Simultaneous Voltammetric Determination of Epinine and Venlafaxine Using Disposable Screen-Printed Graphite Electrode Modified by Bimetallic Ni-Co-Metal-Organic-Framework Nanosheets.

We constructed two-dimensional NiCo-metal-organic-framework (NiCo-MOF) nanosheets based on a facile protocol and then characterized them using multiple approaches (X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and N2 adsorption/desorption isotherms techniques). As a sensitive electroactive material, the as-fabricated bimetallic NiCo-MOF nanosheets were employed to modify a screen-printed graphite electrode surface (NiCo-MOF/SPGE) for epinine electro-oxidation. According to the findings, there was a great improvement in the current responses of the epinine because of the appreciable electron transfer reaction and catalytic performance of the as-produced NiCo-MOF nanosheets. Differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry were utilized to analyze the electrochemical activity of the epinine on the NiCo-MOF/SPGE. A linear calibration plot was obtained in the broad concentration range (0.07-335.0 µM) with a high sensitivity (0.1173 µA/µM) and a commendable correlation coefficient (0.9997). The limit of detection (S/N = 3) was estimated at 0.02 µM for the epinine. According to findings from DPV, the electrochemical sensor of the NiCo-MOF/SPGE could co-detect epinine and venlafaxine. The repeatability, reproducibility and stability of the NiCo-metal-organic-framework-nanosheets-modified electrode were investigated, and the relative standard deviations obtained indicated that the NiCo-MOF/SPGE had superior repeatability, reproducibility and stability. The as-constructed sensor was successfully applicable in sensing the study analytes in real specimens.

Screen-printed graphite electrode modified with Co3O4nanoparticles and 2D graphitic carbon nitride as an effective electrochemical sensor for 4-aminophenol detection.

We fabricated a new electrochemical 4-aminophenol sensor based on a nanocomposite of Co3O4nanoparticles and graphite carbon nitride (Co3O4@g-C3N4), used for the modification of a screen-printed electrode (Co3O4@g-C3N4/SPE). The synthesized nanocomposite was characterized using field-emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and Fourier transform-infrared (FT-IR) techniques. The electro-oxidation of 4-aminophenol in phosphate buffer solution (pH = 7.0) was investigated via cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The peak current of oxidation in the optimized conditions had a linear relationship with various 4-aminophenol contents (0.05-780.0µM) with a correlation coefficient of 0.9996 and the limit of detection (S/N = 3) of 1.5 × 10-8M. The developed method was successful to determine 4-aminophenol in real specimens, with acceptable outcomes.

A novel voltammetric amaranth sensor based on screen printed electrode modified with polypyrrole nanotubes.

Azo dyes are the most used type of dye in the textile industry. Some of these dyes have the potential to be extremely toxic to both human health and the environment. The purpose of this study was to develope an electrochemical sensor for detection of amaranth. The electrochemical sensor based on the modification of a screen-printed electrode via polypyrrole nanotubes (PPy NTs/SPE) for detection of amaranth was developed. The preparation of PPy NTs was performed through the pyrrole monomer oxidation with iron (III) chloride in exposure to methyl orange as structure-guiding agent. Findings exhibited an excellent electrocatalytic activity of as-fabricated sensor for amaranth detection. Our sensor under the optimized circumstances also had a broad linear dynamic range (between 0.03 µM and 290.0 µM) and a narrow limit of detection (0.01 µM) towards the amaranth detection. Moreover, the proposed sensor could practically and successfully determine the amaranth content present in the real food specimens, with acceptable recovery rates.

A Comprehensive Review of Metal-Organic Framework: Synthesis, Characterization, and Investigation of Their Application in Electrochemical Biosensors for Biomedical Analysis.

Many studies have addressed electrochemical biosensors because of their simple synthesis process, adjustability, simplification, manipulation of materials' compositions and features, and wide ranges of detection of different kinds of biomedical analytes. Performant electrochemical biosensors can be achieved by selecting materials that enable faster electron transfer, larger surface areas, very good electrocatalytic activities, and numerous sites for bioconjugation. Several studies have been conducted on the metal-organic frameworks (MOFs) as electrode modifiers for electrochemical biosensing applications because of their respective acceptable properties and effectiveness. Nonetheless, researchers face challenges in designing and preparing MOFs that exhibit higher stability, sensitivity, and selectivity to detect biomedical analytes. The present review explains the synthesis and description of MOFs, and their relative uses as biosensors in the healthcare sector by dealing with the biosensors for drugs, biomolecules, as well as biomarkers with smaller molecular weight, proteins, and infectious disease.

A hierarchical 3D camellia-like molybdenum tungsten disulfide architectures for the determination of morphine and tramadol.

A practical technique was applied to fabricate MoWS2 nanocomposite through a one-pot hydrothermal method for use as the electrocatalyst. The characterization of MoWS2 nanocomposite was investigated by several techniques to identify the size, crystal structure, and elemental composition. MoWS2 nanocomposite exhibited a unique and well-defined hierarchical structure with neatly and densely piled nanopetals acting as the active sites in the electrocatalytic reactions. A carbon screen-printed electrode (CSPE) modified with interesting MoWS2 nanopetals (MoWS2/CSPE) was constructed. Subsequently, the electrochemical oxidation of morphine on fabricated MoWS2/CSPE was studied. Experimental results confirm that under optimized conditions, the maximum oxidation current of morphine occurs at 275 mV in the case of MoWS2/CSPE that is around 100 mV more negative than that observed in the case of the unmodified CSPE and about 2.6 times increase was observed for the oxidation peak current. The analytical approach was obtained by differential pulse voltammetry in accordance with the relationship between the oxidation peak current and the morphine concentration. The oxidation peak currents for morphine were found to vary linearly with its concentrations in the range of 4.8 × 10-8-5.05 × 10-4 M with the detection limit of 1.44 × 10-8 M. Two completely separated signals occured at the potentials of 275 mV and 920 mV for oxidation of morphine and tramadol at the surface of MoWS2/CSPE which are sufficient for determination of morphine in the presence of tramadol. The presence of morphine was also detected in real samples using the introduced approach. Graphical abstract Schematic representation of fabrication of the MoWS2 nanocomposite through a one-pot hydrothermal method for use as the electrocatalyst. A carbon screen-printed electrode was modified with MoWS2 nanocomposite. Subsequently, the electrochemical oxidation of morphine on the fabricated electrode was studied.

Recent Advances in the Electrochemical Sensing of Venlafaxine: An Antidepressant Drug and Environmental Contaminant.

Venlafaxine (VEN), as one of the popular anti-depressants, is widely utilized for the treatment of major depressive disorder, panic disorder, as well as anxiety. This drug influences the chemicals in the brain, which may result in imbalance in depressed individuals. However, venlafaxine and its metabolites are contaminants in water. They have exerted an adverse influence on living organisms through their migration and transformation in various forms of adsorption, photolysis, hydrolysis, and biodegradation followed by the formation of various active compounds in the environment. Hence, it is crucial to determine VEN with low concentrations in high sensitivity, specificity, and reproducibility. Some analytical techniques have been practically designed to quantify VEN. However, electroanalytical procedures have been of interest due to the superior advantages in comparison to conventional techniques, because such methods feature rapidity, simplicity, sensitivity, and affordability. Therefore, this mini-review aims to present the electrochemical determination of VEN with diverse electrodes, such as carbon paste electrodes, glassy carbon electrodes, mercury-based electrodes, screen-printed electrodes, pencil graphite electrodes, and ion-selective electrodes.

Recent Advances in the Aptamer-Based Electrochemical Biosensors for Detecting Aflatoxin B1 and Its Pertinent Metabolite Aflatoxin M1.

The notable toxicological impacts of aflatoxin B1 (AFB1) and its main metabolite, aflatoxin M1 (AFM1), on human being health make the evaluation of food quality highly significant. Due to the toxicity of those metabolites-even very low content in foodstuffs-it is crucial to design a sensitive and reliable procedure for their detection. Electrochemical aptamer-based biosensors are considered the most encouraging option, based on multi-placed analysis, rapid response, high sensitivity and specificity. The present review specifically emphasizes the potential utilization of the electrochemical aptasensors for determining the AFM1 and AFB1 with different electrodes.

Recent Advances in Electrochemical Sensors and Biosensors for Detecting Bisphenol A.

In recent years, several studies have focused on environmental pollutants. Bisphenol A (BPA) is one prominent industrial raw material, and its extensive utilization and release into the environment constitute an environmental hazard. BPA is considered as to be an endocrine disruptor which mimics hormones, and has a direct relationship to the development and growth of animal and human reproductive systems. Moreover, intensive exposure to the compound is related to prostate and breast cancer, infertility, obesity, and diabetes. Hence, accurate and reliable determination techniques are crucial for preventing human exposure to BPA. Experts in the field have published general electrochemical procedures for detecting BPA. The present timely review critically evaluates diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA. Additionally, the essential contributions of these substances for the design of electrochemical sensors are presented. It has been predicted that chemically modified electrode-based sensing systems will be possible options for the monitoring of detrimental pollutants.

Construction of a nanostructure-based electrochemical sensor for voltammetric determination of bisphenol A.

A novel carbon paste electrode modified with graphene oxide nanosheets and an ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for voltammetric oxidation of bisphenol A, is described. The electrode was also employed to study the electrochemical oxidation of bisphenol A, using cyclic voltammetry, chronoamperometry, square wave voltammetry and electrochemical impedance spectroscopy as diagnostic techniques. Square wave voltammetry exhibits a linear dynamic range from 9.0 × 10(-8) to 2.5 × 10(-4) M and a detection limit of 55.0 nM for bisphenol A. Finally, this new sensor was used for determination of bisphenol A in water samples using the standard addition method.

Electrochemical determination of hydrazine using a ZrO2 nanoparticles-modified carbon paste electrode.

In the present paper, the use of a carbon paste electrode modified by 3-(4'-amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid (3,4'AA) and ZrO2 nanoparticles prepared by a simple and rapid method was described. The heterogeneous electron transfer properties of (3,4'AA) coupled to ZrO2 nanoparticles at the carbon paste electrode were investigated using cyclic voltammetry, chronoamperometry, and square wave voltammetry in aqueous buffer solutions. Under the optimized conditions, the square wave voltammetric peak currents of hydrazine increased linearly with hydrazine concentrations in the range of 2.5 × 10(-8) to 5.0 × 10(-5) M, and detection limit of 14 nM was obtained for hydrazine. Finally, this modified electrode was used for the determination of hydrazine in water samples, using standard addition method.

Fabrication of novel TiO2 nanoparticles/Mn(III) salen doped carbon paste electrode: application as electrochemical sensor for the determination of hydrazine in the presence of phenol.

Hydrazine and phenol are two important environmental pollutants. In this work, an electrochemical sensor for the selective and sensitive detection of hydrazine in presence of phenol was developed by the bulk modification of carbon paste electrode (CPE) with TiO2 nanoparticles and Mn(III) salen. Large peak separation, good sensitivity, and stability allow this modified electrode to analyze hydrazine individually and simultaneously along with phenol. Applying square wave voltammetry (SWV), a linear dynamic range of 3 × 10(-8)-4.0 × 10(-4) M with detection limit of 10.0 nM was obtained for hydrazine. Finally, the proposed method was applied to the determination of hydrazine and phenol in some real samples.

Synthesis of ZnO nanorods and their application in the construction of a nanostructure-based electrochemical sensor for determination of levodopa in the presence of carbidopa.

A novel carbon paste electrode modified with ZnO nanorods and 5-(4'-amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid (3,4'-AAZCPE) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for the electrocatalytic oxidation of levodopa, is described. The electrode was employed to study the electrocatalytic oxidation of levodopa, using cyclic voltammetry (CV), chronoamperometry (CHA), and square-wave voltammetry (SWV) as diagnostic techniques. It has been found that the oxidation of levodopa at the surface of the modified electrode occurs at a potential of about 370 mV less positive than that of an unmodified carbon paste electrode. The SWV results exhibit a linear dynamic range from 1.0 × 10(-7) M to 7.0 × 10(-5) M and a detection limit of 3.5 × 10(-8) M for levodopa. In addition, this modified electrode was used for the simultaneous determination of levodopa and carbidopa. Finally, the modified electrode was used for the determination of levodopa and carbidopa in some real samples.

Simultaneous determination of hydroxylamine and phenol using a nanostructure-based electrochemical sensor.

The electrochemical oxidation of hydroxylamine on the surface of a carbon paste electrode modified with carbon nanotubes and 2,7-bis(ferrocenyl ethyl)fluoren-9-one is studied. The electrochemical response characteristics of the modified electrode toward hydroxylamine and phenol were investigated. The results showed an efficient catalytic activity of the electrode for the electro-oxidation of hydroxylamine, which leads to lowering its overpotential. The modified electrode exhibits an efficient electron-mediating behavior together with well-separated oxidation peaks for hydroxylamine and phenol. Also, the modified electrode was used for determination of hydroxylamine and phenol in some real samples.

An electrochemical sensor based on a modified glassy carbon electrode for detection of epinephrine in the presence of theophylline.

Background and purpose: Neurotransmitters are chemical messengers that enhance and balance signals between cells and target cells in the body. They are vital to the body's ability to function. Epinephrine is one of the most essential catecholamine neurotransmitters with an important biological and pharmacological role in the mammalian central nervous system. Therefore, it is very important to develop sensitive, simple, and fast methods for the determination of this compound. Experimental approach: In the present work, a glassy carbon electrode (GCE) modified with the cerium oxide-zinc oxide (CeO2-ZnO) nanocomposite (CeO2-ZnO/GCE) was developed for the sensitive and quick detection of epinephrine. The CeO2-ZnO nanocomposite was prepared by hydrothermal method. Electrochemical methods such as voltammetry and chronoamperometry techniques were used to investigate the performance of the developed sensor. Key results: The resulting CeO2-ZnO/GCE showed a remarkable response towards the determination of epinephrine. The electrochemical sensor demonstrated a wide dynamic linear range from 0.1 to 900.0 µM for analysis of epinephrine. The LOD equalled 0.03 µM for epinephrine. In addition, the electrochemical sensor had good feasibility for concurrent detection of epinephrine and theophylline. Furthermore, experimental outputs indicated that the oxidation peaks of epinephrine and theophylline were separated by a 685 mV difference between the two peaks in PBS at a pH of 7.0. Also, an electrochemical sensor has been employed to analyse epinephrine in real samples (urine and epinephrine Injection). Conclusion: The good and acceptable analytical performance of the developed sensor can provide a promising tool for the analysis of epinephrine in real samples.

Construction and Application of an Electrochemical Sensor for Determination of D-Penicillamine Based on Modified Carbon Paste Electrode.

D-penicillamine (D-PA) is a sulfur-containing drug that has been used for various health conditions. However, like any medication, overdosing on D-PA can have adverse effects and may require additional treatment. Therefore, developing simple and sensitive methods for sensing D-PA can play a crucial role in improving its efficacy and reducing its side effects. Sensing technologies, such as electrochemical sensors, can enable accurate and real-time measurement of D-PA concentrations. In this work, we developed a novel electrochemical sensor for detecting D-PA by modifying a carbon paste electrode (CPE) with a multi-walled carbon nanotube-Co3O4 nanocomposite, benzoyl-ferrocene (BF), and ionic liquid (IL) (MWCNT-Co3O4/BF/ILCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA) were employed to explore the electrochemical response of D-PA on the developed sensor, the results of which verified a commendable electrochemical performance towards D-PA. Under optimized conditions, the developed sensor demonstrated a rapid response to D-PA with a linear dynamic range of 0.05 µM-100.0 µM, a low detection limit of 0.015 µM, and a considerable sensitivity of 0.179 µA µM-1. Also, the repeatability, stability, and reproducibility of the MWCNT-Co3O4/BF/ILCPE sensor were studied and showed good characteristics. In addition, the detection of D-PA in pharmaceutical and biological matrices yielded satisfactory recoveries and relative standard deviation (RSD) values.

Electrochemical Nanosensor for the Simultaneous Determination of Anticancer Drugs Epirubicin and Topotecan Using UiO-66-NH2/GO Nanocomposite Modified Electrode.

In this work, UiO-66-NH2/GO nanocomposite was prepared using a simple solvothermal technique, and its structure and morphology were characterized using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). An enhanced electrochemical sensor for the detection of epirubicin (EP) was proposed, which utilized a UiO-66-NH2/GO nanocomposite-modified screen-printed graphite electrode (UiO-66-NH2/GO/SPGE). The prepared UiO-66-NH2/GO nanocomposite improved the electrochemical performance of the SPGE towards the redox reaction of EP. Under optimized experimental conditions, this sensor demonstrates a remarkable limit of detection (LOD) of 0.003 µM and a linear dynamic range from 0.008 to 200.0 µM, providing a highly capable platform for sensing EP. Furthermore, the simultaneous electro-catalytic oxidation of EP and topotecan (TP) was investigated at the UiO-66-NH2/GO/SPGE surface utilizing differential pulse voltammetry (DPV). DPV measurements revealed the presence of two distinct oxidation peaks of EP and TP, with a peak potential separation of 200 mV. Finally, the UiO-66-NH2/GO/SPGE sensor was successfully utilized for the quantitative analysis of EP and TP in pharmaceutical injection, yielding highly satisfactory results.

Electrochemical sensing of methotrexate in the presence of folic acid using PAMAM dendrimer-functionalized multiwalled carbon nanotube-modified electrode.

This works presents a novel electrochemical sensor based on the third-generation poly(amidoamine) dendrimer (G3 PAMAM)-functionalized multiwalled carbon nanotube (MWCNT)-modified screen-printed graphite electrode (SPGE) for the simple and sensitive detection of methotrexate (MTX). The carboxylated MWCNTs were covalently functionalized with amino groups of G3 PAMAM and characterized using different techniques. The sensing ability of the designed nanosensor (MWCNTs-PAMAM/SPGE) was tested using differential pulse voltammetry (DPV), chronoamperometry (CHA), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). To investigate the electrocatalytic activity of PAMAM-functionalized MWCNTs, a comparative electrochemical analysis was carried out and it was determined that PAMAM-functionalized MWCNT-modified SPGE showed good electrocatalytic performance for MTX oxidation compared to the unmodified SPGE. The MWCNT-PAMAM/SPGE lead to a reduced overpotential of MTX oxidation of about 300 mV and enhanced current of about 9 µA of the unmodified SPGE. Experiments were performed for the quantitative determination of MTX using the DPV technique. The response peak current linearly related against MTX concentration in the ranges from 0.01 to 110.0 µM and a limit of detection (LOD) equal to 0.003 µM. Also, MWCNT-PAMAM/SPGE exhibits good catalytic ability toward MTX determination in the presence of folic acid (FA), and the separation of their oxidation peaks (peak potential difference = 320 mV) simultaneously detected the above compounds. To prove the applicability of the MWCNT-PAMAM/SPGE sensor, the concentrations of MTX and FA in pharmaceutical products and biological samples were determined. The calculated recoveries were close to 100%, which indicates that the method might be assumed to be accurate.

Electrochemical Sensor for Simple and Sensitive Determination of Hydroquinone in Water Samples Using Modified Glassy Carbon Electrode.

This study addressed the use of manganese dioxide nanorods/graphene oxide nanocomposite (MnO2 NRs/GO) for modifying a glassy carbon electrode (GCE). The modified electrode (MnO2 NRs/GO/GCE) was used as an electrochemical sensor for the determination of hydroquinone (HQ) in water samples. Differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry were used for more analysis of the HQ electrochemical behavior. Analyses revealed acceptable electrochemical functions with lower transfer resistance of electrons and greater conductivity of the MnO2 NRs/GO/GCE. The small peak-to-peak separation is an indication of a rapid electron transfer reaction. Therefore, this result is probably related to the effect of the MnO2 NRs/GO nanocomposite on the surface of GCE. In the concentration range of 0.5 µM to 300.0 µM with the detection limit as 0.012 µM, there was linear response between concentration of HQ and the current. The selectivity of the modified electrode was determined by detecting 50.0 µM of HQ in the presence of various interferent molecules. At the end, the results implied the acceptable outcome of the prepared electrode for determining HQ in the water samples.

Development of a highly sensitive voltammetric sensor for the detection of folic acid by using MoS2 and ionic liquid-modified carbon paste electrode.

Background and purpose: Sensitive analytical determination of folic acid is important in clinical laboratories due to its versatile biological functions. Experimental approach: A simple folic acid sensor was successfully fabricated based on two-dimensional transition metal dichalcogenide MoS2 modified carbon ionic liquid paste electrode (MoS2-CILPE). The electrochemical properties of the fabricated electrode were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry. Key results: The fabricated sensor displayed excellent electroactivity towards folic acid using CV. Under optimal conditions (0.1 M PBS (pH 7.0)), the DPV oxidation peak current was proportional to folic acid concentration in the range from 5.0 µM to 100.0 µM with an estimated limit of detection of 1.0 µM and limit of quantification of 5.0 µM. Conclusion: The ability of the sensor for routine analyses was demonstrated by the detection of folic acid present in folic acid tablets and urine samples with appreciable recovery values.

A UiO-66-NH2 MOF/PAMAM Dendrimer Nanocomposite for Electrochemical Detection of Tramadol in the Presence of Acetaminophen in Pharmaceutical Formulations.

In this work, we prepared a novel electrochemical sensor for the detection of tramadol based on a UiO-66-NH2 metal-organic framework (UiO-66-NH2 MOF)/third-generation poly(amidoamine) dendrimer (G3-PAMAM dendrimer) nanocomposite drop-cast onto a glassy carbon electrode (GCE) surface. After the synthesis of the nanocomposite, the functionalization of the UiO-66-NH2 MOF by G3-PAMAM was confirmed by various techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and Fourier transform infrared (FT-IR) spectroscopy. The UiO-66-NH2 MOF/PAMAM-modified GCE exhibited commendable electrocatalytic performance toward the tramadol oxidation owing to the integration of the UiO-66-NH2 MOF with the PAMAM dendrimer. According to differential pulse voltammetry (DPV), it was possible to detect tramadol under optimized circumstances in a broad concentration range (0.5 µM-500.0 µM) and a narrow limit of detection (0.2 µM). In addition, the stability, repeatability, and reproducibility of the presented UiO-66-NH2 MOF/PAMAM/GCE sensor were also studied. The sensor also possessed an acceptable catalytic behavior for the tramadol determination in the co-existence of acetaminophen, with the separated oxidation potential of ΔE = 410 mV. Finally, the UiO-66-NH2 MOF/PAMAM-modified GCE exhibited satisfactory practical ability in pharmaceutical formulations (tramadol tablets and acetaminophen tablets).