An Efficient Electrochemical Sensor Based on NiCo2O4 Nanoplates and Ionic Liquid for Determination of Favipiravir in the Presence of Acetaminophen

Based on the modification of carbon paste electrode with NiCo2O4 nanoplates and 1-hexyl-3-methylimidazolium tetrafluoroborate, a new electrochemical sensing platform for the sensing of favipiravir (a drug with potential therapeutic efficacy in treating COVID-19 patients) in the presence of acetaminophen was prepared. For determining the electrochemical behavior of favipiravir, cyclic voltammetry, differential pulse voltammetry, and chronoamperometry have been utilized. When compared to the unmodified carbon paste electrode, the results of the cyclic voltammetry showed that the proposed NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode had excellent catalytic activity for the oxidation of the favipiravir in phosphate buffer solution (pH = 7.0). This was due to the synergistic influence of 1-hexyl-3-methylimidazolium tetrafluoroborate (ionic liquid) and NiCo2O4 nanoplates. In the optimized conditions of favipiravir measurement, NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode had several benefits, such as a wide dynamic linear between 0.004 and 115.0 µM, a high sensitivity of 0.1672 µA/µM, and a small limit of detection of 1.0 nM. Furthermore, the NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode sensor presented a good capability to investigate the favipiravir and acetaminophen levels in real samples with satisfactory recoveries.

Solvothermal synthesis of organoclay/Cu-MOF composite and its application in film modified GCE for simultaneous electrochemical detection of deoxyepinephrine, acetaminophen and tyrosine

An organoclay/copper-based metal-organic framework (MOF) composite was synthesized using a solvothermal method by growing a Cu-BTC (copper(ii) benzene-1,3,5-tricarboxylate) MOF from a mixture of the MOF precursor solution in which various amounts of organoclay had been dispersed. The organoclay was obtained by intercalating a cationic dye, namely thionin, into a natural Cameroonian clay sampled in Sagba deposit (North West of Cameroon). The organoclay and the as-synthesized composites were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer, Emmett and Teller (BET) techniques. From Scherrer's equation, the crystallite size of the composite was found to be between 55 and 58 nm, twice as large as the pristine MOF's crystallite size. The organoclay/Cu-MOF composite (Sa-TN₅₀/Cu₃(BTC)₂) exhibiting a BET surface area of 192 m² g^-1, about twice that of pristine clay and about one seventh that of pristine MOF, was then utilized to form a stable thin film onto glassy carbon electrodes (GCE) by drop coating (Sa-TN₅₀/Cu₃(BTC)₂/GCE). These electrodes demonstrated electrocatalytic behavior toward deoxyepinephrine (DXEP) and thus enabled selective and simultaneous sensitive detection of three analytes: DXEP, acetaminophen (AC) and tyrosine (TYR) compared with bare GCE and clay modified electrode. Under optimum conditions, Sa-TN₅₀/Cu₃(BTC)₂/GCE exhibited good performance including large calibration curves ranging from 5.0 μM to 138.0 μM for DXEP, 4.0 μM to 153.0 μM for AC and 1.0 μM to 29.4 μM for TYR. The detection limits were found to be, 0.4 μM, 0.7 μM and 0.2 μM for DXEP, AC and TYR, respectively. The developed sensors have been applied successfully in the quantification of AC in a commercial tablet of AC, and DXEP, AC and TYR in tap water.

An Amperometric Acetylcholine Biosensor Based on Co-Immobilization of Enzyme Nanoparticles onto Nanocomposite

An electrochemical biosensor was fabricated using nanoparticles of acetylcholinesterase (AChE) and choline oxidase (ChO)/Pt nanoparticles (PtNPs)/porous graphene oxide nanosheet (GONS) composite. A pencil graphite electrode (PGE) was used for the electrodeposition of nanocomposite and the determination of acetylcholine (ACh), a neurotransmitter. Various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectra and cyclic voltammetry (CV) were used for characterization. This biosensor (AChENPs-ChONPs/GONS/PtNPs/PGE) indicated a very short response time (3 s), a lower limit of detection (0.001 µM), good linearity (0.001-200 µM), longer storage stability (6 months) and better reproducibility. The percent analytical recoveries of added acetylcholine in serum (5.0 and 10 µM) were found to be 97.6 ± 0.7 and 96.5 ± 0.3 for the present biosensor. The coefficients of variation were obtained to be 8% and 3.25%, correspondingly. The biosensor was applied to measure the ACh amount in the serum of healthy individuals and patients with Alzheimer's disease. The number of interferents had no effect on the biosensor at their physiological concentrations.

Electrochemistry Test Strip as Platform for In Situ Detection of Blood Levels of Antipsychotic Clozapine in Finger-Pricked Sample Volume

With the increasing number of patients suffering from Parkinson's disease, the importance of measuring drug levels in patient body fluids has increased exponentially, particularly for the drug clozapine. There is a growing demand for real-time analysis of biofluids on a single low-cost platform in ultra-low fluid volumes with robustness. This study aims to measure the level of clozapine (Clz) with a portable potentiostat using a practical approach. For this purpose, we developed an inexpensive, portable platform via electrochemistry on a commercial glucose test strip (CTS). CTSs were first modified by removing the enzyme mixture from the surface of the sensing zone, which was followed by modification with Multi walled carbon nanotube (MWCNT) and Nafion. The electrochemical characteristics of CTS electrodes were investigated using cyclic voltammetry (CV) and differential voltammetry (DPV) techniques. The designed sensor displayed decent linear range, detection limit, reproducibility, and reusability results. A linear dynamic range of 0.1-5 μM clozapine was observed under optimized conditions with a good sensitivity (1.295 μA/μM) and detection limit (83 nM). Furthermore, the designed sensing electrode was used to measure the amount of Clz in real samples.

Recent Patents and Potential Applications of Homogenisation Techniques in Drug Delivery Systems

BACKGROUND

The term homogenise means "to force or provide coalesce". Homogenisation is a process to attain homogenous particle size. The objective of the homogenisation process is to use fluid force to split the fragments or tiny particles contained in the fluids into very small dimensions and form a sustainable dispersion suitable for further production.

METHODS

The databases were collected through Scopus, google patent, science web, google scholar, PubMed on the concept of homogenisation. The data obtained were systematically investigated.

RESULTS

The present study focus on the use of the homogenisation in drug delivery system. The aim of homogenisation process is to achieve the particle size in micro-and nano- range as it affects the different parameters in the formulation and biopharmaceutical profile of the drug. The particle size reduction plays a key role in influencing drug dissolution and absorption. The reduced particle size enhances the stability and therapeutic efficacy of the drug. Homogenization technology ensures to achieve effective, clinically efficient and targeted drug delivery with the minimal side effect.

CONCLUSION

Homogenization technology has been shown to be an efficient and easy method of size reduction to increase solubility and bioavailability, stability of drug carriers. This article gives an overview of the process attributes affecting the homogenization process, the patenting of homogeniser types, design, the geometry of valves and nozzles and its role in drug delivery.

Ecofriendly Green Synthesis of Copper (II) Oxide Nanoparticles Using Corchorus olitorus Leaves (Molokhaia) Extract and Their Application for the Environmental Remediation of Direct Violet Dye via Advanced Oxidation Process

In this research, copper (II) oxide nanoparticles were prepared by an ecofriendly green method using the extract of corchorus olitorus leaves (Molokhaia) as a surfactant, capping and anti-agglomeration agent. The ecofriendly green CuO NPs were characterized using different chemical and physical techniques and the results confirmed the formation of monoclinic tenorite CuO nanoparticles with an average particle size of 12 nm and BET surface area of 11.1 m²/g. The eco-friendly green CuO NPs were used in environmental remediation for the efficient catalytic degradation of direct violet dye via advanced oxidation process (AOP) in presence of H₂O₂. The impact of AOP environmental parameters affecting the degradation process was investigated. Moreover, the catalytic degradation of the direct violet dye using the ecofriendly green CuO NPs was studied kinetically and thermodynamically and the results showed that the catalytic degradation process agreed well with the pseudo-second-order kinetic model and the process was spontaneous and endothermic in nature. Finally, high catalytic degradation of the direct violet dye was observed when the eco-friendly prepared green CuO NPs were placed in real water samples.

Use of a nano-porous gold film electrode modified with chitosan / polypyrrole for electrochemical determination of metronidazole in the Presence of Acetaminophen

This study, it was aimed to provide a sensitive, easy and selective method for designing Nano-porous gold film electrode (NPGF) electrode for simultaneous measurement of metronidazole (MT) and acetaminophen (AC). For this purpose, the NPGF electrode surface was modified with chitosan (CS) and poly pyrrole (PPY) by electrochemical method, and then CS and PPY modified NPGF (PPY-CS-NPGF) electrode were used to measure these drugs. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are employed for the characterization of the attained PPY-CS-NPGF electrode. Using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and chronoamperometry, the electrochemical behavior of MT was investigated with the modified electrode. By differential pulse voltammetry, linear ranges of concentration 0.005-100 μM with linear coefficients of 0.9898 and a detection limit of 0.0009 μM were obtained for MT. Finally, an electrochemical sensor was used to measure MT in a real sample, which yielded acceptable results. PPY-CS-NPGF electrodes have a wide linear range, high selectivity, sensitivity and stability and can be used successfully to determine these drugs.

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.

Simple Preparation and Characterization of Hierarchical Flower-like NiCo2O4 Nanoplates: Applications for Sunset Yellow Electrochemical Analysis

The current work was performed to construct a novel electrochemical sensing system for determination of sunset yellow via the modification of screen-printed graphite electrode modified with hierarchical flower-like NiCo₂O₄ nanoplates (NiCo₂O₄/SPGE). The prepared material (hierarchical flower-like NiCo₂O₄ nanoplates) was analyzed by diverse microscopic and spectroscopic approaches for the crystallinity, composition, and morphology. Chronoamperometry, differential pulse voltammetry, linear sweep voltammetry, and cyclic voltammetry were used for determination of the electrochemical behavior of sunset yellow. The as-fabricated sensor had appreciable electro-catalytic performance and current sensitivity in detecting the sunset yellow. There were some advantages for NiCo₂O₄/SPGE under the optimized circumstances of sunset yellow determination, including a broad dynamic linear between 0.02 and 145.0 µM, high sensitivity of 0.67 μA/(μM.cm²), and a narrow limit of detection of 0.008 μM. The practical applicability of the proposed sensor was verified by determining the sunset yellow in real matrices, with satisfactory recoveries.

Electrochemical Sensor Based on Ni-Co Layered Double Hydroxide Hollow Nanostructures for Ultrasensitive Detection of Sumatriptan and Naproxen

In this work, Ni-Co layered double hydroxide (Ni-Co LDH) hollow nanostructures were synthesized and characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and Fourier-transform infrared spectroscopy (FT-IR) techniques. A screen-printed electrode (SPE) surface was modified with as-fabricated Ni-Co LDHs to achieve a new sensing platform for determination of sumatriptan. The electrochemical behavior of the Ni-Co LDH-modified SPE (Ni-CO LDH/SPE) for sumatriptan determination was investigated using voltammetric methods. Compared with bare SPE, the presence of Ni-Co LDH was effective in the enhancement of electron transport rate between the electrode and analyte, as well as in the significant reduction of the overpotential of sumatriptan oxidation. Differential pulse voltammetry (DPV) was applied to perform a quantitative analysis of sumatriptan. The linearity range was found to be between 0.01 and 435.0 μM. The limits of detection (LOD) and sensitivity were 0.002 ± 0.0001 μM and 0.1017 ± 0.0001 μA/μM, respectively. In addition, the performance of the Ni-CO LDH/SPE for the determination of sumatriptan in the presence of naproxen was studied. Simultaneous analysis of sumatriptan with naproxen showed well-separated peaks leading to a quick and selective analysis of sumatriptan. Furthermore, the practical applicability of the prepared Ni-CO LDH/SPE sensor was examined in pharmaceutical and biological samples with satisfactory recovery results.

Recent advances in electrochemical sensor developments for detecting emerging pollutant in water environment

In the latest times, considerable studies have been performed closer to detecting emerging pollutant such as paracetamol in wastewater. Electrochemical sensor developments have recently started to determine in fewer concentrations effectively. The detection of paracetamol using standard protocols corresponding to electroanalytical techniques has a greater impact noticed in directing the detecting process toward biosensors. Non-enzymatic sensors are the peak of all electro analysis approaches. Functionalized materials, such as metal oxide nanoparticles, conducting polymers, and carbon-based materials for electrode surface functionalization have been used to create a fortification for distributing passive enzyme-free biosensors. Synergic effects are possible by enhancing loading capacity and mass transfer of reactants for attaining high analytical sensitivity using a variety of nanomaterials with large surface areas. The main focus of this study is to address the prevailing issues in the identification of paracetamol with the tasks in the non-enzymatic sensors field, followed by the useful methods of electro analysis studies.

A modified carbon paste electrode with N-rGO/CuO nanocomposite and ionic liquid for the efficient and cheap voltammetric sensing of hydroquinone in water specimens

This paper reports a voltammetric sensor based on copper oxide nanoparticles on nitrogen-doped reduced graphene oxide nanocomposite (N-rGO/CuO)-ionic liquid modified carbon paste electrode (N-rGO/CuO-ILCPE) for determining the hydroquinone (HQ). The N-rGO/CuO was prepared by a facile protocol, followed by characterization via fourier transform-infrared (FT-IR) patterns, field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) analysis. The electrochemical behaviour was linearly symmetrical to various hydroquinone levels (1.0-600.0 μM) with a narrow limit of detection (LOD = 0.25 μM). The diffusion coefficient was also estimated to be 4.1 × 10^-6 cm²/s. The N-rGO/CuO-ILCPE was impressively applicable in determination of hydroquinone in the real specimens.

Electrochemical monitoring of bisphenol-s through nanostructured tin oxide/Nafion/GCE: A solution to environmental pollution

Over the past few decades, phenolic compounds have been broadly exploited in the industries to be utilized in several applications including polycarbonate plastic, food containers, epoxy resins, etc. One of the major compounds in phenolics is Bisphenol-S (BPS) which has dominantly replaced Bisphenol-A in several applications. Phenolic compounds are extensively drained into the environment without proper treatment and cause several health hazards. Thus, to tackle this serious problem an electrochemical sensor based on SnO₂/GCE has been successfully engineered to monitor the low-level concentration of BPS in water samples. The fabrication of SnO₂ nanoparticles (SnO₂ NPs) was confirmed through FTIR, XRD, and TEM to examine the size, crystallinity, internal texture, and functionalities of the prepared material. The fabricated material was exploited as a chemically modified sensor for the determination of BPS in water samples collected from different sources. Under optimal conditions such as scan sweep 100 mV/s, PBS electrolyte pH of 6, potential window (0.3-1.3 V), the proposed sensor manifested an excellent response for BPS. The LOD of the present method for BPS was calculated as 0.007 μM, respectively. Moreover, the stability and selectivity profile of SnO₂/GCE for BPS in the real matrix was examined to be outstanding.

A Voltammetric Sensor for the Determination of Hydroxylamine Using a Polypyrrole Nanotubes-Modified Electrode

In this work, we develop an electrochemical sensor using a polypyrrole nanotubes-modified graphite screen-printed electrode (PPy NTs/GSPE) for sensing hydroxylamine. The PPy NTs/GSPE-supported sensor has an appreciable electrocatalytic performance and great stability for hydroxylamine oxidation. Compared to a bare graphite screen-printed electrode, we demonstrate that using the PPy NTs/GSPE leads to a significant reduction in the oxidation potential of hydroxylamine. The standard curve shows a linear relationship ranging from 0.005 to 290.0 μM (R2  =  0.9998), with a high sensitivity (0.1349 μA/μM) and a narrow limit of detection (LOD) of 0.001 μM. In addition, the PPy NTs/GSPE has satisfactory outcomes for hydroxylamine detection 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.

Construction of modified screen-printed graphite electrode for the application in electrochemical detection of sunset yellow in food samples

The current work introduced a novel electrochemical sensor (screen-printed graphite electrode (SPGE) modified with MnO₂ nanorods anchored graphene oxide nanocomposite (MnO₂ NRs/GO) for sensitive determination of sunset yellow. The characterization of MnO₂ NRs/GO nanocomposite synthesized through a simple hydrothermal approach was determined employing varied analytical equipment like Field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). Chronoamperometric measurements, differential pulse voltammetry (DPV), cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were recruited to recognize the electrochemical oxidation of sunset yellow on the MnO₂ NRs/GO/SPGE. The results of CV proved that the as-synthesized MnO₂ NRs/GO nanocomposite has a good electrocatalytic activity toward sunset yellow. The MnO₂ NRs/GO/SPGE electrode under optimized conditions using the DPV possessed a linear response for different concentrations of sunset yellow (between 0.01 and 115.0 μM) with a low limit of detection (LOD) (0.008 μM). Finally, the impressive applicability of this sensor was confirmed via real sample analysis with excellent recoveries (between 97.3 and 104.6%).

Nanomaterials: An alternative source for biodegradation of toxic dyes

Environment contamination is a colossal worriment across the world, owing to its detrimental and negative impact on health and ecological systems. Dyes are one of the synthetic organic chemicals that are utilised in a variety of fields, including textiles. As a result, throughout one's production and subsequently in fibre colouring, these are becoming frequent industry-contributed contaminants. Increasing globalisation of international market has presented a problem to textile sector in terms of consistency and production. Textile processors' primary concern, as the highly competitive environment and environmental standards grow more severe is about being mindful of the grade of goods and even non-toxicity of their production processes. There seems to be an immediate necessity to look for methods and technologies which are useful in removing dye colours. Even though each has benefits and weaknesses, many physical, chemical, and biological approaches were explored and used with the application being dependent on the effluent properties, technical feasibility, and cost. Several remediation technologies are already developed, but they seem to be ineffective at removing dyes completely. There is a fast growth of nanoparticles applications in the past few years which has opened up newer, innovating, highly efficient, and low-cost dyes remediation systems. Nanomaterials with large surface areas change surface characteristics and distinctive electron conducting capabilities which make them ideal candidate for the treatment of wastewater that contains dyes. In this review, we have highlighted not only the role of nanotechnology in dye remediation processes but also different types of nanomaterials that can be used for the remediation of dyes.

Hydrothermal synthesis of CuFe2O4 nanoparticles for highly sensitive electrochemical detection of sunset yellow

The sunset yellow, as a synthetic food coloring azo dye, was detected in the present work using a new sensitive and selective sensor based on the modification of screen-printed electrode surface with Copper ferrite nanoparticles (CuFe₂O₄/SPE). Thus, a facile hydrothermal protocol was performed to prepare the CuFe₂O₄ nanoparticles, followed by characterization applying valid techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FE-SEM). Chronoamperometry, differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were employed to determine the electrochemical behavior of as-fabricated sensor. According to the electrochemical findings, a greater anodic peak current was found for the sunset yellow oxidation on the CuFe₂O₄/SPE than that on the unmodified SPE. The electrocatalytic response for the sunset yellow oxidation on the CuFe₂O₄/SPE in phosphate buffer (0.1 M, pH = 7.0) was effective, with an excellent sensitivity (0.1919 μA μM^-1). There was a linear relationship between the voltammetric current and different sunset yellow concentrations (0.03-100.0 μM). The calculated limit of detection (LOD = 3Sb/m) for the sunset yellow was 0.009 μM.

Electrochemical sensors based on carbon nanostructures for the analysis of bisphenol A-A review

Overuse of Bisphenol A (BPA), a proven endocrine disruptor, has become a serious public health problem across the world. It has the potential to harm both the environment and human health, notably reproductive disorders, heart disease, and diabetes. Accordingly, much attention has been paid to the detection of BPA to promote food safety and environmental health. Carbon based nanostructures have proven themselves well in a variety of applications, such as energy storage, catalysis and sensors, due to their remarkable properties. Therefore, researchers have recently focused on fabricating electrochemical BPA sensors based on carbon nanostructures due to their unique advantages, such as real-time monitoring, simplicity, high selectivity, high sensitivity and easy operation. The purpose of the current review was to summarize the recent findings on carbon nanostructures for electrochemically sensing the BPA, as well as relevant future prospects and ongoing challenges.

Advancement in electrochemical strategies for quantification of Brown HT and Carmoisine (Acid Red 14) Drom Azo Dyestuff class

Brown HT and carmoisine, which are the most used dyestuffs in pharmaceuticals, textiles, cosmetics and foods, are important components of the Azo family. Although the Azo group is not toxic or carcinogenic under normal conditions, these dyestuffs require great care due to the reduction of the Azo functional group to amines. In particular, fast, reliable, easy, on-site and precise determinations of these substances are extremely necessary and important. In this review, the properties, applications, and electrochemical determinations of brown HT and carmoisine, which are used as synthetic food colorants, are discussed in detail. Up to now, sensor types, detection limits (LOD and LOQ), and analytical applications in the developed electrochemical strategies for both substances were compared. In addition, the validation parameters such as the variety of the sensors, sensitivity, selectivity and electrochemical technique in these studies were clarified one by one. While the electrochemical techniques recommended for brown HT were mostly used for the removal of dyestuff, for carmoisine they included fully quantitative centered studies. The percentiles of voltammetric techniques, which are the most widely used among these electroanalytical methods, were determined. The benefits of a robust electrochemical strategy for the determination of both food colors are summed up in this review. Finally, the brown HT and carmoisine suggestions for future perspectives in electrochemical strategy are given according to all their applications.

Glassy Carbon Electrode Modified with N-Doped Reduced Graphene Oxide Sheets as an Effective Electrochemical Sensor for Amaranth Detection

Amaranth is one of the synthetic azo colorants used to improve the appearance and to increase the appeal of some foods and soft drinks. The excessive consumption of amaranth can be associated with health side effects, emphasizing the need to monitor this food dye. Accordingly, the present study aimed to introduce an electrochemical sensor of glassy carbon electrode (GCE) modified with N-doped reduced graphene oxide (N-rGO), N-rGO/GCE, to detect the amaranth sensitively and rapidly. Several electrochemical techniques such as differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and cyclic voltammetry (CV) are exploited for the evaluation of the efficiency of the developed electrode for the detection of amaranth. We found that N-rGO/GCE enhanced amaranth oxidation, thus significantly elevating the current signal. Amaranth showed that calibration curves ranged from 0.1 to 600.0 µM, and the limit of detection (LOD) (S/N = 3) was 0.03 μM. Finally, the developed sensor was effectively applied for real samples (tap water, apple juice, and orange juice) with acceptable recovery values from 96.0 to 104.3%.

Application of MnO2 Nanorod–Ionic Liquid Modified Carbon Paste Electrode for the Voltammetric Determination of Sulfanilamide

The current work introduced a convenient single-phase hydrothermal protocol to fabricate MnO₂ nanorods (MnO₂ NRs). Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) and field-emission scanning electron microscopy (FE-SEM) were used to determine the characteristics of MnO₂ NR. Then, ionic liquid (IL) and MnO₂ NRs were utilized to modify a carbon paste electrode (CPE) surface (MnO₂NR-IL/CPE) to voltammetrically sense the sulfanilamide (SAA). An enhanced voltammetric sensitivity was found for the as-developed modified electrode toward SAA when compared with a bare electrode. The optimization experiments were designed to achieve the best analytical behavior of the SAA sensor. Differential pulse voltammetry (DPV) in the optimized circumstances portrayed a linear dependence on various SAA levels (between 0.07 and 100.0 μM), possessing a narrow detection limit (0.01 μM). The ability of the modified electrode to be used in sensor applications was verified in the determination of SAA present in the actual urine and water specimens, with impressive recovery outcomes.

A stable naked-eye colorimetric sensor for monitoring release of extracellular gamma-aminobutyric acid (GABA) neurotransmitter from SH-SY5Y cells

A novel optical γ-aminobutyric acid (GABA)-based sensor was developed on interacting thiol compounds and o-phthalaldehyde (OPA) to form thiacetal compounds. Then, the thiacetal interacts with the GABA molecule to form an isoindole compound. The effects of four thiol compounds on the stability of the resulting isoindole compound were assessed. The 2-mercaptoethanol, "one of the most used derivatizing agents," is unexpectedly the least stable; while, 16-mercaptohexadecanoic acid resulted in the most durable isoindole compound. The developed sensor showed the capability for detecting GABA within a wide concentration range spanning from 500 nmol L^-1 to 100 µmol L^-1. The detection limit was about 330 nmol L^-1, which indicated the high sensitivity of the developed sensor compared with those previously reported. The findings illustrated the ability to detect GABA at the physiological pH (pH = 7.4) without adjusting the pH value, opening the door for real applications. Furthermore, the sensor could detect various GABA concentrations in human serum with good recovery percentages (98% to 101.4%). In addition, this assay was applied to monitor GABA release from the SH-SY5Y cell line to convert glutamate into GABA. This result indicates the capability of the proposed assay for visually monitoring the release of GABA neurotransmitters.

Synthesis and Characterization of GO/ZIF-67 Nanocomposite: Investigation of Catalytic Activity for the Determination of Epinine in the Presence of Dobutamine

In this study, we prepared graphene oxide (GO)/ZIF-67 nanocomposites. Therefore, GO/ZIF-67 nanocomposites were used as a modifier on a screen-printed electrode (GO/ZIF-67/SPE) for studying the electrochemical behavior of epinine in phosphate buffer saline (PBS) at pH 7.0 with voltammetry techniques. The GO/ZIF-67/SPE showed greater electrocatalytic activities than the bare SPE. As a result, the GO/ZIF-67/SPE was utilized for additional electrochemical examinations. The epinine concentration determination was in the range 9.0 × 10-8 M to 5.0 × 10-4 M, and the limit of detection (LOD) as well as the limit of quantification (LOQ) equaled 2.0 and 6.6 nM, respectively. From the scan rate study, the oxidation of epinine was found to be diffusion-controlled, and the simultaneous detection of epinine and dobutamine were well achieved with the differential pulse voltammetric (DPV) technique. Moreover, the stability and reproducibility of epinine at the GO/ZIF-67/SPE was studied, and the use of the GO/ZIF-67/SPE to detect epinine and dobutamine in real samples was furthermore successfully demonstrated.

ZnO/ZnFe2O4 nanocomposite-based electrochemical nanosensors for the detection of furazolidone in pork and shrimp samples: exploring the role of crystallinity, phase ratio, and heterojunction formation

The effect of crystallinity, phase ratio, and heterojunction formation on the FZD sensing performance of ZnO/ZnFe2O4 nanocomposite-based electrochemical sensors was investigated.

Application of Solid-state Electrochemical Analysis in Ancient Ceramic Identification and Characterization: A Review

Background:

Ceramics can reflect ancient technology and art, therefore, it has a very important position in archaeology. However, it is far from enough just to study the shape of pottery and porcelain. It is necessary to use advanced scientific and technological means to conduct a comprehensive analysis of pottery and porcelain, so as to study the information hidden deep in the remains of ceramic objects.

Methods:

The solid voltammetric method can be used to obtain information about the composition of materials used in ancient ceramics. This new method can be applied to insoluble solids for example, providing qualitative and quantitative information and structural information with little soluble solids. The method requires only ng-μg sample.

Results:

In this review, we first describe the development of solid-state voltammetric method and our work in this field. Then, we describe in detail the application of this method in archaeology, especially in the analysis of ceramics. Finally, we describe the analytical applications of other electrochemical techniques for ceramics analysis.

Conclusion:

Due to the low demand for samples and the high-cost performance of analytical instruments, this method has been widely studied in Europe. To sum up, we propose to establish a microsampling method for ancient ceramics. A new method for the protection of fine ancient ceramics by the suitable carrier and the fixation on the surface of the electrode. These improvements can enable solid-state electroanalytical chemistry technology to achieve more comprehensive and accurate quantitative analysis of ancient ceramics particles. We also propose the current challenges and future directions of solid-state electroanalytical chemistry.

Determination of Salicylic Acid Using a Highly Sensitive and New Electroanalytical Sensor

Background:

A drug sensor (salicylic acid, in this case) was designed and made up of this research. The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1-hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution.

Methods:

Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, carbon paste electrode was amplified with conductive materials and used as a working electrode.

Results:

The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 µM using differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuOSWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples.

Conclusion:

The MPE/CuO-SWCNTs/HMICl was successfully used as a new and high performance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.

Recent Advantages of Mediator Based Chemically Modified Electrodes; Powerful Approach in Electroanalytical Chemistry

Background:

Modified electrodes have advanced from the initial studies aimed at understanding electron transfer in films to applications in areas such as energy production and analytical chemistry. This review emphasizes the major classes of modified electrodes with mediators that are being explored for improving analytical methodology. Chemically modified electrodes (CMEs) have been widely used to counter the problems of poor sensitivity and selectivity faced in bare electrodes. We have briefly reviewed the organometallic and organic mediators that have been extensively employed to engineer adapted electrode surfaces for the detection of different compounds. Also, the characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed.

Objective:

Improvement and promotion of pragmatic CMEs have generated a diversity of novel and probable strong detection prospects for electroanalysis. While the capability of handling the chemical nature of the electrode/solution interface accurately and creatively increases , it is predictable that different mediators-based CMEs could be developed with electrocatalytic activity and completely new applications be advanced.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

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N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.