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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]

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10−12–2.5 × 10−10 M and 7.5 × 10−13–2.5 × 10−11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18–102.69% and 98.05–103.72%, respectively. In addition, the relative selectivity coefficient (k′) of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule. [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]

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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]

Polymers containing TEMPO moieties are effective catalysts for the electrochemical oxidation of alcohols. Such polymers, almost exclusively, are non‐commercial and are prepared using multi‐step synthetic procedures. Here we show that a commercially available TEMPO bearing polymer, Polyamine Immobilised Piperidinyl Oxyl (PIPO), is an effective homogeneous and surface‐confined polymeric catalyst for electrochemical alcohol oxidation at carbonaceous electrodes. We probe electrolytic conditions for effective and stable electrocatalytic alcohol oxidation showing that dichloromethane (DCM), containing tetrabutylammonium perchlorate (TBAP) and N‐methyl imidazole (NMI), is a suitable medium for homogeneous catalysis whilst carbonate buffer (pH 9.5) is better suited when PIPO is adsorbed at the electrode surface. These findings demonstrate the viability of PIPO as an effective and accessible catalyst for electrochemical alcohol oxidations. [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]

The successful fabrication is reported of highly crystalline Co nanoparticles interconnected with zeolitic imidazolate framework (ZIF-12) -based amorphous porous carbon using the molten-salt-assisted approach utilizing NaCl. Single crystal diffractometers (XRD), and X-ray photoelectron spectroscopy (XPS) analyses confirm the codoped amorphous carbon structure. Crystallite size was calculated by Scherrer (34 nm) and Williamson-Hall models (42 nm). The magnetic properties of NPCS (N-doped porous carbon sheet) were studied using a vibrating sample magnetometer (VSM). The NPCS has a magnetic saturation (Ms) value of 1.85 emu/g. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses show that Co/Co3O4 nanoparticles are homogeneously distributed in the carbon matrix. While a low melting point eutectic salt acts as an ionic liquid solvent, ZIF-12, at high temperature, leading cobalt nanoparticles with a trace amount of Co3O4 interconnected by conductive amorphous carbon. In addition, the surface area (89.04 m2/g) and pore architectures of amorphous carbon embedded with Co nanoparticles are created using the molten salt approach. Thanks to this inexpensive and effective method, the optimal composite porous carbon structures were obtained with the strategy using NaCl salt and showed distinct electrochemical performance on electrochemical methodology revealing the analytical profile of Erdatifinib (ERD) as a sensor modifier. The linear response spanned from 0.01 to 7.38 μM, featuring a limit of detection (LOD) of 3.36 nM and a limit of quantification (LOQ) of 11.2 nM. The developed sensor was examined in terms of selectivity, repeatability, and reproducibility. The fabricated electrode was utilized for the quantification of Erdafitinib in urine samples and pharmaceutical dosage forms. This research provides a fresh outlook on the advancements in electrochemical sensor technology concerning the development and detection of anticancer drugs within the realms of medicine and pharmacology. [ABSTRACT FROM AUTHOR]

A cutting-edge electrochemical method is presented for precise quantification of amitraz (AMZ), a commonly used acaricide in veterinary medicine and agriculture. Leveraging a lab-made screen-printed carbon electrode modified with a synergistic blend of perylene tetracarboxylic acid (PTCA), mesoporous carbon (MC), and Nafion, the sensor’s sensitivity was significantly improved. Fine-tuning of PTCA, MC, and Nafion ratios, alongside optimization of the pH of the supporting electrolyte and accumulation time, resulted in remarkable sensitivity enhancements. The sensor exhibited a linear response within the concentration range 0.01 to 0.70 μg mL-1, boasting an exceptionally low limit of detection of 0.002 μg mL-1 and a limit of quantification of 0.10 μg mL-1, surpassing maximum residue levels permitted in honey, tomato, and longan samples. Validation with real samples demonstrated high recoveries ranging from 80.8 to 104.8%, with a relative standard deviation below 10%, affirming the method’s robustness and precision. The modified PTCA/MC/Nafion@SPCE-based electrochemical sensor not only offers superior sensitivity but also simplicity and cost-effectiveness, making it a pivotal tool for accurate AMZ detection in food samples. Furthermore, beyond the scope of this study, the sensor presents promising prospects for wider application across various electrochemical analytical fields, thereby significantly contributing to food safety and advancing agricultural practices. [ABSTRACT FROM AUTHOR]

The enhanced cathodic ECL of Ru(bpy)32+ at a bimetallic element MXenes (TiVC MXene) modified electrode in neutral aqueous condition is reported. TiVC MXene significantly catalyzed the oxygen reduction reaction (ORR) as well as the electrochemical reduction of Ru(bpy)32+ to produce reactive oxygen species and Ru(bpy)3+. The obtained hydroxyl radical (OH∙) not only oxidized Ru(bpy)3+ to generate Ru(bpy)32+* and emit light through coreactant pathway, but also oxidized Ru(bpy)32+ to Ru(bpy)33+, which caused an annihilation ECL reaction. As a result, two pathways occurred simultaneously to generate strong cathodic ECL signal. Sulfite removes the dissolved oxygen in water and reduces the occurrence of ORR, which prohibits the generation of OH∙ to decrease the ECL signal. The decrement of ECL intensity varied linearly with the concentration of sulfite in the range 2 nM to 50 μM with a detection limit of 0.14 nM (3σ). The proposed sensor exhibited good analytical performance, and could be used in the detection of sulfite in real samples. The results revealed that the electrocatalytic behavior of TiVC MXene is the key factor for strong cathodic Ru(bpy)32+ ECL, which provides new application in ECL sensing field. [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]

A carbon paste electrode (CPE) modified with multi-walled carbon nanotubes (MWCNTs) and natural deep eutectic solvent (NADES) was prepared and applied for the simultaneous voltammetric determination of acetaminophen (ACP) and thiosalicylic acid (TSA) in real samples. Electrochemical impedance spectroscopy (EIS) was applied for investigation of electron transfer rate of [Fe(CN)6]3-/4- as a redox couple probe on the MWCNTs/NADES/CPE surface. The modified electrode preserved and combined the properties of individual modifiers synergistically. Significant enhancement in the peak current responses of ACP and TSA were observed at the modified electrode compared to the bare electrode. Under the optimal conditions, a linear dynamic range of 5–2900 μM for ACP and 5–2250 μM for TSA was obtained. The limit of detection (LOD) for ACP and TSA were 4.71 μM and 4.35 μM, respectively. Finally, this method was successfully employed for the determination of ACP and TSA in real samples. [ABSTRACT FROM AUTHOR]

A novel luminol derivative of N-(1,4-dioxo-1,2,3,4-tetrahydrophthalazin-5-yl)acrylamide (DTA) with excellent luminescence efficiency was designed and synthesized. Furthermore, a molecularly imprinted electrochemiluminescence sensor (MIECLS) was fabricated to detect ultratrace levels of human serum albumin (HSA) with high sensitivity and selectivity via a click reaction. The molecularly imprinted polymers (MIPs) were formed on the electrode surface via electropolymerization with HSA as a template molecule and catechol as a monomer. In the detection process, the -SH group of HSA on the electrode and the C = C bond of acryloyl group in DTA formed a new C-S bond via the Michael addition reaction to construct the MIECLS. The higher the concentration of HSA, the greater electrochemiluminescence (ECL) intensity measured. Taking advantage of MIECLS for ECL detection (scanning potential, − 0.4 to 0.5 V), there was a good linear relationship between ECL intensity and the logarithm of HSA concentration in the range 5 × 10–9 to 1 × 10–13 mg mL−1. The limit of detection (LOD) of the sensor was 1.05 × 10–15 mg mL−1. The sensor exhibited outstanding selectivity and stability. The sensor was applied to detect HSA in human serum with good recoveries of 97.7–105.2%. The concentration of HSA was detected by electrochemical method using the gating effect of MIP. [ABSTRACT FROM AUTHOR]

A direct electrochemical sensor based on covalent organic frameworks (COFs)/platinum nanoparticles (PtNPs) composite was fabricated for the detection of ofloxacin (OFX) in water. Firstly, the COF material was synthesized via the condensation reaction of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthalaldehyde (TPA) and integrated with PtNPs by in situ reduction. Then, TAPB-TPA-COFs/PtNPs composite was loaded onto the surface of the glassy carbon electrode (GCE) by drip coating to construct the working electrode (TAPB-TPA-COFs/PtNPs/GCE). The electrochemical performance of TAPB-TPA-COFs/PtNPs/GCE showed a significant improvement compared with that of TAPB-TPA-COFs/GCE, leading to a 3.2-fold increase in the electrochemical signal for 0.01 mM OFX. Under optimal conditions, the TAPB-TPA-COFs/PtNPs/GCE exhibited a wide linear range of 9.901 × 10−3–1.406 µM and 2.024–15.19 µM with a detection limit of 2.184 × 10−3 µM. The TAPB-TPA-COFs/PtNPs/GCE-based electrochemical sensor with excellent performance provides great potential for the rapid and trace detection of residual OFX. [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.

This new and simple amperometric method takes advantage of the electroactivity of V2O5 in the oxidation of paracetamol (PCM) on a carbon paste electrode (CPE). With the modified electrode (VOX/CPE) the anode peak current for PCM was more than 100 % than that of the unmodified electrode. The electrode surface was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The amperograms were measured at +0.70 V (vs Ag/AgCl), and the calibration curve indicated a detection limit of 0.06 μmol/L and a sensitivity of 1.93 μA/μM cm2. The modified electrode was used in the detection of solid drugs such as PCM tablets and children's syrup with acceptable results. [ABSTRACT FROM AUTHOR]

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]

A natural stress response induces elevated cortisol levels in biological fluids, such as saliva. While current sensor technologies can detect cortisol in real time, their sensitivity and reliability for human subjects have not been assured. This is due to relatively low concentrations of salivary cortisol, which fluctuate throughout the day and vary significantly between individuals. To address these challenges, we present an improved electrochemical biosensor leveraging graphene's exceptional conductivity and physicochemical properties. A 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE-NHS)–modified commercial graphene foam (GF) electrode is presented to realize an ultra-sensitive biosensor for cortisol detection directly in human saliva. The biosensor fabrication process entails the attachment of anti-cortisol monoclonal antibodies (mAb-cort) onto a PBASE-NHS/GF electrode through noncovalent immobilization on the vertically stratified graphene foam electrode surface. This unique immobilization strategy preserves graphene's structural integrity and electrical conductivity while facilitating antibody immobilization. The binding of cortisol to immobilized mAb-cort is read out via differential pulse voltammetry using ferri/ferro redox reactions. The immunosensor demonstrates an exceptional dynamic range of 1.0 fg mL−1 to 10,000 pg mL−1 (R2 = 0.9914) with a detection limit of 0.24 fg mL−1 (n = 3) for cortisol. Furthermore, we have established the reliability of cortisol sensors in monitoring human saliva. We have also performed multiple modes of validation, one against the established enzyme-linked immunosorbent assay (ELISA) and a second by a third-party service Salimetric on 16 student volunteers exposed to different stress levels, showing excellent correlation (r = 0.9961). These findings suggest the potential for using mAb-cort/PBASE-NHS/GF-based cortisol electrodes for monitoring salivary cortisol in the general population. [ABSTRACT FROM AUTHOR]

A selective and reliable modified glassy carbon sensor, based on a 1.0% Cd zeolitic imidazole framework-67 modified glassy carbon sensor (GCS2), has been developed for ultrasensitive detection of dimethyl methyl phosphonate (DMMP) in human biological fluid. The synthesis of porous nanoparticles of Cd zeolitic imidazole framework-67 (Cd ZIF-67) was carried out via the hydrothermal method. The resulting Cd ZIF-67 powder emerges with good crystallinity, a rhombic dodecahedral morphology with particle size in the range 300 ~ 500 nm, and a specific surface area of 1780 m2·g−1. Furthermore, the fabricated sensor exhibited superior performance in the detection of DMMP with two linearity ranges of 0.02–2.0 nM and 2.0–9.0 nM and a limit of detection (LOD) of 0.06 pM. The fabricated sensor exhibited good reliability, long-term stability, and repeatability, which are favourable attributes for electroanalytical detection. In addition, the fabricated sensor displayed superior performance without significant interference during the assay of DMMP in a biological fluid (human serum sample) within two linearity ranges of 0.1–1.0 nM and 1.0–6.0 nM and a LOD of 0.03 nM. [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]

A polycationic organohalloysite (H‐polyQ22) prepared by the sequential grafting of methylamine and 1,4‐butanediol diglycidyl ether in the interlayer space of (3‐aminopropyl)trimethoxysilane grafted halloysite is herein employed as a carbon paste electrode (CPE) modifier for the electrochemical determination of mangiferin, a bioactive molecule. When H‐polyQ22 was used as CPE modifier, the cyclic voltammetric response of mangiferin increased by ca. 8‐fold. This electrochemical response enhancement was shown to be the result of the great preconcentration capacity of H‐polyQ22. Since the H‐polyQ22 modified CPE proved to be a good signal enhancer, a new methodology for the sensitive determination of mangiferin was developed using square wave voltammetry. Under optimised conditions, a linear correlation between peak current and mangiferin concentration was obtained in the range from 0 to 2775.67 nM. A detection limit of 5.47×10−10 M was obtained based on a signal to noise ratio of 3, with a sensitivity of 193.58 μA/μM. The ability of some possible interferents such as human serum albumin, L‐cystine, ascorbic acid, glucose, dopamine and phenol to perturb the electrochemical signal of mangiferin in real sample analysis was alsoinvestigated. [ABSTRACT FROM AUTHOR]

Efficient oxygen evolution reaction (OER) electrocatalysts are widely required in the realm of water electrolysis and rechargeable metal-air batteries. This work describes an easy and simple method for the synthesis of copper salen (Cu(Salen))-functionalized multiwalled carbon nanotubes (MWCNTs) nanocomposite materials (Cu(Salen)/MWCNTs). It has been used for OER in the basic medium (0.1 M KOH). The resulting nanocomposite, Cu(Salen)/MWCNTs, has been studied using spectroscopic and microscopic techniques such as Fourier transform infrared (FT-IR), UV-visible spectroscopy, powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDAX). The electrochemical characterization of prepared Cu(Salen)/MWCNTs nanocomposite based modified glassy carbon (GC) electrodes (GC/Cu(Salen)/MWCNTs) and their application towards OER have been performed using an electrochemical method. The Tafel slope of nanocomposite material is 159.6 mV/dec in 0.1 M KOH solution, indicating that GC/Cu(Salen)/MWCNTs could be a promising and cost-effective electrode material for the OER. This study demonstrates a novel way for creating an active nanocomposite catalyst for OER in alkaline media. [ABSTRACT FROM AUTHOR]

An electrochemical sensor capable of detecting glutathione (GSH) with high sensitivity and selectivity was developed based on the unique novel electroactive silver-based metal organic framework (Ag-MOF). The Ag-MOF obtained by silver nitrate and 1,3,5-benzoic acid (H3BTC) was thoroughly characterized and was modified onto the electrode via facile drop-casting method. The electrochemical response of GSH on the Ag-MOF modified electrode showed a significant reduction in the current signal because the Ag-GSH complex had stronger specific affinity than Ag-H3BTC and resulted in the collapse of the Ag-MOF. This sensor demonstrated an extensive linear dynamic range of 0.1 nM-1 µM, along with the low detection limit of 0.018 nM. Additionally, it exhibited good reproducibility, stability, and resistance to interfering compounds. The Ag-MOF modified electrode demonstrated superior performance attributed to its rapid electron transfer rate, outstanding electrochemical redox activity, and specific recognition/competitive reaction. These factors improved both sensitivity and selectivity. The high anti-interference ability allowed for the selective detection of GSH in intricate surroundings. In the real sample testing, the RSD was lower than 3.1% and the recovery was between 98.1 and 103%. This research highlights the potential of Ag-MOFs in developing electrochemical sensors and their promising applications in determining GSH for food screening and early disease diagnosis. [ABSTRACT FROM AUTHOR]

The design of a novel electrochemical impedimetric biosensor for label-free analysis of resistin, a biomarker for obesity, is reported. For the fabrication of the immunosensor, a novel approach composed of electrochemical copolymerization of double epoxy groups-substituted thiophene (ThidEp) and 3,4-Ethylenedioxythiophene (EDOT) monomers was utilized. Anti-resistin antibodies were covalently attached to the copolymer-coated electrode. The capture of resistin antigens by anti-resistin antibodies caused significant variations in charge transfer resistance (Rct) because of the immunoreactions between these proteins. Under optimum experimental variables, the changes in impedance signals were employed for the determination of resistin antigen concentration, and the prepared immunosensor based on conjugated copolymer illustrated a wide linear range between 0.0125 and 22.5 pg/mL, a low detection limit (LOD) of 3.71 fg/mL, and a good sensitivity of 1.22 kΩ pg−1mL cm2. The excellent analytical performance of the resistin immunosensor in terms of selectivity, sensitivity, repeatability, reproducibility, storage stability, and low detection limit might be attributed to the conductive copolymer film layer generation on the disposable indium tin oxide (ITO) platform. The capability of this system for the determination of resistin in human serum and saliva samples was also tested. The immunosensor results were in accordance with the enzyme-linked immunosorbent assay (ELISA) results. The matrix effects of human serum and saliva were also investigated, and the proposed immunosensor displayed good recovery ranging from 95.91 to 106.25%. The engineered immunosensor could open new avenues for obesity monitoring. [ABSTRACT FROM AUTHOR]

The development of an electrochemical aptasensor for the detection of CA125 as an ovarian cancer biomarker using gold nanostructures (GNs) modified electrodes is reported. The GNs were deposited on the surface of fluorine-doped tin oxide electrodes using a simple electrochemical method and the effects of pH and surfactant concentration on the topography and electrochemical properties of the resulting GNs modified electrodes were investigated. The electrodes were characterized using field-emission scanning electron microscopy and X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The best electrode, in terms of the uniformity of the deposited GNs and the increase in electroactive surface area, was used for development of an aptasensor for CA125 tumor marker detection in human serum. Signal amplification was done by using aptamer-conjugated gold nanorods resulting in the detection limit of 2.6 U/ml and a linear range of 10 to 800 U/ml. The results showed that without the need for expensive antibodies, the developed aptasensor could specifically measure the clinically relevant concentrations of the tumor marker in human serum. [ABSTRACT FROM AUTHOR]

A new nanocomposite consisting of lanthanum ferrite nanoparticles (LaFeO3 NPs) integrated with carbon nanotubes (CNTs) was fabricated via facile sonochemical approach. The engineered nanocomposite was applied to simultaneously determine acetaminophen (ACP) and dopamine (DA) in a binary mixture. The LaFeO3 NPs@CNT probe possesses several advantages such as superior conductivity, large surface area, and more active sites, improving its electrocatalytic activity towards ACP and DA. Under optimized conditions, the anodic peak currents (Ipa) linearly increased with increasing concentration of ACP and DA in the range 0.069–210 µM and 0.15–210 µM, respectively. The sensitivity of LaFeO3 NPs@CNTs/glassy carbon electrode (GCE) for detecting ACP and DA is 7.456 and 5.980 μA·μM−1·cm−2, respectively. The detection limits (S/N = 3) for ACP and DA are 0.02 μM and 0.05 μM, respectively. Advantages of LaFeO3 NPs@CNTs/GCE for the detection of ACP and DA include wide linear ranges, low-detection limits, good selectivity, and long-term stability. The as-fabricated electrode was applied to determine ACP and DA in pharmaceutical formulations and human serum samples with recoveries ranging from 97.7 to 103.3% and an RSD that did not exceed 3.7%, confirming the suitability of the proposed sensor for the determination of ACP and DA in real samples. This study not only presents promising opportunities for enhancing the sensitivity and stability of electrochemical sensors used in the detection of bioanalytes but also significantly contributes to the progress of unique and comprehensive biochemical detection methodologies. [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]

This article discusses the development of a modified electrode for the electrochemical sensing of dobutamine, a catecholamine compound. The modified electrode showed sensitive and selective detection of dobutamine, with a linear range of 0.1-2.0 ¿M. The electrode remained stable for 15 days without losing its electrochemical activity. The study provides a cost-effective method for the electrochemical determination of dobutamine. The document also includes a list of references to various research articles related to electrochemical sensing and the modification of pencil graphite electrodes for the detection of different substances. [Extracted from the article]

An antifouling electrochemical biosensor was constructed based on chondroitin sulfate (CS)-functionalized polyaniline (CS/PANI) and DNA-peptide conjugates that is capable of assaying cortisol directly in human fluids. First, a CS-doped PANI nanocomposite (sensing substrate) was electrodeposited onto a bare glassy carbon electrode to promote electron transport, providing the sensing signal from high peak currents of PANI to improve the sensitivity of the biosensor. Dendritic DNA-peptide conjugates were assembled onto the CS/PANI by exploiting the highly specific and strong interactions between biotin and streptavidin, which amplified the sensing signals toward cortisol. The integration of the DNA-peptide conjugates into the CS/PANI nanocomposite ensured that the biosensor had a synergistic antifouling effect and was capable of detecting cortisol directly in body fluids (sweat, saliva, and tears). When assaying cortisol levels, the biosensor exhibited a linear range over the cortisol concentrations of 1 × 10–12–1 × 10–7 M and a low limit of detection (0.333 × 10–12 M). In the detection of cortisol in real samples, the relative standard deviation (RSD) of the biological samples ranged from 2.94 to 4.23%, and the recovery were calculated to be in the range 95.2–103.2%. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemical biosensing platform has been designed by combining electrocatalysis-assisted H2S amplification with a chemical reaction-mediated electrochemical signal-boosted system for H2S detection based on Cu-Mn(OH)2 hexagonal nanorings. The signal amplification is initiated by an electrocatalysis reaction that can grasp specific H2S substrates and further highly amplify electrochemical signals. Then, the unique chemical reaction is powered by copper ion and generates a large amount of electroactive CuxS products on the electrode surface, thus achieving the multiple amplification of H2S detection. Finally, the Cu-Mn(OH)2 loaded with plenty of electroactive CuxS can be captured on the electrode for further improving the electrochemical signal thus obtaining ultra-high sensitive determination of H2S. The established electrochemical biosensing platform displays a wide analytical range of 0.1 μM to 265 μM with a low detection limit of 0.096 μM. The satisfactory selectivity allows the electrochemical sensor to distinguish H2S from other interfering substances without any complicated pretreatment, even in complex tumor cell samples. Thus, our designed electrocatalysis-assisted amplification strategy offers a powerful analysis toolkit for the early determination of H2S-related disease in clinical diagnosis. [ABSTRACT FROM AUTHOR]

A new electrochemical biosensor based on the sequence of chromosome Y (SRY) has been introduced to determine the gender of the fetus. At first, the DNA probe was designed based on the SRY gene sequence on chromosome Y. Then, a suitable functional group was added to the DNA probe, and it has been immobilized on the surface of the electrode modified with a nanocomposite containing Cu(OH)2 @N–C n-boxes. This substrate causes more DNA probes to connect to the electrode surface by increasing the effective surface area. The presence of the SRY sequence in the DNA sample extracted from blood was detected by the electrochemical signal of the bio-sensor. After optimizing the parameters, the fabricated genosensor showed linear responses in the two concentration ranges containing 0.5 fM to 50 pM and 50 pM to 500 nM. The limit of detection (LOD) for the proposed method was 0.16 fM. The proposed genosensor has been successfully used to determine the gender of the fetus using cell-free fetal DNA (cffDNA) in the blood plasma of several pregnant mothers. This method has advantages such as being simple, portable, accurate, and non-invasive for early determination of the gender of the fetus and early diagnosis of X-linked genetic disorders. [ABSTRACT FROM AUTHOR]

Nanostructures of graphene were synthesized for electrochemical carbendazim (CBZ) fungicide detection via metal–organic chemical vapor deposition (MOCVD). The arduous process of graphene transfer is eliminated by this innovative approach to MOCVD graphene development. It also generates several defects and impurities and ultimately leads to the uniform deposition of graphene on SiO2/Si. SEM, EDX, and ICP-AES were used to assess the morphological properties and chemical composition of the materials. To obtain in-depth knowledge of the entire system, the electrochemical behavior was also investigated using voltammetric techniques and electrochemical impedance spectroscopy. The interaction of particles of copper with CBZ and the enhanced surface area of graphene, which causes a strong oxidation current, has been demonstrated to achieve the ideal CBZ sensing behavior. The electrode responded linearly at CBZ concentration levels of 1 to 50 nM, and the sensitivity of the sensing materials was estimated to be 0.0337 Ω nM−1. The statistical analysis validates the electrode's exceptional selectivity and remarkable reproducibility in determining CBZ. [ABSTRACT FROM AUTHOR]

This study aims to develop a MIP-Apt-based electrochemical biosensor for the sensitive and selective determination of Lysozyme (Lyz), a food allergen. For the development of the sensor, in the first stage, modifications were made to the screen-printed electrode (SPE) surface with graphene oxide (GO) and gold nanoparticles (AuNPs) to increase conductivity and surface area. The advantages of using aptamer (Apt) and molecularly imprinted polymer (MIP) technology were combined in a single biointerface in the prepared sensing tool. Surface characterization of the biosensor was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectrometry (XPS), contact angle measurements, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). A wide linear range from 0.001 to 100 pM was obtained under optimized conditions for the determination of Lyz detection using the proposed MIP-Apt sensing strategy. The limit of detection (LOD) and limit of quantification (LOQ) for Lyz were 3.67 fM and 12 fM, respectively. This biosensor displays high selectivity, repeatability, reproducibility, and long storage stability towards Lyz detection. The results show that a sensitive and selective sensor fabrication is achieved compared with existing methods. [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]