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Purpose: This study aims to develop an electrochemical sensor for the detection of benzophenone (BP) as an alternative to conventional techniques that are known, expensive, complex and less sensitive. Design/methodology/approach: The developed sensor is a platinum electrode modified with a plasticized polymer film based on ß-cyclodextrin, using PVC as the polymer, PEG as the plasticizer and ß-CD as the ionophore. This sensor is characterized by various techniques, such as optical microscopy, scanning electron microscopy and cyclic voltammetry. This latter is also used for analyzing kinetic processes at the electrode/electrolyte interface and to evaluate the selectivity and sensitivity of the sensor. Findings: The results highlight the performance of our sensor. In fact, it exhibits a linear response extending from 10−19 to 10−13 M, with a correlation coefficient of 0.9836. What is more, it has an excellent detection limit of 10−19 M and a good sensitivity of 21.24 µA/M. Originality/value: The results of this investigation demonstrated that the developed sensor is an analytical tool of choice for the monitoring of BP in the aqueous phase. The suggested sensor is fast, simple, reproducible and inexpensive. [ABSTRACT FROM AUTHOR]

A convenient, non-toxic, and low-cost tin dioxide (SnO2)/nickel oxide (NiO)/reduced graphene oxide (rGO) nanocatalytic electrode was investigated, which can effectively promote the hydrogen evolution reaction and can also be used to construct a sensitive winter wheat cold-tolerant RNA sensor. Due to the good synergy and photocurrent generation between SnO2 and NiO, which accelerates the electron transfer and catalyzes the hydrolysis reaction, the resultant data for the hydrogen evolution reaction in alkaline environment of this material are very impressive, with cathodic current densities of up to 10 mA cm−2. The marvelous heterostructures and photovoltaic properties form a signal amplification system, which enables the nanocomposites to have an excellent linear sensitivity in low-concentration RNA solutions. The single-stranded complementary RNA of the target RNA was immobilized on the surface of the nanocomposites, which enabled the materials to recognize the target RNA under enzyme-free conditions. The test results showed that the modified electrode materials had good single detection performance in a wide linear range from 0.1 nM to 2 mM, with the limit of detection (LOD) of 0.078 nM. The developed nanocomposite electrode has good performance in hydrogen evolution and winter wheat cold-resistant RNA detection, and is a bifunctional device with superior performance. [ABSTRACT FROM AUTHOR]

A new type of label-free electrochemical immunosensor for the high-sensitivity determination of parathion was developed based on the oriented immobilization of nanobody (VHH9) on a gold nanoparticle-loaded polyvinyl alcohol/citric acid nanofiber membrane-modified electrode. The morphology characterization and assembly process of the modified materials were investigated using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, the label-free electrochemical immunosensor for parathion exhibited a linear range of 0.0015–6400 ng/mL and a low detection limit of 0.48 pg/mL, the signal response of which was 10 times higher than that of the randomly immobilized VHH9. The immunosensor possessed high selectivity, good repeatability and reusability (keeping above 90% of its initial activity after repeating 8 times), and stability (remaining 90% after 9 weeks of storage). Finally, the average recoveries of parathion from food samples were 93.76–105.73% with the coefficient of variation being 2.65–6.85%, showing good correlation with UPLC (R2 = 0.9950). Therefore, our nanobody immobilization protocol is simple and effective and proves the potential to be utilized as a promising candidate for sensing platform. [ABSTRACT FROM AUTHOR]

This work comprehends the development and characterization of a carbon black-based electrode modified with Au microflowers to increase its effect as a capacitance biosensor for the determination of PARK7/DJ-1. Due to its high surface-to-volume ratio and biocompatibility, Au particles are suitable for antibody binding, and by monitoring surface capacitance, it is possible to identify the immune-pair interaction. Au microflowers allowed the adequate immobilization of Parkinsonian-related proteins: PARK7/DJ-1 and its antibody. The protein is associated with several antioxidant mechanisms, but its abnormal concentrations or mutations can be the cause of the loss of dopaminergic neurons, leading to Parkinson's disease. The device was characterized by scanning electron microscopy and cyclic voltammetry, revealing the flower-like structures and the electrochemically-interest enhancements they provide, such as increased heterogeneous electron transfer rate coefficient and electroactive area. The self-assembled monolayers of different molecules were optimized with the aid of 22 central composite experiments and a linear calibration curve was obtained between 0.700 and 120 ng mL-1 of PARK7/DJ-1, with a limit of detection of 0.207 ng mL-1. The data confirms that the addition of Au microflowers enhanced the electrochemical signal of the device, as well as allowed for the determination of an early stage Parkinson's disease biomarker with appreciable analytical performance. [ABSTRACT FROM AUTHOR]

The overexpression of interleukin-17A (IL-17A) is closely associated with the pathogenesis of autoimmune diseases and cancer, rendering precise identification of IL-17A level critical for disease diagnosis and prognosis monitoring. In this study, CsPbBr3 nanoclusters (NCs) were embedded in C16H14Br2O6Pb2 organometallic compound (Pb-MA MOC) via a hot injection approach. Through this way, the issue of CsPbBr3 NCs susceptible to decomposition in water was solved, and the photocurrent intensity that is generated by CsPbBr3 was significantly enhanced. A highly sensitive photoelectrochemical (PEC) sensor for detecting IL-17A in human serum was developed using CsPbBr3/Pb-MA as the photoactive material. The electrode was initially modified with CsPbBr3/Pb-MA. Then, antibody-modified Fe3O4 magnetic nanoparticles (MNs) with target analyte IL-17A captured, and IL-17A antibody-modified Au@CuNi diatomic catalyst (DAC) formed sandwich immune complex structure on the electrode. The existence of CuNi DAC led to a substantial reduction in photoelectric signal intensity due to oxidation of ascorbic acid in the supporting electrolyte. The photocurrent intensity exhibited linear correlation with IL-17A concentration within the range 15-750 pg/mL, and achieving an impressive detection limit of 1 pg/mL. Moreover, the sensor was successfully applied to the determination of IL-17A in human serum, suggesting its potential clinical applications. [ABSTRACT FROM AUTHOR]

In order to improve the activity of copper (Cu) towards electrolytic reduction of nitrate, thin films of magnesium hydroxide (Mg(OH)2) were deposited on Cu substrate. For the first time, these films were synthesized by electrochemical deposition in a potassium sulfate bath containing Mg2+ at 70 °C. The effect of various experimental parameters, such as deposition time and potential, on the electrocatalytic activity for the nitrate reduction was investigated. Surface analysis techniques (SEM, EDX and XRD) were used to get information on the morphology, the composition and the structure of the deposits. The activity of the modified electrode was studied by cyclic voltammetry, and amperometric method. The modified Mg(OH)2/Cu sensor exhibited a good electrocatalytic behavior towards the reduction of nitrates with high reproducible reduction peak currents. In addition, the sensor exhibits a linear answer for concentration in nitrate between 0.125 to 7 mM, combined with high sensitivity (24.6 µA mM−1 cm−2) and limit of detection (225.35 µM) values. When common interfering molecules were added to the solution, Mg(OH)2/Cu electrodes have kept their good selectivity. They demonstrated acceptable detection levels for nitrates in tap water. [ABSTRACT FROM AUTHOR]

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 new electrochemical sensor for the highly sensitive and selective determination of dopamine was developed, based on the use of a glassy carbon electrode modified with cobalt(II) polymer. Both electrochemical and morphological characterizations were investigated. Square wave voltammetry (SWV) was used for the determination of dopamine. From the SWV results obtained on the modified electrode under the optimized conditions, the successive addition of dopamine increased the anodic peak current. The results obtained show a linear response of the electrode modified with Co(II) polymer in a wide concentration range. Each concentration decade is characterized by a new calibration plot with a corresponding mathematical expression. The highest sensitivity (13.182) was obtained for the lowest concentration range, and the detection limit of 0.03 µM, calculated based on the 3 × sb/m criterion, indicates a very high sensitivity and great application potential. When analyzing a real sample, the modified electrode showed good electroanalytical activities in terms of oxidation of dopamine, good anti-interference ability, stability, reproducibility, and potential applicability in commercial pharmaceutical samples. [ABSTRACT FROM AUTHOR]

In this study, a zinc/aluminium layered double hydroxide (LDH) was synthesized and characterized using FESEM, EDX, and FT-IR spectroscopy. The LDH was incorporated into carbon paste to create an electrochemical sensor for mesalazine detection. This sensor was employed as the working electrode in voltammetric determination of mesalazine. Experimental conditions were optimized, with 5 mg of modifier and pH 6. Electrochemical parameters were set at 50 mV pulse amplitude, 30 ms pulse time, and 40 mV s−1 scan rate. The sensor displayed linear anodic peak current responses for mesalazine concentrations ranging from 5 to 100 and 100 to 600 μM, with a detection limit of 2.5 μM. Reproducibility was assessed through inter- and intra-day relative standard deviations of 2.2% and 2.9%, respectively. Selectivity was tested against potential interferences like ascorbic acid, oxalic acid, glucose, sucrose, and folic acid. The successful mesalazine detection in real samples highlighted the sensor's potential as an efficient analytical tool. [ABSTRACT FROM AUTHOR]

Modifying the electrodes of electrochemical sensors is critical to enhance sensitivity, selectivity, and stability, ultimately improving both their effectiveness and performance. In this paper, recent advancements in electrochemical sensors are reviewed, focusing on the utilization of layered double hydroxides (LDHs). The first section explores the advantageous and disadvantageous aspects of electrochemical sensing. Benefits include rapid response, ease of operation, and cost-effectiveness, while drawbacks concern the potential instability of prolonged use, susceptibility to interference, and the risk of biomolecule inactivation. Following this, the second section delves into the synthesis, constituents, and structure of LDHs. Moreover, after introducing the chemical mechanisms and functions of LDHs in electrochemical sensors, we concentrate on diverse modifying materials of LDHs and their different performances. Finally, the applications of LDHs in electrochemical sensing across different fields are discussed. This review aims to facilitate the continued advancement for applying LDHs in electrochemical sensors, as well as inspire the evolution of electrochemical sensing technology. [ABSTRACT FROM AUTHOR]

ABSTRACT The development of low‐cost, high‐efficiency, stable, and structurally adjustable electrocatalysts for hydrogen evolution reaction (HER) is of great significance for energy conversion. In this study, two new Cu(I) coordination polymers (CPs), formulated as {[Cu(L1)](PF6)·CH2Cl2}n (1) and {[Cu2(L2)1.5(PPh3)](PF6)2}n (2) (L1 = 1,3‐bis[1‐(pyridin‐3‐ylmethyl) ‐1H‐benzimidazol‐2‐yl]propane, L2 = 1,4‐bis[1‐(3‐pyridylmethyl)‐1H‐benzimidazol‐2‐yl]butane), were synthesized by interfacial diffusion method and characterized by single‐crystal x‐ray diffraction and IR and UV–Vis spectra. Structural analysis shows that the CP‐1 is a one‐dimensional chain structure, whereas the CP‐2 is a two‐dimensional layered structure, which is due to the different coordination modes of ligands L1 (bridging chelation) and L2 (bridging). The electrocatalytic activity for HER of Cu(I) CPs was studied by preparing modified glassy carbon electrodes (CP‐1/GCE and CP‐2/GCE). Electrochemical HER studies manifest that in 0.5 M H2SO4, the overpotential (η10298K) and Tafel slope (b 298K) are −769 mV and 173 mV dec−1 for CP‐1/GCE, −933 mV and 301 mV dec−1 for CP‐2/GCE, and −930 mV and 298 mV dec−1 for bare/GCE, respectively. The η10298K and b298K of CP‐1/GCE were significantly positive shifted and decreased compared with the bare/GCE, indicating that CP‐1/GCE has significant electrocatalytic activity and electrocatalytic HER activity order is CP‐1/GCE > CP‐2/GCE ≈ bare/GCE. This work provides an important reference for the application of non‐noble metal CPs in the field of electrocatalysis. [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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This report presents a new application for yttrium oxide (YOX) in the modification of carbon paste electrodes with excellent electroactivity for the independent detection of dopamine (DA) and ascorbic acid (AA). The surface of the YOX‐modified electrode was characterized with SEM and EDS. The electroactive properties of DP and AA were studied with cyclic voltammetry (CV), square wave voltammetry (SWV) and amperometry (Am). The activity of DA and AA increased by more than 100 % when YOX/CPE was used, which allowed us to obtain detection limits of 0.04 and 0.06 μmol/L for DA and AA, respectively. The usefulness of YOX/CPE was tested with real human urine, fresh orange juice and vitamin C tablets, and the results were acceptable. [ABSTRACT FROM AUTHOR]

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]

A novel photoelectrochemical (PEC) sensor for the detection of microcystic toxins (MC-LR) was developed on the basis of signal-sensitive change strategy. NiO nanoarray as a basic photoactive material was grown directly on the ITO glass electrode via calcination after hydrothermal reaction, while dye N719 was used to sensitize the electrode for enhancing visible light absorption, and the first signal-on stage was obtained. In the meantime, p-type Cu2O was applied as the signal probe attached to probe DNA (DNA2) to improve the sensitivity, and the second "signal-on" stage appeared because of its synergistic effect with NiO nanoarrays. The PEC signal decreases after the target analyte MC-LR is modified on the electrode due to the stronger affinity between MC-LR and its complementary aptamer DNA; part of the Cu2O-DNA2 will dissociate from the electrode. This sensitive signal change strategy allows the detection limit of the MC-LR sensor to be as low as 1.7 pM, which offers an optional method for the sensitive and selective detection of other target molecules, with potential applications in environmental monitoring and toxin determination. [ABSTRACT FROM AUTHOR]

Atherosclerosis cardiovascular disease (ASCVD) has become one of the leading death causes in humans. Low-density lipoprotein (LDL) is an important biomarker for assessing ASCVD risk level. Thus, monitoring LDL levels can be an important means for early diagnosis of ASCVD. Herein, a novel electrochemical aptasensor for determination LDL was designed based on nitrogen-doped reduced graphene oxide-hemin-manganese oxide nanoparticles (NrGO-H-Mn3O4 NPs) integrated with clustered regularly interspaced short palindromic repeats and associated proteins (CRISPR/Cas12a) system. NrGO-H-Mn3O4 NPs not only have a large surface area and remarkable enhanced electrical conductivity but also the interconversion of different valence states of iron in hemin can provide an electrical signal. Nonspecific single-stranded DNA (ssDNA) was bound to NrGO-H-Mn3O4 NPs to form a signaling probe and was immobilized on the electrode surface. The CRISPR/Cas12a system has excellent trans-cleavage activity, which can be used to cleave ssDNA, thus detaching the NrGO-H-Mn3O4 NPs from the sensing interface and attenuating the electrical signal. Significant signal change triggered by the target was ultimately obtained, thus achieving sensitive detection of the LDL in range from 0.005 to 1000.0 nM with the detection limit of 0.005 nM. The proposed sensor exhibited good stability, selectivity, and stability and achieved reliable detection of LDL in serum samples, demonstrating its promising application prospects for the diagnostic application of LDL. [ABSTRACT FROM AUTHOR]

An electrochemical aptasensor was developed by utilizing a DNA walker driven by catalytic hairpin assembly (CHA) with kanamycin as the model analyte. Kanamycin bound to the aptamer, causes the release of DNA walker, triggers the CHA reaction, leads to the cyclic movement of the walker's long arm, and results in cascade amplification of the signal. The guanine-rich sequences of the double-stranded products produced by CHA were folded to form G-quadruplex structures, with electrochemical active molecules Hemin embedded, forms G-quadruplex/Hemin complexes in situ on the electrode surface, thereby achieving sensitive, efficient, and label-free detection of kanamycin with a limit of detection (LOD) of 0.27 pM (S/N = 3). Meaningfully, the aptasensor demonstrated high sensitivity and reliability in the detection of kanamycin in milk and livestock wastewater samples, suggesting that it has great potential for application in detecting antibiotics in food products and water samples from the environment. [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]

Caffeic acid contributes to the flavor and aroma of coffee. Monitoring its levels can be important to guarantee the quality of the coffee produced. An innovative electrochemical sensor for the determination of caffeic acid was developed using banana pulp (Musa sapientum) extract as the precursor for the green synthesis of gold nanoparticles. Microscopic images verified the presence of dispersed gold nanoparticles, with an average diameter of 14.4 ± 2.5 nm on graphene sheets. The electrochemical behavior of caffeic acid demonstrated reversibility, with oxidation and reduction peaks. Under optimized conditions, a calibration curve was developed in 0.1 mol L−1 Britton-Robinson buffer (pH 2.0) with linear range from 0.05 to 10.0 µmol L−1, and a detection limit of 16 nmol L−1. The sensor was effective in coffee samples, and the results were comparable to those obtained using UV–vis spectrometry. [ABSTRACT FROM AUTHOR]

We introduced a voltammetric bisphenol A (BPA) sensor based on NiCo2O4/reduced graphene oxide (rGO) nanocomposite loaded on the screen-printed electrode surface (NiCo2O4/rGO/SPE). NiCo2O4/rGO was characterised using various techniques, including X-ray diffraction (×RD), Raman spectroscopy and scanning electron microscopy (SEM). We used differential pulse voltammetry (DPV) to detect BPA concentrations. We evaluated the key analytical features of NiCo2O4/rGO/SPE for the BPA detection and the effects of important experimental parameters on the voltammetric efficiency. The voltammetric response of the proposed electrode was evaluated towards BPA. We demonstrated that the produced electrode has a wide linear dynamic range (0.03 to 475.0 μM) and a detection limit as low as 0.01 μM at S/N = 3. [ABSTRACT FROM AUTHOR]

Hydroxylamine (HA) is a toxic and mutagenic molecule which are in the top list of environmental pollutants. We developed a sensitive HA electrochemical sensor constructed with electrocatalytic performance of magnesium aluminate spinel nanoparticles (MgAl2O4). The electrochemical activity of HA on magnesium aluminate spinel nanoparticles modified screen-printed electrode (MgAl2O4/SPE) was analysed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and chronoamperometry. According to the findings, the modified electrode had admirable electrocatalytic performance towards HA. As-fabricated electrochemical sensor displayed an unparalleled performance in detection of HA with a low limit of detection (0.035 μM, S/N = 3) in a lengthy linear dynamic range (0.09–375.0 μM). The developed protocol was successful in sensing HA in water specimens, with satisfactory outcomes. [ABSTRACT FROM AUTHOR]

We describe a simple hydrothermal method for preparing a nanocomposite of reduced graphene oxide/Mn3O4 (rGO/Mn3O4), and its use in electrochemically detecting tramadol (TRA). The sensor was constructed by using a glassy carbon electrode modified with a rGO/Mn3O4 nanocomposite (rGO/Mn3O4/GCE) as an electro‐catalyst. The electrochemical properties of TRA at rGO/Mn3O4/GCE were studied using cyclic voltammetry (CV), chronoamperometry, and differential pulse voltammetry (DPV) in a phosphate buffer solution (PBS) with a pH of 8.0. The oxidation peak currents of TRA on rGO/Mn3O4/GCE increased compared to the bare GCE. This enhancement was attributed to the high surface area and excellent electron transfer performance of the rGO/Mn3O4 nanocomposite on the surface of the electrode. Under optimal conditions, the oxidation peak currents exhibited a linear increase with the concentration of TRA within the range of 0.5 to 700.0 μM, and a detection limit (LOD) of 0.16 μM was achieved. This study has shown that the rGO/Mn3O4/GCE can effectively be used to analyze TRA in real specimens. [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 novel electrochemical method is presented for ultrasensitive detection of the organophosphate pesticide (OPP) fenitrothion by using Ti3C2 MXene/CoAl-LDH nanocomposite as the electrode modifier. The Ti3C2 MXene/CoAl-LDH nanocomposite is synthesized by growing CoAl-LDH in situ on MXene nanosheets. The combination of two ultrathin 2D materials provides more active sites, larger specific surface area, superior adsorption properties, and better electrical conductivity, which leads to rapid electron-transfer and mass-transfer between the substrate electrode and analytes when it is acted as the electrochemical sensing material. In addition, through the chelation of phosphate groups with the Ti defect sites enriched in MXene, OPP is adsorbed on the electrode. Consequently, the corresponding modified electrode gives rise to a wide linear response range of 0.03 ~ 120 μmol/L for the differential pulse voltammetry detection of fenitrothion with a low detection limit of 5.8 nmol/L (3σ). The method offers good repeatability, stability, selectivity, and practicability for real samples. This strategy provides a reference platform for the electrochemical monitoring of trace OPPs residue by using MXene/LDH-based nanocomposites. [ABSTRACT FROM AUTHOR]

An electrochemical sensor assisted by primer exchange reaction (PER) and CRISPR/Cas9 system (PER-CRISPR/Cas9-E) was established for the sensitive detection of dual microRNAs (miRNAs). Two PER hairpin (HP) were designed to produce a lot of extended PER products, which could hybridize with two kinds of hairpin probes modified on the electrode and initiate the cleavage of two CRISPR/Cas9 systems guided by single guide RNAs (sgRNAs) with different recognition sequences. The decrease of the two electrochemical redox signals indicated the presence of dual-target miRNAs. With the robustness and high specificity of PER amplification and CRISPR/Cas9 cleavage system, simultaneous detection of two targets was achieved and the detection limits for miRNA-21 and miRNA-155 were 0.43 fM and 0.12 fM, respectively. The developed biosensor has the advantages of low cost, easy operation, and in-situ detection, providing a promising platform for point-of-care detection of multiple miRNAs. [ABSTRACT FROM AUTHOR]

A Ti3C2TxMXene-based biosensor has been developed and the photocatalytic atom transfer radical polymerization (photo ATRP) amplification strategy applied to detect target miRNA-21 (tRNA). Initially, Ti3C2TxMXene nanosheets were synthesized from the Ti3AlC2 MAX precursor via selective aluminum etching. Then, functionalization of Ti3C2TxMXene nanosheets with 3-aminopropyl triethoxysilane (APTES) via silylation reactions to facilitate covalent bonding with hairpin DNA biomolecules specifically designed for tRNA detection. Upon binding with the tRNA, the hairpin DNA liberated the azide (N₃) group, initiating a click reaction to affix to the photo ATRP initiator. Through the ATRP photoreaction, facilitated by an organic photoredox catalyst and light, a significant amount of ferrocenyl methyl methacrylate (FMMA) monomer was immobilized on the electrode. Therefore, the electrochemical signal is amplified. The electrochemical efficacy of the biosensor was assessed using square wave voltammetry (SWV). Under optimized conditions, the biosensor demonstrated remarkable sensitivity in detecting tRNA, with a linear detection range from 0.01 fM to 10 pM and a detection limit of 2.81 aM. The findings elucidate that the developed biosensor, in conjunction with the photo ATRP strategy, offers reproducibility, stability, and increased sensitivity, underscoring its potential applications within the experimental medical sector of the biomolecular industry. [ABSTRACT FROM AUTHOR]

CoFe@C was first prepared by calcining the precursor of CoFe-metal–organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC). [ABSTRACT FROM AUTHOR]

Polydopamine (PDA) has garnered significant interest for applications in biosensors, drug delivery, and tissue engineering. However, similar polycatecholamines like polynorepinephrine (PNE) with additional hydroxyl groups and poly-α-methylnorepinephrine (PAMN) with additional hydroxyl and methyl groups remain unexplored in the biosensing domain. This research introduces three innovative biosensing platforms composed of ternary nanocomposite based on reduced graphene oxide (RGO), gold nanoparticles (Au NPs), and three sister polycatecholamine compounds (PDA, PNE, and PAMN). The study compares and evaluates the performance of the three biosensing systems for the ultrasensitive detection of Mycobacterium tuberculosis (MTB). The formation of the nanocomposites was meticulously examined through UV–Visible, Raman, XRD, and FT-IR studies with FE-SEM and HR-TEM analysis. Cyclic voltammetry and differential pulse voltammetry measurements were also performed to determine the electrochemical characteristics of the modified electrodes. Electrochemical biosensing experiments reveal that the RGO-PDA-Au, RGO-PNE-Au, and RGO-PAMN-Au-based biosensors detected target DNA up to a broad detection range of 0.1 × 10−8 to 0.1 × 10−18 M, with a low detection limit (LOD) of 0.1 × 10−18, 0.1 × 10−16, and 0.1 × 10−17 M, respectively. The bioelectrodes were proved to be highly selective with excellent sensitivities of 3.62 × 10−4 mA M−1 (PDA), 7.08 × 10−4 mA M−1 (PNE), and 6.03 × 10−4 mA M−1 (PAMN). This study pioneers the exploration of two novel mussel-inspired polycatecholamines in biosensors, opening avenues for functional nanocoatings that could drive further advancements in this field. [ABSTRACT FROM AUTHOR]

In this research, CuCo2O4 nanorods (CuCo2O4 NRs) were prepared using a simple hydrothermal technique and characterized by using various techniques. Subsequently, a highly sensitive and simple electrochemical sensor was prepared by modifying a screen-printed graphite electrode with CuCo2O4 NRs (CuCo2O4 NRs/SPGE) and applied for the detection of sudan I. The electrocatalytic oxidation of sudan I was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry, and linear sweep voltammetry (LSV). The modification of the electrode surface with CuCo2O4 NRs exhibited the highest electro-catalytic activity towards sudan I oxidation, resulting in an improved sensitivity compared to the unmodified electrode. Based on these findings, we analyzed a screen-printed sensor (CuCo2O4 NRs/SPGE) using DPV for sudan I determination. The sensor demonstrated a linear response ranging from 0.04 µM to 560.0 µM, with a limit of detection (LOD) of 0.01 µM and a sensitivity of 0.097 µM/µA. The suitability of the proposed sensor for sudan I determination in real samples was also demonstrated, with good recovery results ranging from 97.6 to 104.0% and a maximum relative standard deviation (RSD) of 3.5%. [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]

Amlodipine (AM) is a long active calcium channel blocker used to relax blood vessels by preventing calcium ion transport into the vascular walls and its supporting molecules acetaminophen (AP) and ascorbic acid (AA) are recommended for hypertension control and prevention. Considering their therapeutic importance and potential side effects due to over dosage, we have fabricated a sensor for individual and simultaneous determination of AA, AP, and AM in pharmaceuticals and human urine using novel Zn-doped Ca2CuO3 nanoparticles modified glassy carbon electrode (GCE). Optimally doped Ca2CuO3 (2.5 wt% Zn at Cu site) enhanced the detection of target molecules over much wider concentration ranges of 50 to 3130 µM for AA, 0.25 to 417 µM for AP, and 0.8 to 354 µM for AM with the corresponding lowest detection limits of 14 µM, 0.05 µM, and 0.07 µM, respectively. Furthermore, the Zn-Ca2CuO3/GCE exhibited excellent selectivity and high sensitivity even in the presence of several potential interfering agents. The usefulness of the developed electrode was tested using an amlodipine besylate tablet and urine samples of seven hypertension patients under medication. The results confirmed the presence of a significant amount of AP and AM in six patients' urine samples indicating that the personalized medication is essential and the quantum of medication need to be fixed by knowing the excess medicines excreted through urine. Thus, the Zn-Ca2CuO3/GCE with a high recovery percentage and good sensitivity shall be useful in the pharmaceutical and biomedical sectors. [ABSTRACT FROM AUTHOR]

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn2S4 as the photoanode and Cu2O@Ag@Ag3PO4 as the sensing cathode is designed for the detection of Hg2+. An indium tin oxide (ITO) electrode modified with ZnIn2S4 was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn2S4 can generate photogenerated electrons well. The unique hydrangea structure of ZnIn2S4 can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu2O@Ag@Ag3PO4 with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn2S4 photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg2+ (1 mM–1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform. [ABSTRACT FROM AUTHOR]

A sensing interface co-constructed from the two-dimensional conductive material (Ag@MXene) and an antifouling cyclic multifunctional peptide (CP) is described. While the large surface area of Ag@MXene loads more CP probes, CP binds to Ag@MXene to form a fouling barrier and ensure the structural rigidity of the targeting sequence. This strategy synergistically enhances the biosensor's sensitivity and resistance to contamination. The SPR results showed that the binding affinity of the CP to the target was 6.23 times higher than that of the antifouling straight-chain multifunctional peptide (SP) to the target. In the 10 mg/mL BSA electrochemical fouling test, the fouling resistance of Ag@MXene + CP (composite sensing interface of CP combined with Ag@MXene) was 30 times higher than that of the bare electrode. The designed electrochemical sensor exhibited good selectivity and wide dynamic response range at PD-L1 concentrations from 0.1 to 50 ng/mL. The lowest detection limit was 24.54 pg/mL (S/N = 3). Antifouling 2D materials with a substantial specific surface area, coupled with non-straight chain antifouling multifunctional peptides, offer a wide scope for investigating the sensitivity and antifouling properties of electrochemical sensors. [ABSTRACT FROM AUTHOR]

A competitive-type photoelectrochemical (PEC) aptasensor coupled with a novel Au@Cd:SnO2/SnS2 nanocomposite was designed for the detection of 17β-estradiol (E2) in microfluidic devices. The designed Au@Cd:SnO2/SnS2 nanocomposites exhibit high photoelectrochemical activity owing to the good matching of cascade band-edge and the efficient separation of photo-generated e−/h+ pairs derived from the Cd-doped defects in the energy level. The Au@Cd:SnO2/SnS2 nanocomposites were loaded into carbon paste electrodes (CPEs) to immobilize complementary DNA (cDNA) and estradiol aptamer probe DNA (E2-Apt), forming a double-strand DNA structure on the CPE surface. As the target E2 interacts with the double-strand DNA, E2-Apt is sensitively released from the CPE, subsequently increasing the photocurrent intensity due to the reduced steric hindrance of the electrode surface. The competitive-type sensing mechanism, combined with high PEC activity of the Au@Cd:SnO2/SnS2 nanocomposites, contributed to the rapid and sensitive detection of E2 in a "signal on" manner. Under the optimized conditions, the PEC aptasensor exhibited a linear range from 1.0 × 10−13 mol L−1 to 3.2 × 10−6 mol L−1 and a detection limit of 1.2 × 10−14 mol L−1 (S/N = 3). Moreover, the integration of microfluidic device with smartphone controlled portable electrochemical workstation enables the on-site detection of E2. The small sample volume (10 µL) and short analysis time (40 min) demonstrated the great potential of this strategy for E2 detection in rat serum and river water. With these advantages, the PEC aptasensor can be utilized for point-of-care testing (POCT) in both clinical and environmental applications. [ABSTRACT FROM AUTHOR]

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn2S4 as the photoanode and Cu2O@Ag@Ag3PO4 as the sensing cathode is designed for the detection of Hg2+. An indium tin oxide (ITO) electrode modified with ZnIn2S4 was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn2S4 can generate photogenerated electrons well. The unique hydrangea structure of ZnIn2S4 can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu2O@Ag@Ag3PO4 with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn2S4 photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg2+ (1 mM–1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform. [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]

The electrochemical and electrocatalytic behavior of gold electrodes modified with tetra-4-sulfophthalocyaninates of nickel(II) (NiPc) and copper(II) (CuPc) is studied in aqueous alkaline solutions using cyclic voltammetry. The electrocatalytic activity of phthalocyaninates of these metals in the oxidation of hydroxide ions to form molecular oxygen is assessed and compared with the literature data. [ABSTRACT FROM AUTHOR]

A nanocomposite of Ce-doped ZnO/r-GO was synthesized using a conventional hydrothermal method. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of cyclobenzaprine hydrochloride (CBP). The properties of the composite were extensively analyzed, including its morphology, structure, and electrochemical behavior. This study investigates the application of a modified glassy carbon electrode for the detection of CBP, a muscle relaxant used to treat musculoskeletal diseases that cause muscle spasms. The electrode is modified with Ce-doped ZnO/r-GO. Various detection methods, such as cyclic voltammetric and square wave techniques (SWV), were utilized. The composite material showed high effectiveness as an electron transfer mediator in the oxidation of CBP. The electrode showed a good response for SWV evaluations in CBP identification, with a minimum detection limit of 1.6 × 10−8 M and a wide linear range from 10 × 10−6 M to 0.6 × 10−7 M, under ideal conditions. The rate constant for charge transfer (ks) and the estimation of the electrochemical active surface area were obtained. A developed sensor exhibited desirable selectivity, long-lasting stability, and remarkable reproducibility. A sensor was used to analyze water, human serum, and urine samples, resulting in positive recovery results. [ABSTRACT FROM AUTHOR]

An innovative electrochemical sensing method is introduced for dihydroxy benzene (DHB) isomers, specifically hydroquinone (HQ) and pyrocatechol (PCC), employing a zinc-oxide/manganese-oxide/reduced-graphene-oxide (ZnO/MnO2/rGO) nanocomposite (NC) as an electrode modifier material. Comprehensive characterization confirmed well-dispersed ZnO/MnO2 nanoparticles on rGO sheets. Electrochemical analysis revealed the ZnO/MnO2/rGO-NC-based modified electrode possesses low electrical resistance (126.2 Ω), high electrocatalytic activity, and rapid electron transport, attributed to the synergies between ZnO, MnO2 and rGO. The modified electrode demonstrated exceptional electrochemical performance in terms of selectivity for the simultaneous detection of HQ and PCC. Differential pulse voltammetry studies validated the proposed sensor's ability to detect HQ and PCC within linear response ranges of 0.01–115 μM and 0.03–60.53 μM, with detection limits of 0.0055 µM and 0.0053 µM, respectively. Practical validation using diverse water samples showcased excellent percent recovery of HQ and PCC using the ZnO/MnO2/rGO-based electrochemical sensor, underscoring the sensor's potential for real-world applications in environmental monitoring. [ABSTRACT FROM AUTHOR]

A signal-amplified platform was designed to construct a label-free electrochemical aptasensor for lead ions (Pb2+) assay. First, flower-like molybdenum disulfide-supported AuNPs (AuNPs@MoS2) nanocomposites were synthesized and used as substrates for modifying the electrode. The AuNPs@MoS2 material possessed large surface area and superior biocompatibility, which was beneficial to improve the loading amount of the complementary DNA (cDNA) and amplified the response signal. Importantly, the prepared core–shell Pt@Pd bimetallic nanoparticles (Pt@PdNPs) were used to conjugate with redox marker thionine (Thi) and aptamer (Apt) for further signal amplification; the obtained signal probes (Thi-Pt@PdNPs-Apt) were connected by the cDNA assembled on the electrode through DNA hybridization. Differential pulse voltammetry was performed to monitor the signal of Thi. After incubating of aptasensor with Pb2+, the specific recognition of Pb2+ and Apt resulted in the dissociation of aptamer-cDNA complex, thereby the Thi-Pt@PdNPs-Apt separated from the electrode surface and decreased current response was obtained. The prepared electrochemical sensor exhibited linear response to Pb2+ in the range 5.0 × 10−4–100 nM and a detection limit of 1.0 × 10−4 nM was achieved. The sensor was applied to the determination of Pb2+ in actual sample with high sensitivity and accuracy, demonstrating potential applications in heavy metal monitoring. [ABSTRACT FROM AUTHOR]

Single atom catalysts (SACs) have attracted attention due to their excellent catalysis activity under specific reactions and conditions. However, the low density of SACs greatly limits catalytic performance. The three-dimensional graphene hollow nanospheres (GHSs) with very thin shell structure can be used as excellent carrier materials. Not only can its outer surface be used to anchor metal single atoms, but its inner surface can also provide rich sites. Here, a novel step-by-step assembly strategy is reported to anchor nickel single atoms (Ni SAs) on the inner and outer surfaces of GHSs (Ni SAs/GHSs/Ni SAs), which significantly increases the loading capacity of Ni SAs (4.8 wt%). Compared to conventional materials that only anchor Ni SAs to the outer surface of the carrier (Ni SAs/GHSs), Ni SAs/GHSs/Ni SAs exhibits significantly higher electrocatalytic activity toward glucose oxidation in alkaline media. The sensitivity of Ni SAs/GHSs/Ni SAs/GCE is nearly five times higher than that of Ni SAs/GHSs/GCE. Moreover, the sensor based on Ni SAs/GHSs/Ni SAs can detect glucose in a wide concentration range of 0.8 µM–1.1244 mM with a low detection limit of 0.19 µM (S/N = 3). This study not only provides an effective sensing material for glucose detection, but also opens a new avenue to construct high-density metal SACs. [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]