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This work describes the development and evaluation of a novel electrochemical aptasensor for testosterone detection. The sensor utilizes a specifically designed DNA immobilized on a screen-printed gold electrode (SPGE) modified with a conductive hydrogel and gold nanoparticles (HG/NP) composite. The aptasensor exhibited a dose-dependent response to testosterone (0.05 to 50 ng/mL) with a detection limit of 0.14 ng/mL and a good sensitivity of 0.23 μA ng -1 mL cm -2 . The sensor displayed excellent selectivity towards testosterone compared to structurally similar steroid hormones. Importantly, the incorporation of HG/NP not only improved the sensor's conductivity but also acted as an antifouling layer, minimizing signal interference from non-specific biomolecule interactions in complex biological samples like human serum. The results obtained from the aptasensor showed good correlation with a standard ELISA method, demonstrating its effectiveness in real-world scenarios., (© 2024 Wiley-VCH GmbH.)

In this study, we focused on the successful construction of [(4,4'-bipy/P 2 Mo 17 Co) 6 ] modified electrodes using the layer-by-layer assembly method for the sensitive detection of sulfathiazole (ST). The redox reaction between ST and the metal ions in the modified layer leads to the transfer of electrons, resulting in the generation of the electrical signal. The introduction of 4,4'-bipyridine (4,4'-bipy) enhanced the molecular recognition of ST by the modified electrode. Under the combined effect of P 2 Mo 17 Co and 4,4'-bipy, the sensor exhibited good performance for ST detection (LOD: 0.5616 μM, linear ST concentration range: 0-50 μM). The spiked recoveries of the two groups were 84.4%-103.2% and 90.9%-109.4% for the determination of ST residues in large yellow croaker and South American white shrimp, respectively. In addition, the electrode showed excellent performance in terms of stability, reproducibility, and anti-interference ability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this work, a carbon felt (CF) was utilized to fabricate electrochemical sensors for the simultaneous detection of Cd 2+ , Pb 2+ and Hg 2+ . The working conditions of CF sensors including thermal activation, electrolytes, and enrichment potentials and times were systematically investigated. Under the optimal detection conditions, the resulting sensors showed good linearity in the concentration ranges of 3-10,000, 2-10,000 and 5-10,000 μg/L for the detection of Cd 2+ , Pb 2+ and Hg 2+ , corresponding to the detection limits of 1, 0.5, and 1 μg/L, respectively. Meanwhile, the resulting electrochemical sensor demonstrates excellent reproducibility and anti-interference. In addition, the CF electrodes maintain good stability even after 180 days of storage at room temperature. In real water, rice and milk samples, the CF electrodes have been successfully utilized for the detection of Cd 2+ , Pb 2+ and Hg 2+ and the results were in agreement with those obtained from the inductively coupled plasma mass spectrometry., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024. Published by Elsevier Ltd.)

This review explores the emerging role of screen-printed electrodes (SPEs) in the detection of breast cancer biomarkers. We discuss the fundamental principles and fabrication techniques of SPEs, highlighting their adaptability and cost-effectiveness. The review examines various modification strategies, including nanomaterial incorporation, polymer coatings, and biomolecule immobilization, which enhance sensor performance. We analyze the application of SPEs in detecting protein, genetic, and metabolite biomarkers associated with breast cancer, presenting recent advancements and innovative approaches. The integration of SPEs with microfluidic systems and their potential in wearable devices for continuous monitoring are explored. While emphasizing the promising aspects of SPE-based biosensors, we also address current challenges in sensitivity, specificity, and real-world applicability. The review concludes by discussing future perspectives, including the potential for early screening and therapy monitoring, and the steps required for clinical implementation. This comprehensive overview aims to stimulate further research and development in SPE-based biosensors for improved breast cancer management.

Electrochemical biosensors hold the exciting potential to integrate molecular detection with signal processing and wireless communication in a miniaturized, low-cost system. However, as electrochemical biosensors are miniaturized to the micrometer scale, their signal-to-noise ratio degrades and reduces their utility for molecular diagnostics. Studies have reported that nanostructured electrodes can improve electrochemical biosensor signals, but since the underlying mechanism remains poorly understood, it remains difficult to fully exploit this phenomenon to improve biosensor performance. In this work, electrochemical aptamer biosensors on nanoporous electrode are optimized to achieve improved sensitivity by tuning pore size, probe density, and electrochemical measurement parameters. Further, a novel mechanism in which electron transfer is physically accelerated within nanostructured electrodes due to reduced charge screening, resulting in enhanced sensitivity is proposed and experimentally validated. In concert with the increased surface areas achieved with this platform, this newly identified effect can yield an up to 24-fold increase in signal level and nearly fourfold lower limit of detection relative to planar electrodes with the same footprint. Importantly, this strategy can be generalized to virtually any electrochemical aptamer sensor, enabling sensitive detection in applications where miniaturization is a necessity, and should likewise prove broadly applicable for improving electrochemical biosensor performance in general., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Classic chemical sensors integrated in phones, vehicles, and industrial plants monitor the levels of humidity or carbonaceous/oxygen species to track environmental changes. Current projections for the next two decades indicate the strong need to increase the ability of sensors to sense a wider range of chemicals for future electronics not only to continue monitoring environmental changes but also to ensure the health and safety of humans. To achieve this goal, more chemical sensing principles and hardware must be developed. Here, a proof-of-principle for the specific electrochemistry, material selection, and design of a Li-garnet Li 7 La 3 Zr 2 O 12 (LLZO)-based electrochemical sensor is provided, targeting the highly corrosive environmental pollutant sulfur dioxide (SO 2 ). This work extends the prime use of LLZO as a battery component as well as the range of trackable pollutants for potential future sensor-noses. Novel composite sensing-electrode designs using LLZO-based porous scaffolds are employed to define a high number of reaction sites, and successfully track SO 2 at the dangerous levels of 0-10 ppm with close-to-theoretical SO 2 sensitivity. The insights on the sensing electrochemistry, phase stability and sensing electrode/Li + electrolyte structures provide first guidelines for future Li-garnet sensors to monitor a wider range of environmental pollutants and toxins., (© 2021 Wiley-VCH GmbH.)

Glucose is a popular biosensor target due to its closely with diabetes or hypoglycemia in blood. Designing efficiency electrocatalysts for the determination of glucose is vital to develop glucose detection devices. CoMoO 4 , as a kind of bimetallic oxide material, exhibits unique electrochemical properties. 3D macroporous carbon (MPC) has large specific surface area and excellent electrical conductivity, providing an effective support for loading other nano-entities to form novel composite with good synergetic effects. Herein, nanorod-like CoMoO 4 anchored onto MPC support was synthesized for the development of a promising electrochemical sensing platform for glucose. Attributing to the synergic effects between the good electrocatalytic performance of CoMoO 4 nanorods and the extraordinary electrical conductivity of 3D layered MPC, the novel CoMoO 4 /MPC composites non-enzymatic sensor shows excellent electrocatalytic performance for oxidation of glucose. Under the optimum conditions, the proposed CoMoO 4 /MPC hybrids provided a reliable linear range of 5 × 10 -7 to 1.08 × 10 -4  M with a low limit of detection (0.13 μM) for the detection of glucose. Meanwhile, the CoMoO 4 /MPC sensing platform shows fast response time of 1.76 s, good stability and selectivity for detecting glucose. Moreover, this non-enzymatic sensor also has been successfully applied to measure glucose level in human blood samples. Therefore, the developed sensor holds a new promise for the construction of facile and sensitive non-enzymatic glucose analytical platform., (Copyright © 2019 Elsevier Inc. All rights reserved.)

A novel nanocomposite of molecularly imprinted polymers and graphene sheets was fabricated and used to obtain a highly conductive acetylene black paste electrode with high conductivity for the detection of bisphenol A. The two-dimensional structure and the chemical functionality of graphene provide an excellent surface for the enhancement of the sensitivity of the electrochemical sensor and the specificity of molecularly imprinted polymers to improve detection of bisphenol A. The synergistic effect between graphene and molecularly imprinted polymers confers the nanocomposite with superior conductivity, broadened effective surface area and outstanding electrochemical performance. Factors affecting the performance of the imprinted sensor such as molecularly imprinted polymers concentration, foster time and scan rate are discussed. The sensor successfully detects bisphenol A with a wide linear range of 3.21 × 10 -10 to 2.8 × 10 -1 g/L (R = 0.995) and a detection limit of 9.63 × 10 -11 g/L. The fabricated sensor also possessed high selectivity and stability and exhibits potential for environmental detection of contaminants and food safety inspection., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

With the advances in the field of nanotechnology, significant progress is being achieved in fabrication of nanoscale electrodes (nanoelectrodes) and using their properties for applications in multiple fields. Compared with conventional macroscale electrodes, nanoelectrodes offer many advantages that arise from their limited size. Self-assembled chains of metal nanoparticles in particular have drawn interest for fabrication of nanoelectrodes because of their unique electrical properties and geometric morphology. This article discusses the fabrication methods and potential applications of nanoparticle chains as nanoelectrodes in electrochemical systems and also as conductometric sensors. The challenges for such systems are also summarized.

The preparation, characterization and analytical application of a chemically modified gold electrode (CME), based on ω-thio nitrilotriacetic acid derivative (N-[5-[[[[20-(acetylthio)-3,6,9-trioxaeicos-1-yl]oxo]carbonyl]amino]-1carboxypentyl]iminodiacetic acid) self-assembled monolayer (SAM), have been described. The electrode has been characterized by electrochemical techniques and tested for its response towards metallic ions, demonstrating to be effective for the determination of ionized iron at sub-μg L(-1) level by differential pulse cathodic stripping voltammetry (DPCSV). The analytical response towards iron in natural water (tap water, marine water) and the interference of ions usually present and chelating agents (humic acids and EDTA as model ligand of high complexing capacity) have been evaluated., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The multi-channel screen-printed array of electrodes (MUX-SPE16) was used in our study for the first time for electrochemical monitoring of nucleic acid hybridization related to different miRNA sequences (miRNA-16, miRNA-15a and miRNA-660, i.e, the biomarkers for Alzheimer disease). The MUX-SPE16 was also used for the first time herein for the label-free electrochemical detection of nucleic acid hybridization combined magnetic beads (MB) assay in comparison to the disposable pencil graphite electrode (PGE). Under the principle of the magnetic beads assay, the biotinylated inosine substituted DNA probe was firstly immobilized onto streptavidin coated MB, and then, the hybridization process between probe and its complementary miRNA sequence was performed at MB surface. The voltammetric transduction was performed using differential pulse voltammetry (DPV) technique in combination with the single-use graphite sensor technologies; PGE and MUX-SPE16 for miRNA detection by measuring the guanine oxidation signal without using any external indicator. The features of single-use sensor technologies, PGE and MUX-SPE16, were discussed concerning to their reproducibility, detection limit, and selectivity compared to the results in the earlier studies presenting the electrochemical miRNA detection related to different miRNA sequences., (© 2013 Elsevier B.V. All rights reserved.)

The intensifying global opioid crisis, majorly attributed to fentanyl (FT) and its analogs, has necessitated the development of rapid and ultrasensitive remote/on-site FT sensing modalities. However, current approaches for tracking FT exposure through wastewater-based epidemiology (WBE) are unadaptable, time-consuming, and require trained professionals. Toward developing an extended in situ wastewater opioid monitoring system, we have developed a screen-printed electrochemical FT sensor and integrated it with a customized submersible remote sensing probe. The sensor composition and design have been optimized to address the challenges for extended in situ FT monitoring. Specifically, ZIF-8 metal-organic framework (MOF)-derived mesoporous carbon (MPC) nanoparticles (NPs) are incorporated in the screen-printed carbon electrode (SPCE) transducer to improve FT accumulation and its electrocatalytic oxidation. A rapid (10 s) and sensitive square wave voltammetric (SWV) FT detection down to 9.9 µgL-1 is thus achieved in aqueous buffer solution. A protective mixed-matrix membrane (MMM) has been optimized as the anti-fouling sensor coating to mitigate electrode passivation by FT oxidation products and enable long-term, intermittent FT monitoring. The unique MMM, comprising an insulating polyvinyl chloride (PVC) matrix and carboxyl-functionalized multi-walled carbon nanotubes (CNT-COOH) as semiconductive fillers, yielded highly stable FT sensor operation (> 95% normalized response) up to 10 h in domestic wastewater, and up to 4 h in untreated river water. This sensing platform enables wireless data acquisition on a smartphone via Bluetooth. Such effective remote operation of submersible opioid sensing probes could enable stricter surveillance of community water systems toward timely alerts, countermeasures, and legal enforcement.

AbstractAn overview of the latest advances in the design of electrochemical sensor architectures dedicated to the determination of drugs from the statin class is presented in this review. Statins are drugs widely consumed for cholesterol control, and their determination in different matrices through the application of electroanalysis is growing considering advantages such as operational simplicity, lower cost and ease of sample preparation. Within the context of statins, electrochemical sensor architectures can be subdivided into conventional/classical electrodes such as glassy carbon electrodes, carbon paste electrodes, pencil graphite electrodes, boron-doped diamond electrodes and metallic electrodes, and more modern electrode systems, including the screen-printed electrodes and 3D-printed electrodes. Thus, different aspects related to the preparation of these electrochemical sensors and analytical performance are presented, also reflecting advances in terms of designs of new architectures and possible improvements not previously reviewed. Analyzed samples, advantages and disadvantages of different implemented sensor’s modification strategies and perspectives for the electroanalysis of statins are also included throughout the work. [ABSTRACT FROM AUTHOR]

The significance of food nutrients and bioactive compounds in human health has driven the development of many methods for their determination in different matrices. Among these, electroanalysis has gained popularity due to its cost-effectiveness, rapidity, and, in many cases, portability and minimal sample treatment. This review highlights key advances in electrochemical sensors and biosensors from 2019 to the present. Given the variability and the challenges of managing food matrices, the focus is limited to methods that have been thoroughly assessed for their applicability to real samples. The technical characteristics and analytical performance of the proposed sensors are discussed, along with breakthrough features and future trends. [ABSTRACT FROM AUTHOR]

The noble metal-based electrochemical sensor design for efficient and stable formaldehyde(FA) detection is important ongoing research. In this paper, PtPd/Nafion/GCE is prepared by electrochemical cyclic voltammetry deposition method based on electrodepositing nanostructured platinum (Pt)-palladium (Pd) nanoparticles in Nafion film-coated glassy carbon electrode (GCE). The influence of deposition parameters and chemical composition (atomic ratio of Pt and Pd) on the electrochemical behaviour of PtPd/Nafion/GCE has been investigated. PtPd/Nafion/GCE displays a remarked electrocatalytic activity for the oxidation of FA and exhibits a linear relationship in the range of 10–5000 μ M, with a detection limit of 3.3 μ M in 0.1 M H2SO4 solution. It is proved that the detection performance of PtPd/Nafion/GCE electrode is valuable for further application with low detection limit, wide linear range, favourable selectivity and high response. [ABSTRACT FROM AUTHOR]

Here, we characterize the photovoltage of n-Si/Au light-addressable electrodes (LAEs) over a range of solution potentials from ca. −1 to +1 V. We find that the n-Si/Au photoelectrodes show photovoltages consistent with a semiconductor/liquid junction in contrast to a buried junction, which opposes our previous understanding of how photovoltage originates in these sensors. [ABSTRACT FROM AUTHOR]

Electrochemical sensors are a class of sensors in which the electrode is the transducer element. In this type of sensor, an electrode is a critical component employed as a solid support for immobilizing biomolecules and electron movement. The material, fabrication approach, and design affect the electrode's structure and properties, which ultimately determine the biosensor's performance, including sensitivity, selectivity, limit of detection, and dynamic range. They also influence the biosensor's cost, manufacturability, disposability, and measurement capabilities. This review article describes recent advances in using non-modified and modified electrodes as support in electrochemical biosensors for the determination of biomolecules. It summarizes recent work on modifying electrodes using carbonaceous materials, conducting polymers, MXenes, and transition metal oxide nanomaterials. It also focuses on current techniques, types of materials, designs, simulation studies, and fabrication methods on unmodified and modified electrodes. Lastly, challenges in electrochemical sensors were identified, and future directions were presented comprehensively. [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 present study used CeO2-Co3O4 quantum dots@porous carbon/multiwalled carbon nanotube (CeO2-Co3O4 QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO2-Co3O4 QDs@PC/MWCNT/GE, with a peak current density of 1.276 mA/cm2. Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO2-Co3O4 QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm2, almost seven times that of the bare graphite electrode (0.079 cm2). The results showed that the CeO2-Co3O4 QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10−8 to 2.04 × 10−7 M (i.e., 0.005–0.1 ppm) and 1.007 × 10−6 to 1.209 × 10−4 M (i.e., 0.5–60 ppm). The limit of detection and limit of quantification were 1.23 nM (0.61 ppb) and 4.09 nM (2.03 ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7 weeks. This method provides a new way to prepare electrochemical sensors for OTC detection. [ABSTRACT FROM AUTHOR]

Gold nanomaterials have been widely explored in electrochemical sensors due to their high catalytic property and good stability in multi-medium. In this paper, the reproducibility of the signal among batches of gold nanorods (AuNRs)-modified electrodes was investigated to improve the data stabilization and repeatability. Ordered and random self-assembled AuNRs-modified electrodes were used as electrochemical sensors for the simultaneous determination of dopamine (DA) and topotecan (TPC), with the aim of obtaining an improved signal stability in batches of electrodes and realizing the simultaneous determination of both substances. The morphology and structure of the assemblies were analyzed and characterized by UV–Vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Electrochemical studies showed that the ordered AuNRs/ITO electrodes have excellent signal reproducibility among several individuals due to the homogeneous mass transfer in the ordered arrangement of the AuNRs. Under the optimized conditions, the simultaneous detection results of DA and TPC showed good linearity in the ranges 1.75–45 μM and 1.5–40 μM, and the detection limits of DA and TPC were 0.06 μM and 0.17 μM, respectively. The results showed that the prepared ordered AuNR/ITO electrode had high sensitivity, long-term stability, and reproducibility for the simultaneous determination of DA and TPC, and it was expected to be applicable for real sample testing. [ABSTRACT FROM AUTHOR]

Food quality assessment is becoming a global priority due to population growth and the rise of ionic pollutants derived from anthropogenic sources. However, the current methods used to quantify toxic ions are expensive and their operation is complex. Consequently, there is a need for affordable and accessible methods for the accurate determination of ion concentrations in food. Electrochemical sensors based on potentiometry represent a promising approach in this field, with the potential to overcome limitations of the currently available systems. This review summarizes the current advances in the electrochemical quantification of heavy metals and toxic anions in the food industry using potentiometric sensors. The healthcare impact of common heavy metal contaminants (Cd2+, Hg2+, Pb2+, As3+) and anions (ClO4−, F−, HPO4−, SO42−, NO3−, NO2−) is discussed, alongside current regulations, and gold standard methods for analysis. Sensor performances are compared to current benchmarks in terms of selectivity and the limit of detection. Given the complexity of food samples, the percentage recovery values (%) and the methodologies employed for ion extraction are also described. Finally, a summary of the challenges and future directions of the field is provided. An overview of technologies that can overcome the limitations of current electrochemical sensors is shown, including new extraction methods for ions in food. [ABSTRACT FROM AUTHOR]

Recent advancements in wearable technology have led to a new era of intelligent wound dressings capable of monitoring vital healing biomarkers. While a significant leap from traditional gauze dressings, these innovations still necessitate periodic removal and disposal. Bioresorbable electrochemical sensors have emerged as a promising and sustainable solution, offering continuous monitoring of critical wound healing biomarkers in real‐time and in situ, followed by their full physiological resorption. The current challenge lies in the susceptibility of metallic electrodes to harsh electrolytic biofluids, hindering the development of viable transient electrochemical sensors. This study pioneers a bioresorbable electrochemical material and unique architecture comprising engineered sputtered tungsten (W) plus tungsten oxide (WOx) thin films, taking advantage of their high catalytic activity and uniquely gradual biodissolution. While a bare W film electrode detached from the wafer substrate within 5 hours of soaking, an annealed W‐WOx electrode showcases a notable electrochemical stability at body temperature, for up to several days. The latter reliably senses multiple analytes during 24‐hour room‐temperature tests. These findings underscore the potential of annealed W plus WOx electrodes in future bioresorbable wound management systems. [ABSTRACT FROM AUTHOR]

The determination of pharmaceutical compounds in various samples is considered an effective way to evaluate their effectiveness. Nanomaterials-based electrochemical sensors have proven to offer the desired affordability, portability and high-performance for this purpose. In this work, an electrochemical sensor is described to detect droxidopa in the presence of carbidopa using a screen-printed graphite electrode (SPGE) modified with graphitic carbon nitride (g-C3N4). Admirable electrocatalytic behavior was found for g-C3N4/SPGE towards the droxidopa oxidation, with minimized oxidation overpotential and boosted voltammetric response peak current. Under the optimal circumstances, the peak currents of droxidopa oxidation were proportional to its concentrations (0.15–325.0 µM), with the limit of detection of 0.04 µM. Also, this sensor was applied to detect droxidopa in the presence of carbidopa. The g-C3N4/SPGE successfully resolved the oxidation signals of droxidopa and carbidopa, and the peak separation was calculated to be 310 mV. The g-C3N4/SPGE presented good stability, and repeatability. Finally, the developed g-C3N4/SPGE sensor displayed a satisfactory recovery of the spiked droxidopa and carbidopa in real-sample matrices (tap water and urine). [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]

In the present study, we reported the successful synthesis of a ternary nano hybrid polymer composite system obtained by solution casting. Composing carbon nanotubes (CNTs) and molybdenum disulfide (MoS2) in ethylene vinyl acetate (EVA) derived ECM ternary electrode. It demonstrated an excellent electrochemical sensor performance and a more efficient supercapacitor. Chemical structure of hybrid electrode Fourier transform Infrared Spectroscopy (FTIR) illustrated the CS and CN stretching with MoS2 and CNT new bands (at 1368 and 1032 cm−1). FE‐SEM and Atomic force microscopy (AFM) 3D topographic image identified the decreased rough morphology of the hybrid electrode. Whereas contact angle measurements revealed the enhanced wettability of electrode system. Microporous nature of the hybrid electrode was observed through SEM investigation. Transmission electron microscopy (TEM) revealed the nano hybrid entity in a hybrid electrode system. XRD and TEM investigation confirmed semicrystalline phase of the hybrid electrode system due to the presence of MoS2. D band, G bands, E12g and A1g vibrational modes in Raman spectroscopy revealed the occupied hybrid filler CNTs and MoS2. An electroactive site for the Cd2+ ion sensor was confirmed by the ECM/PGE hybrid electrode. It comply the desirable sensor qualities, such as excellent selectivity, reproducibility and repeatability with a high accuracy and lower detection limit of 15 nM. Additionally, the ECM/PGE electrode demonstrated a capacitive nature with an aerial capacitance of 73 μF/cm2 at an applied current density of 3 μA/cm2. Furthermore, it exhibited a power density of 44 mW/cm2 and an energy density of 148 μWh/cm2 over a wide potential range of 1 V. [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]

Integrating electrochemistry into capillary-flow driven immunoassay devices provides unique opportunities for quantitative point-of-care testing. Although custom electrodes can be inexpensive and are tunable, they require skilled fabrication. Here, we report the incorporation of a commercial electrode into a capillary-flow driven immunoassay (iceCaDI) device for a single end-user step sandwich electrochemical enzyme-linked immunosorbent assay (ELISA). The iceCaDI device is a pump-free portable microfluidic device with an integrated commercial screen-printed electrode and flow driven by capillary action. The iceCaDI device is composed of alternating polyester transparency film and double-sided adhesive film layers that are patterned with a laser cutter. This platform was designed to address known limitations of laminated device fabrication methods and operation. First, we developed a foldable laminated device fabrication using hinges for easy assembly and precise alignment. Second, reagent dispersing was achieved by incorporating a 1 mm wide arrow-shaped notch in the middle of the channel that trapped an air bubble and formed a baffle that facilitated reagent spreading to cover the detection area. Third, small vent holes were added to the top layer of the channels to prevent air bubbles from blocking flow. Finally, we fabricated a CRP immunosensor with a detection range of 0.625 to 10.0 μg mL−1 as a proof-of-concept to demonstrate an automatically driven sandwich electrochemical ELISA using the iceCaDI device. Three concentrations of CRP were successfully measured under flow conditions within 8 min. Our proposed device is a promising approach and a step forward in the development of point-of-care (POC) devices for techniques that traditionally require multiple user steps. [ABSTRACT FROM AUTHOR]

The sensitive detection of antioxidants in food is essential for the rational control of their usage and reducing potential health risks. A simple three-dimensional (3D) electrode integrated with an anti-fouling/anti-interference layer possesses great potential for the direct and sensitive electrochemical detection of antioxidants in food samples. In this work, a 3D electrochemical sensor was developed by integrating a 3D graphene electrode (3DG) with vertically ordered mesoporous silica film (VMSF), enabling highly sensitive detection of the common antioxidant, butylated hydroxyanisole (BHA), in food samples. A simple electrochemical polarization was employed to pre-activate the 3DG electrode (p3DG), enhancing its hydrophilicity. Using the p3DG as the supporting electrode, stable modification of VMSF was achieved using the electrochemical assisted self-assembly (EASA) method, without the need for any adhesive agents (VMSF/p3DG). Taking BHA in food as a model analyte, the VMSF/p3DG sensor demonstrated high sensitivity, due to the enrichment by nanochannels, towards BHA. Electrochemical detection of BHA was achieved with a linear range of 0.1 μM to 5 μM and from 5 μM to 150 μM with a low limit of detection (12 nM). Owing to the fouling resistance and anti-interference capabilities of VMSF, the constructed 3D electrochemical sensor can be directly applied for the electrochemical detection of BHA in complex food samples. [ABSTRACT FROM AUTHOR]

This paper describes an electrochemical sensor based on a Cu-modified boron-doped diamond (BDD) electrode for the detection of nitrate-contaminated water. The sensor utilizes the catalytic effect of copper on nitrate and the stability of the BDD electrode. By optimizing the electrolyte system, the linear detection range was expanded, allowing the sensor to detect highly concentrated nitrate samples up to 100 mg/L with a low detection limit of 0.065 mg/L. Additionally, the stability of the sensor was improved. The relative standard deviation of the current responses during 25 consecutive tests was only 1.03%. The wide detection range and high stability of the sensor makes it suitable for field applications and the on-site monitoring of nitrate-contaminated waters. [ABSTRACT FROM AUTHOR]

Electrochemical sensing techniques rely on redox reactions taking place at the electrode surface. The configuration of this surface is of the utmost importance in the advancement of electrochemical sensors. The majority of previous electrode manufacturing methods, including 3D printing have produced electrodes with flat surfaces. There is a distinct potential for 3D printing to create intricate and distinctive electrode surface shapes. In the proposed work, 3D printed carbon black polylactic acid electrodes with nine different surface morphologies were made. These were compared to a flat surface electrode. To evaluate the performance of the electrodes, measurements were conducted in three different redox probes (ferrocene methanol, ferricyanide, and dopamine). Our findings highlighted that when electrodes were normalised for the geometric surface area of the electrode, the surface pattern of the electrode surface can impact the observed current and electron transfer kinetics. Electrodes that had a dome and flag pattern on the electrode surface showed the highest oxidation currents and had lower values for the difference between the anodic and cathodic peak current (ΔE). However, designs with rings had lower current values and higher ΔE values. These differences are most likely due to variations in the accessibility of conductive sites on the electrode surface due to the varying surface roughness of different patterned designs. Our findings highlight that when making electrodes using 3D printing, surface patterning of the electrode surface can be used as an effective approach to enhance the performance of the sensor for varying applications. [ABSTRACT FROM AUTHOR]

In this study, the development of a graphite paste electrode (GPE) modified by copper oxide nanoparticles (CuO@GP) to be used as a practical and economical sensor for the electrochemical sensing of malachite green (MG) has been elucidated. The sol–gel technique was applied for the synthesis of CuO nanoparticles (NPS) from copper chloride (CuCl 2) , where the surfactant cetylpyridinium chloride (C 2 1 H 3 8 NCl) played the role of a capping agent. The synthesized CuO NPS were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). A bare GPE was modified using these CuO NPS and thus developed; the new electrode was used as a working electrode (WE) in a 3-electrode system for studying the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) responses of MG. Phosphate buffered saline (PBS) with a pH value of 6 was used as the optimum buffer. Using DPV, a widely linear operational range of 1–1000 μ M was obtained with a detection limit of 0.18 μ M. This CuO@GP provided excellent repeatability, reproducibility and prolonged stability for the MG molecule. For the selectivity study, various common interfering agents were used to observe MG's corresponding peak current variation. Moreover, this electrode demonstrated a successful application for detecting MG in pond water and fish flesh. This method is effective for similar other applications. [ABSTRACT FROM AUTHOR]

An electrochemical sensor based on a thin-layer flow cell and a boron-doped diamond (BDD) working electrode was fabricated for heavy metal ions determination using anodic stripping voltammetry. Furthermore, a fluidic automatic detection system was developed. With the wide potential window of the BDD electrode, Zn2+ with high negative stripping potential was detected by this system. Due to the thin-layer and fluidic structure of the sensor system, the electrodepositon efficiency for heavy metal ions were improved without using conventional stirring devices. With a short deposition time of 60 s, the system consumed only 0.75 mL reagent per test. A linear relationship for Zn2+ determination was displayed ranging from 10 μg/L to 150 μg/L with a sensitivity of 0.1218 μA·L·μg−1 and a detection limit of 2.1 μg/L. A high repeatability was indicated from the relative standard deviation of 1.60% for 30 repeated current responses of zinc solution. The system was applied to determine Zn2+ in real water samples by using the standard addition method with the recoveries ranging from 92% to 118%. The system was also used for the simultaneous detection of Zn2+, Cd2+, and Pb2+. The detection results indicate its potential application in on-site monitoring for mutiple heavy metal ions. [ABSTRACT FROM AUTHOR]

Sodium nitrite (NO2−) is widely present in human daily life, so accurate, sensitive, and selective NO2− detection has implications for food safety. Novel composite films based on vanadium-substituted tungstophosphate (K7P2W17VO62·18H2O, P2W17V) in polyoxometalate and the Au magnetic nanocomposites (Fe3O4@Au) have been successfully proposed. The electrodeposition method and the layer-by-layer (LBL) method can be utilized to self-assemble and produce composite films with modified electrodes, allowing for the creation of a highly sensitive electrochemical sensor for detecting NO2−. The application of composite films on the GCE resulted in improved sensing for the detection of NO2− when compared to the use of P2W17V or Fe3O4 electrodes alone. The composite electrode has a linear range of 1–100 mM for sodium nitrite with a detection limit of 0.787 μM (S/N = 3). The effective combination of P2W17V with Fe3O4@Au not only overcame the defects of polyoxometalates but also had the advantages of fast charge transfer and multiple sensing sites in the electrochemical detection of NO2−. Additionally, the composite films meet the demand for quickly and accurately detecting sodium nitrite concentration in real samples (red sausages, pickles, sauerkraut, and ham sausages). [ABSTRACT FROM AUTHOR]

This study introduces a disposable electrochemical sensor for measuring caffeine (CAF) based on a screen-printed electrode modified with a copper-based metal organic framework and multi-walled carbon nanotube nanocomposite (Cu-MOF@f-MWCNTs/SPE). The f-MWCNTs improved the conductivity and specific surface area of the electrode, and the f-MWCNTs/SPE demonstrated excellent electrocatalytic activity toward CAF oxidation. Incorporating Cu-MOF with f-MWCNTs increased the number of active sites for CAF oxidation, leading to a significant increase in the oxidation current response of CAF. The morphology of the Cu-MOF@f-MWCNT nanocomposite was observed by scanning electron microscopy. The electrochemical behavior of CAF on different electrode modifications was investigated using cyclic voltammetry and differential pulse voltammetry. The optimal detection conditions were also evaluated. The linear range of the developed sensor was from 0.010 to 1.50 mM, and the detection limit was 7.9 μM. The sensor showed selectivity against six possible interferents and achieved recoveries from 85.0 to 104.6% of CAF in black coffee samples. Hence, the proposed disposable CAF sensor could be used in real-world applications. [ABSTRACT FROM AUTHOR]

Using a molecularly imprinted polymer (MIP) as a recognition element, a selective voltammetric sensor for ketoconazole (KC) was designed and constructed. MIP was synthesized using methacrylic acid as a functional monomer and KC as a template, and then into the carbon paste electrode as a ketoconazole sensor, was incorporated. A new chemically modified electrode containing MIP compound on the surface of a glassy carbon electrode (GCE) by sol-gel method was obtained. The electrochemical behavior of the resulting modified electrode by cyclic voltammetry method in detail was investigated. The obtained film electrode had very good stability and thus exhibited a good electrocatalytic response for KC oxidation. A sharp catalytic oxidation peak was observed at around 53 mV in the MIP/CCE electrode and GCE, a small oxidation peaks current at about 63 mV was observed. The diffusion coefficient and transfer coefficient (α) for the electrocatalytic oxidation of KC were also studied under experimental conditions. [ABSTRACT FROM AUTHOR]

Dopamine (DA) and uric acid (UA), which are vital components in human metabolism, cause several health problems if they are present in altered concentrations; thus, the determination of DA and UA is essential in real samples using selective sensors. In the present study, graphite carbon paste electrodes (CPE) were fabricated using ZnO/carbon quantum dots (ZnO/CQDs) and employed as electrochemical sensors for the detection of DA and UA. These electrodes were fully characterized via different analytical techniques (XRD, SEM, TEM, XPS, and EDS). The electrochemical responses from the modified electrodes were evaluated using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The results showed that the present electrode has exhibited high sensitivity towards DA, recognizing even at low concentrations (0.12 μM), and no inference was observed in the presence of UA. The ZnO/CQD electrode was applied for the simultaneous detection of co-existing DA and UA in real human urine samples and the peak potential separation between DA and UA was found to be greatly associated with the synergistic effect originated from ZnO and CQDs. The limit of detection (LOD) of the electrode was analyzed, and compared with other commercially available electrodes. Thus, the ZnO/CQD electrode was used to detect DA and UA in real samples, such as Saccharomyces cerevisiae cells. [ABSTRACT FROM AUTHOR]

[Objective] Brassinolide is an important endogenous plant hormone. In this work, an electrochemical immunosensor for in situ detection of brassinolide was constructed using screen-printed electrode (SPE). [Methods] Au nanoparticles (AuNPs) were firstly electrodeposited on the surface of SPE electrode by electrochemical workstation, and then CuCl2 nanowires (CuCl2 NWs) were added to the electrode, which can not only increase the conductivity of the electrode, but also Cu2+ can be used as a REDOX probe for the sensor. Finally, Mxene and polydopamine nanocomposite (Mxene@PDA) were selected as the modification materials for SPE electrodes because Mxene has the advantages of large surface area and good electrical conductivity, which can further amplify Cu2+ signals. However, Mxene is easily oxidized and unstable in air. Polydopamine (PDA) contains a large number of catechol and amino groups, which are coated on the surface of Mxene after self-polymerization by dopamine, cutting off the path of oxygen penetration, making Mxene difficult to be oxidized. Mxene@PDA can also be used as a coupling agent to fix more antibodies on the electrode surface, improving the overall biocompatibility, and improve the overall biocompatibility. [Results and Discussions] The sensor has a wide lin‐ ear detection range: 0.1 pg/mL to 1 mg/mL, and the detection limit was 0.015 pg/ml (S/N=3). In addition, the content of endogenous brassinolide in wheat was detected by SPE electrodes in vitro and the recovery rate was 98.13% to 104.74%. While verifying the accuracy of the sensor, it also demonstrated its superior stability and sensitivity. Besides, the sensor al‐ so showed excellent application potential in the in situ detection of brassinosteroids from wheat leaves. Compared with other brassinolide detection methods, the immunosensor developed in this study has better analytical performance. [Conclusions] An electrochemical immunosensor for in situ detection of brassinolide was developed for the first time, providing a good electrochemical platform for in situ determination of brassinolide in plant leaves, which has great application potential in precision agriculture. [ABSTRACT FROM AUTHOR]

The research paper focused on fabrication of an electrochemical sensor to sensing and monitoring of vanillin in aqueous solution. In this regard, NiO/nitrogen doped carbon quantum dots (NiO-NCQD) nanocomposite was synthesized as a highly conductive catalyst and used to modification of carbon paste electrode (CPE) and fabricated a sensitive voltammetric sensor. The oxidation signal of vanillin showed a catalytic activity at surface of NiO-NCQD/CPE compare to CPE in aqueous solution at pH = 7.0. The NiO-NCQD/CPE showed a linear range 0.01–280 µM, with a limit of detection (LOD) 5.0 nM, respectively. The NiO-NCQD/CPE was test to monitoring of vanillin in different food products and results compare with HPLC method. Results confirmed accuracy and precision suggested method to sensing of vanillin in food products. [ABSTRACT FROM AUTHOR]

Rapid screening of tuberculosis by evaluation of associated volatile organic biomarkers in breath is a promising technology that is significantly faster and more convenient than traditional sputum culture tests. Methyl nicotinate (MN) and methyl p-anisate (MPA) have been isolated as potential biomarkers for mycobacterium tuberculosis and have been found in the breath of patients with active pulmonary tuberculosis. A novel approach to detection of these biomarkers in liquid droplets (e.g. from breath condensate) using inexpensive screen-printed electrodes is presented. Previous modelling studies suggest that these biomarkers complex with certain transition metals of particular valence state. This interaction can be exploited by mixing the biomarker sample into an electroactive solution (EAS) containing the functional metal ion and observing the change electrochemically. The study focuses on low biomarker concentrations, determined to be clinically relevant based on preliminary GC-MS studies of the levels found in patient breath. It was found that both the cyclic voltammogram and square wave voltammogram of copper(II) change significantly when as little as 0.1 mM MN is added to the solution, with analysis times of less than 2 min. Copper(II) exhibits three separate peaks during square wave voltammetry. The location and area of each peak are affected differently as the concentration of MN increases, suggesting a reaction with specific oxidation states of the metal. In this way, a "fingerprint" method can be used to identify biomarkers once their known interaction is established.

Introduction: Heart failure can lead to death and hospitalization, especially among older adults, and pimobendan is used with human patients. We investigated the electrochemical behavior of Au/g-C3N4 electrochemical sensors to detect the concentration of pimobendan. Experimental: Characterization of the materials was conducted using XRD, TEM, SEM, EDS and FTIR. Cyclic voltammetry (CV) was used to measure the concentration and redox properties of pimobendan. Result and Discussions: At a voltage of 0.05 V, a reduction peak appeared, indicating an association between pimobendan concentration (ranging from 0 to 55 µM) and reductive current. At low concentrations of pimobendan concentration from 0.0 to 1.3 µM, the linearity R² = 0.9149 with a detection limit of 0.29 µM. Dopamine, epinephrine, and uric acid did not interfere with the detection of pimobendan. Conclusions: A composite sensing electrode consisting of 3% Au/g-C3N4 was fabricated for the detection of pimobendan. A potential pimobendan sensing mechanism on 3% Au/g-C3N4 was proposed on the basis of these findings. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/polydiallyl dimethylammonium chloride/silver nanoparticles (rGO/PDDA/AgNPs) composite material was fabricated, and characterized by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). A sensitive electrochemical sensor was constructed based on rGO /PDDA/AgNPs hybrid modified glassy carbon electrode for the determination of nicardipine (NP). The electrochemical behavior of NP on this sensor was investigated by cyclic voltammetry (CV). The measurement conditions such as supporting electrolyte and scanning speed were also optimized. Under optimized conditions, this proposed sensor showed a good linear relationship between the peak current and the concentration of NP in the range of 1.0 × 10–7 ~ 1.2 × 10–4 M, and the detection limit was 3.3 × 10–8 M. The possible interference of different compounds on the determination of NP was investigated in detail. The recovery of NP was 98.0 ~ 104.1%, which indicated that the composite modified electrode had high accuracy. This electrochemical method is low cost, sensitive, and can be applied to the determination of NP in drugs or preparations. [ABSTRACT FROM AUTHOR]

We created novel Pd/CB-Ni@rGO nanomaterials for glucose detection. The as-synthesized nanomaterials were dropped on the electrode surface using the drop casting technique. The prepared electrode was then attached to a paper-based device containing the sample zone and the reaction zone, enabling plasma isolation and an enzymatic reaction for glucose detection in whole blood. The nanomaterials and surfaces of electrodes were characterized by FTIR, TEM, and SEM. The proposed approach is a disposable glucose detection method that is unaffected by protein fouling on the electrode, and it requires only one drop of human blood. Therefore, there is no need for extensive sample preparation, and there is less sample consumption. Under optimal conditions, Pd/CB-Ni@rGO can accurately measure blood glucose levels with a linear range of 7 to 7140 μM (R2 = 0.9986) and a low detection limit of 0.82 μM. Besides, the developed sensor shows excellent anti-interference capacity, stability, and satisfactory reproducibility and repeatability. Importantly, Pd/CB-Ni@rGO was successfully applied for glucose in whole blood from 4 volunteers, with results that correlated well with those obtained using an Accucheck glucometer at a 95% confidence level. Given its low cost, high accuracy, and ease of use, the blood glucose sensor holds significant potential for clinical use and broadens the area of future noninvasive sensor development. [ABSTRACT FROM AUTHOR]

The carbazole compound (C-C8) containing aromatic ring with 8 carbon alkyl group (C8) was synthesized. The thiophene-derived compound that was abbreviated as (T) was synthesized, and (CT-C8) was obtained by adding of (T) to the starting compound (C-C8). Additionally, the electrochemical polymers of CT-C8 were synthesized and accumulated onto different surface types such as an indium tin oxide (ITO) coated glass, aluminum (Al) layer, copper (Cu) sheet and pen tip electrode (PTE). The electrochemical syntheses of the polymers were performed by using 0.05 M NaClO4 as an electrolyte in acetonitrile (AN) solvent. The electrochemical behaviors of the polymers were also investigated by taking the cyclic voltammeric measurements with a triple electrode system, and the electrochemical behaviors of the coated polymers on different electrode surfaces were also researched in the presence of Fe3+ and Fe2+ metals. According to the obtained voltammogram results, it can be said that the electrochemically synthesized polymers on different electrode surfaces were sensitive to Fe3+ metal and they could be used as an electrochemical sensor for all electrode surfaces as mentioned above. For the performed electrochemical measurements, the oxidation and reduction peak values obtained for different electrode surfaces were different from each other. When it is desired to examine the electrochemical property of a material, there is a need to search for more useful and economical insoles, since the conductive surface like ITO is deformed after repeated applications and expensive. This study, which offers an alternative conductive base to replace ITO, is important in this regard. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the morphological changes and molecular structure changes on the surface of single-walled carbon nanotube (SWCNT) films during oxygen plasma (O2) etching of SWCNT surfaces formed by the spray method and analyzed their potential use as electrochemical electrodes. For this purpose, a SWCNT film was formed on the surface of a glass substrate using a self-made spray device using SWCNT powder prepared with DCB as a solvent, and SEM, AFM, and XPS analyses were performed as the SWCNT film was O2 plasma etched. SEM images and AFM measurements showed that the SWCNT film started etching after about 30 s under 50 W of O2 plasma irradiation and was completely etched after about 300 s. XPS analysis showed that as the O2 plasma etching of the SWCNT film progressed, the sp2 bonds representing the basic components of graphite decreased, the sp3 bonds representing defects increased, and the C–O, C=O, and COO peaks increased simultaneously. This result indicates that the SWCNT film was etched by the O2 plasma along with the oxygen species. In addition, electrochemical methods were used to verify the damage potential of the remaining SWCNTs after O2 plasma etching, including cyclic voltammetry, Randles plots, and EIS measurements. This resulted in a reversible response based on perfect diffusion control in the cyclic voltammetry, and an ideal linear curve in the Randles plot of the peak current versus square root scan rate curve. EIS measurements also confirmed that the charge transfer resistance of the remaining SWCNTs after O2 plasma etching is almost the same as before etching. These results indicate that the remaining SWCNTs after O2 plasma etching do not lose their unique electrochemical properties and can be utilized as electrodes for biosensors and electrochemical sensors. Our experimental results also indicate that the ionic conductivity enhancement by O2 plasma can be achieved additionally. [ABSTRACT FROM AUTHOR]

In this study, for the first time, the electro‐polymerization of Direct blue15 (DB15), an azo dye, was carried out on the surface of ITO. Furthermore, the poly(DB15) surface was electrochemically decorated with Ag nanoparticles (AgNPs), and the fabricated AgNPs/PDB15 electrodes were examined as nitrate sensors. Compared to unmodified ITO electrode, the AgNPs/PDB15 electrode had greatly improved electrochemical response to nitrate reduction. The nitrate determination in a linear range from 1.0×10−5 mol L−1 to 2.27×10−3 mol L−1 was performed with a detection limit of 9.66 μM. The synthesized electrode is a promising sensor for the electrochemical detection of nitrate pollutants in water. [ABSTRACT FROM AUTHOR]

The development of hydrogen sulfide (H2S) sensors is essential to address H2S‐related pharmacology since slow‐releasing H2S medications have been identified to be prospective options for cancer treatments. Here, we described an electrochemical sensor for highly selective and sensitive detection of aqueous H2S, using a thin film of fumarate‐based face‐centered cubic (fcu)‐based metal–organic frameworks (fum‐fcu‐MOF) modified on laser‐scribed graphene (LSGE). The fum‐fcu‐MOF has shown a strong affinity and chemical stability to H2S analysis. The electrochemical and H2S catalytic properties were studied for fum‐fcu‐MOF/LSGE. An amperometry and differential pulse voltammetry techniques were demonstrated to validate the sensor. The resulting sensor delivered acceptable analytical parameters in terms of; detection limit (3.0 µM), dynamic range (10–500 µM), reproducibility, and stability (94.7%). The sensor's practical validity was demonstrated in bacterial cells and H2S‐releasing drug, where the sensor was able to monitor the continuous release of in‐situ H2S. The pharmacokinetics of a slow releasing H2S donor is accessed at different time intervals and different concentration levels. Our research indicate that this fum‐fcu‐MOF based H2S sensor holds potential in understanding pharmacokinetics of H2S releasing drugs. [ABSTRACT FROM AUTHOR]