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Upadacitinib (UPA) is a selective and reversible oral Janus kinase (JAK) 1 inhibitor and is of great importance in treating inflammatory bowel disease (Zheng et al., Int Immunopharmacol 126:111229, 2024; Foy et al., JAAD Case Rep 42:20–22, 2023). Although there are limitations to the effectiveness of UPA, it has received positive responses in clinical trials and is approved for the treatment of atopy dermatitis (AD) (Li et al., Int Immunopharmacol 125:111193, 2023). In this study, a nanoparticle-doped molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for sensitive and selective detection of UPA. The developed sensor was designed as a thin film layer using the photopolymerization method on the surface of the prepared nanoparticle-doped polymerization solution glassy carbon electrode (GCE). Various nanoparticles, such as multi-walled carbon nanotube, titanium dioxide, oxide, and zinc oxide (ZnO) nanoparticles, were the most suitable for UPA. Surface characterization of the developed sensor was done by scanning electron microscopy (SEM), and electrochemical characterization was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The quantitative analysis of UPA was performed in 5.0 mM [Fe (CN)6]3−/4− solution using the differential pulse voltammetry (DPV) technique. Under optimum conditions, the calibration range was between 0.1 and 1 pM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.005 pM and 0.017 pM, respectively. The sensor's accuracy was proven by performing a recovery study in serum. The sensor's selectivity was also evaluated using common interfering substances such as KNO3, CaCl2, Na2SO4, uric acid, ascorbic acid, dopamine, and paracetamol. According to the results obtained, the performance of the designed sensor was found to be quite sensitive and selective in determining UPA. The developed UPA-ZnO/3-APBA@MIP-GCE sensor showed high sensitivity and selectivity towards UPA. In addition, the selectivity, the most important feature of the MIP-based sensor, was confirmed by imprinting factor (IF) calculations using tofacitinib (TOF) and ruxolitinib (RUX). The sensor's unique selectivity is demonstrated by its successful performance even in the presence of UPA impurities. [ABSTRACT FROM AUTHOR]

AbstractCaffeic acid (CA) based polyurethane (PU) films were synthesized and characterized for the simultaneous determination of melatonin (MT) and serotonin (5-HT). The CA based PUs were synthesized using a polyol mixture of 4,4’-diisocyanodiphenylmethane (MPI), polyethylene glycol-200 (PEG), and CA. The PEG–CA monomer units in the polyol were varied in molar ratios of 99:1, 97:3, 95:5, and 90:10. The synthesized PUs were characterized by FTIR spectroscopy and thermal analysis. These CA based PU films were coated onto screen-printed carbon electrodes (SPCEs) with varying thicknesses and used for the simultaneous determination of MT and 5-HT. Electrochemical responses of MT and 5-HT were evaluated using differential pulse voltammetry. The limit of detection and correlation coefficient for MT were 280 µM and 0.9797, respectively, while for 5-HT, the detection was 150 µM with a correlation coefficient of 0.9690. The precision, expressed as the relative standard deviation was 2.633% for MT and 4.668% for 5-HT. These findings suggest that CA based PU-modified electrodes hold potential in medical and biomedical applications. [ABSTRACT FROM AUTHOR]

The goal of this study was to design and construct a biosensor for detecting domoic acid (DA) using bioimmobilization of DA antibodies on the surface of screen‐printed carbon electrodes (SPCEs) enhanced with gold nanoparticles (AuNPs). To accomplish this aim, the SPCE surface was modified by applying AuNPs using electrodeposition, and the optimum modification time was determined by using cyclic voltammetry (CV). Electrochemical impedance spectroscopy (EIS) was performed to thoroughly analyze the electrochemical alterations in SPCEs prior to and during the modification with AuNPs. In addition, we conducted a comprehensive analysis of the structural surface characteristics, topography, and contact angle measurements. The limit of detection (LOD) for the AuNPs‐modified SPCE was determined to be 1.069 ng/mL, whereas the limit of quantification (LOQ) for DA was found to be 3.52 ng/mL using the EIS technique. While many studies concentrate on identifying target molecules through nanoparticle modification, our research surpasses this by offering a comprehensive electrochemical analysis of the modification of AuNPs and a thorough assessment of the changes in the microstructure of the electrode surface. This strategy greatly enhances the progress of biosensor development in the area. In addition, we investigated the harmful effects of DA on human endothelial cells EA.hy926 by subjecting them to different concentrations ranging from 0.001 to 1 ng/mL for a duration of 24 h. This experiment demonstrated that there was a decrease in cell viability that was directly proportional to the concentration of DA. [ABSTRACT FROM AUTHOR]

UiO-66 based materials (University of Oslo-66), with large surface area and abundant active sites, exhibit high water/solution stability due to a strong interaction between zirconium ion and the oxygen atom in carboxylate linkers. Therefore, they are potential electrode modifiers for electrochemical analysis because most of the electrochemical sensors have been used in aqueous media. In the present study, a potential electrochemical technique to detect uric acid (URA) and xanthine (XAN) is described using a Co/UiO-66 modified glassy carbon electrode. The Co/UiO-66 materials with different Co/Zr molar ratios were synthesized by hydrothermal process and were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The characterization showed a low loading and high dispersion of doped Co onto UiO-66 matrix. It was also found that the doped Co element may be grafted into the lattice of UiO-66. Co/UiO-66 exhibited better electrochemical activity toward URA and XAN detection. Under optimum conditions, 0.08Co/UiO-66/GCE demonstrated the best response compared to other material of different Co/Zr ratio, with three linear calibration ranges of 5–10 µM, 10-49.5 µM, and 49.5–327.1 µM and the limit of detection of 0.544 and 0.547 µM for URA and XAN, respectively. This proposed sensor offers a simple and low-cost pathway to quantify URA and XAN and was successfully employed to simultaneously determine URA and XAN in human urine with exceptional recoveries (97.61 to 104.79%). [ABSTRACT FROM AUTHOR]

Screen‐printed electrochemical sensing platforms are ubiquitous within the field of electrochemistry where they provide benefits of being disposable, cost‐effective, reproducible, easily customisable, portable and allow one to transfer the laboratory approach into the field. In this review, we introduce the concept of screen‐printed electrodes, we summarise positive and negative aspects before moving into the current highlights of using traditional screen‐printed carbon electrodes within the field of electroanalysis. We then look to cover metallic and bulk modified varieties, geometric changes (micro, microband and associated arrays), electrode activation and finally the physical length of screen‐printed electrodes, providing insights for future research. [ABSTRACT FROM AUTHOR]

An electrochemical aptasensor was established for the fast and sensitive determination of tetracycline based on the synergistic effect of MoS2-thionine nanocomposite and aptamer. The glassy carbon electrode was coated with MoS2 nanosheets of thionine to immobilize the tetracycline aptamer. In the absence of tetracycline, large quantities of thionin were loaded on the surface of the MoS2 nanosheet to serve as the electrochemical probe. After tetracycline was added to the surface of the electrode, an aptamer analyte complex was produced on the modified electrode. Through intercalation and electrostatic interactions, the complex was substantially adsorbed onto thionine, and the peak currents of the redox signal of thionine decreased. Therefore, the concentration of tetracycline was monitored by the change in signal intensity. Under optimized conditions, the developed electrochemical strategy with MoS2-thionine composite and aptamer exhibited an excellent linear detection range of 1.0 nM–1.0 μΜ and a low detection limit of 0.6 nM with suitable selectivity and stability. Therefore, the fabricated platform offers great potential for food safety, medical detection, and drug analysis. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) is a bioelectrochemical‐based reactor that can generate electrical energy directly from wastewater by utilizing microbial activity that oxidizes the waste organic matter. This study aims to synthesize polyaniline (PANI) and deposit on a graphite carbon electrode (GCE) and activated carbon cloth (ACC) surface to use as an anode material for MFCs. The MFC performance was evaluated using oxygen and ferricyanide as electron acceptors. PANI was electropolymerized from its aniline monomer and deposited using an electrophoretic deposition method onto the electrode surface. A PANI thin film was characterized using FTIR, field emission scanning electron microscopy (FESEM), BET, and electrochemical analysis. The analysis results show the characteristic peaks of PANI at 1557 cm−1, demonstratinjg the existence of quinoid rings (NQN), while the peaks at 1479 and 1400 cm−1 corresponding to the benzenoid (NBN) stretching in the PANI structure. The FESEM analysis confirmed that PANI appeared to have a porous structure on modified electrodes. It was found that the best system was MFC with ferricyanide as the electron acceptor. The highest power density produced is 254 mWm−2 from GCE‐PANI and 16.47 mWm−2 from ACC‐PANI. The normalized energy recovery of GCE‐PANI and ACC‐PANI in ferricyanide is 0.115 kWh kgCOD−1 and 5.67 × 10−3 kWh kgCOD−1, respectively. The COD removal was observed to be 88.8% for GCE‐PANI and 87.2% for ACC‐PANI from 1000 mg/L COD. [ABSTRACT FROM AUTHOR]

A novel graphene-modified molecularly imprinted polymer-based electrochemical sensor (MIP/RGO-GCE) was developed for the sensitive and selective detection of sibutramine in sports doping control. The sensor was fabricated by electropolymerizing o-phenylenediamine on a reduced graphene oxide-modified glassy carbon electrode in the presence of sibutramine as the template molecule. Under optimized conditions, the MIP/RGO-GCE sensor exhibited a wide linear range (0.05 to 20 μM), low detection limit (0.02 μM), high sensitivity (1.27 μA/μM), good precision (RSD < 2.7%), and long-term stability (93.5% retention after two weeks). The sensor's applicability was successfully demonstrated by analyzing spiked human urine and serum samples, with recoveries ranging from 95.8 to 103.2% and good agreement with the reference HPLC method. Furthermore, the sensor showed a rapid response time of 5 s and excellent reproducibility with an RSD of 1.5% for repeated measurements. The proposed sensor offers a rapid, cost-effective, and reliable alternative to traditional chromatographic methods for sibutramine detection in sports doping control. [ABSTRACT FROM AUTHOR]

AbstractSimple and highly sensitive voltammetric methods were developed using a poly(bromocresol purple) modified glassy carbon electrode to quantify cetirizine. Poly(bromocresol purple) film was synthesized on the surface of a glassy carbon electrode by cyclic voltammetry for 50 potential cycles in 0.1 M phosphate buffer at pH 6.0 containing 5.0 × 10−4 M of the monomer. Quantification of cetirizine exhibiting irreversible properties using the optimized conditions with a linear dependence between cetirizine concentration and peak currents from 0.2 to 100 µM for differential pulse voltammetry (DPV) and 0.1 to 100 µM for square wave voltammetry (SWV). Detection limits were 21.8 and 15.1 nM for DPV and SWV, respectively. Relative standard deviation (RSD) values below 0.98% indicated good precision. Recovery values from 100.12% to 100.90% with relative standard deviations below 1.14% for DPV and SWV in pharmaceutical formulations and urine samples demonstrated the high accuracy of the developed methods. The prepared modified electrode exhibited good fabrication reproducibility and suitable long-term stability. Finally, no interferences were observed in cetirizine determination in the presence of co-existing substances in the biological samples. [ABSTRACT FROM AUTHOR]

An electrochemical approach has been employed for the selective and sensitive determination of fast sulphon black F (FSB-F) using an electrochemically polymerized L-tyrosine (L-TN)-modified carbon paste electrode (L-TNMCPE). This modified electrode exhibits an effective irreversible oxidation peak at a potential of 0.6180 V, with a current sensitivity of 17.88 µA in 0.2 M phosphate-buffered saline (PBS) at pH 6.5, indicating its ability to clearly detect the oxidation of FSB-F. The characterization of the L-TNMCPE and the bare carbon paste electrode (BCPE) was observed using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The developed sensor presents a favorable approach for simultaneously detecting FSB-F and indigo carmine (IC), while also investigating potential interference from various metals and organic compounds. Scan rate results indicate that the reaction is absorption-controlled. Additionally, various experimental aspects are examined, including the pH and concentration variation. The modified electrode exhibits remarkable electrochemical behavior with a limit of detection (LOD) of 0.75 × 10−6 M and a limit of quantification (LOQ) of 2.5 × 106 M. The L-tyrosine (L-TN)-modified carbon paste electrode shows good reproducibility, repeatability, and stability. [ABSTRACT FROM AUTHOR]

Environmental pollution resulting from the use of pesticides such as fenuron poses significant health risks due to the carcinogenic and teratogenic properties of these compounds. There is an urgent need to develop rapid and cost‐effective detection methods for quantifying fenuron. In this study, an inorganic‐organic composite material was obtained by intercalating sodium dioctylsulfosuccinate (DSS) within the interlayer space of a nickel‐aluminum‐layered double hydroxide (NiAl‐LDH). The pristine and modified LDHs (NiAl‐LDH) were characterized using Fourier transform infrared, X‐ray diffraction, and thermogravimetric analysis, confirming the successful intercalation of DSS in the mineral structure. The modified LDH was used to elaborate a sensor for detecting fenuron herbicide via differential pulse voltammetry (DPV) employing a carbon paste electrode (CPE). The electrochemical procedure for fenuron analysis consisted of immersing the working electrode in an electrolytic solution containing the appropriate amount of fenuron, followed by voltammetry detection without any preconcentration step. Compared to CPE modified by pristine LDH, the peak current obtained on the organo‐LDH‐modified CPE was twice as high. The increase in the fenuron signal was attributed to the high organophilic feature of this composite material induced by DSS modification. To optimize the sensitivity of the organo‐LDH modified electrode, the effects of several experimental parameters such as pH of the medium and proportion of the modifier in the paste on the stripping response were examined. Linear calibration curves were obtained for the fenuron concentrations ranging from 0.5 × 10−6 to 1 × 10−6 mol.L−1 and 1 × 10−6 to 5 × 10−6 mol.L−1. The limit of detection (LOD) calculated on the basis of a signal‐to‐noise ratio of 3 was found to be 1.8 × 10−8 mol.L−1 for the low concentration range with a limit of quantification (LOQ) which was 6 × 10−8 mol.L−1. Furthermore, the interference effect of several inorganic ions and other pesticides potentially affecting fenuron stripping was explored, and the method's applicability was confirmed by determining fenuron levels in a river sample taken from down‐town Yaoundé. [ABSTRACT FROM AUTHOR]

The electroanalytical characteristics of double-stranded DNA (dsDNA) and the complex of dsDNA with the anticancer drug metabolite, abiraterone D4A, in the concentration range of 25–200 μM were investigated using differential pulse voltammetry. The effect of D4A on dsDNA was detected by changes in the intensity of the electrochemical oxidation of the heterocyclic bases guanine, adenine, and thymine. This investigation used screen-printed electrodes modified with carbon nanotubes. Binding constants (Kb) for guanine, adenine, and thymine in the dsDNA/D4A complexes were calculated to be 1.1 × 104, 5.5 × 103, and 2.5 × 103 M–1, respectively. The DNA-mediated electrochemical coefficients of the toxic effect were calculated as the ratio of the signal intensities of guanine and adenine in the presence of D4A compared to those without the drug (T, %). Based on an analysis of electrochemical parameters and binding constant values, an assumption was made regarding the mechanism of the interaction between D4A and DNA, predominantly through electrostatic interactions and the formation of hydrogen bonds with the minor groove. Conclusions about the mechanism of the interaction of the abiraterone D4A metabolite with the dsDNA minor groove, obtained by electrochemical methods, were supported by the molecular simulation of the DNA/D4A complex. [ABSTRACT FROM AUTHOR]

Heavy metal poisoning is the most prevalent health hazard at hazardous waste sites, affecting a large population on daily basis, with arsenite poisoning ranking third in terms of prevalence and severity. Therefore, the main objective of this study is to develop a novel, highly efficient sensor for detecting trace amounts of arsenite (AsIII) in human serum by utilising reduced graphene oxide/gold nanoparticles (rGO/AuNPs) based nanocomposite structure. In this work, a screen-printed carbon electrode (SPE) was modified using rGO/AuNPs nanocomposite to detect AsIII in human serum. The detection data were recorded and analysed using Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV), whereas transmission electron microscope (TEM), scanning electron microscope (SEM) as well as Fourier transform infrared (FTIR) spectroscopy were used to determine the surface morphological features and the presence of significant elements/groups in the prepared nanocomposite structure. Under the optimised conditions, the linear regression coefficient (R2) for the DPV response of the fabricated electrode (rGO/AuNPs@SPE) was observed to be 0.98. The rGO/AuNPs@SPE demonstrated remarkable sensor response for AsIII with detection limits of 10 ppb via DPV in standard samples, due to the synergistic effect of rGO and AuNPs based nanocomposite. The sensitivity of the sensor was found to be 0.0142 Appb−1cm−2 for 100–1000 ppb concentration range of AsIII. The rGO/AuNPs@SPE sensor also displayed good stability and reproducibility when used in AsIII spiked human serum samples in which the limit of detection was observed at 100ppb. The porous structure of rGO on the sensing interface efficiently improves the electrode's adsorption and conductivity, while citrate capped AuNPs offer the functional groups required for maximum adsorption of AsIII. Hence, the developed electrochemical sensor (rGO/AuNPs@SPE) can be used very precisely and reliably in various applications for trace level detection of AsIII in human serum. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (RGO) was first synthesized and then it was reacted by alizarin red S (ARS), and therefore RGO functionalized with ARS was prepared (ARS/RGO). Then, structural analysis of the manufactured material was done by SEM and FTIR techniques. The FTIR results confirmed the interaction between ARS and RGO and the formation of ARS/RGO. A new electrochemical sensor was fabricated on the surface of a glassy carbon electrode modified with ARS/RGO. The prepared electrode showed a quasi-reversible electrochemical behavior and also had a significant effect on the electrocatalytic oxidation of caffeine (CAF). The modified electrode was able to measure the CAF as an electrochemical sensor. The effect of different parameters was investigated on the oxidation of CAF at the modified electrode; the sensor has the highest current at pH = 4.0. The effect of different interference species on the response of CAF, and also the reproducibility and repeatability of the sensor was investigated and acceptable results were obtained. The electrochemical determination of CAF on the electrode surface was investigated by differential pulse voltammetry and in the linear range of 1.0-100.0 µM, the detection limit value was obtained as 0.022 µM. Finally, the designed sensor was used to measure the amount of CAF in some real samples and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the influence of scanning rate, electrolyte concentration, temperature and electrode rotation speed on the capacitance of glassy carbon electrode in sulfuric acid solution using cyclic voltammetry (CV). The results show that they have a significant influence on the capacitance with varying experimental conditions. In addition, the electrochemical impedance spectroscopy (EIS) method was employed to conduct a more thorough analysis of the ways in which hydrodynamic circumstances resulting from a rotating electrode affect the electrode capacity and the charge storage process. Step potential electrochemical spectroscopy (SPECS) was used to identify the various charge storage mechanisms involved. It was shown that the voltammograms measured by the CV method and determined from the SPECS method have a quasi‐rectangular shape, revealing a predominantly capacitive behavior and that capacitance decreases with increasing scanning rate. Furthermore, both methods confirm that the contribution of the diffusion process is the main factor influencing the charge storage mechanism when the sweep rate is taken into account. However, the SPECS approach provides more accurate and detailed information regarding the kinetic characteristics of the electrode. [ABSTRACT FROM AUTHOR]

Indigo carmine (IC) was used as an analyte and a layer of film with serine as the functional monomer was electropolymerized to create a poly(serine)-modified carbon paste electrode (PSMCPE). Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and electrochemical technology, in that order, were used to characterize the morphology, structure, and electrochemical characteristics of the PSMCPE. Experimental parameters including the reagent molar ratio, the number of electropolymerization cycles, scan rate, and electrolyte pH level, were methodically optimized during the sensor's fabrication. Under optimal conditions, cyclic voltammetry (CV) and differential pulsed voltammetry (DPV) were used for IC detection. The PSMCPE response current for IC exhibited a significant enhancement compared to that of the bare carbon paste electrode (BCPE). The linear range of IC measured by DPV was determined to be 0.2–3.5 μM, with the corresponding lower detection limit (LOD) 1.3211 × 10−7 M and lower limits of quantification (LOQ) 4.403 × 10−7 M. The modified electrode confirmed outstanding repeatability, reproducibility, and stability. Finally, the real-time application of the sensor was confirmed by investigating IC in a water sample, when good IC recovery was observed. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) has been classified as an endocrine-disrupting substance that may cause adverse effects on human health and the environment. The development of simple and sensitive electrochemical biosensors is crucial for the rapid and effective quantitative determination of BPA. This work presents a study on electrochemical sensors utilizing gold nanoparticle-modified multi-walled carbon nanotubes (CNT/AuNPs). Glassy carbon electrodes (GCEs) and screen-printed electrodes (SPEs) were conveniently modified and used for BPA detection. AuNPs were electrodeposited onto the CNT-modified electrodes using the galvanostatic method. The electrodes were properly modified and characterized by using Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance analysis (EIS). The electrochemical response of the sensors was studied using differential pulse voltammetry (DPV) and constant potential amperometry (CPA) for modified GCE and SPE electrodes, respectively, and the main analytical parameters were studied and optimized. Problems encountered with the use of GCEs, such as sensor degradation and high limit of detection (LOD), were overcome by using modified SPEs and a flow injection device for the measurements. Under this approach, an LOD as low as 5 nM (S/N = 3) was achieved and presented a linear range up to 20 μM. Finally, our investigation addressed interference, reproducibility, and reusability aspects, successfully identifying BPA in both spiked and authentic samples, including commercial and tap waters. These findings underscore the practical applicability of our method for accurate BPA detection in real-world scenarios. Notably, the integration of SPEs and a flow injection device facilitated simplified automation, offering an exceptionally efficient and reliable solution for precise BPA detection in water analysis laboratories. [ABSTRACT FROM AUTHOR]

Voltammetric analysis of Levofloxacin (LF) using an electrochemically polymerized composite of DL‐phenylalanine (DLP) alongside a bare carbon paste electrode. The constructed electrodes are polymerized DL‐phenylalanine modified carbon paste electrodes P(DLP/MCPE) and bare carbon paste electrodes (BCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and other electrochemical techniques used for characterization of P(DLP/MCPE) and BCPE in 0.2 M phosphate buffer solution (PBS) with pH 4.5 were conformed using the P(DLP/MCPE), and it shows the highest current responses compared to the BCPE. This research work examines the effect of pH in PBS, scan rate, and LF concentration on the surface of P(DLP/MCPE). The outcome result shows that the oxidation reaction of LF pH is an adsorption‐controlled path. The detection limit of LF ranges from 0.2 μM to 7.0 μM, and the lower limits of detection (LOD) is 0.613x10−7 M and the lower limits of quantification (LOQ) is 2.051X10−7 M. The electrochemical P(DLP/MCPE) shows good repeatability, reproducibility, and stability. Finally, by analyzing LF in a pharmacological sample, the real time application of the sensor was assessed, and significant recoveries were observed. [ABSTRACT FROM AUTHOR]

Herein, an efficient and sensitive methyl parathion (MP) electrochemical sensor was fabricated by using β-cyclodextrin (β-CD) decorated single-wall carbon nanotubes (SCN), which were used to modify the glassy carbon electrode (GCE). The β-CD@SCN/GCE sensor achieved the sensitive MP detection. For the obtained β-CD@SCN nanocomposite, SCN could form three-dimensional reinforced carbon conductive network with good conductivity property and efficient charge transport channels; β-CD could promote the dispersion of carbon materials and boost the accumulation capability of MP on the surface of β-CD@SCN/GCE. The combination of β-CD and SCN significantly optimized the electrochemical property of β-CD@SCN/GCE sensor for the detection of MP. The β-CD@SCN/GCE sensor exhibited good MP electrochemical detection performance with low limit of detection of 7.23 nM. When used for the detection of MP in grape juice, the β-CD@SCN/GCE sensor exhibited good MP electrochemical sensing analysis performance with satisfactory recovery rates (96.54–98.18%) and relative standard deviation values (1.60–2.07%). [ABSTRACT FROM AUTHOR]

Gold star (AuST), which is one of the important anisotropic gold structures, finds applications in catalysis, sensing, and photothermal therapy by virtue of its branches of high aspect ratio. The preparation of AuSTs can prove challenging as it requires stringent reaction condition(s) and solution composition including various chemical additives, which are not suitable for either disposal in the environment or use in health‐related studies. Furthermore, these chemical additives often cover the gold surface and hence cause interferences in the applications of AuSTs. In this work, we have reported a proof of concept for preparing AuSTs of monodispersed size on glassy carbon electrodes by developing a simple electrosynthesis method using an aqueous acid solution of chloroauric acid in the absence of any chemical additive, structure‐directing or surface‐protecting agent. This electrosynthesis strategy was developed by understanding the corresponding electrocrystallization mechanism and designing a suitable potentiostatic pulse strategy. The current response per unit area of the gold content for the oxidation of N‐Acetyl‐L‐cysteine was found to be superior on AuSTs compared to widely used citrate‐capped gold nanoparticles (cit‐AuNPs) and bare gold. [ABSTRACT FROM AUTHOR]

BACKGROUND: Organophosphorus pesticides (OPs) were used in large quantities, and pesticide residues have caused different degrees of environmental pollution. Because the current laboratory detection techniques cannot meet the requirements of quickly and accurately monitoring pesticide concentration, there is an urgent need for a portable and accurate method to trace pesticide residues. This paper reports an effective electrochemical sensor composed of ZrO2@PDA electrode material and glassy carbon electrode (GCE). RESULTS: This sensor displayed optimal selectivity for dichloride among various OPs with a low limit of detection (LOD = 1.318 × 10−3 mg L−1). Wherein the accuracy and reliability of this electrochemical sensor were verified through the standard method of gas chromatography–mass spectrometry (GC–MS) (p = 0.977 > 0.05), as well as the stability and anti‐interference capabilities. In addition, the results of recovery experiments have shown that the recovery rate of the electrochemical sensor for dichlorvos ranged from 89.2% to 103.8%, with RSD less than 5%, indicating its practical application in the actual sample detection. CONCLUSIONS: Finally, the portable sensing platform for on‐site analysis of dichlorvos concentration in farmland water samples was also demonstrated with excellent results. All the results suggested that the prepared ZrO2@PDA composites could serve as a prospective microchip sensor for the on‐site detection of dichlorvos. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

To reach a deeper understanding of the charge storage mechanisms of electrode materials is one of the challenges toward improving their energy storage performance. Herein, we investigate the interfacial ion exchange of a composite electrode made of carbon nanotube/poly(ortho-phenylenediamine) (CNT/PoPD) in a 1M NaCl aqueous electrolyte via advanced electrogravimetric analyses based on electrochemical quartz crystal microbalance (EQCM). Classical EQCM at different scan rates of the potential revealed the complex electrogravimetric behavior likely due to multi-species participation at different temporal scales. Thereafter, in order to better understand the behavior of each species (ions, counter ions, and co-ions) in the charge compensation mechanism, the electrogravimetric impedance spectroscopy analysis (also called ac-electrogravimetry) was pursued. Ac-electrogravimetry revealed the role of each species where Na+ cations and Cl− anions as well as protons participate in the charge compensation mechanism of the CNT/PoPD composite with different kinetics and proportions. The water molecules with opposite flux direction with the cations are also detected, suggesting their exclusion during cationic species transfer. Having analyzed ac-electrogravimetry responses in depth, the synergistic interaction between the CNT and PoPD is highlighted, revealing the improved accessibility of species to new sites in the composite. [ABSTRACT FROM AUTHOR]

This work revealed the development of a novel non-enzymatic electrochemical sensor for glucose detection based on a modified glassy carbon electrode made of graphene oxide nanoribbons (GONRs). The TEM, XRD), XPS, FTIR, and Raman spectroscopy were used to characterize the shape and structure of the modified electrode made of GONRs. Using amperometry and cyclic voltammetry (CV), the nanocomposite's electrochemical performance was assessed (AMP). The TEM results support the XPS, Raman, and XRD observations, demonstrating the capability of the suggested approach to generate single-layered GONRs with good edge linearity. The suggested non-enzymatic glucose sensing method was found to be selective, stable, repeatable, and reproducible through electrochemical analyses. The response behavior of GONRs/GCE was found to be linear within the 0.1–105 mM range, and the sensitivity and detection limit were found to be roughly 20.815 µA/mM and 3 µM, respectively. To verify the GONRs/GCE sensor's practicality and viability, tests were conducted on human serum and orange juice samples. The recovery rate ranged from 94.00% to 99.20%, according to the results, and the relative-standard deviation (RSD) values were 3.21% to 4.41%. These encouraging RSD and recovery rates showed that GONRs/GCE would work well as electrodes for measuring glucose in actual samples. [ABSTRACT FROM AUTHOR]

Curcumin is a compound of great importance in the food industry due to its biological and pharmacological properties, which include being an antioxidant, anti-inflammatory, antibacterial, antiviral, and anticarcinogenic. This paper proposes the synthesis of an electrochemical sensor based on molecularly imprinted polymers (MIPs) and MWCNT by drop casting deposited on a glassy carbon electrode (GCE) for the selective quantification of curcumin in food samples. The synthesized compounds are characterized by Fourier transform infrared (IR), Brunauer–Emmett–Teller (BET), and electrochemical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The optimal conditions for further experiments were determined by selecting these parameters. We examined three food products, commercial capsules, turmeric rhizomes, and commercial turmeric powder, employing both electrochemical and HPLC methods for the analysis. The electrochemical method revealed a limit of detection (LOD) value of 0.1365 µmol L−1, compared with the HPLC analysis, which gave a value of 3.55 µmol L−1. Furthermore, the MIP material demonstrated superior selectivity for the analyte compared to potential interferents. The recovery percentage, determined using the HPLC method, fell within the range of 87.5% to 102.6% [ABSTRACT FROM AUTHOR]

Due to the multitude of physiological functions, ferulic acid (FA) has a wide range of applications in the food, cosmetic, and pharmaceutical industries. Thus, the development of rapid, sensitive, and selective detection tools for its assay is of great interest. This study reports a new electroanalytical approach for the quantification of ferulic acid in commercial pharmaceutical samples using a sulphur-doped graphene-based electrochemical sensing platform. The few-layer graphene material (exf-SGR) was prepared by the electrochemical oxidation of graphite, at a low applied bias (5 V), in an inorganic salt mixture of Na2S2O3/(NH4)2SO4 (0.3 M each). According to the morpho-structural characterization of the material, it appears to have a high heteroatom doping degree, as proved by the presence of sulphur lines in the XRD pattern, and the C/S ratio was determined by XPS investigations to be 11.57. The electrochemical performances of a glassy carbon electrode modified with the exf-SGR toward FA detection were tested by cyclic voltammetry in both standard laboratory solutions and real sample analysis. The developed modified electrode showed a low limit of detection (30.3 nM) and excellent stability and reproducibility, proving its potential applicability as a viable solution in FA qualitative and quantitative analysis. [ABSTRACT FROM AUTHOR]

For the development and optimization of solid-state symmetrical supercapacitors, herein, we propose using carbon-based electrodes and sodium- and lithium-form Aquivion electrolyte membranes, which serve as the separator and electrolyte. Carbon xerogels, synthesized using microwave-assisted sol-gel methodology, with designed and controlled properties were obtained as electrode materials. Commercial activated carbon (YP-50F, "Kuraray Europe" GmbH) was used as the active material for comparison. Notably, the developed solid-state symmetrical supercapacitors provide sufficiently high specific capacitances of 105–110 F g−1 at 0.2 A g−1, along with an energy density of 4.5 Wh kg−1 at 300 W kg−1, and a voltage window of 0–1.2 V in aqueous environments, also demonstrating an excellent cycling stability for up to 10,000 charge/discharge cycles. These results can demonstrate the potential applications of carbon xerogel as the active electrode material and cation exchange membrane as the electrolyte in the development of solid-state supercapacitor devices. [ABSTRACT FROM AUTHOR]

Electrochemical analysis of 2‐(2‐methylbenzyl)‐4(7)‐phenyl‐1‐H‐benzo[d]imidazole (MPB), a new benzimidazole derivative with tyrosinase inhibitory effect and antioxidant activity, was performed in this study. The electro‐oxidation behavior of MPB was investigated by cyclic voltammetry (CV), differential pulse stripping voltammetry (DPSV), and square wave voltammetry (SWV) on glassy carbon electrode. The oxidation process of MPB showed an irreversible behavior. The highest peak current was obtained in 0.5 M H2SO4 containing 10 % methanol and used as the supporting electrolyte. As a result of the calibration study, two linear responses in the range of 0.06–1.00 μM and 2.00–100 μM were obtained with a detection limit of 10.4 nM by DPSV. Linearity for SWV was between 0.1 and 10.0 μM with a detection limit of 29.3 nM. Precision of the methods was obtained as relative standard deviation (RSD) and was below 2.0 %. Developed methods were applied for the recovery of MPB from spiked serum samples. Accordingly, recoveries of 100.39 % for DPSV and 100.07 % for SWV were obtained with RSD below 0.48 %. MPB was stable for at least 2 weeks as a result of retaining 97 % of the peak current when stored at +4 °C. Finally, the possible responsible group in MPB oxidation was proposed. [ABSTRACT FROM AUTHOR]

The halogen, bromine (Br) doped layered graphitic carbon nitride (gCN) nanosheets are constructed for a novel electrochemical detection of dopamine (DA). The Br is successfully immobilized in the gCN host lattice, in which Br provides an N-vacancy for -C-N bonding to improve electron transfer and enhance its electrocatalytic properties. The prepared nanosheets are studied by various analytical analyses and the electrochemical behavior of the designed electrode is studied using cyclic voltammetry (CV). The Br-gCN decorated screen-printed carbon electrode (SPCE) has superior electrochemical activity and is stable during exposure to varied pH, however, exhibited better catalytic activity at pH 7. The Br-gCN/SPEC electrodes and their high electrocatalytic performance are used for the detection of dopamine with a lower limit of detection (LoD) of 5 nM concentration. The Br-gCN decorated electrodes exhibited satisfactory results for cyclic stability (up to 100th cycle), repeatability (up to 6 cycles), reproducibility of similarly constructed 6 electrodes, and their electrochemical performance. Furthermore, the fabricated sensor also exhibited a better recovery (>80%) for real-time urine sample analyses. [ABSTRACT FROM AUTHOR]

The rising popularity of herbal medicine as a weight loss remedy, fueled by misleading propaganda, raises concerns about the manufacturing processes and potential inclusion of controlled substances such as fluoxetine (FLU). The objective of this work is to develop and evaluate the performance of an electrochemical device by modifying a glassy carbon electrode (GC) with a nanocomposite based on reduced graphene oxide (rGO) and copper nanoparticles (CuNPs) for detecting FLU in manipulated herbal medicines. Scanning electron microscopy (FEG-SEM) and cyclic voltammetry (CV) were applied for morphological and electrochemical characterization and analysis of the composite's electrochemical behavior. Under optimized conditions, the proposed sensor successfully detected FLU within the range of 0.6 to 1.6 µmol L−1, showing a limit of detection (LOD) of 0.14 µmol L−1. To determine the presence of FLU in herbal samples, known amounts of the analytical standard were added to the sample, and the analyses were performed using the standard addition method, yielding recoveries between −2.13 and 2.0%. [ABSTRACT FROM AUTHOR]

In this study, Pt‐decorated poly(3,4‐ethylenedioxythiophene) (PEDOT) electrocatalyst was uniformly coated electrochemically reduced graphene oxide (ERGO) layer on glassy carbon electrode (GCE) has been created using appropriate procedures to facilitate the implementation of the methanol oxidation reaction (MOR). This multi‐layer catalyst was characterized in each production step via Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field‐emission scanning electron microscopy and energy‐dispersive x‐ray analysis (FESEM‐EDX) morphological analysis beside the electrochemical tests. The favorable structures of both ERGO and PEDOT increase conductivity and electrocatalytic activity toward methanol oxidation, which may create a suitable matrix for Pt loading thanks to the formation of much more active centers for methanol electrooxidation. The results demonstrate that the electrochemical surface area (ECSA) of Pt/PEDOT/ERGO/GCE was 39.1 m2 g−1, and it has a convenient mass activity (MA with 467 mA mg Pt−1) compared to that of commercial Pt/C. According to chronoamperometric analysis, the current density of Pt/PEDOT/ERGO/GCE was stable during the 1200 s of operation. It demonstrated remarkable stability with a final current density of 4.36 mA cm−2. [ABSTRACT FROM AUTHOR]

The present paper deals with the development of a new and original hexadecyltrimethylammonium bromide (CTAB)-modified carbon paste electrode (CPE) dedicated for the direct analysis of nitrites in aquaculture and rat blood. The surface morphologies and contact angles of unmodified and modified CPEs were performed using Scanning Electron Microscopy (SEM), Optical Microscopy (OM) and sessile drop techniques, respectively. Cyclic Voltammetry (CV) was used to study the electrochemical behaviour of nitrites, whilst Differential Pulse Voltammetry (DPV) and Linear Sweep Voltammetry (LSV) techniques were used to investigate their quantitative analysis. DPV operating parameters were optimized and the optimum values were pulse height 0.4 V, scan increment 0.015 V, pulse width 0.01 s and step time 0.5 s. The repeatability and reproducibility of the CPE were studied, and the effect of some interfering ions was evaluated to highlight the selectivity of the electrode. The modified CTAB/CPE showed a good stability and proved to be more sensitive, leading to a Limit of Detection (LOD) of 0.034 mg L−1 and a Limit of Quantification (LQ) of 0.152 mg L−1. The elaborated sensors were applied with success for nitrites analysis in aquaria with CPE and in rat blood with CTAB/CPE, preparing human blood measurements in near future work. [ABSTRACT FROM AUTHOR]

In the background of the rapid development of artificial intelligence, big data, IoT, 5G/6G, and other technologies, electrochemical sensors pose higher requirements for high-throughput detection. In this study, we developed a workstation with up to 10 channels, which supports both parallel signal stimulation and online electrochemical analysis functions. The platform was wired to a highly integrated Bluetooth chip used for wireless data transmission and can be visualized on a smartphone. We used this electrochemical test platform with carbon–graphene oxide/screen-printed carbon electrodes (CB-GO/SPCE) for the online analysis of L-tyrosine (Tyr), and the electrochemical performance and stability of the electrodes were examined by differential pulse voltammetry (DPV). The CB-GO-based screen-printed array electrodes with a multichannel electrochemical platform for Tyr detection showed a low detection limit (20 μM), good interference immunity, and 10-day stability in the range of 20–200 μM. This convenient electrochemical analytical device enables high-throughput detection and has good economic benefits that can contribute to the improvement of the accuracy of electrochemical analysis and the popularization of electrochemical detection methods in a wide range of fields. [ABSTRACT FROM AUTHOR]

This study addressed the use of manganese dioxide nanorods/graphene oxide nanocomposite (MnO2 NRs/GO) for modifying a glassy carbon electrode (GCE). The modified electrode (MnO2 NRs/GO/GCE) was used as an electrochemical sensor for the determination of hydroquinone (HQ) in water samples. Differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry were used for more analysis of the HQ electrochemical behavior. Analyses revealed acceptable electrochemical functions with lower transfer resistance of electrons and greater conductivity of the MnO2 NRs/GO/GCE. The small peak-to-peak separation is an indication of a rapid electron transfer reaction. Therefore, this result is probably related to the effect of the MnO2 NRs/GO nanocomposite on the surface of GCE. In the concentration range of 0.5 μM to 300.0 μM with the detection limit as 0.012 μM, there was linear response between concentration of HQ and the current. The selectivity of the modified electrode was determined by detecting 50.0 μM of HQ in the presence of various interferent molecules. At the end, the results implied the acceptable outcome of the prepared electrode for determining HQ in the water samples. [ABSTRACT FROM AUTHOR]

The global consumption of vegan foods is experiencing an expressive upward trend, underscoring the critical need for quality control measures based on nutritional and functional considerations. This study aimed to evaluate the functional quality of caviar and salmon analog food inks based on pulses combined with nano ingredients and produced in our laboratory (LNANO). The primary objective of this work was to determine the total antioxidant compounds contained in these samples using a voltammetric technique with a glassy carbon electrode. The samples underwent ethanolic extraction (70%) with 1 h of stirring. The voltammograms were acquired in a phosphate buffer electrolyte, pH 3.0 with Ag/AgCl (KCl 3 mol L−1) as the reference electrode and platinum wire as the auxiliary electrode. The voltammograms revealed prominent anodic current peaks at 0.76–0.78 V, which are attributed to isoflavones. Isoflavones, known secondary metabolites with substantial antioxidant potential commonly found in pulses, were identified. The total isoflavone concentrations obtained ranged from 31.5 to 64.3 mg Eq genistein 100 g−1. The results not only validated the efficacy of the electrochemical sensor for quantifying total antioxidant compounds in the samples but also demonstrated that the concentration of total isoflavones in caviar and salmon analogs fell within the expected limits. [ABSTRACT FROM AUTHOR]

To move electrochemical sensing technology from the laboratory into point‐of‐care (POC)‐based settings, electrochemical platforms must be cost‐effective, portable, and user‐friendly. Here, we present the comparison of a near‐field communication (NFC) potentiostat with a traditional potentiostat. The NFC potentiostat is roughly the size of a credit card and is wirelessly powered by a smartphone with a user‐friendly application for electrochemical analysis. The proposed system is portable, affordable, and provides analytical capabilities comparable to traditional benchtop potentiostats. Different redox probes were investigated, including ferricyanide, ruthenium hexamine, and hydroquinone, highlighting the ability of the NFC potentiostat to measure a variety of target analytes. In addition, the NFC potentiostat can perform several electrochemical techniques, such as cyclic voltammetry, differential pulse voltammetry, chronoamperometry and square wave voltammetry. The combination of affordable screen‐printed carbon electrodes (SPCE)s with the portable, inexpensive NFC potentiostat highlights this platform's promise towards POC electrochemical sensing applications, particularly for medical diagnostics in rural or low‐income areas. [ABSTRACT FROM AUTHOR]

In this study, a facile protocol was used to convert non-valuable orange peels (OP) waste into a new sensing iron oxide orange-peel nanomaterial (FeOP). The presence of iron oxide nanoparticles in the modified OP was confirmed by physicochemical characterisations including Fourier-transform infrared spectroscopy, X-ray diffractometry, thermogravimetry, and scanning electron microscopy-energy dispersive X-ray. FeOP was used to modify a carbon paste electrode (CPE/FeOP) which displayed a significant increase in specific capacitance of 2939 F.g−1, two folds higher than that obtained with CPE at 10 m.s−1 in NaCl. The electroanalysis of Congo red (CR) in aqueous solutions using CPE/FeOP displayed detection limits of 2.8 × 10−7 mol.L−1 and 8.2 × 10−7 mol.L−1 respectively in deionised and spring waters, in the linear range of 5 to 55 µM. CPE/FeOP electrochemical sensor is therefore suitable for the determination of Congo red in wastewater. [ABSTRACT FROM AUTHOR]

Reliable quantitative analysis using electrochemical sensors remains a challenge due to the differences in the effective area after surface modification of the electrodes, resulting in poor precision of the signals between electrodes. Herein, a novel quantitative approach called standard curved surface for the electrochemical detection is reported which does not require identical electrodes, high modification, or the use of internal standards that may cause calibration interferences. The technique is based upon the principle that the current is linearly correlated with the electroactive area of the electrodes. By introducing the electroactive area as a new variable into the standard curve, a three-dimensional standard curved surface was obtained to correct for differences among electrodes, thereby improving the accuracy of electrochemical detection. Furthermore, it was applied to the determination of tert-butylhydroquinone (TBHQ) in edible oil. Compared with the traditional standard curve, the reported method reduced the relative standard deviation values from 13.22% to 4.01%. The current response was linear with the concentration of TBHQ between 5 × 10−6 and 1.25 × 10−3 mol/L. The limit of detection was 1.07 × 10−6 mol/L and the spike recovery was from 90.44% to 112.09%. Therefore, a universal calibration method has been reported with expected additional applications for electrochemical sensors. [ABSTRACT FROM AUTHOR]

A study of keracyanin chloride (KC) electrochemical behavior in an aqueous buffer solution using screen-printed carbon electrodes (SPCEs) and glassy carbon electrodes (GCEs) was performed. Cyclic voltammetry (CV) and square-wave voltammetry (SWV) were used to analyze the electrochemical response of KC under studied conditions. A clear redox wave was observed for KC, primarily due to the oxidation of the catechol 3′,4′-dihydroxyl group of its ring B, with a minor redox wave from oxidation of the hydroxyl groups in ring A. Compared to GCEs, using modified SPCEs resulted in two-fold amplification in the electrochemical oxidation signal of KC. Using SPCEs as a working electrode could provide high sensitivity in the quantification of KC and the ability to gauge KC quantification to significantly lower detection limits. [ABSTRACT FROM AUTHOR]

The interactions of zopiclone with electrochemically reduced graphene oxide (rGO) modified electrode were examined. A comparison of GC/rGO and glassy carbon electrode (GC) by electrochemical impedance spectroscopy and scanning electrochemical microscopy (SECM) shows that the modified surface is much less conductive than GC. The role of rGO is to act as a site of specific adsorption of the analyte. Molecular dynamics showed that the monoanionic form of zopiclone presents more interactions with defects of rGO. The analytical methodology allowed obtaining a linearity of 10–130 μg L−1, with a limit of detection of 2.14 μg L−1 using SWAdSV at pH 10.0. [ABSTRACT FROM AUTHOR]

Electrochemical properties of quetiapine fumarate were examined on the anodic direction with multi‐walled carbon nanotube modified glassy carbon electrode using voltammetric methods. The ratio of multi‐walled carbon nanotube has been optimized using its various concentrations. The oxidation process was found to be irreversible, and adsorption controlled. The linear ranges were determined as 4×10−9–2×10−6 M for differential pulse stripping voltammetry and 2×10−9–2×10−6 M for square‐wave stripping voltammetry with detection limits of 8.07×10−10 and 2.71×10−10 M, respectively. The methods were validated and successfully applied for the analysis of quetiapine fumarate tablets. The groups responsible for the oxidation reaction of quetiapine fumarate were investigated with model substances. [ABSTRACT FROM AUTHOR]

In the present study, the electrochemical behavior of antiviral drug umifenovir (Umi) and umifenovir encapsulated in phospholipids micelles (nanosome/umifenovir, NUmi) were investigated for the first time on screen-printed electrodes modified by carbon nanotubes. We have shown that Umi can be electro oxidized around the potential of +0.4 V in the concentration range of 50–500 µM (R2 = 0.992). Non-overlapping signatures of DNA and umifenovir (10–150 µM) permit to register interaction between umifenovir (or umifenovir encapsulated in phospholipids micelles), purine, and pyrimidine heterocyclic bases of DNA separately. The type of interaction is most likely via electrostatic interactions and groove binding in drug-DNA formed complex, as was revealed based on the values of binding constants Kb and the cathodic shifts of oxidation potentials for heterocyclic bases with increasing Umi or NUmi concentration. The negative values of Gibbs free energy (ΔG) for all nucleobases confirm the process spontaneity. This study is the first one presenting the effect of antiviral drug umifenovir and umifenovir encapsulated in phospholipids micelles on dsDNA as a target of pharmacogenomics. [ABSTRACT FROM AUTHOR]

Accurate and effective diagnosis and individualized management of gout can be potentially achieved by detecting uric acid (UA) and xanthine (XT) simultaneously using an easy-to-use method. Herein, we report simultaneous detection of UA and XT using a 3-dimensional (3D) macroporous gold nanoparticle-incorporated reduced graphene oxide–carbon nanotube nanocomposite (GNP/rGO-CNT). The GNP/rGO-CNT was simply prepared on a glassy carbon electrode (GCE) by one-step electrochemical deposition/co-reduction. It displayed highly sensitive and selective responses to UA and XT, showing excellent stability and good reproducibility in neutral pH. It was demonstrated that 3D GNP/rGO-CNT on GCE could detect UA and XT in human saliva and blood serum simultaneously. This GNP/rGO-CNT for simultaneous detection of UA and XT in human body fluids can be utilized for monitoring drug adherence for gout treatment, together with gout diagnosis. [ABSTRACT FROM AUTHOR]

In order to prepare fiber-type nanohybrid composites for electrochemical and antimicrobial applications, polypyrrole was combined with carboxymethylcellulose and multiwalled carbon nanotubes (PPy/CMC/MWCNTS). These composite materials were synthesized using ultrasonication and in situ polymerization. By using analytical methods, the structure and morphology of the synthesized nanohybrid composite material were confirmed. Slurry of fiber-type PPY/CMC/MWCNT composites synthesized in ethanol was deposited as a thin-uniform layer with conductive nafion (5% ethanolic solution of nafion) binder. Based on electrochemical measurements in a phosphate buffer medium, Sb3+ ions have linear responses between 0.1 nM and 0.01 mM, which is known as linear dynamic range (LDR). A sensor's sensitivity (22.4304 µAµM−1cm−2) is calculated using the LDR slope by considering the GCE surface area (0.0316 cm2). A signal-to-noise ratio of 3 is used to estimate the lower limit of detection which is equal to 96.82 ± 4.84 pM. Moreover, the antibacterial activity of the obtained polypyrrole/carboxymethylcellulose/MWCNT composite has also been evaluated "against Gram-positive bacteria B. subtilis along with S. aureus, as well as Gram-negative bacteria, P. aeruginosa along with Escherichia coli by utilizing" autoclave of agar media. In electrochemical analysis, the proposed Sb3+ cationic sensor exhibits appreciable reproducibility, response time, stability, and outstanding outcome in analysis of real samples. In the field of metal ion sensor, this reliable method might be prospective in the recent future. [ABSTRACT FROM AUTHOR]

Due to the great significance of amino acids, a substantial number of research studies has been directed toward the development of effective and reliable platforms for their evaluation, detection, and identification. In order to support these studies, a new electrochemical platform based on PANI/ZnO nanowires' modified carbon inks screen-printed electrodes was developed for qualitative analysis of electroactive amino acids, with emphasis on tyrosine (Tyr) and tryptophan (Trp). A comparative investigation of the carbon ink before and after modification with the PANI/ZnO was performed by scanning electron microscopy and by Raman spectroscopy, confirming the presence of PANI and ZnO nanowires. Electrochemical investigations by cyclic voltammetry and electrochemical impedance spectroscopy have shown a higher charge-transfer rate constant, which is reflected into lower charge-transfer resistance and higher capacitance values for the PANI/ZnO modified ink when compared to the simple carbon screen-printed electrode. In order to demonstrate the electrochemical performances of the PANI/ZnO nanowires' modified carbon inks screen-printed electrodes for amino acids analysis, differential pulse voltammograms were obtained in individual and mixed solutions of electroactive amino acids. It has been shown that the PANI/ZnO nanowires' modified carbon inks screen-printed electrodes allowed for tyrosine and tryptophan a peak separation of more than 100 mV, enabling their screening and identification in mixed solutions, which is essential for the electrochemical analysis of proteins within the proteomics research field. [ABSTRACT FROM AUTHOR]

The current work presents a sensitive, selective, cost-effective, and environmentally benign protocol for the detection of ibuprofen (IBP) by an electrochemical probe made of a glassy carbon electrode modified with Ag-ZnO and MWCNTs. Under optimized conditions, the designed sensing platform was found to sense IBP up to a 28 nM limit of detection. The interaction of IBP with bovine serum albumin (BSA) was investigated by differential pulse voltammetry. IBP−BSA binding parameters such as the binding constant and the stoichiometry of complexation were calculated. The results revealed that IBP and BSA form a single strong complex with a binding constant value of 8.7 × 1013. To the best of our knowledge, this is the first example that reports not only IBP detection but also its BSA complexation. [ABSTRACT FROM AUTHOR]

Phenolic compounds are well-known as antioxidants including many other important bioactive agents that have long been interested due to their benefits for human health, curing and preventing many diseases. Gallic acid (GA), is a naturally occurring most abundant phenolic acid compound found in groundnut, honey, mango, tea, wine, and various medicinal plants. Different techniques have been used for determination of GA. Electrochemical technique is of the best methods. A sensor with improved sensitivity for GA determination in real samples is developed. This work presents preparation of glycine modified carbon paste electrode (GMCPE) for square wave voltammetry determination of GA in groundnut and tea samples. Cyclic voltammetry and Electrochemical impedance spectroscopy results evidenced that modification of the surface of CPE by glycin improves the surface area and conductivity of the electrode. The appearance of an irreversible oxidative peak for GA with much reduced oxidative potential and about four folds current enhancement at GMCPE than the bare CPE showed the catalytic property of the modifier towards oxidation of GA. Under optimized conditions, SWV current response of GMCPE showed a linear dependence on the concentration of GA in the range 1.0 × 10-6 - 2.0 × 10-4 M, with LoD and LoQ 1.53 × 10-8 M and 5.1 × 10-8 M, respectively. Spike recovery results in groundnut and tea samples in the range 89.75-98.98% and 92.15-97.10%, respectively. Interference effect in the presence of selected potential interferents at their various levels with associated errors under 4.63% showed no interference on the current response of GA. The stability of the modifier with analysis time validated the applicability of the method for the determination of GA in real samples. Relative to previously reported works wider linear dynamic range, low LoD, high accuracy and selectivity make the present developed method an excellent candidate for determination of GA in real samples. [ABSTRACT FROM AUTHOR]

A simple, sensitive, cost effective, and reliable enzymatic glucose biosensor was developed and tested. Nitrogen-doped heat-treated graphene oxide nanoribbons (N-htGONR) were used for modification of commercially available screen-printed carbon electrodes (SPCEs), together with MnO2 and glucose oxidase. The resulting sensors were optimized and used to detect glucose in a wide linear range (0.05–5.0 mM) by a simple amperometric method, where the limit of detection was determined to be 0.008 mM. (lifetime), and reproducibility studies were also carried out and yielded favorable results. The sensor was then tested against potential interfering species present in food and beverage samples before its application to real matrix. Spiked beer samples were analyzed (with glucose recovery between 93.5 and 103.5%) to demonstrate the suitability of the developed sensor towards real food and beverage sample applications. [ABSTRACT FROM AUTHOR]

Quantum dots functionalization has been proven to be a simple modification strategy for improving the electroanalytical performance of two-dimensional electrode materials by increasing the specific surface area and active reaction sites. Herein, a new electrochemical sensing platform was fabricated by SnO2 quantum dot-functionalized Ti3C2 MXene (Ti3C2-SnO2QDs) for the highly sensitive detection of Sudan I in food. Ti3C2-SnO2QDs were prepared via in situ synthesis, which can control the nucleation and growth of SnO2QDs, resulting in the well-dispersed SnO2QDs with 2–3 nm size on the intersheet surface of MXene. Moreover, the formation of Ti3C2-SnO2QDs can effectively restrict the aggregation of Ti3C2 and improve the stability of SnO2QDs in aquatic environment. The prepared nanocomposite can be used as an improved modified material to further increase the electrocatalytic performance and electrochemical signal of Sudan I on the surface of a glassy carbon electrode. Under optimized conditions, the proposed analytical method displayed a linear dependence for Sudan I concentration ranging from 0.008 to 10 μM with a detection limit of 0.27 nM (S/N = 3) by electrochemical cyclic voltammetry. This sensor with excellent selectivity, reproducibility and accuracy was quantitatively validated in commercial ketchup and chili powder. This Ti3C2-SnO2QDs-based Sudan I sensor is expected to expand the application of MXene nanocomposites in electrochemical analysis and is envisioned as a promising candidate for monitoring illegal food additives in real food samples. [ABSTRACT FROM AUTHOR]

Tenofovir disoproxil fumarate (TDF) is an antiretroviral medication with significant curative effects, so its quantitative detection is important for human health. At present, there are few studies on the detection of TDF by electrochemical sensors. This work can be a supplement to the electrochemical detection of TDF. Moreover, bare electrodes are susceptible to pollution, and have high overvoltage and low sensitivity, so it is crucial to find a suitable electrode material. In this work, zirconium oxide (ZrO2) that has a certain selectivity to phosphoric acid groups was synthesized by a hydrothermal method with zirconyl chloride octahydrate as the precursor. A composite modified glassy carbon electrode for zirconium oxide-chitosan-multiwalled carbon nanotubes (ZrO2-CS-MWCNTs/GCE) was used for the first time to detect the TDF, and achieved rapid, sensitive detection of TDF with a detection limit of sub-micron content. The ZrO2-CS-MWCNTs composite was created using sonication of a mixture of ZrO2 and CS-MWCNTs solution. The composite was characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV). Electrochemical analysis was performed using differential pulse voltammetry (DPV). Compared with single-material electrodes, the ZrO2-CS-MWCNTs/GCE significantly improves the electrochemical sensing of TDF due to the synergistic effect of the composite. Under optimal conditions, the proposed method has achieved good results in linear range (0.3~30 μM; 30~100 μM) and detection limit (0.0625 μM). Moreover, the sensor has the merits of simple preparation, good reproducibility and good repeatability. The ZrO2-CS-MWCNTs/GCE has been applied to the determination of TDF in serum and urine, and it may be helpful for potential applications of other substances with similar structures. [ABSTRACT FROM AUTHOR]