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In this study, a highly sensitive electrochemical sensor for the detection of bisphenol A (BPA) was developed by modifying a screen-printed carbon electrode (SPCE) with silver nanoparticles (AgNPs) and graphene oxide (GO) composites. The electrochemical properties of the modified electrode interface were meticulously investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy, employing 1.0 mM [Fe(CN)6]3–/[Fe(CN)6]4– as a redox probe. The findings demonstrate that the AgNPs/GO/SPCE composite exhibits superior electrical conductivity and facilitates rapid electron transfer compared to both GO/SPCE and SPCE alone. The electrochemical behavior of BPA on the AgNPs/GO/SPCE electrode was comprehensively studied using CV, revealing exceptional electrocatalytic properties for BPA oxidation. To assess the analytical performance, differential pulse voltammetry was employed. Results unequivocally show a significant improvement in the electrochemical responses when using AgNPs/GO/SPCE. Calibration curves exhibited linear ranges of 0.25–2.19 μM with a remarkable limit of detection of 0.046 μM for BPA. Furthermore, the established method was applied for the determination of BPA in plastic products, achieving satisfactory reproducibility and recovery. This novel AgNPs/GO/SPCE-based sensor holds promise for the sensitive and reliable detection of BPA in various environmental and industrial applications. [ABSTRACT FROM AUTHOR]

A pure natural kaolinite (K) was modified by intercalation and grafting into the interlayer space of 1-(2-hydroxyethyl)piperazine (HEP). The resulting organo-inorganic hybrid material (referred as KHEP) was characterised using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and 29Si nuclear magnetic resonance (NMR) techniques. The electrochemical characterisation of K and KHEP materials was carried out by studying the electrochemical behaviour using cyclic voltammetry of [Fe(CN)6]3− ions on the surface of a glassy carbon electrode (GCE) modified with a film of each of these materials (GCE/K and GCE/KHEP). The GCE/KHEP organokaolinite film electrode was successfully applied for the simultaneous detection of Pb(II) and Cu(II) in contaminated media. The peak currents of Pb(II) and Cu(II) obtained under the same optimal conditions on GCE/KHEP were much more intense than those obtained on GCE/K and bare GCE. Under optimal conditions, the influence of the concentration of Cu2+ and Pb2+ ions on the peak currents was studied for several concentration ranges. The obtained linear calibration curves were then used to calculate the different limits of detection (LOD) on the basis of a signal-to-noise ratio of 3. Thus, in simultaneous detection and for the concentration range from 0.02 to 0.12 µmol L−1 (pH accumulation medium 5.0) and for each of the ions analysed, LODs of 1.942 nmol L−1 for Cu(II) and a LOD of 1.072 nmol L−1 for Pb(II) were obtained. The GCE/KHEP sensor developed in this work was successfully applied for the simultaneous detection of Pb(II) and Cu(II) in real samples. ASSWV signal corresponding to the simultaneous detection of Pb2+ and Cu2+ ions recorded on unmodified GCE (black curve), GCE/K; (red curve) and GCE/KHEP (blue curve) in 0.2 mol L−1 NaNO3 (with pH adjusted at 2.5) after 7 min of accumulation in aqueous medium (pH 5.0) of each ion at the concentration at 2.0 µmol L−1. Other experimental conditions are as follows: telec: 80 s, Eelec: − 0.90 V, Potential amplitude: 0.05 V, Step potential (V): 0.005 V and Frequency: 50 Hz. [ABSTRACT FROM AUTHOR]

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Effectively detecting catechol (CC) and hydroquinone (HQ) simultaneously is crucial for environmental protection and human health monitoring. In the study presented herein, a novel electrochemical sensor for the sensitive simultaneous detection of CC and HQ was constructed based on an electrochemically reduced graphene oxide (ERGO)-modified multi-walled carbon nanotube paste electrode (MWCNTPE). Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electrochemical techniques were utilized to characterize the sensing interface and investigate the sensing mechanism. Under the optimal detection conditions, the oxidation peak currents of CC and HQ show a good linear relationship with their concentrations in the range of 0.4–400 μM with a detection limit of 0.083 μM for CC and 0.028 μM for HQ (S/N = 3). Moreover, the sensor exhibits good performance and can be applied successfully in the simultaneous detection of CC and HQ in tap water samples and urine samples with satisfactory results, indicating its promising application prospects. [ABSTRACT FROM AUTHOR]

In this study, a new and simple glassy carbon electrode modified with carbon nanohorns (SWCNH/GCE) was used for the determination of Cr(VI) in aqueous matrices via adsorptive cathodic stripping voltammetry (AdCSV). The modified electrode was characterized via field emission scanning electron microscopy and cyclic voltammetry, which revealed a homogeneous distribution of spherical agglomerates of SWCNH on the electrode surface. The modification increased the electrochemically active area from 0.10 cm2 ± 0.01 (GCE) to 0.16 cm2 ± 0.01 (SWCNH/GCE). The optimized analytical conditions were as follows: a supporting electrolyte (0.15 mol L−1 HCl), an accumulation potential of 0.8 V versus Ag/AgCl, and an accumulation time of 240 s. Validation of the analytical methodology was performed, obtaining a linear range between 20 and 100 µg L−1, a limit of detection of 3.5 µg L−1, and a limit of quantification of 11.6 µg L−1 with good accuracy and precision. The method was applied to the analysis of spiked tap water samples, and the results were compared using a flame atomic absorption spectrophotometer (FAAS) with no significant statistical differences. [ABSTRACT FROM AUTHOR]

Gold electrode modification with nafion and WO3 has been done for oxalate ion detection. The voltammogram of oxalate ion on the surface gold with and without modification showed a significant difference. This means that the modified gold electrode is sensitive to oxalate ions. The performance of the modified electrode in different pH (5, 7, and 12) in the KCl solution also has been studied using cyclic voltammetry. The range of the measurement is from – 1.0 to + 1.0 at a scan rate of 100 mV s -1. The result showed that the optimum measurement pH is 12 with an anodic peak at 0.143 V and no reduction peak. The measurements of 0, 50, 100, 150, 200, and 250 mg L-1 oxalic ion also have been conducted, showing a linear increase in current. The equation obtained is y = 0.5426 x + 0.9127. In addition, the modified gold electrode showed good selectivity towards oxalate detection, as cyclic voltammetry measurements of some interference components did not produce redox peaks in the oxalate oxidation potential range. These findings indicate that gold electrodes modified with Nafion/WO3 significantly affect the potential development of electrochemical oxalate sensors. [ABSTRACT FROM AUTHOR]

Nanocomposite nanozeolite/acetylene carbon black was prepared by combining a type A zeolite with acetylene carbon black (AcB) and used to modify glassy carbon electrode (GCE) without polymer. The zeolite was prepared by hydrothermal method using natural kaolin. The physicochemical characterization of the composite showed a well-integrated composite in which the cubic crystal of the zeolite A and the graphitic aggregate of the carbon black were maintained. The electrochemical impedance spectroscopy study revealed that the composite film GCE (ZA-AcB/GCE) prepared by drop coating displayed a higher kinetic charge transfer compared to pristine zeolite modified GCE (ZA/GCE) and bare GCE. ZA-AcB/GCE, ZA/GCE and GCE were subsequently used to investigate the electrochemical behaviour of acetaminophen (AC) in acidic, neutral and alkaline pHs. The results demonstrate a good electrocatalytic property toward AC at composite film GCE in all these electrolytes compared to bare GCE and confirm the dependence of the electrochemical reaction mechanism of AC on the electrolyte's pHs. Under optimal conditions, ZA-AcB/GCE exhibited higher sensitivity and selectivity toward both analytes taken individually or simultaneously within large concentration range: 0.5–89 µM for AC and 5–99 µM for caffeine (CAF) with the respective limit of detection of 0.38 and 0.82 µM. The developed sensors were applied successfully in the quantification of the both analytes in pharmaceutical tablets. [ABSTRACT FROM AUTHOR]

A nanosodalite (SOD) was synthesized utilizing Cameroonian kaolin and then used to prepare a nanocomposite (SOD‐GF) with graphene foam (GF). The as‐synthesized materials were characterized using X‐ray diffractometry (XRD), Fourier transform‐infrared (FT‐IR) spectroscopy, N2 adsorption‐desorption and scanning electron microscopy coupled with emission dispersive X‐ray (SEM/EDX). The results show a pure sodalite with high degree of crystallinity with crystallite size and BET surface area of 38.3 nm and 22 m2/g, respectively. The composite's characterization revealed a well‐integrated material in which the structural integrity of each material is maintained, its surface area being 4‐fold that of pristine SOD. Stable SOD and SOD‐GF modified glassy carbon electrode (GCE) were prepared by drop coating without a binder and utilized to study the electrochemistry of chlorpromazine (CPZ) in acidic, neutral and basic pHs. It appeared that (i) CPZ's electrochemical oxidation was a two‐step one‐electron process at SOD/GCE and a one‐step two‐electron process at SOD‐GF/GCE and (ii) the electrochemical reaction mechanism was an EEC mechanism at SOD/GCE while at SOD‐GF/GCE the mechanism was EEC at pH<4 and EC for greater pH. SOD/GCE and SOD‐GF/GCE were used to sense CPZ within CPZ's concentration ranging from 0.5‐30 μM with low detection limits. [ABSTRACT FROM AUTHOR]

A new modified electrode was developed employing an environmentally friendly method to be used in a square-wave voltammetry technique, with advantages such as low cost, rapid response, and high sensitivity, to determine iron in milk powder samples. For this purpose, a novel lab-made electrode based on a borate glassy matrix, doped with molybdenum, lithium, and vanadium oxides, and surface modified with carbon nanoparticles was synthesized. The glassy matrix was obtained by the quenching methodology and the carbon nanoparticles were synthesized using microwave-assisted method and honey as a precursor. The voltammetric behavior of the proposed electrode was evaluated with a potassium hexacyanoferrate(II) solution. Moreover, since iron plays an important role in human nutrition, its quantification in fortified powder milk analysis employing the proposed electrode and square-wave voltammetry was studied. The linear response of iron concentration was in the range of 0.3 to 5.9 mg/L with a limit of detection of 0.18 mg/L. The iron content in the proposed method is in accordance with the inductively coupled plasma atomic emission spectroscopy values and those declared on the label. This electrochemical sensor shows great potential for the determination of iron in food samples and it can be incorporated into a portable device for in situ detection of this analyte. [ABSTRACT FROM AUTHOR]

Herein, a simple electrochemical process was proposed for the electrochemical modification of a graphite rod electrode (GrE) with a zinc hydroxide thin film. Two sequential steps were enough for the modification of the graphite rod using chronoamperometry technique. In the first step, the metallic zinc film was electrochemically deposited on GrE surface at pH 4.5, by reducing Zn2+ on GrE at − 1.78 V vs. saturated calomel electrode (SCE) for only 210 s forming GrE@ZnNPs. In the second step, the electrode previously coated with a metallic zinc film was oxidized in buffer solution at pH 7, at 0.1 V vs. SCE for 360 s to form GrE@Zn(OH)2NPs. X-ray diffraction, optical microscope and interferometric microscope were used to confirm and identify the obtaining of the desired layer (Zn and Zn(OH)2 nanoparticles (NPs) thin layer). Then, several electrochemical techniques were used before and after the modification in order to study the electrochemical properties of the bare and modified electrodes. These analyses are based on the comparison of open-circuit potentials, polarization resistances of fast electrochemical systems (Rp), potentiodynamic polarizations (Tafel curves) and electrochemical impedances. [ABSTRACT FROM AUTHOR]

In this study, a novel nanocomposite of graphene oxide-zinc oxide-manganese (GO-ZnO-M) was successfully synthesized using a modified Hummers method and hydrothermal technique. Enhanced electrochemical performance was observed in the GO-ZnO-M nanocomposite when utilized as an electrode material for the detection of rutin, a flavonoid known for its significant health benefits. The GO-ZnO-M modified electrode demonstrated excellent sensitivity, selectivity, reproducibility, and stability during rutin detection. Furthermore, the sensor exhibited a wide linear detection range and a low detection limit. The practical applicability of the GO-ZnO-M/GCE sensor was assessed by detecting rutin in pharmaceutical tablet samples, yielding satisfactory results. This study highlights the potential of GO-ZnO-M nanocomposites as promising materials for the electrochemical detection of rutin and other biologically significant compounds.

[Display omitted] The mounting global energy demand urges surplus electricity generation. Due to dwindling fossil resources and environmental concerns, shifting from carbon-based fuels to renewables is vital. Though renewables are affordable, their intermittent nature poses supply challenges. In these contexts, aqueous flow batteries (AFBs), are a viable energy storage solution. This study tackles AFBs' energy density and efficiency challenges. Conventional strategies focus on altering molecule's solubility but overlook interface's transport kinetics. We show that triggering electrostatic forces at the interface can significantly enhance the mass transport kinetics of redox active molecules by introducing a powerful electrostatic flux over the diffusional flux, thereby exerting a precise directionality on the molecular transport. This approach of controlling the directionality of molecular flux in an all iron redox flow battery amplifies the current and power rating with approximately 140 % enhancement in the energy density. [ABSTRACT FROM AUTHOR]

The low sensitivity of working electrodes is usually the bottleneck of the electrochemical testing method. In this work, bismuth antimonate nanosheets have excellent electrochemical performance and are used as the modified materials for glassy carbon electrodes. Bismuth antimonate nanosheets were prepared by a simple coprecipitation method. By changing the calcination temperature and holding time, the effects of these factors on the morphology and structure of the bismuth antimonate nanosheets were investigated. The bismuth antimonate-modified electrode was used for the electrochemical detection of benzoic acid. The results showed that a pair of semi-reversible redox peaks appeared at − 0.48 V and + 0.05 V, and the intensity of the redox peaks gradually increased with the increase of benzoic acid concentration and scan rate. The bismuth antimonate nanomaterial-modified glassy carbon electrode has a wide linear detection range (0.0002–2 mM), low detection limit (0.053 µM) and good cycling performance for detecting benzoic acid. The good electrochemical performance shows that bismuth antimonate nanomaterials have potential application value in the detection of benzoic acid. The glassy carbon electrode modified by bismuth antimonate nanosheets can effectively detect benzoic acid, with linear detection range (0.0002–2 mM) and detection limit (0.053 µM) and good repeatability [ABSTRACT FROM AUTHOR]

This work presents the detection of hypoxanthine (HXA), a purine derivative that is similar to nucleic acids who overconsumption can cause health issues, by using hydrothermally synthesized cerium phosphate (CePO4) followed by a sonochemical approach for CePO4 decorated with a functionalized carbon nanofiber (CePO4@f-CNF) nanocomposite. The formation of the nanocomposite was confirmed with X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). A CePO4@f-CNF nanocomposite is used to modify a glassy carbon electrode (GCE) to analyze the electrochemical detection of HXA. Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and Differential pulse voltammetry (DPV) were used to examine the electrochemical properties of the composite. As a result, the modified electrode exhibits a larger active surface area (A = 1.39 cm2), a low limit of detection (LOD) at 0.23 µM, a wide linear range (2.05–629 µM), and significant sensitivity. Therefore, the CePO4@f-CNF nanocomposite was used to study the real-time detection in chicken and fish samples, and it depicted significant results. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A non-enzymatic glucose sensor using a nickel particles/polyaniline composite has been synthesized on an indium tin oxide electrode. The PAni thin films were deposited onto the ITO surfaces using a repeated potential cycling technique in an aqueous solution containing aniline, sulfuric acid, and lithium perchlorate. Nickel particles were incorporated into the PAni/ITO surfaces using chronopotentiometry. Scanning electron micrograph and X-ray diffraction were employed to investigate the surface morphology and structure of the Ni-PAni composite, while Ultraviolet–visible spectroscopy was used to study the optical properties. The modified electrode was electrochemically characterized using cyclic voltammetry and impedance spectroscopy. The effect of PAni thin film thickness on the nickel deposition process has also been studied. Nickel was chosen due to its reduction potential being within the range where the PAni layer is in a reduced, non-conducting state. The electroactivity of the Ni-PAni/ITO electrode was evaluated through cyclic voltammetry and chronoamperometry and explored its potential for electrocatalytic glucose oxidation in an alkaline (NaOH) electrolyte. Excellent linearity in the peak oxidation current of glucose within the concentration range from 0.02 mM to 9 mM was observed with a high linear regression coefficient of 0.997. The Ni-PAni/ITO electrode displayed a high sensitivity of 215.8 mA mM−1 cm−2 in addition to the fast response time, which is less than 2 s. These results suggest that the Ni-PAni composite has the potential to be an effective electrode material to develop a cost-effective glucose sensor. Schematic illustration of the preparation of Ni-polyaniline electrode for glucose sensing Research Highlights: Nickel nanoparticles were incorporated in the polyaniline thin films by chronopotentiometry method. The prepared Ni-polyaniline hybrids materials exhibit high sensitivity of 215.8 mA mM−1 cm−2 low-response time (2 s), good linearity in the concentration range from 0.1 mM to 12 mM, and low detection limit (0.01mM, S/N = 3). The good analytical performance, low cost, and facile fabrication method make this new electrode material promising for the development of effective glucose sensors. [ABSTRACT FROM AUTHOR]

In this study, a novel nanocomposite of graphene oxide-zinc oxide-manganese (GO-ZnO-M) was successfully synthesized using a modified Hummers method and hydrothermal technique. Enhanced electrochemical performance was observed in the GO-ZnO-M nanocomposite when utilized as an electrode material for the detection of rutin, a flavonoid known for its significant health benefits. The GO-ZnO-M modified electrode demonstrated excellent sensitivity, selectivity, reproducibility, and stability during rutin detection. Furthermore, the sensor exhibited a wide linear detection range and a low detection limit. The practical applicability of the GO-ZnO-M/GCE sensor was assessed by detecting rutin in pharmaceutical tablet samples, yielding satisfactory results. This study highlights the potential of GO-ZnO-M nanocomposites as promising materials for the electrochemical detection of rutin and other biologically significant compounds. [ABSTRACT FROM AUTHOR]

Abstract A nanosodalite (SOD) was synthesized utilizing Cameroonian kaolin and then used to prepare a nanocomposite (SOD‐GF) with graphene foam (GF). The as‐synthesized materials were characterized using X‐ray diffractometry (XRD), Fourier transform‐infrared (FT‐IR) spectroscopy, N2 adsorption‐desorption and scanning electron microscopy coupled with emission dispersive X‐ray (SEM/EDX). The results show a pure sodalite with high degree of crystallinity with crystallite size and BET surface area of 38.3 nm and 22 m2/g, respectively. The composite's characterization revealed a well‐integrated material in which the structural integrity of each material is maintained, its surface area being 4‐fold that of pristine SOD. Stable SOD and SOD‐GF modified glassy carbon electrode (GCE) were prepared by drop coating without a binder and utilized to study the electrochemistry of chlorpromazine (CPZ) in acidic, neutral and basic pHs. It appeared that (i) CPZ's electrochemical oxidation was a two‐step one‐electron process at SOD/GCE and a one‐step two‐electron process at SOD‐GF/GCE and (ii) the electrochemical reaction mechanism was an EEC mechanism at SOD/GCE while at SOD‐GF/GCE the mechanism was EEC at pH

In this work, we developed a simple technique to produce an effective electrode material consisting of nickel-cobalt-layered double hydroxide/multi-walled carbon nanotubes nanocomposite (Ni-Co-LDH/MWCNTs). This nanocomposite was prepared and characterization techniques such as field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FT-IR) and x-ray powder diffraction (XRD) were used to characterize its morphology and structure. The electrochemical studies and measurements were carried out by using various techniques including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA). The Ni-Co-LDH/MWCNTs nanocomposite-modified carbon paste electrode (Ni-Co-LDH/MWCNTs/CPE) exhibited enhanced electrocatalytic performance for the determination of 4-aminophenol. Detection of 4-aminophenol was done by using DPV. According to the results of DPV, the Ni-Co-LDH/MWCNTs/CPE sensor demonstrated a linear response to 4-aminophenol in the linear range of 0.02–700.0 µM, with a limit of detection (LOD) of 0.01 µM, and a sensitivity of 0.076 µA/µM. Also, the modified CPE presented reproducible and repeatable responses to determine 4-AP. The prepared sensor was also applied for determination of 4-aminophenol in the presence of possible interfering species and good results were obtained. In addition, the sensor successfully detected 4-aminophenol in real water samples with recoveries ranging from 98.0 % to 104.0 %, and with relative standard deviation (RSD) below 3.3 %. Therefore, the obtained results indicate that the prepared sensor can be an effective tool for the simple, fast, and sensitive detection of 4-aminophenol in water samples.

Resulted from the severe side effects, the development of inexpensive, simple and sensitive method for amethopterin (ATP, an antineoplastic drug) is very important but it still remains a challenge. In this work, low cost nanohybrid composed of carbon nanobowl (CNB) and β-cyclodextrins (β-CD) (CNB-CD) was prepared with a simple autopolymerization way and applied as electrode material to develop a novel electrochemical sensor of ATP. Scanning-/transmission-electron microscopy, Fourier transform infrared spectrum, photographic image and electrochemical technologies were utilized to characterize morphologies and structure of the as-prepared CNB and CNB-CD materials. On the basic of the coordination advantages from CNB (prominent electrical property and surface area) and β-CD (superior molecule-recognition and solubility capabilities), the CNB-CD nanohybrid modified electrode exhibits superior sensing performances toward ATP, and a low detection limit of 0.002 μM coupled with larger linearity of 0.005–12.0 μM are obtained. In addition, the as-prepared sensor offers desirable repeatability, stability, selectivity and practical application property, confirming that this proposal may have important applications in the determination of ATP.

Herein, SnO2-NiO nanocomposite was prepared via a hydrothermal method and characterized by various techniques consisting X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). The FESEM image showed particles with the size at about 20–130 nm in diameters. The electrochemical oxidation of hydrochlorothiazide (HCTZ) at a carbon paste electrode modified with SnO2-NiO nanocomposite and an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)) (SnO2-NiO/IL/CPE) was evaluated in phosphate buffer (PB) pH 8, by using cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and chronoamperometry. The SnO2-NiO/IL/CPE indicated a good electrocatalytic behavior towards to oxidation of hydrochlorothiazide. The anodic peak currents were increased with the HCTZ concentration and indicated two linear dynamic range from 0.01 to 0.1 µM and 0.1 to 100 µM and a detection limit of 0.002 µM (S/N = 5) under the optimized conditions. The introduced electrochemical sensor was utilized for the determination of HCTZ in the pharmaceutical formulations and biological sample.

In this study, a new and simple glassy carbon electrode modified with carbon nanohorns (SWCNH/GCE) was used for the determination of Cr(VI) in aqueous matrices via adsorptive cathodic stripping voltammetry (AdCSV). The modified electrode was characterized via field emission scanning electron microscopy and cyclic voltammetry, which revealed a homogeneous distribution of spherical agglomerates of SWCNH on the electrode surface. The modification increased the electrochemically active area from 0.10 cm2 ± 0.01 (GCE) to 0.16 cm2 ± 0.01 (SWCNH/GCE). The optimized analytical conditions were as follows: a supporting electrolyte (0.15 mol L−1 HCl), an accumulation potential of 0.8 V versus Ag/AgCl, and an accumulation time of 240 s. Validation of the analytical methodology was performed, obtaining a linear range between 20 and 100 µg L−1, a limit of detection of 3.5 µg L−1, and a limit of quantification of 11.6 µg L−1 with good accuracy and precision. The method was applied to the analysis of spiked tap water samples, and the results were compared using a flame atomic absorption spectrophotometer (FAAS) with no significant statistical differences.

The photoelectrochemical cells (PECs) performing high-efficiency conversions of solar energy into both electricity and high value-added chemicals are highly desirable but rather challenging. Herein, we demonstrate that a PEC using the oxidatively electropolymerized film of a heteroleptic Ru(II) complex of [Ru(bpy)(L)2](PF6)2 Ru1 {bpy and L stand for 2,2′-bipyridine and 1-phenyl-2-(4-vinylphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline respectively}, polyRu1, as a working electrode performed both efficient in situ synthesis of hydrogen peroxide and photocurrent generation/switching. Specifically, when biased at −0.4 V vs. saturated calomel electrode and illuminated with 100 mW·cm−2 white light, the PEC showed a significant cathodic photocurrent density of 9.64 μA·cm−2. Furthermore, an increase in the concentrations of quinhydrone in the electrolyte solution enabled the photocurrent polarity to switch from cathodic to anodic, and the anodic photocurrent density reached as high as 11.4 μA·cm−2. Interestingly, in this single-compartment PEC, the hydrogen peroxide yield reached 2.63 μmol·cm−2 in the neutral electrolyte solution. This study will serve as a guide for the design of high-efficiency metal-complex-based molecular systems performing photoelectric conversion/switching and photoelectrochemical oxygen reduction to hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Herein, SnO2-NiO nanocomposite was prepared via a hydrothermal method and characterized by various techniques consisting X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). The FESEM image showed particles with the size at about 20-130 nm in diameters. The electrochemical oxidation of hydrochlorothiazide (HCTZ) at a carbon paste electrode modified with SnO2-NiO nanocomposite and an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)) (SnO2-NiO/IL/CPE) was evaluated in phosphate buffer (PB) pH 8, by using cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and chronoamperometry. The SnO2- NiO/IL/CPE indicated good electrocatalytic behaviour towards to oxidation of hydrochlorothiazide. The anodic peak currents were increased with the HCTZ concentration and indicated two linear dynamic range from 0.01 to 0.1 µM and 0.1 to 100 µM and a detection limit of 0.002 µM (S/N = 5) under the optimized conditions. The introduced electrochemical sensor was successfully utilized for the determination of HCTZ in the pharmaceutical formulations and biological sample. [ABSTRACT FROM AUTHOR]

In this study, we propose an eco-friendly method for synthesizing cerium tungstate nanoparticles using hydrothermal techniques. We used scanning, transmission electron microscopy, and X-ray diffraction to analyze the morphology of the synthesized nanoparticles. The results showed that the synthesized nanoparticles were uniform and highly crystalline, with a particle size of about 50 nm. The electrocatalytic properties of the nanoparticles were then investigated using cyclic voltammetry and electrochemical impedance spectroscopy. We further used the synthesized nanoparticles to develop an electrochemical sensor based on a carbon paste electrode that can detect hydroquinone. By optimizing the differential pulse voltammetric method, a wide linearity range of 0.4 to 45 µM and a low detection limit of 0.06 µM were obtained. The developed sensor also expressed excellent repeatability (RSD up to 3.8%) and reproducibility (RSD below 5%). Interferences had an insignificant impact on the determination of analytes, making it possible to use this method for monitoring hydroquinone concentrations in tap water. This study introduces a new approach to the chemistry of materials and the environment and demonstrates that a careful selection of components can lead to new horizons in analytical chemistry. [ABSTRACT FROM AUTHOR]

The use of nanomaterials is a modern trend in electrochemical analysis because of the ease and accuracy of the analysis that, in addition, being non-destructive to the samples, gives the possibility of repeating the analysis to obtain better results. In this research, films of a co-conductive polymer of pyrrole and one of its derivatives are fabricated by docking on a graphite substrate. The film and the substrate form a modified electrode described by EIS and CV in the presence and absence of valsartan. Using a modified electrode, the concentration of valsartan is determined in titres and blood samples of patients with a standard deviation (SD-0.6). The quantitative and detection limit are LOQ-6 µM and LOD-1.8 µM, respectively. DPV with standard addition method has standard deviation (SD-0.34). The new method succeeds in being more accurate with LOQ-3.4 µM and LOD-1.1 µM, respectively. F-test proves that the HPLC method is not better than DPV and DPV with modified standard addition methods in determining the drug concentration of valsartan. The modified standard addition method is probably the best. [ABSTRACT FROM AUTHOR]

Hormones regulate several physiological processes in living organisms, and their detection requires accuracy and sensitivity. Recent advances in nanostructured electrodes for the electrochemical detection of hormones are described. Nanostructured electrodes' high surface area, electrocatalytic activity, and sensitivity make them a strong hormone detection platform. This paper covers nanostructured electrode design and production using MOFs, zeolites, carbon nanotubes, metal nanoparticles, and 2D materials such as TMDs, Mxenes, graphene, and conducting polymers onto electrodes surfaces that have been used to confer distinct characteristics for the purpose of electrochemical hormone detection. The use of aptamers for hormone recognition is producing especially promising results, as is the use of carbon-based nanomaterials in composite electrodes. These materials are optimized for hormone detection, allowing trace-level quantification. Various electrochemical techniques such as SWV, CV, DPV, EIS, and amperometry are reviewed in depth for hormone detection, showing the ability for quick, selective, and quantitative evaluation. We also discuss hormone immobilization on nanostructured electrodes to improve detection stability and specificity. We focus on real-time monitoring and tailored healthcare with nanostructured electrode-based hormone detection in clinical diagnostics, wearable devices, and point-of-care testing. These nanostructured electrode-based assays are useful for endocrinology research and hormone-related disease diagnostics due to their sensitivity, selectivity, and repeatability. We conclude with nanotechnology–microfluidics integration and tiny portable hormone-detection devices. Nanostructured electrodes can improve hormone regulation and healthcare by facilitating early disease diagnosis and customized therapy. [ABSTRACT FROM AUTHOR]

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.

In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were confirmed by UV-Vis spectroscopy, Confocal Raman Microscopy and High Resolution Transmission Electron Microscopy (HRTEM) studies. The electrochemical response of the TH@CdSe QDs-modified PIGE was studied by cyclic voltammetry. The voltammetric response of RF at the TH@CdSe QDs-modified PIGE showed higher current than the bare PIGE. Under optimum conditions, the electrocatalytic reduction currents of RF was found to be linearly related to its concentration over the range of 1.6 × 10−7 M to 1.4 × 10−4 M with a detection limit of 53 × 10−9 M (S/N = 3). The TH@CdSe QDs-modified PIGE was utilized as an amperometric sensor for the detection of RF in flow systems was performed by carrying out hydrodynamic and chronoamperometric experiments. The TH@CdSe QDs-modified PIGE showed very good stability and a longer shelf life. The applicability of the fabricated electrode was justified by the quantification of RF in commercial tablets.

Monitoring of anticancer drugs is an important strategy in clinical investigation. Determining the level of these drugs in chemotherapy processes provides useful information about the treatment process. The etoposide is one of the important drugs approved to lung cancer with many side effects. Therefore, monitoring of it is so important in clinical process and specially chemotherapy processes. The presence study focused on design of a new, simple, electrical-based, safe and fast response sensor to trace level monitoring of etoposide in biological fluids and pharmaceutical samples. The sensor successfully determined etoposide in nano-level concentration that is very important to investigation role of this anticancer drug in biological fluids. To this goal, the graphene nanoribbon nano-catalyst (GNR) was synthesized and characterized by MAP and SEM methods. The electrochemical catalytic activity of it was investigated by electrochemical impedance spectroscopy method. In continuous, glassy carbon electrode (GCE) modified with GNR was fabricated and ability of sensor to sensing of etoposide was investigated by differential pulse voltammetric (DPV) method. The GNR/GCE monitored etoposide in the concentration range 0.4–150 µM with detection limit 0.1 µM by DPV methods. At biological condition (pH = 7.4), the GNR/GCE was successfully used to monitoring of etoposide in urine, serum and injection samples and data confirmed with HPLC method and Statistical tests.

In this research, graphene oxide (GO) was functionalized with D-penicillamine (DPA) and used to develop an electrochemical sensor for Cu(II) cation. For the successful synthesis of D-penicillamine-functionalized graphene oxide (DPA-GO), Fourier Transfer Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), X-ray diffraction pattern (XRD), and Transmission Electron Microscopy (TEM) are used. DPA-GO modified glassy carbon electrode (DPA-GO / GCE) was prepared and its electrochemical behavior was studied in the presence of Cu(II) cations by cyclic voltammetry, and the results showed the better performance of the DPA-GO-modified electrode compared to unmodified and GO-modified electrode, which related to GO nanostructure and complexing ability of sulfur, nitrogen, and oxygen-containing functional groups in the DPA structure. The prepared sensor was used for the selective and sensitive measurement of Cu(II) cations by square-wave anodic stripping voltammetry (SW-ASV) and the factors affecting the sensor performance were investigated and optimum conditions for sensor operation were determined. Under the optimal conditions, the prepared electrode has a linear response in the range of 1 pM to 0.1 µM and its detection limit was 0.31 pM. The proposed sensor was used satisfactorily to measure copper cation in real water samples with suitable reproducibility and stability.

A new electrochemical sensor, poly(bis(2,2′-bipyridine)hydroxycopper(II) iodide modified glassy carbon electrode (poly([Cu(Bip)2OH]I)/GCE), was prepared by electropolymerization of bis(2,2′-bipyridine)chlorocopper(II) iodide ([Cu(Bip)2Cl]I) on glassy carbon electrode (GCE) for voltammetric determination of chloroquine (CQ). The synthesized complex (bis(2,2′-bipyridine)chlorocopper(II) iodide) was characterized using UV–Vis, CHN elemental analysis, atomic absorption spectroscopy (AAS), electrolytic conductivity, melting point and Fourier transform infrared spectroscopy (FT-IR) were used to characterize and confirm the synthesis of the desired complex (bis(2,2′-bipyridine)chlorocopper(II) iodide). The Uv-Vis, FTIR and electrochemical data of the synthesized polymer supports the replacement of chloro ligand by hydroxyl ligand during electropolymerization of the monomer in aqueous solution. The fabricated electrode (poly([Cu(Bip)2OH]I)/GCE) was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The voltammetric behavior of CQ was examined using CV and square wave voltammetry (SWV). Compared to the bare GCE, poly(Bip)/GCE, and Cu/GCE, the current signal of CQ was significantly enhanced at poly([Cu(Bip)2OH]I)/GCE, which demonstrates excellent electrocatalytic behavior of poly([Cu(Bip)2OH]I)/GCE towards electrochemical oxidation of CQ. Under the optimum experimental conditions, the SWV current signal of poly([Cu(Bip)2OH]I)/GCE offered linearity on the concentration range of CQ between 0.5 and 250 μM with LOD and LOQ values of 4.22 ×10−2 and 1.4 × 10−1 μM, respectively. In the presence of possible interfering substances including glucose, paracetamol, adenine and guanine, the voltammetric determination of CQ was also considered, and their interventions were found to be insignificant, which evidenced the selectivity of the introduced electrode. The analytical application of the established sensor was successfully applied in the determination of CQ in pharmaceuticals, milk, serum, and urine samples. The detected amount of CQ in the tablet samples was in the range between 100.5 and 110.2% with RSD of 1.5 and 1.87%, respectively. The spiked recovery results in pharmaceuticals, milk, serum, and urine biological samples were in the range of 100.5 to 110.2%, 97.13 to 98.12, 103.7 to 103.6% and 95.50 to 97.05%, respectively. These results confirm that the developed method exhibits high applicability for electrochemical determination of CQ in various real samples.

Herein, ZIF-67-derived Co and N-doped carbon (Co/NC) particle-modified multilayer MXene (MXene@Co/NC) was developed as remarkable electrode material for carbendazim (CBZ) detection. MXene as a substrate provides an excellent conductive framework and plentiful accessibility sites. Co/NC particles embedding in MXene can not only prevent the interlayer stacking of MXene but also contribute a great deal of metal catalytic active sites and finally improve the adsorption and catalytic properties of the composite. Accordingly, the MXene@Co/NC electrode displays excellent electrocatalytic activity toward CBZ oxidation. Experimental parameters such as pH value, accumulation time, MXene@Co/NC modification volume and constituent materials' mass ratios were optimized. Under optimal conditions, the as-prepared sensor based on MXene@Co/NC holds a broad linearity range from 0.01 μM to 45.0 μM with a low limit of detection (LOD) of 3.3 nM (S/N = 3, S means the detection signal, while N represents the noise of the instrument). Moreover, the proposed sensor displays excellent anti-interference ability, superior reproducibility, excellent stability, and successfully achieves actual applications for CBZ detection in a lettuce sample. [ABSTRACT FROM AUTHOR]

In this study, for the detection of taurine in philological fluids, modified electrodes were prepared from glassy carbon electrodes with MWCNT (multi-wall carbon nanotube) + Cu(NO3)2 + carbon-based material. A carbon-based material was obtained by carbonization of Pinus sylvestris branch needles (CPS). Cu(NO3)2 and MWCNT structure (Cu(NO3)2/MWCNT) were added to the carbon-based material and the obtained mixture was used in the modification of the glassy carbon electrode surface. The surface morphology and structure of the prepared electrodes were characterized by electron microscopy scanning (SEM) and atomic force microscopy (AFM). Taurine detection with a modified electrode was made by cyclic voltammetry (CV) in 0.1 M KCl (vs. Ag/AgCl). The calibration curve of the modified electrode for taurine in the 10-150 µM range showed a linear response, and R2 value was 0.976. Limit of detection (LOD) and limit of quantification (LOQ) of the modified electrode were found 19 µM and 9.75 µM, respectively. The application of the electrode as a chemical sensor was carried out with commercially available energy drink samples. Satisfactory results have been obtained from the samples. The sensor can be used for routine taurine analysis. This electrode can quickly determine the amount of taurine in real samples with 90% accuracy in two minutes. [ABSTRACT FROM AUTHOR]

Salbutamol is an important drug that opens the medium and large air spaces in the lungs. In this study, CoFe3O4, CoFe3O4/MWCNT, and CoFe3O4/TiO2/MWCNT modified electrode structures are prepared separately to determine the effect of each modification agent on salbutamol responses. The prepared electrodes are firstly structurally characterized by the FT-IR technique. The surface morphology and structure of electrodes are then analyzed by SEM, and AFM techniques. EDX analyses were performed to clarify this structural change on the electrode surface. The salbutamol activity of the modified electrodes is determined by DPV in 0.1 M PBS. The modified electrode shows a linear response in the concentration range of 2-18 µM salbutamol, and an R² value of 0.9587 is achieved. LOD and LOQ of the modified electrode are determined as 1.39 µM and 22.87 µM, respectively. Considering the reproducibility of the experimental results, non-interference of the interfering species, and the measurement range, it is determined that it can be successfully used to figure out the concentration of salbutamol in physiological fluids and commercial form. [ABSTRACT FROM AUTHOR]

Developing new flexible and electroactive materials is a significant challenge to producing safe, reliable, and environmentally friendly energy storage devices. This study introduces a promising electrolyte system that fulfills these requirements. First, polypyrrole (PPy) nanotubes are electropolymerized in graphite‐thread electrodes using methyl orange (MO) templates in an acidic medium. The modification increases the conductivity and does not compromise the flexibility of the electrodes. Next, flexible supercapacitors are built using hydrogel prepared from poly(vinyl alcohol) (PVA)/sodium alginate (SA) obtained by freeze–thawing and swollen with ionic solutions as an electrolyte. The material exhibits a homogenous and porous hydrogel matrix allowing a high conductivity of 3.6 mS cm−1 as‐prepared while displaying great versatility, changing its electrochemical and mechanical properties depending on the swollen electrolyte. Therefore, it allows its combination with modified graphite‐thread electrodes into a quasi‐solid electrochemical energy storage device, achieving a specific capacitance (Cs) value of 66 F g−1 at 0.5 A g−1. Finally, the flexible device exhibits specific energy and power values of 19.9 W kg−1 and 3.0 Wh kg−1, relying on the liquid phase in the hydrogel matrix produced from biodegradable polymers. This study shows an environment friendly, flexible, and tunable quasi‐solid electrolyte, depending on a simple swell experiment to shape its properties according to its application. [ABSTRACT FROM AUTHOR]

In this paper, a MnO2 nanowire (MnO2-NW) modified carbon paper electrode (CP) was developed as a novel electrochemical sensor for the sensitive determination of tetrabromobisphenol A (TBBPA). The MnO2 nanowire was prepared by a hydrothermal synthesis method, and the morphology and structure of MnO2 were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical performance of TBBPA on MnO2-NW/CP was investigated by cyclic voltammetry, and the result confirmed that MnO2-NW/CP exhibited excellent sensitivity for the determination of TBBPA due to the high specific surface area and good electrical conductivity of the nanowire-like MnO2. Moreover, the important electrochemical factors such as pH value, incubation time and modified material proportion were systematically studied to improve the determination sensitivity. The interferences from similar structure compounds on TBBPA have also been investigated. Under the optimal conditions, MnO2-NW/CP displayed a linear range of 70~500 nM for TBBPA with a detection limit of 3.1 nM. This was superior to some electrochemical methods in reference. The work presents a novel and simple method for the determination of TBBPA. [ABSTRACT FROM AUTHOR]

In this paper, the electrochemical non-enzymatic detection of Riboflavin (RF) was proposed based on its catalytic reduction in a Thionine-coated Cadmium Selenide Quantum dots (TH@CdSe QDs)-modified paraffin wax-impregnated graphite electrode (PIGE) that was prepared using a novel approach. The synthesized TH@CdSe QDs were confirmed by UV-Vis spectroscopy, Confocal Raman Microscopy and High Resolution Transmission Electron Microscopy (HRTEM) studies. The electrochemical response of the TH@CdSe QDs-modified PIGE was studied by cyclic voltammetry. The voltammetric response of RF at the TH@CdSe QDs-modified PIGE showed higher current than the bare PIGE. Under optimum conditions, the electrocatalytic reduction currents of RF was found to be linearly related to its concentration over the range of 1.6 × 10−7 M to 1.4 × 10−4 M with a detection limit of 53 × 10−9 M (S/N = 3). The TH@CdSe QDs-modified PIGE was utilized as an amperometric sensor for the detection of RF in flow systems was performed by carrying out hydrodynamic and chronoamperometric experiments. The TH@CdSe QDs-modified PIGE showed very good stability and a longer shelf life. The applicability of the fabricated electrode was justified by the quantification of RF in commercial tablets. [ABSTRACT FROM AUTHOR]

With the aim of designing electrode surface with porous materials, facile synthesis method to generate mesoporous architectures that are activated with conductive metal oxide as dopants with high thermal stability is of huge demand. The present work demonstrates the robust synthesis of CdO nanocrystals incorporated on the mesoporous TiO2-based materials for electrochemical detection of pyridoxine. Herein, the presence of mesoporous structure on the surface of TiO2 could act as host matrix, whereas the CdO acts as hetero-metal oxides loaded on the host matrix, which together combined to deliver large enhancement in pyridoxine oxidation response. The resulting nanocomposite will collectively deliver 1. Improvement in electron conducting pathways when vacant mesoporous sites are occupied with CdO nanocrystals 2. Enhancement in the current response for oxidation of pyridoxine due to large surface area and high conductivity offered by synergetic effect between TiO2 and CdO. The DPV response toward determination of pyridoxine exhibited a linear response within the concentration range from 0.5 µM to 45 µM, with a detection limit of about 0.2 µM. Therefore, these results collectively provide the activation of vacant mesoporous sites with metal oxides as dopants will effectively improve the electrochemical response for wide range of analytes with large enhancement in the sensitivity and selectivity. These mesoporous materials could also be employed as fruitful electrocatalyst for various electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Nicotine is the one of the major addictive substances; the overdose of nicotine (NIC) consumption causes increasing heart rate, blood pressure, stroke, lung cancer, and respiratory illnesses. In this study, we have developed a precise and sensitive electrochemical sensor for nicotine detection in saliva samples. It was built on a glassy carbon electrode (GCE) modified with graphene (Gr), iron (III) phthalocyanine-4,4′,4″,4′′′-tetrasulfonic acid (Fe(III)Pc), and gold nanoparticles (AuNPs/Fe(III)Pc/Gr/GCE). The AuNPs/Fe(III)Pc/Gr nanocomposite was prepared and characterized by using FE-SEM, EDX, and E-mapping techniques to confirm the composite formation as well as the even distribution of elements. Furthermore, the newly prepared AuNPs/Fe(III)Pc/Gr/GCE-nanocomposite-based sensor was used to detect the nicotine in phosphate-buffered solution (0.1 M PBS, pH 7.4). The AuNPs/Fe(III)Pc/Gr/GCE-based sensor offered a linear response against NIC from 0.5 to 27 µM with a limit of detection (LOD) of 17 nM using the amperometry (i–t curve) technique. This electrochemical sensor demonstrated astounding selectivity and sensitivity during NIC detection in the presence of common interfering molecules in 0.1 M PBS. Moreover, the effect of pH on NIC electro-oxidation was studied, which indicated that PBS with pH 7.4 was the best medium for NIC determination. Finally, the AuNPs/Fe(III)Pc/Gr/GCE sensor was used to accurately determine NIC concentration in human saliva samples, and the recovery percentages were also calculated. [ABSTRACT FROM AUTHOR]

Hydroquinone (HQ) was used to catalyze Methanobactin (Mb) to reduce chlorauric acid to prepare Gold Nanoparticles (AuNPs). Mb@AuNPs was modified onto the surface of a bare gold electrode via electrodeposition to prepare the Mb@AuNPs/Au electrode. Subsequently, differential pulse voltammetry was conducted for the simultaneous determination of nitrite and ascorbic acid concentrations as well as condition optimization. For the electrode assembly, electrodeposition was performed with a 0.20 mol/L and pH6.5 PBS at a 100 mV/s scan rate for 40 cycles. In the linear range of 2~5600 μmol/L and 1~6000 μmol/L, the oxidation peak current of both nitrite and ascorbic acid detected by Mb@AuNPs/Au showed a good linear relationship with the concentration (R2>0.9928), and the limit of detection (LOD) was 0.31 and 0.57 μmol/L, respectively. The recovery rates of standard addition for the actual samples were 92.59%~109.26%, 90.01%~103.51%. The method has good reproducibility and stability and can be used for simultaneous determination of nitrite and ascorbic acid in fruits and vegetables.

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.

This work presents the detection of hypoxanthine (HXA), a purine derivative that is similar to nucleic acids who overconsumption can cause health issues, by using hydrothermally synthesized cerium phosphate (CePO4) followed by a sonochemical approach for CePO4 decorated with a functionalized carbon nanofiber (CePO4@f-CNF) nanocomposite. The formation of the nanocomposite was confirmed with X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). A CePO4@f-CNF nanocomposite is used to modify a glassy carbon electrode (GCE) to analyze the electrochemical detection of HXA. Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and Differential pulse voltammetry (DPV) were used to examine the electrochemical properties of the composite. As a result, the modified electrode exhibits a larger active surface area (A = 1.39 cm2), a low limit of detection (LOD) at 0.23 µM, a wide linear range (2.05–629 µM), and significant sensitivity. Therefore, the CePO4@f-CNF nanocomposite was used to study the real-time detection in chicken and fish samples, and it depicted significant results.

In this study, an electrochemical sensor was introduced as a simple and fast electro­analytical tool to monitor and sensing of tert-butylhydroquinone (TBHQ) in food products. The suggested electrochemical sensor is fabricated by modification of paste electrode (PE) by single wall carbon nanotubes (SWCNTs) as nanocatalyst. The oxidation current of TBHQ was improved by about 2.62 times and its oxidation potential was reduced by about 50 mV after using SWCNTs as conductive catalyst on a carbon paste matrix. The oxidation current of TBHQ showed a linear dynamic range of 0.05 to 390 µM in the sensing process using SWCNTs/PE as the electroanalytical sensor. On the other hand, SWCNTs/PE successfully monitored TBHQ with a detection limit of 10 nM at optimum conditions. The real sample analysis data clearly showed a recovery range of 97.2 to 104.3 %, which is very interesting for a new analytical tool in the food-sensing process.

Over the past few decades, nanotechnology evolved into a significant, interdisciplinary research field on a global scale. Due to their extraordinary physicochemical, optical, and biological qualities, noble metal nanoparticles like gold, silver, palladium, and platinum are widely used in a variety of industrial and pharmaceutical procedures. In this study, a quick, low-cost, and environmentally friendly approach was used to create GAgNPs. Without using hazardous chemical substances, GAgNPs were produced using Phoenix dactylifera seeds extract as a reducing and stabilizing agent. The synthesized GAgNPs were characterized by UV-Visble, X-ray diffraction, and scanning electron microscopy. The presence of GAgNPs confirmed by the appearance of peak at 420 nm employing UV-Vis method, also affirmed by X-ray diffraction pattern, and the calculated size was about 28.72 nm. The electrochemical activity of GAgNPs was investigated through the elaboration of carbon paste-based sensor for the determination of ornidazole. The GAgNPs modified carbon paste electrode displayed a linear concentration range from 1.0 × 10−3 mol L−1 to 5.0 × 10−5 mol L−1 with a detection limit and quantification limit of 3.8 × 10−6 mol L−1 and 1.2 × 10−5 mol L−1, respectively. The proposed sensor was used for ornidazole analysis in milk samples, providing satisfactory recoveries of 105.7% and 102.7% with RSD below 4%.

Abstract Developing new flexible and electroactive materials is a significant challenge to producing safe, reliable, and environmentally friendly energy storage devices. This study introduces a promising electrolyte system that fulfills these requirements. First, polypyrrole (PPy) nanotubes are electropolymerized in graphite‐thread electrodes using methyl orange (MO) templates in an acidic medium. The modification increases the conductivity and does not compromise the flexibility of the electrodes. Next, flexible supercapacitors are built using hydrogel prepared from poly(vinyl alcohol) (PVA)/sodium alginate (SA) obtained by freeze–thawing and swollen with ionic solutions as an electrolyte. The material exhibits a homogenous and porous hydrogel matrix allowing a high conductivity of 3.6 mS cm−1 as‐prepared while displaying great versatility, changing its electrochemical and mechanical properties depending on the swollen electrolyte. Therefore, it allows its combination with modified graphite‐thread electrodes into a quasi‐solid electrochemical energy storage device, achieving a specific capacitance (Cs) value of 66 F g−1 at 0.5 A g−1. Finally, the flexible device exhibits specific energy and power values of 19.9 W kg−1 and 3.0 Wh kg−1, relying on the liquid phase in the hydrogel matrix produced from biodegradable polymers. This study shows an environment friendly, flexible, and tunable quasi‐solid electrolyte, depending on a simple swell experiment to shape its properties according to its application.