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This study applied screen printed graphite electrode (SPGE) modified with the Fe2MoO4 magnetic nanocomposite for simultaneously determining nalbuphine and diclofenac to fabricate a sensitive simple electrochemical sensor. A simple process was designed for preparing Fe2MoO4 magnetic nanocomposite. In addition, electrochemical features of the modified electrodes were characterized by differential pulse voltammetry (DPV), chronoamperometry (CHA) and cyclic voltammetry (CV). According to the analysis, very good electrocatalytic activities towards nalbuphine were shown by the modified electrode (PBS at a pH of 7.0). According to DPV measurements, the linear response to detect nalbuphine ranged between 0.02 and 250.0 μM. Furthermore, limit of detection (LOD) equaled 8.0 nM (S/N = 3). DPV was employed for the simultaneous determination of nalbuphine and diclofenac, which showed a significant peak potential difference equal to 0.14 V. Therefore, this new sensor exhibited acceptable repeatability, reproducibility and stability. Finally, the functional utility of the sensor was examined in the real samples, followed by attractive findings to detect nalbuphine and diclofenac.

Determination of food toxic compounds is one of the significant strategies for investigating food quality. The presence research introduces an electrochemical approach for toxic ractopamine sensing using a gold electrode amplified with gold nanoparticles (Au-Nps/AuME). The oxidation signal of ractopamine was investigated at the surface of Au-Nps/AuME, and results showed a 2.36-fold amplification in current and reducing 100 mV in oxidation potential compare to the pristine gold electrode. The redox reaction of ractopamine shows a pH dependence behavior with two electrons and two protons. Furthermore, the scan rate and chronoamperometric investigation showed a diffusion coefficient of 1.0 × 10−6 cm2/s to the oxidation reaction of ractopamine at the surface of Au-Nps/AuME. Analytical investigation showed a linear dynamic range of 0.1–380 µM for sensing of ractopamine using square wave voltammetric technique. Also, Au-Nps/AuME could be used to measure ractopamine in food samples such as pork samples with a recovery range of 98.3–103.9% and a detection limit of 50 nM.

A flower-like binary transition metal oxide, in the form of MgCo2O4, was successfully synthesized and investigated by XRD and Raman spectroscopy as well as by SEM and TEM micrographs. A hybrid of MgCo2O4 with reduced graphene oxide (rGO) was prepared to distinguish between the rGO-riched and rGO-free catalysts for potential applications in direct methanol fuel cell (DMFC) anodes (methanol electro-oxidation process). The synergetic effect due to the proximity of magnesium and cobalt oxides, along with their hybridization on the rGO, makes MgCo2O4-rGO an efficient and low-cost catalyst for an anode electrode in the DMFC applications. EIS, CV, LSV tests, and cyclic stability of MgCo2O4-rGO for 2000 subsequent CV cycles confirm the pivotal role of rGO in the catalyst structure. Finally, the single-cell test indicated the suitability of our proposed catalyst for practical applications of DMFC. Indeed, the single-cell polarization diagrams show a significantly improved power density for single cells with MgCo2O4-rGO-based anode (19 mW cm−2) compared to MgCo2O4- based anode (11 mW cm−2).

There is an urgent need to develop a highly sensitive detection system for detecting trace amount of food contaminants. The environmental analysis of Sudan I, a carcinogenic azo-dye, has attracted wide attention due to their increasing levels and high toxicities. Several methods have been developed to detect the presence of this compound. For example, analytical methods based on chromatography and spectroscopy has attracted significant attentions for the determination of Sudan I. However, these methods require complex separation processes, expensive equipment, toxic chemicals, long analysis times, and expert staff. Electroanalytical methods can be considered as promising alternative techniques due to their advantages such as simplicity, low cost, high sensitivity, and fast analysis speed. Electroanalytical methods have been also investigated for the determination of Sudan I. Chemically modified electrodes have been widely used to counter the problems of poor sensitivity and selectivity faced at bare electrodes. We have reviewed the materials that have been extensively used to fabricate modified electrode surfaces for detection of Sudan I. The characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed.

The present research presents synthesis and substantial utilization of a nanocomposite of boron nitride-Fe3O4–Pd (BN–Fe3O4–Pd) for modifying carbon paste electrode (CPE) to determine sulfamethoxazole (SMZ). Various techniques such as transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were applied to characterize the synthesized nanocomposite. In addition, differential pulse voltammetry (DPV) was employed for anodic peak and quantitatively detecting SMZ. Based on the optimized condition, this novel sensor exhibited a linear response of 0.02–420.0 μM. The limitation of detection and quantitation values for SMZ were determined to be 0.008 μM and 0.027 μM, respectively. Moreover, this electrode could substantially be applied for the analysis of SMZ in the real samples (e.g., urine, tap water, river water).

In the present paper, a screen printed electrode was modified with ZnFe2O4 magnetic nanoparticles and then used for an electrooxidation investigation of vitamin B6; in addition, its sensing was studied via differential pulse voltammetry. The current response in the case of vitamin B6 is considerably enhanced on the modified electrode in comparison with that on an unmodified screen printed electrode. A linear relationship among the concentration and the current is achieved in a range of 0.2–350.0 µM for vitamin B6 at optimized states of differential pulse voltammetric values, and the detection limit is equal to 0.07 µM. For the detection of vitamin B6, the fabricated electrode mentioned above showed a fast response. The experiments demonstrated that this simple, eco-friendly, economic, and rapid approach of ZnFe2O4 magnetic nanoparticles/screen printed electrode production has a high potential to fabricate a sensor in order to detect vitamin B6 in real samples.

The electrocatalytic performance of carbon paste electrode (CPE) modified with ferrocene-derivative (ethyl2-(4-ferrocenyl[1,2,3]triazol-1-yl)acetate), ionic liquid (n-hexyl-3-methylimidazolium hexafluorophosphate), and CoS2-carbon nanotube nanocomposite (EFTA/IL/CoS2-CNT/CPE) was investigated for the electrocatalytic detection of hydrazine. CoS2-CNT nanocomposite was characterized by field emission scanning electron microscopy, X-ray powder diffraction, and transmission electron microscopy. According to the results of cyclic voltammetry, the EFTA/IL/CoS2-CNT-integrated CPE has been accompanied by greater catalytic activities for hydrazine oxidation compared to the other electrodes in phosphate buffer solution at a pH 7.0 as a result of the synergistic impact of fused ferrocene-derivative, IL, and nanocomposite. The sensor responded linearly with increasing concentration of hydrazine from 0.03 to 500.0 μM with a higher sensitivity (0.073 μA μM-1) and lower limit of detection (LOD, 0.015 μM). Furthermore, reasonable reproducibility, lengthy stability, and excellent selectivity were also attained for the proposed sensor. Finally, EFTA/IL/CoS2-CNT/CPE was applied for the detection of hydrazine in water samples, and good recoveries varied from 96.7 to 103.0%.

Daunorubicin is a famous anthracycline anticancer chemotherapy drug with many side effects that is very important to measure in biological samples. A daunorubicin electrochemical biosensor was fabr...

Environmental pollution has been a known threat to our world due to the rapid urbanization, changing lifestyle of people, and modern industrialization. Therefore, there is an urgent need to develop novel sensing approaches having promising performance with high reliability and sensitivity for the precise monitoring of various pollutants. Metal–organic frameworks (MOFs) have been intensively investigated by many researchers as electrode modifiers for electrochemical sensing due to their excellent properties and efficiency. Diverse MOF-based electrochemical sensing systems are applied for environmental analysis for the sensitive, rapid and cost-effective determination of various analytes because of their unique structures, and properties, including the tunable pore size, high surface area, high catalytic activity, and high density of active sites. The aim of this review article is to evaluate the application of MOFs in the electrochemical sensing of environmental pollutants including heavy metal ions, pesticides, phenolic compounds, nitroaromatic compounds, antibiotics, nitrite, and hydrazine. Current limitations and future directions for the application of MOF-based electrochemical sensors for the detection of environmental pollutants are discussed.

It is essential to develop easy-to-use sensors towards a better monitoring of food additives so that human health can be positively influenced. A type of critical food additive that is widely used in making soft drinks and diverse foodstuff is called amaranth. This study aimed at presenting a novel Pd/GO nanomaterial-modified screen-printed electrode (Pd/GO/SPE), which is responsible for providing a sensing interface during the process of specifying the electrochemical features of amaranth. The morphology and structure of the Pd/GO nanomaterial was investigated by Fourier-transform infrared spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy, and high-resolution transmission electron microscopy. When the optimized conditions was adjusted, Pd/GO/SPE proved to be a capable sensor for conducting a very sensitive sensing towards the amaranth under a common working situation of 575 mV. In this regard, it was embarked on measuring some of the sensor features, including its sensitivity, linear dynamic range, and detection limit for amaranth with the values of 0.0948 μA μM−1, 0.08 μM–360.0 μM and 30.0 nM were obtained, respectively.

This review article aims to provide an overview of the recent advances in the voltammetric and amperometric sensing of cysteine (Cys). The introduction summarizes the important role of Cys as an essential amino acid, techniques for its sensing, and the utilization of electrochemical methods and chemically modified electrodes for its determination. The main section covers voltammetric and amperometric sensing of Cys based on glassy carbon electrodes, screen printed electrodes, and carbon paste electrodes, modified with various electrocatalytic materials. The conclusion section discusses the current challenges of Cys determination and the future perspectives.

The current study was conducted to synthesize 2-(4-ferrocenyl-[1,2,3]triazol-1-yl)-1-(naphthalen-2-yl) ethanone (2FTNE) as a mediator and magnetic core–shell manganese ferrite nanoparticles (CMNP) as a nanoparticle for construction of a modified carbon paste electrode (CPE). The electrochemical behavior of norepinephrine (NEP) was assessed using cyclic voltammetry and its determination was done by using differential pulse voltammetry (DPV) in the presence of tryptophan (TRP) and acetaminophen (AC). The 2FTNECMNP-modified CPE (2FTNECMNPPE) in comparison with bare CPE and CMNP modified CPE exhibited high electro-catalytic activity to the NEP oxidation. Linearity of the oxidation peak current with concentration of NEP was maintained between 0.075–60 μM (R2 = 0.9995). Limit of detection for NEP was obtained 0.016 μM on the basis of three times of standard deviation (3Sb) of blank. High selectivity, proper stability and suitable reproducibility are some advantages of the 2FTNECMNPPE that was successful in the measurement of NEP, AC and TRP in NEP ampoule, acetaminophen tablet and urine samples.

The new Co(II) compound [Co(5,5′-dmbpy)2(NCS)2] (a1) was prepared by reacting Co(NO3)2·6H2O, 5,5′-dimethyl-2,2′-bipyridine ligand, and Na(SCN). The nano-scale size of [Co(5,5′-dmbpy)2(NCS)2] (a1) was synthesized using sonochemical process. The size of the nanoparticles (a2) was ∼13 ± 2 nm. We have also provided a new platform of electrochemical sensing for simultaneous detection of acetaminophen and naproxen using (a2) surface modified graphite screen printed electrode (SPE) in 0.1 M phosphate buffer solution (PBS, pH 7.0). In contrast to bare SPE, the modified SPE could significantly improve the electrooxidation activity of acetaminophen along with the rise in the current of an anodic peak. The peak currents acquired using differential pulse voltammetry (DPV) raised linearly with the raising of acetaminophen concentration and the sensor had a detection range over the concentration range of 0.009–325.0 μM, with a detection limit of 5.0 nM (S/N = 3). In the case of naproxen peak, currents of naproxen oxidation at the modified SPE were linearly dependent on the naproxen amounts in the range of 1.0–500.0 μM. The detection limit (S/N = 3) was calculated to be 0.03 μM. The DPV responses show that the peaks of acetaminophen and naproxen oxidation were vividly separated from one other with a potential difference of 410 mV between them. The low detection limit, high sensitivity, and stability made the relevant electrode applicable for the analysis of acetaminophen and naproxen in real samples. Further, its practical applicability was reliable and desirable in the analysis of pharmaceutical compounds and biological fluids. The benefits of using this modified electrode for the determination of analytes are compared with other works in the manuscript.

The current work introduced a novel electrochemical sensor (screen-printed graphite electrode (SPGE) modified with MnO

We fabricated a new electrochemical 4-aminophenol sensor based on a nanocomposite of Co

One of the new electrochemical sensors to detect (N2H4) has been constructed on the basis of the screen printed electrode (SPE) modified with poly(vinyl alcohol)/chitosan/TiO2/chlorophyll nanocompo...

The present research reported the synthesis and electrochemical activities of CuO/GO nanocomposites modified screen-printed graphite electrode (CuO/GO/SPGE) as one of the highly sensitive electrochemical sensors to determine Sudan I. Therefore, we utilized cyclic voltammetry, chronoamperometry, and differential pulse voltammetry (DPV) to examine electrochemical behavior of Sudan I at CuO/GO/SPGE. This modified electrode shows very good electrochemical activities to oxidize Sudan I with a potential shift about 220 mV toward a less positive potential. In optimum conditions, linear calibration ranged between 0.3 and 700.0 µM and limit of detection equal to 0.093 µM is obtained to measure Sudan I concentration using the DPV method. In addition, the modified electrode could be applied to determine simultaneously Sudan I and bisphenol A at potentials of 370 and 510, respectively. It was proved that the proposed CuO/GO/SPGE can be performed to detect Sudan I and bisphenol A into the food as well as water samples, and reasonable results were obtained.

Here, CeO2 nanorods (CeO2NRs) were successfully synthesized and characterized. Pt nanoparticles were synthesized in the presence of CeO2NRs and the matrix of polyaniline (PA) and chitosan (CH) as support to prepare the novel Pt-CeO2NRs/PA-CH nanocomposite. The electrocatalytic performance of Pt-CeO2NRs/PA-CH was investigated for methanol oxidation (MO) through chronoamperometry, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Durability of the prepared catalyst was also evaluated. The effects of several factors such as temperature, methanol concentration and scan rate were also studied for MO experimentally and statistically. Pt-CeO2NRs/PA-CH had enhanced electrocatalytic activity, compared to Pt/PA-CH, revealing that it would be a promising catalyst for MO in fuel cells. The variations of anodic peak potential and current density of MO with three main factors (temperature, concentration and scan rate), their binary and triple interactions were investigated statistically. The results showed that both anodic peak potential and current density can be significantly affected by main factors and their interactions at 0.05 level of probability. Meanwhile, the proposed statistical models can accurately estimate the variation of peak potential and current density with studied factors. The results showed that increase in temperature and scan rate leads to the enhancement of both responses.

The present research devised a strongly sensitive user-friendly electrochemical sensor to determine Sudan I with regard to ZnFe2O4 nanoparticles (NPs) modified graphite screen-printed electrode (GS...

Belonging to the category of catecholamine-based medications, isoprenaline is excessively beneficial in the heart disease management. Nevertheless, serious adverse consequences can occur following the consumption of high concentrations of this drug. The present study aimed for highly sensitivity co-detection of isoprenaline and paracetamol in aqueous solutions by designing and synthesizing a novel sensor based on feather-like La3+/ZnO nano-flowers and N-(ferrocenylmethylidene)fluoren-2-amine-modified carbon paste electrode (La3+/ZnONFMF2ACPE). To this end, the electrocatalytic oxidation of isoprenaline on the surface of La3+/ZnONFMF2ACPE was evaluated by varied techniques, including chronoamperometry, cyclic voltammetry and differential pulse voltammetry. A linear calibration curve was plotted for different concentrations of isoprenaline (0.1–400.0 μM) with 0.05 μM of detection limit. Finally, acceptable results were obtained after the detection of isoprenaline and paracetamol in human serum, urine and drug real samples using the produced sensor.

In the present paper, Fe3O4@SiO2/GO nanocomposite was synthesized and used to modify a graphite screen-printed electrode. This modified electrode was used to determine levodopa in the presence of tryptophan. Differential pulse voltammetry data showed that the obtained anodic peak currents were linearly dependent on levodopa concentrations in a range of 0.5–800.0 µM, with the detection limit of 0.09 µM. This novel sensor has several advantages such as rapid response, high stability, reproducibility, and high sensitivity. In addition, this proposed sensor was used to determine levodopa and tryptophan in human blood serum and urine samples.

In this paper, the use of a screen printed electrode modified by feather like La3+/ZnO nano-flowers for the determination of sertraline was described. These nano-flowers showed satisfactory catalytic activity for determination of sertraline by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. At the optimum pH of 7.0, the oxidation of sertraline occured at a potential about 280 mV less positive than that of an unmodified screen printed electrode. Based on DPV, the oxidation of sertraline exhibited a dynamic range between 0.5 and 150.0 µM and a detection limit (3σ) of 0.15 ± 0.01 µM. The modified electrode had a good performance for sertraline detection in real samples by the standard addition method.

A novel electrochemical sensor for the selective and sensitive detection of droxidopa in presence of carbidopa at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with copper oxide (CuO), ionic liquid and Mn (III) salen (CuO-IL-MS/CPE). Large peak separation, good sensitivity and stability allow this modified electrode to analyze droxidopa individually and in the presence of carbidopa. Applying differential pulse voltammetry (DPV), a linear dynamic range of 0.5-600.0 µM with detection limit of 0.2 µM was obtained for droxidopa. Finally, the proposed method was applied to the determination of droxidopa and carbidopa in real samples.

A screen-printed electrochemical sensor based on Fe3O4@cellulose nanocrystals/Cu nanocomposite (Fe3O4@CNC/Cu) has been constructed for the sensitive detection of venlafaxine. The magnetic Fe3O4@cel...

A simple, sensitive and selective electrochemical method was developed for the determination of morphine using a graphite screen printed electrode (SPE) modified with the magnetic core–shell graphene oxide (GO)/Fe3O4@SiO2 nanocomposite using cyclic voltammetry, differential pulse voltammetry (DPV) and chronoamperometry techniques. The magnetic core–shell GO/Fe3O4@SiO2 nanocomposite was prepared via a facile and simple process. The prepared nanocomposite modified SPE showed enhanced peak currents for the oxidation of morphine compared to the bare SPE. Under optimum conditions the sensor provided linear DPV responses in the range of 1.0–100 μM for morphine with a detection limit of 7.5 × 10–7 M. The proposed sensor was successfully applied to morphine monitoring in biological fluids and satisfactory results were obtained.

La2O3/Co3O4 nanocomposite was synthesized and then used for the modification of screen-printed electrode (SPE) prior to the electrochemical determination of sertraline. A significant increment in peak current response was observed and peak potential also shifted towards less positive potentials showing the facilitated oxidation procedure at surface of modified SPE (La2O3/ /Co3O4/SPE). The quantitative determination of sertraline was carried out by using different pulse voltammetry and the anodic peak current was found to increase with increasing sertraline concentration in the linear range of 5.0400.0 ?M with limit of detection as 1.0 ?M. The prepared La2O3/Co3O4/SPE has been successfully used for detecting sertraline in sertraline tablet and urine samples with excellent recoveries.

In the present work, Fe3O4@SiO2 decorated on graphene (Fe3O4@SiO2/GR) nanocomposite was successfully synthesized. The voltammetric sensor was used for electrochemical determination of folic acid. Its electrochemical behaviour was investigated by cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The voltammetric data obtained confirm the significant enhancement of oxidation current and reduction overvoltage for electro-oxidation of folic acid at the surface of Fe3O4@SiO2/GR/screen-printed electrode (SPE). Differential pulse voltammetry response shows the linear increment of oxidation signal with an increase in the concentration of folic acid in the range of 0.1–600.0 μM with a detection limit of 0.05 μM. Finally, the Fe3O4@SiO2/GR/SPE was used for the determination of folic acid in real samples.

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe3O4/CuO nanoparticles (NPs). Fe3O4/CuO NPs were synthesized via a coprecipitation procedure, and the products were characterized via energy disperse spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and vibrating sample magnetometer. The voltage–current curve and differential pulse voltammetry examinations of Fe3O4/CuO-modified screen-printed electrode (Fe3O4/CuO/SPE) were followed by the determination of electro-catalytic activities toward desipramine oxidation in a phosphate buffer solution (pH = 7.0). In addition, the value of diffusion coefficient (D = 3.0 × 10−6 cm2 s−1) for desipramine was calculated. Then, based on the optimum conditions, it was observed that the currents of the oxidation peak were linearly proportionate to the concentration of desipramine in the broad range between 0.08 and 400.0 μM and LOD of 0.03 μM (S/N = 3). Finally, our new sensor was successfully utilized to detect desipramine in the real samples, with reasonable recovery in the range of 97.2% to 102.7%.

Neuro-transmitters have been considered to be essential biochemical molecules, which monitor physiological and behavioral function in the peripheral and central nervous systems. Thus, it is of high pharmaceutical and biological significance to analyze neuro-transmitters in the biological samples. So far, researchers have devised a lot of techniques for assaying these samples. It has been found that electro-chemical sensors possess features of robustness, selectivity, and sensitivity as well as real-time measurement. Graphene quantum dots (GQDs) and carbon QDs (CQDs) are considered some of the most promising carbon-based nanomaterials at the forefront of this research area. This is due to their characteristics including lower toxicity, higher solubility in various solvents, great electronic features, strong chemical inertness, high specific surface areas, plenty of edge sites for functionalization, and versatility, in addition to their ability to be modified via absorbent surface chemicals and the addition of modifiers or nano-materials. Hence in the present review, the synthesis methods of GQDs and CQDs has been summarized and their characterization methods also been analyzed. The applications of carbon-based QDs (GQDs and CQDs) in biological and sensing areas, such as biological imaging, drug/gene delivery, antibacterial and antioxidant activity, photoluminescence sensors, electrochemiluminescence sensors and electrochemical sensors, have also been discussed. This study then covers sensing features of key neurotransmitters, including dopamine, tyrosine, epinephrine, norepinephrine, serotonin and acetylcholine. Hence, issues and challenges of the GQDs and CQDs were analyzed for their further development.

This study is on current developments concerning ferrocene (FC) and its derivatives on the basis of electrochemical biosensors and sensors. The distinct physiochemical characteristics of FC have enabled the development of new sensor devices, specifically electrochemical sensors. Several articles have focused on the implementation of FC as an electrode constituent while discussing its electrochemical behavior. Furthermore, typical FC-design-based biosensors and sensors are considered as well as practical examples. The favorable design of FC-based biosensors and general sensors needs adequate control of their chemical and physical characteristics in addition to their surface immobilization and functionalization.

The detection of hydrazine (HZ) is an important application in analytical chemistry. There have been recent advancements in using electrochemical detection for HZ. Electrochemical detection for HZ offers many advantages, e.g., high sensitivity, selectivity, speed, low investment and running cost, and low laboriousness. In addition, these methods are robust, reproducible, user-friendly, and compatible with the concept of green analytical chemistry. This review is devoted to the critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used HZ in water resources with desirable recovery. Attention is focused on the working electrode and its possible modification which is crucial for further development.

The focus of this report is electroanalysis performed via screen-printed electrodes. All the basic characteristics required in this field are taken into account, including the fundamental assessments of screen-printed materials used as electrodes, the use of testing electrode prototypes in the laboratory, fundamental and progressive studies on different electrode fabrication procedures, and their practical uses in quantifying biological species, pharmaceutical compositions, environmental contaminants and heavy metals. The last case is presented as a set of comprehensive tables that show an overall summary of the published approaches. Lastly, current trends and significant achievements are delineated along with future options.

The human population is generally subjected to diverse pollutants and contaminants in the environment like those in the air, soil, foodstuffs, and drinking water. Therefore, the development of novel purification techniques and efficient detection devices for pollutants is an important challenge. To date, experts in the field have designed distinctive analytical procedures for the detection of pollutants including gas chromatography/mass spectrometry and atomic absorption spectroscopy. While the mentioned procedures enjoy high sensitivity, they suffer from being laborious, expensive, require advanced skills for operation, and are inconvenient to deploy as a result of their massive size. Therefore, in response to the above-mentioned limitations, electrochemical sensors are being developed that enjoy robustness, selectivity, sensitivity, and real-time measurements. Considerable advancements in nanomaterials-based electrochemical sensor platforms have helped to generate new technologies to ensure environmental and human safety. Recently, investigators have expanded considerable effort to utilize polymer nanocomposites for building the electrochemical sensors in view of their promising features such as very good electrocatalytic activities, higher electrical conductivity, and effective surface area in comparison to the traditional polymers. Herein, the first section of this review briefly discusses the most important methods for polymer nanocomposites synthesis, such as in situ polymerization, direct mixing of polymer and nanofillers (melt-mixing and solution-mixing), sol–gel, and electrochemical methods. It then summarizes the current utilization of polymer nanocomposites for the preparation of electrochemical sensors as a novel approach for monitoring and detecting environmental pollutants which include heavy metal ions, pesticides, phenolic compounds, nitroaromatic compounds, nitrite, and hydrazine in different mediums. Finally, the current challenges and future directions for the polymer nanocomposites-based electrochemical sensing of environmental pollutants are outlined.

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%.

The current work introduced a convenient single-phase hydrothermal protocol to fabricate MnO

Recent advances in nanotechnology have introduced transition-metal dichalcogenides (TMDs) as inorganic nanomaterials with exceptional properties and structures, suitable also for catalytic applications. The admirable properties of TMDs include the impressive capability of charge transfer, the large surface to volume ratio (S/V), the energy band gap controllable by the number of layers, the strong interaction with light and the mechanical robustness. They are also cost-effective and highly accessible. The unique features and morphology make TMDs excellent candidates for the fabrication of electrochemical sensing devices. This review article was designed to scrutinize the existing applications of nanostructures TMDs to fabricate electrochemical (bio) sensors. The first part focuses on the production techniques and structural properties of TMD nanostructures. The second part examines the progress made for different TMD bio (sensing) schemes and applications in safety of foodstuff, monitoring of environmental contaminations, analysis of pharmacological preparations and clinical determinations. The last part discusses reported challenges and suggestions on promising opportunities.

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.

Metal organic frameworks (MOF) are a class of hybrid networks of supramolecular solid materials comprising a large number of inorganic and organic linkers, all bound to metal ions in a well-organized fashion. Zeolitic imidazolate frameworks (ZIFs) are a sub-group of MOFs with imidazole as an organic linker to metals; it is rich in carbon, nitrogen, and transition metals. ZIFs combine the classical zeolite characteristics of thermal and chemical stability with pore-size tunability and the rich topological diversity of MOFs. Due to the energy crisis and the existence of organic solvents that lead to environmental hazards, considerable research efforts have been devoted to devising clean and sustainable synthesis routes for ZIFs to reduce the environmental impact of their preparation. Green chemistry is the key to sustainable development, as it will lead to new solutions to existing problems. Moreover, it will present opportunities for new processes and products and, at its heart, is scientific and technological innovation. The green chemistry approach seeks to redesign the materials that make up the basis of our society and our economy, including the materials that generate, store, and transport our energy, in ways that are benign for humans and the environment and that possess intrinsic sustainability. This study covers the principles of green chemistry as used in designing strategies for synthesizing greener, less toxic ZIFs the consume less energy to produce. First, the necessity of green methods in today’s society, their replacement of the usual non-green methods and their benefits are discussed; then, various methods for the green synthesis of ZIF compounds, such as hydrothermally, ionothermally, and by the electrospray technique, are considered. These methods use the least harmful and toxic substances, especially concerning organic solvents, and are also more economical. When a compound is synthesized by a green method, a question arises as to whether these compounds can replace the same compounds as synthesized by non-green methods. For example, is the thermal stability of these compounds (which is one of the most important features of ZIFs) preserved? Therefore, after studying the methods of identifying these compounds, in the last part, there is an in-depth discussion on the various applications of these green-synthesized compounds.

We fabricated a new electrochemical 4-aminophenol sensor based on a nanocomposite of Co3O4 nanoparticles 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 (0.05–780.0 μM) with a correlation coefficient of 0.9996 and the limit of detection (S/N = 3) of 1.5 × 10−8 M. The developed method was successful to determine 4-aminophenol in real specimens, with acceptable outcomes.

We have developed a highly sensitive sensor of ZnFe

This study was performed to investigate the simultaneous detection of carmoisine and tartrazine, two food azo dyes, with a new voltammetric sensor based on graphene oxide-Fe

The purpose of this study was to fabricate an electrochemical sensor for the detection of methotrexate and folic acid based on a screen-printed graphite electrode (SPGE) modified with prepared iron oxide (Fe

BACKGROUND: Chlorpheniramine (CPA), thanks to its relatively lower side effects, is a widely prescribed medicine for alleviating allergic symptoms as well as some medical emergencies. Owning to this extensive use, many efforts have been directed to measure chlorpheniramine both in vivo and in vitro. High performance liquid chromatography (HPLC), both normal and reverse phase, as well as spectrochemical and electrochemical methods are analytical approaches which have been extensively exploited for determination of CPA. Among them, electrochemical techniques have found elegant place for analysis of CPA due to simplicity, sensitivity and ease of instrumentation. METHODS: Herein, we have reported the preparation and characterization of a biosensor by immobilization of double-stranded DNA on the surface of overoxidizedpolypyrrole-reduced graphene oxide modified pencil graphite electrode (ds-DNA-PPyox/RGO/PGE) as well as its novel usability in measurement of chlorpheniramine (CPA). Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), UV-Vis spectroscopy and differential pulse voltammetry (DPV) were exploited in order to characterize and evaluate the performance of the proposed biosensor. RESULTS: Final results showed that proposed strategy for modification of PGE introduces an ultra-sensitive biosensor for CPA which offers the best detection limitamong all previously reported electrochemical sensors for CPA. Taking advantage of this biosensor for determination of CPA, a wide linear dynamic range from 0.05 to 200 μM, and a low limit of detection 0.023 μM were obtained by using DPV method. Usability of this biosensor was also confirmed by determination of CPA in tablet and spiked urine samples. CONCLUSIONS: Overoxidized polypyrrole-reduced graphene oxide offered a suitable substrate for immobilization of ds-DNA by which a new biosensor for determination of CPA was fabricated. Proposed biosensor can successfully be used for determination of CPA in urine samples taking advantage of electroanalytical methods. [Figure: see text]