Modified Pencil Graphite Electrode Research Articles

Electrochemical DNA-nano biosensor for the detection of Goserelin as anticancer drug using modified pencil graphite electrode.

Goserelin is an effective anticancer drug, but naturally causes several side effects. Hence the determination of this drug in biological samples, plays a key role in evaluating its effects and side effects. The current studies have concentrated on monitoring Goserelin using an easy and quick DNA biosensor for the first time. In this study, copper(II) oxide nanoparticles were created upon the surface of multiwalled carbon nanotubes (CuO/MWCNTs) as a conducting mediator. The modified pencil graphite electrode (ds-DNA/PA/CuO/MWCNTs/PGE) has been modified with the help of polyaniline (PA), ds-DNA, and CuO/MWCNTs nanocomposite. Additionally, the issue with the bio-electroanalytical guanine oxidation signal in relation to ds-DNA at the surface of PA/CuO/MWCNTs/PGE has been examined to determination Goserelin for the first time. It also, established a strong conductive condition to determination Goserelin in nanomolar concentration. Thus, Goserelin's determining, however, has a 0.21 nM detection limit and a 1.0 nM-110.0 µM linear dynamic range according to differential pulse voltammograms (DPV) of ds-DNA/PA/CuO/MWCNTs/PGE. Furthermore, the molecular docking investigation highlighted that Goserelin is able to bind ds-DNA preferentially and supported the findings of the experiments. The determining of Goserelin in real samples has been effectively accomplished in the last phase using ds-DNA/PA/CuO/MWCNTs/PGE.

Ultra-thrifty/cost-effective approach to determine Alizarin Red S (ARS) in natural water supplies through ruthenium-cobalt modified pencil graphite as minuscule electrode

ABSTRACT Herein, we present an extremely cost-effective approach to analyse and evaluate the fabric dye Alizarin red-S (ARS), one of the critical water pollutants. Moreover, this work shows an interesting and a one-step budget friendly promising electrochemical route for valorising ruthenium-cobalt bimetallic nanoparticles fabricated on graphene-chitosan modified pencil graphite electrode (RuNPs@CoNPs/Gr-Chi/PGE) in determining ARS in phosphate buffered saline (PBS) of pH −3 at the minute level. To analyse and evaluate the morphology of the sensor, we leveraged X-ray diffraction techniques, Scanning electron microscopy, and energy-dispersive X-ray analysis. Using (SWV)Square wave voltammetry, under the optimised experimental conditions, the response currents of the composite electrode exhibited a wide linearity of 2.5 µM to 2550 µM with an LOD and LOQ of 0.277 µM and 0.839 µM respectively. The composite exhibited promising results concerning stability over five weeks further focusing on the electrode’s reliability. It is validated in tap water, Buckingham Canal water, and textile water for the assay of ARS.

Voltammetric performance of nanofiber structured over-oxidized poly(3,4-ethylenedioxythiophene) modified pencil graphite electrodes for dobutamine sensing

A modified electrode was developed for the electrochemical sensing of dobutamine (DBT), one of the catecholamines. For this modification process, pencil graphite electrodes (PGE) were modified with over-oxidized nanofiber structured poly (3,4-ethylenedioxythiophene) (PGE/OPEDOTNF) by electropolymerization. The electrochemical performance of PGE/OPEDOTNF was evaluated by cyclic and differential pulse voltammetry. In addition, the performances of non-nanofiber PEDOT-modified PGE electrodes were also examined for comparison. The characterization of the modified electrodes was carried out by scanning electron microscopy and electrochemical methods. The signal of the modified electrodes was observed in a linear range of 0.1-2.0 µM against DBT using the differential pulse voltammetry method. The limit of detection and quantification are calculated as 0.026 µM and 0.086 µM, respectively. The effect of the interfering species was examined. It has been shown that DBT can be detected sensitively and selectively using pencil graphite electrodes modified with nanofiber-structured poly(3,4-ethylenedioxythiophene). The repeatability of PGE/OPEDOTNF electrodes was found to be 5.2%. PGE/OPEDOTNF electrodes remained stable for 15 days without losing their electrochemical activity.

Development of simple and effective poly methyl orange modified pencil graphite electrode for the voltammentric investigation of aminotriazole in presence of 2,4-dichlorophenoxyacetic acid

The growing health risks linked to environmental exposure to mutagenic, teratogenic, and carcinogenic herbicides have sparked a significant interest in developing rapid and cost-effective detection technologies for accurate quantification of these compounds. Therefore, current research concerns a selective and sensitive electrochemical determination of Aminotriazole (AMT) using an inexpensive modified polymerized methyl orange pencil graphite electrode (PMO/PGE). The PMO/PGE and bare pencil graphite electrode (BPGE) have been characterized through various analytical techniques such as scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS). The electro-oxidation behavior of AMT was investigated by utilizing various methodologies including cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) of pH 7.0. AMT exhibits a significant increase in anodic peak current of 7.15 µA at PMO/PGE compared to BPGE. The effect of electro-kinetic factors involved in the electro-oxidation of AMT, such as the heterogeneous rate constant, scan rate, surface concentration, pH and the number of electrons and protons transferred were resolved. The electro-oxidation reaction involves two protons and two electrons, according to the electrochemical analysis of AMT at PMO/PGE. The number of electrons involved in a redox reaction is often determined experimentally, and it is a key parameter in understanding the reaction mechanism. Under the investigational conditions, the anodic peak current of the analyte is directly proportional to its concentration in the range 1.0 – 13.0 µM with the limit of detection (LOD) being 1.24 × 10−8 M. The developed modifiedsensor has got good reproducibility, sensitivity, selectivity and stability, and it could be successfully validated for the detection of AMT present in real samples.

A novel molecularly rabeprazole imprinted electrochemical sensor based on Fe3O4@SiO2–MWNTs nanocomposite

A sensitive and selective electrochemical sensor was designed for rabeprazole (RAB) detection using a molecularly imprinting polymer (MIP) modified with Fe3O4@SiO2–MWNTs nanocomposite. Calculation methods were utilized to determine the best monomer and also to check the geometry of the optimized RAB molecule and RAB-PY complex. To obtain the maximum extraction recovery of RAB, the influence of various parameters was investigated and experimental settings were optimized with two multivariable optimization methods of Placket–Burman design (PBD) and central composite design (CCD). Cyclic voltammetry (CV) was used to synthesis the polypyrrole film on a modified pencil graphite electrode (PGE). Analyte extraction from the polymer film and all quantitative measurements were performed by differential pulse voltammetry (DPV). The morphology and characteristics of Fe3O4@SiO2–MWNTs nanocomposite, the modified electrode surface, and also the synthesized sensor surface was investigated with field emission scanning electron microscope (FESEM) coupled to an energy dispersive x-ray (EDX). In optimal conditions, the modified sensor depicted desirable figures of merit of a limit of detection (LOD) of 0.035 μM (S/N = 3), a limit of quantitation (LOQ) of 0.15 μM (S/N = 10), and a linear detection range from 5 to 500 μM. Moreover, the MIP–Fe3O4@SiO2–MWNTs − PGE sensor was showed acceptable repeatability (RSD value of 4.18 %), reproducibility (RSD value of 5.53 %), and stability (reusability) up to one month (92 %). The proposed method was employed for preconcentration and extraction of rabeprazole in pharmaceutical and biological samples, successfully.

Electrochemical investigation of an anticancer drug 5-Fluorouracil in the presence of Theophylline using low-cost and disposable poly(GLY) modified pencil graphite electrode

Herein this study, a facile, efficient and disposable electrochemical sensor has been prepared by electropolymerization of glycine (poly(GLY)) on the surface of pencil graphite electrode (PGE). The surface topology of the equipped poly(GLY) modified pencil graphite electrode (poly(GLY)/PGE) and bare pencil graphite electrode (BPGE) has been characterized by the scanning electron microscopy (SEM) combined with energy dispersive x-ray analysis (EDX) and charge transfer behaviour was measured by electron impedance spectroscopy (EIS) method. The voltammetric behaviour of anticancer, 5-fluorouracil (5-FU) in the presence of theophylline (THP) has been carried out in 0.1 M phosphate buffer solution (PBS) of physiological pH 7.0 using different techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). The proposed poly(GLY)/PGE shows augmented peak current for 5-FU at lower potential side over the BPGE due to the electrocatalytic behaviour of modifier layers wrapped on the electrode surface. The kinetic behaviour of 5-FU at modified electrode surface was studied by varying different parameters such as pH, scan rate and concentration study in 0.1 M PBS used as a supporting electrolyte. The limit of detection (LOD) for 5-FU was attained using DPV method with different concentrations (1.0–13.0 μM) and it was found to be 0.012 μM. The possible electrochemical reaction of 5-FU was proposed and it was incorporated by two electrons and two protons mechanism at modified electrode surface. The voltammetric response of poly(GLY)/PGE towards the determination of 5-FU was unaffected in the presence of some excipients in addition to the remarkable stability and reproducibility. The applicability of the proposed sensor has been performed by real sample investigation of 5-FU with a substantial percentage of recovery results in all optimized conditions.

Electrochemical determination of insensitive munition constituents 3‐nitro‐1,2,4‐triazol‐5‐one (NTO) using gold nanoparticle/carbon nanotube‐modified pencil graphite electrode in groundwater sample

AbstractFor the electrochemical detection of nitrotriazolone (NTO), multiwalled carbon nanotubes (MWCNT) and gold nanoparticles have been combined to generate nanocomposites. Electrochemical analysis and surface characterisation using scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy techniques were used to confirm the presence of gold nanoparticles on MWCNT. The electrochemical behavior of NTO at the modified pencil graphite electrode in the pH range of 2.0–10.0 (0.04 M Britton‐Robinson buffer solution) was evaluated using cyclic (CV) and differential pulse voltammetry (DPV).The suggested electrochemical sensor displayed a quick reaction to NTO with an optimal set of experimental parameters, a linear calibration curve spanning 30 to 1500 nM, and a detection limit of 22.6 nM. Using the differential pulse voltammetry technique, the usefulness of the MWCNT/AuNPs, and PGE for the determination of NTO in groundwater was evaluated.

Voltammetric Determination of Acrylamide Using Coal Tar Pitch Modified Pencil Graphite Electrode by SWV

Voltammetric Determination of Acrylamide Using Coal Tar Pitch Modified Pencil Graphite Electrode by SWV

A disposable voltammetric sensor for the determination of diphenylamine using modified pencil graphite electrode.

This study reports the electrochemical monitoring and sensing of diphenylamine (DPA), an anti-scald agent on a modified pencil graphite electrode (PGE). DPA is also a potentially toxic environmental pollutant. A polymer of tyrosine synthesized by electrochemical process was utilized for the determination of DPA in real samples. The electrodes were characterized using IR, SEM, EDAX, AFM and EIS analyses. As far as we know, this is first time reporting the utilization of modified PGE via green approach for the monitoring of DPA. A dynamic linear range of 1.00-117.11µM with a lower detection limit (LOD) of 0.7050µM was showed by this sensor for the electrochemical quantification of DPA. The electrochemical oxidation of DPA on the modified sensor followed a mixed adsorption -diffusion controlled kinetics. The sensor also showed good anti-interference property for the determination of DPA in real samples. Furthermore, the developed sensor was applied for the selective sensing of DPA from real apple extracts with good recovery. The real sample analysis was validated with standard spectrophotometric method.

Conductive PEDOT:PSS copolymer electrode coatings for selective detection of dopamine in ex vivo mouse brain slices

A novel voltammetric sensor was developed to selectively determine dopamine (DA) concentration in the presence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC). This sensor utilizes a modified pencil graphite electrode (PGE) coated with a newly synthesized poly (3,4-ethylene dioxythiophene) (PEDOT):poly (styrene sulfonate-co-2-(3-(6-Methyl-4-oxo-1,4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate) (P(SS-co-UPyMA)) composite. The PEDOT:P(SS-co-UPyMA) (PPU) composite was characterized using nuclear magnetic resonance, X-ray photoelectron, and Raman spectroscopies. The PPU-coated PGE was characterized using electrochemical techniques, including cyclic and differential pulse voltammetry. Compared to uncoated, PPU-coated PGE demonstrated improved sensitivity and selectivity for DA. The sensor exhibited a dynamic linear range of 0.1–300 μM for DA, with a detection limit of 44.4 nM (S/N = 3). Additionally, the PPU-coated PGE showed high reproducibility and storage stability for four weeks. To demonstrate its practical applicability, the PPU-coated PGE sensor was used for ex vivo brain slice samples from control and Parkinson's disease model mice.

Electrocatalytic Determination of Uric Acid with the Poly(Tartrazine)-Modified Pencil Graphite Electrode in Human Serum and Artificial Urine.

A novel electrocatalytic sensing strategy was built for uric acid (UA) determination with an exceptionally developed poly(tartrazine)-modified activated pencil graphite electrode (pTRT/aPGE) in human serum and artificial urine. The oxidation signal of UA at 275 mV in pH 7.5 phosphate buffer solution served as the analytical response. Cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the sensing platform, which was able to detect 0.10 μM of UA in the ranges of 0.34-60 and 70-140 μM. The samples of human serum and artificial urine were analyzed by both the pTRT/aPGE and the uricase-modified screen-printed electrode. The results were statistically evaluated and compared with each other within the confidence level of 95%, and no significant difference between the results was found.

Development of a Disposable Pencil Graphite Electrode Modified with Poly 1,5-Diaminonaphthalene for Voltammetric Determination of Flufenamic Acid

Due to their comparable electrical properties, pencil graphite electrodes (PGE) have become a more popular electrode in electrochemical applications than traditional carbon electrodes, mostly because of their affordability and availability, which allows for disposable applications. Both cyclic voltammetry (CV) and chronoamperometry (CA) techniques were used to develop a new disposable modified pencil graphite electrode based on the electropolymerization of 1,5-diaminonaphthalane (1,5-DAN). Characterization results confirmed that the modified p-1,5-DAN/PGE(CV) sensor showed much enhanced sensitivity and lower resistivity than the bare and p-1,5-DAN/PGE(CA) sensor, therefore, it was used for the sensitive and selective voltammetric determination of flufenamic acid (FFA). Under the optimum experimental conditions, the p-1,5-DAN/PGE(CV) sensor showed limits of detection (LOD) and quantitation (LOQ) of 4.97 × 10−10 (0.14 ng ml−1) and 1.66 × 10−9 M (0.47 ng ml−1), respectively, applying square wave anodic stripping voltammetry method. The p-1,5-DAN/PGE(CV) sensor also exhibits good accuracy, repeatability, storage stability and selectivity for detecting FFA in biological fluids. These results confirms that the developed p-1,5-DAN/PGE(CV) sensor is more sensitive to measuring FFA in biological fluids, pharmaceutical formulations, and pharmacokinetic studies compared with the previous electrochemical sensors.

Atomic layer deposited zinc oxide thin film on pencil graphite for DNA sensor applications

Atomic Layer Deposition (ALD) enables precise thin-film deposition on electrode substrates for electrochemical sensors. In this work, we present the first example of ALD grown zinc oxide (ZnO) deposition on pencil graphite surfaces for deoxyribonucleic acid (DNA) sensory applications, including its detection and DNA damage investigation. For DNA sensing studies, the use of highly productive materials is essential. In this context, the ZnO modified pencil graphite electrodes (ZnO/PGEs) exhibited good electrochemical properties that make them a suitable substrate. ZnO films were characterized using scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The DNA recognition capability of the thin film coated electrodes was tested by using differential pulse voltammetry (DPV), which showed a linear response ranging from 1 mg L−1 to 200 mg L−1 based on the oxidation of guanine (G) with a limit of detection value (LOD) of 0.53 mg L−1 (n = 3). In addition to this, impedimetric monitoring of oxidative DNA damage was performed in the presence of copper(II)/hydrogen peroxide (Cu(II)/H2O2) reagents, and protection studies were conducted in the presence of ascorbic acid. ZnO thin film-based electrodes exhibited good sensor performance in terms of sensitivity, stability, and reproducibility.

Determination of Dipyridamole Using a MIP-Modified Disposable Pencil Graphite Electrode

A new method for the determination of the antiplatelet drug dipyridamole (DIP) in pharmaceuticals using a molecularly imprinted polymer (MIP)-modified pencil graphite electrode (PGE) is proposed. The modified electrode was prepared simply and rapidly by electropolymerization of caffeic acid (CA) in the presence of DIP and subsequent DIP extraction with ethanol, resulting in a cost-effective, eco-friendly disposable modified electrode (MIP_PGE). Several working conditions (monomer and template concentration, number of voltametric cycles, scan rate extraction time, and solvent) for the MIP_PGE preparation were optimized. The differential pulse voltammetric (DPV) oxidation signal of DIP obtained at MIP_PGE was 28% higher than that recorded at bare PGE. Cyclic voltammetry emphasized DIP irreversible, pH-dependent, diffusion-controlled oxidation at MIP_PGE. Differential pulse and adsorptive stripping voltammetry at MIP_PGE in phosphate buffer solution pH = 7.00 were applied for the drug quantitative determination in the range of 1.00 × 10−7–1.00 × 10−5 and 1.00 × 10−8–5.00 × 10−7 mol/L DIP, respectively. The obtained limits of detection were at the tens nanomolar level.

Development of gallic acid sensor based on metal oxide modified pencil graphite electrode

This study reports the fabrication of a new voltammetric sensor for the quantification of gallic acid (GA) in green tea samples. A pencil graphite electrode (PGE) modified with MnO2 (MnO2-PGE) was utilized for the electrochemical assay of GA. The developed electrode was characterized by scanning electron microscopy (SEM), Energy dispersive X-Ray analysis (EDAX), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The sensor showed a wide linear range of 20 µM – 500 µM. Scan rate studies showed that the electro oxidation process of GA on MnO2-PGE is diffusion controlled in nature. The MnO2 modified PGE was analytically used to detect the GA content in green tea samples.

ZnO nanoflowers modified pencil graphite electrode for voltammetric DNA detection and investigation of Gemcitabine–DNA interaction

In this study, ZnO nanoflowers (ZnONFs) were synthesized using sonochemical method, which is a simple, environmentally friendly, low-cost and rapid method. ZnONFs was characterized by using FE-SEM, EDS, elemental mapping, FTIR and XRD techniques. Single use pencil graphite electrode (PGE) modified with ZnONFs was characterized using FE-SEM, EDS, elemental mapping, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. This developed electrode was used for the first time for the determination of calf thymus double-stranded DNA (dsDNA) and the chemotherapeutic drug Gemcitabine (GEM) using differential pulse voltammetry (DPV). The detection limits (DLs) of dsDNA and GEM were calculated as 1.91 μg/mL and 2.47 μg/mL, respectively. The interaction of GEM and dsDNA at different times was investigated by measuring the changes in both GEM and guanine oxidation signals by DPV technique. The developed nanoflower-based biosensor responded in as short as 5 min in the DNA-anticancer drug interaction study. The study provides advantages such as low cost, biocompatibility, and easy synthesis of the used nanomaterial synthesis, as well as low detection limit and short interaction time at the sensor stage.

The application of multi-walled carbon nanotubes modified pencil graphite electrode for voltammetric determination of favipiravir used in COVID-19 treatment.

This study describes the first application of an improved procedure on a pencil graphite electrode decorated with functionalized multi-walled carbon nanotubes (f-MWCNTs/PGE) for the determination of the COVID-19 antiviral drug, favipiravir (FVP). The electrochemical behavior of FVP at f-MWCNTs/PGE was examined by cyclic voltammetry and differential pulse voltammetry (DPV) methods, and it was noted that the voltammetric response significantly increased with the modification of f -MWCNTs to the surface. The linear range and limit of detection from DPV studies were determined as 1–1500 µM and 0.27 µM, respectively. In addition, the selectivity of the method was tested toward potential interferences, which can be present in pharmaceutical and biological samples, and it was found that f-MWCNTs/PGE showed high selectivity for the determination of FVP in the presence of probable interferences. The results with high accuracies and precisions from the obtained feasibility studies also revealed that the designed procedure can be used for accurate and selective voltammetric determination of FVP in real samples.

Carbon Nanofiber-Ionic Liquid Nanocomposite Modified Aptasensors Developed for Electrochemical Investigation of Interaction of Aptamer/Aptamer-Antisense Pair with Activated Protein C.

Selective and sensitive detection of human activated protein C (APC) was performed herein by using carbon nanofiber (CNF) and ionic liquid (IL) composite modified pencil graphite electrode (PGE) and electrochemical impedance spectroscopy (EIS) technique. A carbon nanomaterial-based electrochemical aptasensor was designed and implemented for the first time in this study for the solution-phase interaction of DNA-Apt with its cognate protein APC as well as APC inhibitor aptamer-antidote pair. The applicability of this assay developed for the determination of APC in fetal bovine serum (FBS) and its selectivity against different proteins (protein C, thrombin, bovine serum albumin) was also examined. CNF-IL modified aptasensor specific to APC provided the detection limit as 0.23 μg/mL (equal to 3.83 nM) in buffer medium and 0.11 μg/mL (equal to 1.83 nM) in FBS. The duration of the proposed assay from the point of electrode modification to the detection of APC was completed within only 55 min.

Signal-Enhanced Electrochemical Determination of Quercetin with Poly(chromotrope fb)-Modified Pencil Graphite Electrode in Vegetables and Fruits.

A novel signal-enhanced electrochemical sensing strategy was constructed for quercetin determination with a peculiarly developed poly(chromotrope fb)-modified activated pencil graphite electrode in vegetables and fruits. The oxidation signal of quercetin at 118 mV in an alcoholic solution served as the analytical response. The produced platform, characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, could detect 1.9 nM of quercetin in the range of 0.01-1.2 μM. The extracted quercetin contents of red onion, red cabbage, cranberry, black mulberry, black raisin, and carob were determined by both the developed method and UV-visible spectroscopy. The results were statistically evaluated at the 95% confidence level, and no significant difference between the results was found.

A novel, extreme low-cost poly (Erythrosine) modified pencil graphite electrode for determination of Adrenaline

A simple, novel, and less cost yellow (Erythrosine) modified pencil graphite electrode (Po-ERY/MGPE) was successfully fabricated via electropolymerization method using cyclic voltammetric techniques. The fabricated Po-ERY/MGPE opted as a sensor for the detection of Adrenaline (ADR) in 0.2 M PBS (7.4 pH). This reported senor displayed excellent electrocatalytic activity, increased sensitivity, high stability, superior electron transfer kinetics in the oxidation of ADR once relative to BGPE. The significance of pH, scan rate, and impact of concentration was assessed at the sensor. As per the pH and scan rate study, redox routes carry the same number of electrons and protons, and electro-oxidation of ADR was adsorption controlled respectively. The LOD of ADR was found to be 0.499 µM. The DPV data indicate that there is a significant peak divergence among ADR and uric acid (UA) which could make it easier to determine them alone and simultaneously on the sensor. The described method has been employed for the determination of ADR in injection sample. Good recovery values indicate the efficacy and applicability of the sensor in detecting ADR.