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Molybdenum diselenide (MoSe2) is a potential catalyst for the electrocatalytic hydrogen evolution reaction (HER). However, MoSe2 exhibits a high overpotential in HER due to its low density of active sites, which may limit its practical applicability. Tuning the assisted metal interaction is an effective method for altering the atomic structure and catalytic efficiency of transition metal catalysts. Herein, we report a simple hydrothermal process for synthesising hybrid MoSe2-La2O3 heterostructures for HER. The electrocatalytic HER of nanoflower MoSe2 was improved in the presence of a supported lanthanide-oxide interaction (La2O3), proving that La2O3 materials produce additional activity sites in the MoSe2 materials. The nanocomposite was drop-cast onto screen-printed carbon electrodes (SPCE) and showed reduced overpotential values compared to pristine MoSe2 and La2O3 materials. Across all ratios tested, the MoSe2-La2O3 (M-L2) nanocomposites with a molar ratio of 1:2 exhibit rapid charge transfer during HER performance, with a Tafel slope value of 66 mV/dec and an onsetpotential of 270 mV. [ABSTRACT FROM AUTHOR]

This study presents the development of copper oxide–modified screen-printed carbon electrodes (CuO/SPCE) for the sensitive electrochemical detection of isoniazid (INZ). The electrodeposition of CuO on the surface of SPCE in a dilute CuSO4 solution forms CuO amorphisms or clusters, which catalyze the oxidation of INZ. The sensor exhibited a linear response to INZ concentrations ranging from 4 to 200 μM with a correlation coefficient of 0.991 and a limit of detection (LoD) of 8.39 μM. Stability and reproducibility were confirmed through repetitive measurements with relative standard deviations of 0.27% and 1.20%, respectively. Interference studies demonstrated the sensor's selectivity toward INZ, and a real sample analysis of pharmaceutical tablets yielded recovery rates ranging from 99.50 to 105.03%. Hence, regular monitoring of INZ dosage levels in human body fluids is critical, necessitating the development of sensitive, effective, and consistent methods to quantify INZ in clinical and pharmaceutical samples. [ABSTRACT FROM AUTHOR]

Integration of gold nanoparticles onto electrochemical biosensor electrodes has been widely conducted to improve the performance of biosensors. Gold nanospikes (AuNS), as one of the gold nanoparticle morphologies, can be integrated into biosensors through electrodeposition and has the potential to immobilize bioreceptor on biosensors using the self-assembled monolayer (SAM) method. This paper examines the potential of AuNS-deposited Screen-Printed Carbon Electrodes (SPCEs) on immobilizing enzymes as label-based electrochemical biosensor by evaluating the optimum parameter for glucose oxidase (GOx) enzyme immobilization on the SPCE that consists of incubation time and concentration of SAM molecule—L-cysteine—and GOx enzyme, then reviews its performances. The developed biosensor exhibits excellent performance in detecting glucose (linear range of 0.2–15 mM and limit of detection (LOD) of 116 µM), with good selectivity against uric acid, urea, ascorbic acid, dopamine, and lactic acid, and superiority towards gold nanosphere modified biosensor. [ABSTRACT FROM AUTHOR]

Disposable electrochemical biosensors with high sensitivity are very fit for point-of-care testing in clinical diagnosis. Herein, amino-functionalized, vertically ordered mesoporous silica films (NH2-VMSF) attached to an electrochemically polarized screen-printed carbon electrode (p-SPCE) are prepared using a simple electrochemical method and then utilized to construct a gated electrochemical aptasensor for rapid and sensitive determination of carcinoembryonic antigen (CEA). After being treated with the electrochemical polarization procedure, p-SPCE has plentiful oxygen-containing groups and improved catalytic ability, which help promote the stability of NH2-VMSF on SPCE without the use of an adhesive layer and simultaneously generate a highly electroactive sensing interface. Owing to the numerous uniform and ultrasmall nanopores of NH2-VMSF, CEA-specific aptamer anchored on the external surface of NH2-VMSF/p-SPCE serves as the gatekeeper, allowing the specific recognition and binding of CEA and eventually impeding the ingress of electrochemical probes [Fe(CN)63−/4−] through the silica nanochannels. The declined electrochemical responses of Fe(CN)63−/4− can be used to quantitatively detect CEA, yielding a wide detection range (100 fg/mL to 100 ng/mL) and a low limit of detection (24 fg/mL). Moreover, the proposed NH2-VMSF/p-SPCE-based electrochemical aptasensor can be applied to detect the amount of CEA in spiked human serum samples, which extends the biological application of a disposable NH2-VMSF/p-SPCE sensor by modulating the biological recognition species. [ABSTRACT FROM AUTHOR]

Interleukin-6 (IL6) is a cytokine mainly involved in inflammatory processes associated with various diseases, from rheumatoid arthritis and pathogen-caused infections to cancer, where malignant cells exhibit high proliferation and overexpression of cytokines, including IL6. Furthermore, IL6 plays a fundamental role in detecting and differentiating tumor cells, including colorectal cancer (CRC) cells. Therefore, given its range of biological activities and pathological role, IL6 determination has been claimed for the diagnosis/prognosis of immune-mediated diseases. Herein, a comparative study is presented of labeled and label-free electrochemical immunosensors involving a hierarchical Au@Pt nanoparticle/polymer hybrid material for detecting IL6. The electrochemical immunosensors were independently coupled to the surface of screen-printed carbon electrodes (SPCEs) previously modified with polymeric layers. While in the label-free immunosensor, an anti-IL6 antibody (IL6-Ab) was covalently bound to the modified SPCE surface, in the sandwich-like amperometric immunosensor, an anti-biotinylated-IL6 antibody (B-IL6-Ab) was attached to the electrode through biotin-avidin affinity interactions. The label-free format employed a straightforward detection of IL6 by differential pulse voltammetry (DPV). The resulting electrochemical immunosensors exhibited a linear dynamic range from 50 to 750 pg/mL IL6, with detection limits (LOD) of 14.4 and 6.0 pg/mL for label-free and sandwich-like immunosensors, respectively. This outstanding performance makes them versatile platforms for clinical analysis of a panel of biomarkers for early diagnosis/prognosis of inflammatory processes associated with oncological diseases, among other pathologies. [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]

Addressing the challenges of tuberculosis drug detection, this study investigates the application of copper(II) oxide modified screen-printed carbon electrodes (CuO/SPCEs) for the electrochemical detection of rifampicin, a critical drug in the treatment of tuberculosis and mycobacterial infections. The CuO/SPCE was fabricated via a constant potential electrodeposition technique and characterized using voltammetry. The bare SPCE surface exhibited a rough, porous structure, whereas the electrodeposition of CuO resulted in a smoother CuO/SPCE surface. The sensor exhibited high sensitivity with a detection limit of 2.89 μM for rifampicin and demonstrated excellent stability with a relative standard deviation of 3.5% over 10 measurements. The reproducibility was confirmed with an RSD of 4.2% across different electrodes. It also showed a linear response to rifampicin concentrations ranging from 10 to 200 μM. The real sample analysis showed a linear relationship between rifampicin concentration and peak current (I = 0.739 + 0.008 c), with a high correlation coefficient (R2 = 0.995). This electrochemical sensor's simplicity, cost-effectiveness, and rapid response make it a promising tool for point-of-care applications in tuberculosis management. [ABSTRACT FROM AUTHOR]

Water pollution with phenolic compounds is a serious environmental issue that can pose a major threat to the water sources. This pollution can come from various agricultural and industrial activities. Phenolic compounds can have detrimental effects on both human health and the environment. Therefore, it is essential to develop and improve analytical methods for determination of these compounds in the water samples. In this work, the aim was to design and develop an electrochemical sensing platform for the determination of 2,4-dichlorophenol (2,4-DCP) in water samples. In this regard, a nanocomposite consisting of CoWO4 nanoparticles (NPs) anchored on reduced graphene oxide nanosheets (rGO NSs) was prepared through a facile hydrothermal method. The formation of the CoWO4/rGO nanocomposite was confirmed via different characterization techniques. Then, the prepared CoWO4/rGO nanocomposite was used to modify the surface of a screen-printed carbon electrode (SPCE) for enhanced determination of 2,4-DCP. The good electrochemical response of the modified SPCE towards the oxidation of 2,4-DCP was observed by using cyclic voltammetry (CV) due to the good properties of CoWO4 NPs and rGO NSs along with their synergistic effects. Under optimized conditions, the CoWO4/rGO/SPCE sensor demonstrated a broad linear detection range (0.001 to 100.0 µM) and low limit of detection (LOD) (0.0007 µM) for 2,4-DCP determination. Also, the sensitivity of CoWO4/rGO/SPCE for detecting 2,4-DCP was 0.3315 µA/µM. In addition, the good recoveries for determining spiked 2,4-DCP in the water samples at the surface of CoWO4/rGO/SPCE showed its potential for determination of this compound in real samples. [ABSTRACT FROM AUTHOR]

Integration of gold nanoparticles onto electrochemical biosensor electrodes has been widely conducted to improve the performance of biosensors. Gold nanospikes (AuNS), as one of the gold nanoparticle morphologies, can be integrated into biosensors through electrodeposition and has the potential to immobilize bioreceptor on biosensors using the self-assembled monolayer (SAM) method. This paper examines the potential of AuNS-deposited Screen-Printed Carbon Electrodes (SPCEs) on immobilizing enzymes as label-based electrochemical biosensor by evaluating the optimum parameter for glucose oxidase (GOx) enzyme immobilization on the SPCE that consists of incubation time and concentration of SAM molecule—L-cysteine—and GOx enzyme, then reviews its performances. The developed biosensor exhibits excellent performance in detecting glucose (linear range of 0.2–15 mM and limit of detection (LOD) of 116 µM), with good selectivity against uric acid, urea, ascorbic acid, dopamine, and lactic acid, and superiority towards gold nanosphere modified biosensor.

Pharmaceutical compounds, such as ibuprofen and metoprolol, are of increasing concern due to their persistence in the environment and potential adverse effects on human health. In this work, we developed an electrochemical sensor system for the determination of ibuprofen and metoprolol based on a modified manganese oxide nanoparticle (MnO2NPs) on a screen‐printed carbon electrode (SPCE). The characterisation of MnO2NPs modifier was investigated via Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy techniques, Uv/vis spectroscopy, and small‐angle X‐ray scattering spectroscopy. The electrochemical behaviour of the MnO2NPs was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The optimum experimental conditions were investigated by examining the effects of scan rates, pH on the CV responses, and electrolytes on the DPV response. The MnO2NPs modified electrode demonstrated enhanced catalytic activity in the electro‐oxidation of both ibuprofen and metoprolol. The oxidation peaks of ibuprofen and metoprolol were observed at +1.14 V and +1.46 V, respectively, for the MnO2NPs/SPCE sensor. The sensor's limit of detection was 3.81 pM and 4.6 pM respectively and its linear response was from 0.97–5.82 pM. Furthermore, interference and stability studies were conducted to evaluate the performance of the MnO2NPs/SPCE sensor under optimum conditions, which resulted in a good performance. The proposed sensor was successfully used for the determination of ibuprofen and metoprolol in the application of real water samples. [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]

Herein, we report a ratio-based electrochemical biosensor for the detection of interleukin-6 (IL-6). We electropolymerized methylene blue (MB) on the surface of screen-printed carbon electrodes; introduced an internal reference signal probe; modified the carboxylate multi-walled carbon nanotubes on the electrode surface to increase the electrochemically active area; and finally linked the amino-modified IL-6 aptamer to the electrode surface through the Schiff base reaction, with bovine serum albumin (BSA) added to mask non-specific adsorption. After adding IL-6 to the samples, the signal of IMB remained almost unchanged, while the signal of I[Fe(CN)6]3−/4− decreased with increasing IL-6 concentration. Thus, a novel ratiometric electrochemical sensor with a linear range of 0.001~1000.0 ng/mL and a low detection limit of 0.54 pg/mL was successfully developed. The sensor had high repeatability, stability, sensitivity, and practicability. It provides a new method for constructing proportional electrochemical sensors and detecting IL-6. [ABSTRACT FROM AUTHOR]

In this study, nanoporous gold (NPG) was deposited on a screen-printed carbon electrode (SPCE) by the dynamic hydrogen bubble template (DHBT) method to prepare an electrochemical sensor for the simultaneous determination of Pb2+ and Cu2+ by square wave anodic stripping voltammetry (SWASV). The electrodeposition potential and electrodeposition time for NPG/SPCE preparation were investigated thoroughly. Scanning electron microscopy (SEM) and energy-dispersive X-ray diffraction (EDX) analysis confirmed successful fabrication of the NPG-modified electrode. Electrochemical characterization exhibits its superior electron transfer ability compared with bare and nanogold-modified electrodes. After a comprehensive optimization, Pb2+ and Cu2+ were simultaneously determined with linear range of 1–100 μg/L for Pb2+ and 10–100 μg/L for Cu2+, respectively. The limits of detection were determined to be 0.4 μg/L and 5.4 μg/L for Pb2+ and Cu2+, respectively. This method offers a broad linear detection range, a low detection limit, and good reliability for heavy metal determination in drinking water. These results suggest that NPG/SPCE holds great promise in environmental and food applications. [ABSTRACT FROM AUTHOR]

A portable voltammetric sensor for toxicity assessment was developed based on a screen‐printed carbon electrode modified with SiO2‐CuO‐glucose oxidase (GOx) film. The method is based on the detection of the metabolic activity of E. coli towards glucose as an indicator systems in the presence of antiseptic drugs as model toxic compounds. CuO particles exhibited catalytic activity toward hydrogen peroxide produced by the GOx‐induced oxidation of glucose. A well‐defined reduction peak was registered at E=−0.50 V (vs. Ag/AgCl). The metabolism of glucose by E. coli resulted in a decrease in analytical signal of glucose with the increasing bacteria content in the range of 0.8×109–5.0×109 CFU mL−1 with a calculated limit of detection (LOD) of 0.59×109 CFU mL−1. To evaluate the effect of antiseptics the biosensor was tested in E. coli solution with chlorhexidine (CHD) or decamethoxine (DMT). A linear dependence of glucose consumption by E. coli solution on the antiseptic concentration was obtained in the range of 3.0–12.0 μg mL−1 for CHG and 1.0–12.0 μg mL−1 for DMT, respectively. The developed third generation biosensor showed satisfactory stability and reproducibility of the analytical response. A modified electrode can be used for at least two months. [ABSTRACT FROM AUTHOR]

We report on the fabrication of a robust non-enzymatic glucose sensor featuring a sensing electrode composed of pyramid-shaped copper/copper oxide (Cu/Cu2O) nanostructures formed through a simple electrodeposition process on a screen-printed carbon electrode (SPCE). The fabrication of Cu/Cu2O nanostructures on the SPCE enhances the charge transfer and electrocatalytic performance of the sensor, proving advantageous for glucose sensing. Notably, this morphology contributes to electrochemical glucose determination over a wide linear range of 0.01 to 6 mM, with a sensitivity of 214.04 μA/(mM·cm2) and a low detection limit of 0.03 μM. The proposed simple approach ensures high reproducibility, stable attachment to the printed layer, and cost-effectiveness, making it well-suited for scalable production of non-enzymatic glucose sensors.

Featured Application: Measurement of glycerol content for wine safety and quality. This paper describes the design and development of a novel electrochemical biosensor for measuring glycerol in wine. Our initial detailed studies were aimed at deducing the optimum conditions for biosensor operation by conducting hydrodynamic voltammetric and amperometric studies. The resulting voltammograms revealed a maximum electrocatalytic current at 0.0 V vs. Ag/AgCl, which we used for all further studies. We also examined the effect of pH (8–10) on the amperometric responses of different glycerol concentrations over a range of 0.04 to 0.20 mM. Based on our findings, we propose that pH 9 would be suitable as the supporting electrolyte for further studies with the amperometric biosensor. The biosensor was constructed by immobilising 10 units of GLDH and 660 μg NAD+ onto the MB-SPCE surface using glutaraldehyde (GLA) as a cross-linking agent. Calibration studies were performed with glycerol over the 1.0–7.5 mM concentration range. Chronoamperometry was the electrochemical technique chosen for this purpose as it is convenient and can be performed with only 100 μL of sample directly deposited onto the biosensor's surface. In the current study, we observed linear calibration plots with the above standard solutions using current measurements at a selection of sampling times along the chronoamperograms (30–340 s). We have evaluated the glycerol biosensor by carrying out an analysis of commercially available red wine. Overall, these findings will form a platform for the development of novel rapid technology for point-of-test evaluation of glycerol in the production and quality control of wine. [ABSTRACT FROM AUTHOR]

A trendsetting direct competitive-based biosensing tool has been developed and implemented for the determination of the polyunsaturated fatty acid arachidonic acid (ARA), a highly significant biological regulator with decisive roles in viral infections. The designed methodology involves a competitive reaction between the target endogenous ARA and a biotin-ARA competitor for the recognition sites of anti-ARA antibodies covalently attached to the surface of carboxylic acid-coated magnetic microbeads (HOOC-MµBs), followed by the enzymatic label of the biotin-ARA residues with streptavidin-horseradish peroxidase (Strep-HRP) conjugate. The resulting bioconjugates were magnetically trapped onto the sensing surface of disposable screen-printed carbon transducers (SPCEs) to monitor the extent of the biorecognition reaction through amperometry. The operational functioning of the exhaustively optimized and characterized immunosensing bioplatform was highly convenient for the quantitative determination of ARA in serum samples from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-) and respiratory syncytial virus (RSV)-infected individuals in a rapid, affordable, trustful, and sensitive manner. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant interest in the advancement of electrochemical sensing platforms to detect antipyretic drugs with high sensitivity and selectivity. The electrochemical determination of acetaminophen (PCT) was studied with strontium molybdate with a functionalized carbon nanotube (SrMoO4@f-CNF) nanocomposite. The SrMoO4@f-CNF nanocomposite was produced by a facial hydrothermal followed by sonochemical treatment, resulting in a significant enhancement in the PCT determination. The sonochemical process was applied to incorporate SrMoO4 nanoparticles over f-CNF, enabling a network-like structure. Moreover, the produced SrMoO4@f-CNF composite structural, morphological, and spectroscopic properties were confirmed with XRD, TEM, and XPS characterizations. The synergistic effect between SrMoO4 and f-CNF contributes to the lowering of the charge transfer resistance ( R c t = 85   Ω · c m 2 ), a redox potential of E p c = 0.15   V and E p a = 0.30   V (vs. Ag/AgCl), and a significant limit of detection (1.2 nM) with a wide response range of 0.01–28.48 µM towards the PCT determination. The proposed SrMoO4@f-CNF sensor was studied with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques and demonstrated remarkable electrochemical properties with a good recovery range in real-sample analysis. [ABSTRACT FROM AUTHOR]

A core–shell ZIF-67@ZIF-8-derived Co nanoparticles embedded in N-doped carbon nanotube polyhedra (Co/C-NCNP) hybrid nanostructure was prepared by a pyrolysis method. The synthesized Co/C-NCNP was modified on the screen-printed carbon electrode and used for the portable wireless sensitive determination of breviscapine (BVC) by differential pulse voltammetry. The Co/C-NCNP had a large surface area and excellent catalytic activity with increasing Co sites to combine with BVC for selective determination, which led to the improvement of the sensitivity of the electrochemical sensor. Under optimized conditions, the constructed sensor had linear ranges from 0.15 to 20.0 µmol/L and 20.0 to 100.0 µmol/L with the limit of detection of 0.014 µmol/L (3S0/S). The sensor was successfully applied to BVC tablet sample analysis with satisfactory results. This work provided the potential applications of zeolitic imidazolate framework-derived nanomaterials in the fabrication of electrochemical sensors for the sensitive detection of drug samples. [ABSTRACT FROM AUTHOR]

Background and purpose: Chronic myeloid leukaemia (CML) is one of the most lethal types of leukaemia and can rapidly progress if not treated properly. Therefore, having an effective diagnostic strategy is crucial. Various methods are available for diagnosis, including electrochemical biosensors with aptamer bioreceptors. Experimental approach: In this study, we immobilized the KK1D04 aptamer on a screen-printed carbon electrode (SPCE) supported by CeO2 nanoparticles (CeO2NPs) to detect K562 cells, a type of CML cell line. Several parameters were optimized to enhance the aptasensor response using the Box-Behnken experimental design. Key results: The developed aptasensor demonstrated good performance with a limit of detection (LOD) and limit of quantification (LOQ) of 16 cells/mL and 3,882 cells/mL, respectively, in the K562 cell concentration range of 102 to 106 cells/mL. The optimum experimental conditions were an aptamer concentration of 0.8 ppm, an aptamer incubation time of 36 minutes, and a K562 aptamer-cell incubation time of 13 minutes. The aptasensor also exhibits selectivity for K562 cells compared to Vero cells, THP1 cells, and Raji cells. Conclusion: The aptasensor in this study demonstrated the potential to detect K562 cells. These results could contribute to the advancement of point-of-care (POC) devices for the detection of CML.

Abstract Glyphosate (GLY) is a widely used herbicide with an important role in agriculture. It effectively controls weeds, enhancing agricultural yield and product quality. However, its use raises significant concerns such as potential risks to non-target ecosystems and human health. In response to these concerns, we develop an electrochemical sensor with a molecularly imprinted polymer (MIP) and gold nanoparticles for GLY detection. The sensor includes a screen-printed carbon electrode (SPCE) functionalized with gold nanoparticles and a self-assembled polyvinyl carboxylic acid chloride (PVC-COOH) layer. GLY compounds interact with carboxylic groups and are encapsulated by a polymer of methacrylic acid (MAA) cross-linked with ethylene glycol dimethacrylate (EGDMA). Electrochemical performance was assessed using differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Morphological characterization was performed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). The sensor exhibits impressive selectivity, detecting GLY within a range of 273–1200 pg/mL with minimal interference from other pesticides. It boasts a low detection limit of 0.8 pg/mL (signal-to-noise ratio S/N = 3) by DPV and 0.001 pg/mL by EIS. The sensor’s versatility extends to various sample types, including surface water, agricultural wastewater, soil, and cucumber, demonstrating high recovery rates (> 96.05%) and low relative standard deviation (RSD) (

Water pollution with phenolic compounds is a serious environmental issue that can pose a major threat to the water sources. This pollution can come from various agricultural and industrial activities. Phenolic compounds can have detrimental effects on both human health and the environment. Therefore, it is essential to develop and improve analytical methods for determination of these compounds in the water samples. In this work, the aim was to design and develop an electrochemical sensing platform for the determination of 2,4-dichlorophenol (2,4-DCP) in water samples. In this regard, a nanocomposite consisting of CoWO4 nanoparticles (NPs) anchored on reduced graphene oxide nanosheets (rGO NSs) was prepared through a facile hydrothermal method. The formation of the CoWO4/rGO nanocomposite was confirmed via different characterization techniques. Then, the prepared CoWO4/rGO nanocomposite was used to modify the surface of a screen-printed carbon electrode (SPCE) for enhanced determination of 2,4-DCP. The good electrochemical response of the modified SPCE towards the oxidation of 2,4-DCP was observed by using cyclic voltammetry (CV) due to the good properties of CoWO4 NPs and rGO NSs along with their synergistic effects. Under optimized conditions, the CoWO4/rGO/SPCE sensor demonstrated a broad linear detection range (0.001 to 100.0 µM) and low limit of detection (LOD) (0.0007 µM) for 2,4-DCP determination. Also, the sensitivity of CoWO4/rGO/SPCE for detecting 2,4-DCP was 0.3315 µA/µM. In addition, the good recoveries for determining spiked 2,4-DCP in the water samples at the surface of CoWO4/rGO/SPCE showed its potential for determination of this compound in real samples.

An enzyme immunoassay was developed based on the coulometric measurement of immunoglobulin M (IgM) against Hantaan viruses (HTNV) by using virus-like particles (VLPs) as recognition molecules. The surface functionalization of screen-printed carbon electrodes (SPCEs) was achieved through paste-exfoliated graphene that was modified with a COOH group and a thionine mediator through supramolecular-covalent scaffolds, on SPCEs by using the binder contained in the ink. After the covalent immobilization of the antibody, the sensor was used for the sandwich enzyme immunoassay of IgM against HTNV. By using HTNV VLPs as the second recognization molecules, the resulting sensor efficiently monitored the reaction of IgM against HTNV and anti-IgM antibody with high specificity. By attaching HTNV nucleocapsid protein antibody conjugate with horseradish peroxidase (HRP) onto VLPs, the signal response of the assay was derived from the coulometric measurement of H2O2 reduction mediated by thionine on the electrode surface after the application of a potential (− 0.2 V vs. Ag/AgCl). The ratio of charges measured before or after H2O2 addition was used to quantify IgM because these charges could be used as background charges or total charges, respectively. The ratio exhibited good agreement with IgM concentration within a range 0.1 to 1000 pg mL−1, and a detection limit of 0.06 pg mL−1 was obtained. The assay demonstrated high sensitivity and specificity toward HTNV-specific IgM in serum. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemical sensor was created by fabricating a screen-printed carbon electrode with diamond nanoparticles (DNPs/SPCE). The successful development of the sensor enabled the specific detection of the anti-cancer drug flutamide (FLT). The DNPs/SPCE demonstrated excellent conductivity, remarkable electrocatalytic activity, and swift electron transfer, all of which contribute to the advantageous monitoring of FLT. These qualities are critical for monitoring FLT levels in environmental samples. Various structural and morphological characterization techniques were employed to validate the formation of the DNPs. Remarkably, the electrochemical sensor demonstrated a wide linear response range (0.025 to 606.65 μM). Additionally, it showed a low limit of detection (0.023 μM) and high sensitivity (0.403 μA μM−1 cm−2). Furthermore, the practicability of DNPs/SPCE can be successfully employed in FLT monitoring in water bodies (pond water and river water samples) with satisfactory recoveries. [ABSTRACT FROM AUTHOR]

In this paper, a highly conductive alkali-activated graphitized carbon (a-GC) was prepared using tilapia fish scales as precursors through enzymolysis, activation and pyrolytic carbonization methods. The prepared a-GC was modified on the surface of a screen-printed carbon electrode to construct a flexible portable electrochemical sensing platform, which was applied to the differential pulse voltametric detection of dopamine (DA) using a U-disk electrochemical workstation combined with a smart phone and Bluetooth. The prepared a-GC possesses good electrical conductivity, a large specific surface area and abundant active sites, which are beneficial for the electrooxidation of DA molecules and result in excellent sensitivity and high selectivity for DA analysis. Under the optimal conditions, the oxidation peak current of DA increased gradually, with its concentrations in the range from 1.0 μmol/L to 1000.0 μmol/L, with the detection limit as low as 0.25 μmol/L (3S/N). The proposed sensor was further applied to the determination of DA in human sweat samples, with satisfactory results, which provided an opportunity for developing noninvasive early diagnosis and nursing equipment. [ABSTRACT FROM AUTHOR]

Glyphosate (GLY) is a widely used herbicide with an important role in agriculture. It effectively controls weeds, enhancing agricultural yield and product quality. However, its use raises significant concerns such as potential risks to non-target ecosystems and human health. In response to these concerns, we develop an electrochemical sensor with a molecularly imprinted polymer (MIP) and gold nanoparticles for GLY detection. The sensor includes a screen-printed carbon electrode (SPCE) functionalized with gold nanoparticles and a self-assembled polyvinyl carboxylic acid chloride (PVC-COOH) layer. GLY compounds interact with carboxylic groups and are encapsulated by a polymer of methacrylic acid (MAA) cross-linked with ethylene glycol dimethacrylate (EGDMA). Electrochemical performance was assessed using differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Morphological characterization was performed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). The sensor exhibits impressive selectivity, detecting GLY within a range of 273–1200 pg/mL with minimal interference from other pesticides. It boasts a low detection limit of 0.8 pg/mL (signal-to-noise ratio S/N = 3) by DPV and 0.001 pg/mL by EIS. The sensor's versatility extends to various sample types, including surface water, agricultural wastewater, soil, and cucumber, demonstrating high recovery rates (> 96.05%) and low relative standard deviation (RSD) (< 5.7%). The developed MIP sensor is proven to be a valuable tool for rapid and highly sensitive detection of GLY in diverse environmental and agri-food samples. [ABSTRACT FROM AUTHOR]

Herein, we report a ratio-based electrochemical biosensor for the detection of interleukin-6 (IL-6). We electropolymerized methylene blue (MB) on the surface of screen-printed carbon electrodes; introduced an internal reference signal probe; modified the carboxylate multi-walled carbon nanotubes on the electrode surface to increase the electrochemically active area; and finally linked the amino-modified IL-6 aptamer to the electrode surface through the Schiff base reaction, with bovine serum albumin (BSA) added to mask non-specific adsorption. After adding IL-6 to the samples, the signal of IMB remained almost unchanged, while the signal of I[Fe(CN)6]3−/4− decreased with increasing IL-6 concentration. Thus, a novel ratiometric electrochemical sensor with a linear range of 0.001~1000.0 ng/mL and a low detection limit of 0.54 pg/mL was successfully developed. The sensor had high repeatability, stability, sensitivity, and practicability. It provides a new method for constructing proportional electrochemical sensors and detecting IL-6.

Over the last decade, many applications of electrochemical sensors/biosensors have been developed with various considerations such as cost-effectiveness, process simplicity, high sensitivity and accuracy, the need for the amount of analyte, and a miniature structure with portability. Until now, various electrochemical methods have been used to develop biosensors for detecting molecular markers, especially their modifications with nanoparticles. Historically, gold is a very inert material with little or no reactivity; thus, nanosized gold particles have been shown to function as an effective catalyst for a number of chemical reactions under various experimental conditions. In this study, the design of experiment (DoE) is used to create a model and analyze the best response that is affected by several independent variables with the aim of optimizing the response. The results showed that gold nanoparticles (AuNPs) were able to increase the peak current on the screen-printed carbon electrode-gold nanoparticle electrode and produced two of the most significant factors, namely, the concentration of single-stranded deoxyribonucleic acid (ssDNA) probe and the attachment time of AuNPs. [ABSTRACT FROM AUTHOR]

Fusidic acid and betamethasone are two pharmaceutically active compounds found in topical dosage forms. Sometimes, they can unintentionally wind up in surface water via skin washing. Therefore, a stochastic platform based on a type of calix[4]arene and polyaniline modified screen-printed electrode was developed for their on-site analysis. For both analytes, remarkably wide dynamic ranges (1.0 × 10−17–1.0 × 10−4 for fusidic acid, and 1.0 × 10−18–1.0 × 10−3 for betamethasone) and considerably low limits of quantitation (1.0 × 10−17 for fusidic acid, and 1.0 × 10−18 for betamethasone) were attained. Moreover, the proposed platform was successfully applied to real samples such as topical dosage form and surface water, obtaining recovery values higher than 90.0 % with relative standard deviation values below 0.1 %.

A simple and selective method for the determination of caffeine (CAF) and theophylline (THEO) has been developed for a glassy carbon electrode (GCE) modified with a composite including carbon dots (CDs) and chitosan (CS). To our knowledge, there are no previous studies that analyze a CDs-modified GCE for the presence of CAF and THEO. The electrochemical behavior of a GCE modified with a CDs-CS composite was studied in acidic medium by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Considering the sensor analytical parameters, the same linear concentrations range was found for CAF and THEO ranging from 1 × 10−5 to 5 × 10−3 mol L−1 with the same detection limit (LOD) of 1 × 10−6 mol L−1. The reproducibility and repeatability data were satisfactory in terms of RSD%. Moreover, the storage stability was evaluated, evidencing good results whatever the experimental conditions used. The developed sensor was applied for the simultaneous determination of CAF and THEO in tea and drug, and results were compared with those obtained with HPLC-ESI-MS in SIR mode as an independent method optimized on purpose. The electrochemical sensor presents the undoubled advantages in terms of cheapness, portability, and ease of use, since it does not require skilled personnel. [ABSTRACT FROM AUTHOR]

An electrochemical immunosensor based on carbon nanofibers (CNFs) and gold nanoparticles (AuNPs) was developed for detecting anti-Toxoplasma gondii antibodies (anti-T. gondii) IgG in human serum. CNFs were produced using electrospinning and carbonization processes. Screen-printed carbon electrode (SPCE) surface was modified with CNFs and AuNPs which were electrodeposited onto the CNFs. Then, T. gondii antigen was immobilized onto the AuNPs/CNFs/SPCE. Afterward, anti-T. gondii IgG positive serum samples were coated on the modified electrode and assessed via adding anti-human IgG labeled with horseradish peroxidase (HRP) enzyme. The morphology of SPCE, CNFs, and AuNPs/CNFs/SPCE surface was characterized using field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS). Characterization of CNFs was evaluated by Raman spectroscopy and X-ray diffraction (XRD). Electrochemical characterization of the immunosensor was verified using cyclic voltammetry (CV), and electrochemical response of modified electrode for anti-T. gondii IgG was detected via differential pulse voltammetry (DPV). This immunosensor was detected in the range 0–200 U mL−1 with a low detection limit (9 × 10−3 U mL−1). In addition, the proposed immunosensor was exhibited with high selectivity, strong stability, and acceptable reproducibility and repeatability. Furthermore, there was a strong correlation between results obtained via the designed immunosensor and enzyme-linked immunosorbent assay (ELISA) as gold standard. In conclusion, the developed immunosensor is a promising route for rapid and accurate clinical diagnosis of toxoplasmosis. [ABSTRACT FROM AUTHOR]

Capsaicinoids, mostly from chili peppers, are widely used in daily life. Capsaicinoids are considered to be markers for the identification of illegal cooking oil (ICO), which is a serious threat to public health. The identification of capsaicinoids can help reveal food-related fraud, thereby safeguarding consumers' health. Here, a novel and ultrasensitive method was established with a signal amplification strategy for the detection of capsaicinoids. AuNPs@Fe3O4 nanocomposites were functionalized with 4-aminothiophenol (4-atp). After diazotization, 4-atp on AuNPs@Fe3O4 reacted with capsaicinoids and formed capsaicinoids-azo-atp-AuNPs@Fe3O4. Ultimately, capsaicinoids-azo-atp-AuNPs@Fe3O4 was dropped onto the surface of a screen-printed carbon electrode (SPCE) and detected via the differential pulse voltammetry (DPV) method. AuNPs@Fe3O4 nanocomposites increased the specific surface area of the electrode. Moreover, the diazotization–coupling reaction enriched the analytes on the electrode surface. Liquid–liquid extraction was used for sample pretreatment. Under a pH value of 9.0 and concentration of 0.20 mol/L for the supporting electrolyte, the linearity of capsaicinoids in ICO is from 0.10 to 10.00 ng/mL, and the limit of detection (S/N = 3) is 0.05 ng/mL. This method is ultra-sensitive, reliable, and cost-effective for the detection of capsaicinoids. Herein, this method provides a promising tool for the identification of ICO. [ABSTRACT FROM AUTHOR]

Study of the use of polymers with higher conductivity like polypyrrole, and polyaniline in the electrochemical insulin sensors can overcome the drawbacks arising from the ongoing use of non-conductive polymer membrane. Conductive polymer membranes maintain the positive properties of polymers, like improved stability, reproducibility, and even increase the current response of the prepared sensor toward insulin oxidation. Three different screen-printed electrodes modified with polyaniline, polypyrrole, or chitosan with electrochemically deposited nickel nanoparticles ensuring insulin oxidation were prepared. The electrode morphology was examined via SEM with EDX analysis. Also, the electroactive surface area and stability were determined by voltammetric methods. Based on the results, the SPCEs modified by polypyrrole and nickel nanoparticles were determined as the most appropriate for the insulin determination. The NiNPs-PPy-SPCE exhibited a linear range (500 nM–5 µM), a low-down limit of detection (38 nM), high sensitivity (3.98 µA/µM), and excellent result from insulin determination in real samples (human blood serum). The results confirmed the high potential of developed sensor for future research focused on detection of insulin via electrochemistry methods in clinical samples. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) is a sensitive analytical method for surface and bulk properties. Classical EIS and derived electrochemical capacitance spectroscopy (ECS) with a redox couple are label-free approaches for biosensor development, but doubts arise regarding interpretability when a redox couple is employed (redox EIS) due to interactions between electroactive probes and interfacial charges or forced potential. Here, we demonstrated redoxless ECS for directly determining surfactant adsorption on screen-printed carbon electrodes (SPCEs), validated through a simulation of equivalent circuits and the electrochemistry of electronic dummy cells. Redoxless ECS provides excellent capacitance plot loci for quantifying the interfacial permittivity of di-electric layers on electrode surfaces. Redoxless ECS was compared with redox EIS/ECS, revealing a favorable discrimination of interfacial capacitances under both low and high SDS coverage on SPCEs and demonstrating potential for probeless (reagentless) sensing. Furthermore, the proposed method was applied in an electrolyte without a redox couple and bare electrodes, obtaining a high performance for the adsorption of surfactants Tween-20, Triton-X100, sodium dodecyl sulfate, and tetrapropylammonium bromide. This approach offers a simple and straightforward means for a semi-quantitative evaluation of small molecule interactions with electrode surfaces. Our proposed approach may serve as a starting point for future probeless (reagentless) and label-free biosensors based on electrochemistry, eliminating disturbance with surface charge properties and minimizing forced potential bias by avoiding redox couples. An unambiguous and quantitative determination of physicochemical properties of biochemically recognizable layers will be relevant for biosensor development. [ABSTRACT FROM AUTHOR]

In this research, carbon powder produced from bagasse, solid waste of sugarcane production, was used as raw material for creating screen-printed carbon electrode (SPCE), which is named SPAC600. Bagasse was carbonized at 600 °C under N2 flows to produce carbon. The carbonized bagasse was then treated with alkaline solution to leach out the impurities; therefore, the result, AC600, provides a significant increase in surface area from 24.8 to 197.10 m2 g−1. Alkaline treatment also changed the morphology of carbon powder into smaller flakes and removed C–H- aromatic vibration and C–O stretching within Fourier transformed- infrared (FTIR) spectra. The treatment also increases the electric conductivity from 10.01 S/cm to 25.39 S/cm. Alkaline leaching also increases the electrochemical performance of the electrode, proven by the significant increase of anodic current density, Ipa from 5.5 to 12.8 μA, for screen-printed carbon without alkaline leaching (SPC600) and SPAC600, respectively. Furthermore, ferrocene addition to the working electrode (WE) part of the prepared SPCE even increases the electrochemical performance as an analytic electrode, proven by the anodic current density of 173.0 μA. Even though the performance is still lower than a commercial SPCE which provides anodic current density up to 2000 μA, further treatment and modification may enhance the performance of the SPAC600. [ABSTRACT FROM AUTHOR]

Screen-printed carbon electrodes (SPCEs) were modified with gold particles to improve luminol electrochemiluminescence (ECL) in the presence of H2O2 as the co-reactant. Gold particles with sizes ranging from 10 to 50 nm were successfully deposited by the electrochemical technique with around 3.4% (w/w) gold on the carbon surface. The gold-modified SPCE (Au-SPCE) increases the ECL intensity of luminol around 2.5 times more than that using the unmodified SPCE. These signals were also found to be linearly correlated to H2O2 concentration. At an optimum pH of 9, the ECL signals of 1 mM luminol in 0.1 M phosphate buffer solution using the Au-SPCE are linear in the H2O2 concentration range from 0.5 to 200 pM (R2 = 0.99) with an estimated detection limit of 4.78 pM. The developed sensor also showed the excellent repeatability and reproducibility of the ECL signals. Moreover, H2O2 detection in milk and tap water samples was also successfully demonstrated, indicating that the developed sensor is promising for H2O2 detection applications. [ABSTRACT FROM AUTHOR]