact of effective parameters on voltammetric response of Tyr was analyzed with design of experiments (DOE) and response surface methodology (RSM). Under the optimized conditions, the oxidation peak current of Tyr was linear over a range of 0.08–400.0 μM with a detection limit of 7.7 nM. Finally, the usage of the proposed method was confirmed by the recovery tests of Tyr in biological samples.

Sensitively-selective determination of Propyl Paraben preservative based on synergistic effects of polyaniline-zinc-oxide nano-composite incorporated into graphite paste electrode

The application of Propyl Paraben (PP) as a chemical preservative has expanded and diversified. Widespread use of products containing PP has resulted in its ubiquitous occurrence in environment and biological fluids among the general population. Several in-vivo studies have associated PP with estrogenic activity and malfunctioning of reproductive organs. In this work, we have developed a highly sensitive voltammetric sensor for PP detection based on polyaniline-zinc-oxide nano-composite modified carbon paste electrode (PANI/ZnO/MCPE). The synthesized nano-composite was characterized using spectroscopic techniques. Experimental conditions such as supporting electrolyte, their pH and scan rate were optimized to attain a well defined PP anodic peak current at 690 mV. Our experiments indicate a strong synergistic interaction between ZnO and PANI, resulting in the magnification of PP current with a declined over-potential, compared to bare CPE. We have proposed a mechanism of π-π interaction between PP and PANI/ZnO/MCPE. The electrode process was characterized to be irreversible; diffusion controlled and proceeds with an exchange of 1eˉ and H+. Noteworthy analytical performance over wide linear range from 100.0 to 1.0 μM, with a detection limit of 0.13 μM and anti-interference characteristics were ascertained. A significant advantage of this sensor is its inability to detect micro molar concentrations of ascorbic acid (AA) while PP is detected at micro levels in the presence of high concentrations of AA. The versatility of this sensor was demonstrated by efficaciously applying it to trace analysis of complex real samples such as pharmaceutical formulations, biological samples and lake water with good recoveries.

A novel electrochemical sensor based on silver/halloysite nanotube/molybdenum disulfide nanocomposite for efficient nitrite sensing

In the present study, the silver/halloysite nanotube/molybdenum disulfide (Ag/HNT/MoS2) nanocomposite was successfully synthesized. For this purpose, the lumen of HNTs was firstly modified by silver to generate Ag nanorods via chemical process and then the MoS2 layers deposited on the Ag/HNT nanocomposite by hydrothermal method. The characterization of Ag/HNT/MoS2 nanocomposite were investigated by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The nanocomposite modified carbon paste electrode (CPE) was applied for the electrocatalytic detection of nitrite in aqueous solutions. It was demonstrated that the treatment of HNTs with Ag and MoS2 materials enhanced the catalytic performance of modified CPE. At optimal experimental conditions, the designed sensor displayed remarkable sensing ability toward nitrite oxidation, offering a good linearity from 2 to 425 µM. The limit of detection (LOD) of the proposed strategy was estimated to be 0.7 µM based S/N = 3. The good reproducibility, acceptable stability, fast response time and anti-interference performance of the proposed assay suggests that the modified CPE has great potential working as a nitrite electrochemical sensor for environmental applications.

Fabrication of biosensor based on Chitosan-ZnO/Polypyrrole nanocomposite modified carbon paste electrode for electroanalytical application

A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and polypyrrole was developed. The sensor was prepared by oxidative polymerization of pyrrole using (NH4)2S2O8 as the oxidant followed by mixing a Chitosan-Zinc oxide composite with a different content of Chitosan. The morphology and surface area of the nanocomposites were changed by changing the percentage of chitosan. The newly developed nanocomposites also showed a significant improvement in electrical conductivity as mentioned from the cyclic voltammetry measurements of the K3[Fe(CN)6] sample. A square-wave adsorptive anodic stripping voltammetry method successfully measured Isoxsuprine hydrochloride using different types of nanocomposite modified CPEs and showed a large enhancement of stripping peak current compared to bare CPE. Consequently, the proposed sensors proved to have a promissing feature for applications in biosensors.

Electrochemical Sensing of Nitrite at Aminophenol-Formaldehyde Polymer/Phosphomolybdic Acid Nanocomposite Modified Electrode

Abstract An aminophenol-formaldehyde polymer/phosphomolybdic acid nanocomposite modified carbon paste electrode for detection of nitrite was developed. The integration of polymer matrix to form materials is an effective way to harness the electrochemical activity. The aminophenol-formaldehyde polymer/phosphomolybdic acid nanocomposite modified carbon paste electrode showed high electrocatalytic activity for nitrite reduction, enabling the detection of nitrite within a linear range of 10.0–1000 µM ( r = 0.998). The limit of detection was 9.8 µM ( S/N = 3). The method showed excellent selectivity for nitrite detection in the presence of phosphate, acetate, ammonium, fluoride, chloride and nitrate.

Synthesis and characterization of graphene quantum dots/CoNiAl-layered double-hydroxide nanocomposite: Application as a glucose sensor

In the present work, a novel nanocomposite based on the graphene quantum dots and CoNiAl-layered double-hydroxide was successfully synthesized by co-precipitation method. To achieve the morphological, structural and compositional information, the resulted nanocomposite was characterized by scanning electron microscopy X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and photoluminescence. Then, the nanocomposite was used as a modifier to fabricate a modified carbon paste electrode as a non-enzymatic sensor for glucose determination. Electrochemical behavior and determination of glucose at the nanocomposite modified carbon paste electrode were investigated by cyclic voltammetry and chronoamperometry methods, respectively. The prepared sensor offered good electrocatalytic properties, fast response time, high reproducibility and stability. At the optimum conditions, the constructed sensor exhibits wide linear range; 0.01–14.0 mM with a detection limit of 6 μM (S/N = 3) and high sensitivity of 48.717 μAmM−1. Finally, the sensor was successfully applied to determine the glucose in real samples which demonstrated its applicability.

Fabrication of a new nanocomposite modified carbon paste Al3+-ion selective electrode based on N,N′-dipyridoxyl (1,2-cyclohexanediamine) (PYCA) as an active material

Construction and feature of a nanocomposite modified carbon paste electrode for aluminum(III) ion determination based on N,N′-dipyridoxyl (1,2-cyclohexanediamine) (PYCA) as a novel selector material will be covered by this paper. The optimum composition, Nernstian slope/linear range/detection limit in the forms of calibration graph, response time, utilizable pH range, repeatability and precision of measurements of the aluminum(III) ion using the new fabricated Al3+-CPE was evaluated. The optimal composition which performed over Al+3 ion concentration range 1.0 × 10−8 mol L−1–1.0 × 10−1 mol L−1 with near-Nernstian slope equal 20.9 ± 0.2 mV decade−1 and low detection limit about 5.0 × 10−9 mol L−1, was formed of ionophore (PYCA 3 %), binder (paraffin oil 30 %), modifier [multi-wall carbon nanotubes (MWCNTs) 1 %] & [Nanosilica (NS) 0.5 %], and inert matrix (graphite powder 65.5). The request time to give rise Nernstian response of electrode for concentrations from 1.0 × 10−8 mol L−1 to 1.0 × 10−1 mol L−1 of Al3+ ion solution was estimated about ~6 s. The new Al3+-CPE was applied in pH range 2.0–5.0 with no consequential change in potential response. To verify the selectivity of electrode toward aluminum(III) ion in the presence of different metallic cations, matched potential method was used. The obtain results in analytical applications reflect the excellent ability of this electrode to play the role as endpoint indicator electrode in both titration and direct potentiometric measurements.

Amperometric Determination of Ascorbic Acid in Pharmaceutical Formulations by a Reduced Graphene Oxide-cobalt Hexacyanoferrate Nanocomposite.

Investigation of the redox properties of drugs and their determination are performed by electrochemical techniques. Data obtained from electrochemical techniques are often correlated with molecular structure and pharmacological activity of drugs. In this regard, different modified electrodes were applied as sensors for quantification of different drugs. A nanocomposite of reduced graphene oxide-cobalt hexacyanoferrate was synthesized by a simple precipitation route. Scanning electron microscopy revealed that the nanocomposite comprised nanoparticles of cobalt hexacyanoferrate attached to the reduced graphene oxide nanosheets. A nanocomposite-modified carbon paste electrode was then fabricated. It represented prominent activity toward the electrocatalytic oxidation of ascorbic acid, and the kinetics of the electrooxidation process was evaluated. Finally, an amperometric method was developed for the quantification of ascorbic acid in different pharmaceutical formulations.

Electroanalytical determination of diazepam in tablet and human serum samples using a multiwalled carbon nanotube embedded molecularly imprinted polymer-modified carbon paste electrode

In this study a new MWCNT–MIP nanocomposite modified carbon paste electrode for determination of diazepam has been developed.