Electrochemical Quantification Research Articles

Sensitive and eco-friendly voltammetric detection of galantamine using a screen-printed sensor with a functional boron-doped diamond electrode

The presented study focused on developing and optimizing a modern electroanalytical platform for the direct quantitative determination of galantamine. This work used different voltammetric methods to use a screen-printed sensor with a working boron-doped diamond electrode (SP/BDDE). Beneficial analytical performance for detecting galantamine was achieved in a Britton-Robinson buffer with pH 3.0. The oxidation peaks at 0.92 V and 1.20 V were followed for electrochemical quantification of galantamine. High-resolution mass spectrometry was used for the first time to analyze the products of preparative electrolysis, and a mechanism for the electrochemical oxidation of galantamine was proposed, which describes the demethylation of galantamine and the further oxidation of the hydroxyl group to a ketone group in the galantamine molecule.Coupled with the optimized parameters of differential pulse voltammetry and square-wave voltammetry on the SP/BDDE detected galantamine in two linear ranges (the first range was from 1.22 μM to 10 μM; the second range was from 10 μM to 200 μM), providing the limit of detection and limit of quantification on a micromolar level (0.50 μM and 1.48 μM, respectively). Amperometry and chronoamperometry were employed to develop a rapid detection method for galantamine. In this approach, galantamine can be detected at a level of 1.08 μM (amperometry at the second peak). The selectivity of the optimized amperometric methods was found to be excellent in the presence of ten times higher concentrations of certain interferences. The practical applicability of the SP/BDDE for detecting galantamine was demonstrated through the analysis of pharmaceutical products and human urine samples. The proposed procedure fully complies with the latest requirements of green analytical chemistry.

Adenine-originated N-doped C3N4 modified glassy carbon electrode for ultra-sensitive electrochemical quantification of cysteamine drug

Cystinosis is a rare autosomal recessive illness in which cystine accumulates in lysosomes, causing crystallisation in important organs. Cysteamine, the only approved therapy, demands precise concentration control because of its therapeutic importance. Cysteamine detection methods, including fluorescence spectroscopy, chemical etching, and HPLC, need sophisticated sample preparation and expensive equipment. Electrochemical sensing provides a simpler alternative with higher sensitivity and selectivity. However, traditional carbon electrodes have limited sensitivity and detection limits. Nitrogen (N-CN), sulfur (S-CN), and nitrogen/sulfur co-doped (N, S-CN) graphitic carbon nitride materials were produced using a one-pot calcination of adenine and methionine precursors. N-CN-modified glassy carbon electrodes demonstrated higher electrocatalytic activity, quicker electron transfer, and increased selectivity, sensitivity, and stability for cysteamine detection. Structural and morphological characterisation of the synthesised materials was performed using various analytical techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller plots, X-ray diffraction, and X-ray photoelectron spectroscopy. The sensor showed a linear relationship between anodic peak current and cysteamine concentration in the range of 0 µM to 1 mM, with a low detection limit of 82.5 nM (0.0825 µM). Moreover, the modified electrode exhibited good reproducibility and stability with a recovery rate of 95.5 % and a relative standard deviation (RSD < 5 %). Real-sample analysis revealed a good agreement between LSV and HPLC for detecting cysteamine in blood serum. The paper describes a unique metal-free N-CN synthesis utilising adenine, allowing effective electrochemical detection.

Innovative Electrochemical Quantification of Brilliant Blue Dye with Polyvinylpyrrolidone-Stabilized MoS₂

In this study, the synthesis of a composite material such as molybdenum disulphide/poly vinylene pyrrolidone (MoS2/PVP) using a simple hydrothermal method is showcased. Also discovered its capability for electrochemical detection of a well-known food dye, brilliant blue (BB), which has not been previously reported. The incorporation of PVP into MoS2 significantly enhanced the electrochemical stability of the composite for the detection of brilliant blue. The comprehensive analysis of the material in its original state provided a thorough understanding of its structural and morphological properties, both prior to and following the incorporation of PVP. The modifications resulting from the action of PVP intercalation were intriguing and sufficiently capable of causing a considerable impact on the electrochemical output of the entire investigation. The significant transformation in morphology, from nanoflowers to a sheet-like structure, in the presence of PVP is remarkable. The MoS2/PVP coated glassy carbon electrode (MoS2/PVP/GCE) demonstrated the broadest linear range for BB determination compared to any previously reported results, spanning from 0.8 μM to 1150.0 μM, with a limit of detection (LOD) value of 9.0 nm. The manufactured electrode has significant repeatability and reproducibility. The selectivity analysis highlights the sensor's ability to accurately and specifically detect the target analyte, even in the presence of potential interfering substances. The evaluation of MoS2/PVP/GCE in several authentic samples demonstrates the sensor's dependability in detecting BB in real-time situations.

Laser-induced stripping defect for highly selective electrochemical quantification of dopamine: Anti-interference from other catecholamine neurotransmitters

Detecting dopamine (DA) is critical for early diagnosis of neurological and psychiatric disorders. However, the presence of other catecholamine neurotransmitters with structural similarities to DA causes significant interference in its detection. Herein, we introduce S stripping defects via laser-induced MoS2 to functionalize MoS2 electrodes and improve their selectivity for DA electrochemical detection. The sensing results show its excellent immunity to interference from other neurotransmitters, ensuring the preservation of the DA electrochemical signal even in the mixed neurotransmitters such as acetylcholine (ACh), γ-aminobutyric acid (GABA), epinephrine (EP), norepinephrine (NP), and serotonin (5-HT). DFT calculations further reveal that the negatively charged S-stripping defects enhance DA adsorption on the surface of the functionalized MoS2 electrode, contributing to its excellent performance. Moreover, this functionalized electrodes successfully monitor DA released from living PC12 cells in the presence of other interference, highlighting its potential applicability in intercellular signaling communication.

Electrochemical identification and quantification of through-plane proton channels in graphene oxide membranes.

Stacked graphene oxide (GO) proton membranes are promising candidates for use in energy devices due to their proton conductivity. Identification of through-plane channels in these membranes is critical but challenging due to their anisotropic nature. Here, we present an electrochemical reduction method for identifying and quantifying through-plane proton channels in GO membranes. The simplicity lies in the operando optical observation of the change in contrast as GO is electrochemically reduced. Here, we find three proton-dominated three-phase interfaces, which are critical for the reduction reactions of GO membranes. Based on these findings, a method is proposed to identify and quantify through-plane channels in stacked GO proton membranes using a simple three-electrode device in combination with real-time imaging of the membrane surface.

Developing dual detection platforms for the electrochemical quantification of homocysteine in biological samples

This study presents a novel dual electrochemical sensor developed using simple electropolymerization technique to detect and measure homocysteine (HC). The developed electrode modification was confirmed using FTIR, XRD, and SEM-EDX examinations. The poly(N-phenylanthranilic acid) modification of the glassy carbon electrode (GCE) and Screen-printed electrode (SPE) significantly enhanced the response for HC, surpassing the findings of previous studies. The improvement can be credited to the exceptional catalytic efficiency of the electro-polymer in electro-oxidizing HC. The electrochemical investigations were conducted utilizing analytical methods such as cyclic voltammetry and differential pulse voltammetry, with a 0.1 M phosphate buffer solution employed as the supporting medium. The poly-NPAA/GCE and poly-NPAA/SPE sensor has demonstrated exceptional sensing properties such as excellent selectivity, sensitivity, reproducibility and and repeatability. It is highly effective in identifying and quantifying HC. The exhibited linear range of both poly-NPAA/GCE and poly-NPAA/SPE are the widest, ranging from 1.0 to 2300.0 μM for poly-NPAA/GCE and from 3.0 to 3000.0 μM for poly-NPAA/SPE, making it the most remarkable result ever reported. The detection limit (LOD) of poly-NPAA/GCE was determined to be 0.165 µM while that of poly-NPAA/SPE was obtained as 0.618 µM. Furthermore, real-sample analysis was performed using biological fluids at the advanced sensor. Therefore, the fabricated poly-NPAA/GCE and poly-NPAA/SPE exhibited exceptional electrocatalytic capabilities for HC sensing, rendering it appropriate for continuous monitoring.

Ratiometric electrochemical detection of alkaline phosphatase based on SWCNTs/Cu-MOF modified graphite paper electrodes

Alkaline phosphatase (ALP) is integral to a diverse array of biological processes, consequently, its presence is frequently linked to the onset of various pathologies. In the current investigation, 1-naphthyl phosphate (1-Npp) served as a substrate, with the catalytic hydrolysis of phosphate groups by ALP being leveraged to engender a detectable current at an applied potential of 0.277 V. Initially, carbon nanotubes (SWCNTs) were deposited via drop-coating onto graphite paper (Gp), a material characterized by exceptional electrical conductivity. Subsequently, Cu-MOF was uniformly deposited on Gp/SWCNTs composites by rapid electrodeposition technique, that is, chronocurrent method (i–t), at a potential of −1.1 V for 240 s, thereby fabricating an electrochemical sensor platform denominated Gp/SWCNTs/Cu-MOF. This platform enabled the ratiometric electrochemical quantification of ALP, utilizing the signal from Cu-MOF as an internal standard. This platform’s integrated design facilitates signal amplification and provides an inbuilt reference, which was instrumental in mitigating the impact of environmental fluctuations and enhancing the precision of the obtained data. The ratiometric signals exhibited strong linear correlations within the 0.014–14.29 U mL−1 concentration, with a detection limit of 0.005 U mL−1. Moreover, the sensor exhibited robust selectivity, repeatability, and excellent detection performance in real-world samples, with recovery rates spanning 99.3 %–103.5 %, making it a suitable candidate for the expedient and precise quantification of ALP in serum.

Multi-core–shell nanoboxes comprising polydopamine-derived C coated NiCo@C and FeCo@C nanohybrid for enhanced electrochemical quantification of nitrofurantoin

The development of a high-performance electrochemical sensing platform for monitoring nitrofurantoin (NFT) levels in various real samples plays an important role in the research community worldwide. To accomplish this objective, the crucial challenge is to construct sensing interfaces with outstanding electrocatalytic capabilities. In the present work, a highly efficient metal@carbon electrocatalyst with porous and multi-core–shell nanobox structure comprising polydopamine (PDA)-derived C coated NiCo@C and FeCo@C nanohybrid (named as NiCo@C/FeCo@C@C) was fabricated by simply pyrolyzing NiCo@FeCo Prussian blue analogues (PBA)@PDA. The carbonization of PDA into carbon shells protected the framework from collapsing during high-temperature pyrolysis process, thus enlarging the specific surface areas and porosity. The NiCo@C/FeCo@C@C composite attained an enhanced electrochemical capability, such as an outstanding electronic conductivity from the double carbon shell with porous structure, a large number of active sites and a high electrocatalytic activity from the metallic alloy nanoparticles, which exhibited a highly sensitive response to NFT. Under optimized experimental conditions, the established NiCo@C/FeCo@C@C electrochemical sensor displayed a wide linear range of 0.05–100 μM for NFT determination, coupled with a low detection limit of 14 nM. The practical feasibility of this sensor was also confirmed by the analysis of NFT in tablet and lake water samples with outstanding recovery rates. Moreover, the sustainability of the sensor was demonstrated through its prominent performance in high reproducibility, selectivity and long-term stability. This study thus introduces an innovative approach for the advance of highly efficient electrocatalysts in the area of electrochemical sensing.

Carbon‐Nanotube Microelectrodes for Electrochemical Determination of Melatonin

AbstractVoltammetric methods hold promise for the rapid and sensitive quantification of melatonin. This study reports the direct electrochemical quantification of melatonin using carbon nanotube (CNT) fiber cross‐sections as microelectrodes. Six identical highly densified CNT fiber cross‐sections were employed to quantify melatonin in the range of 0.05–100 μM. The limit of detection and quantification were 10 and 35 nM, respectively, with a sensitivity of 0.1322 nA/μM. Interference studies with uric acid, hypoxanthine, and ascorbic acid demonstrate its performance. Real‐world application was highlighted by measuring melatonin in food, pharmaceutical, and human urine samples.

Platinum-Selenopeptide Interfaces in Support of High Fidelity Electrochemical Biomarker Quantification in Complex Biological Matrices.

The real world applications of conventional antifouling biosensors based on gold-thiol (Au-S) interfaces are hampered by the progressive competitive displacement of key functionality by ubiquitous biothiols. To overcome this limitation, we introduce here novel platinum-selenium (Pt-Se) interfaces. Thiol displacement tests, antifouling analyses, and density functional theory calculations confirm markedly improved interfacial stability. This was then leveraged through the application of a seleno-multifunctional peptide platform, tailored to the detection of murine double minute 2, in biological samples. A derived amperometric sensing platform exhibited a notably lower detection limit and more accurate target quantification than that supported by analogous Au-S and Pt-S interfaces. We believe that this work broadens the scope of electrochemical sensor construction and holds significant promise for the development of high-fidelity impactful bioassay platforms.

First voltammetric studies, spectrophotometric and molecular docking investigations of the interaction of an anticancer drug ribociclib-DNA and analytical applications of disposable pencil graphite sensor

Ribociclib (RIB) is a cyclin-dependent kinase inhibitor used in the treatment of breast cancer. In this study, for the first time, the electrochemical behavior, quantification and interaction of RIB with DNA were carried out using voltammetric, spectrophotometric and molecular docking techniques. An environmentally-friendly disposable pencil graphite electrode (PGE) sensor was used as the working electrode. Utilizing the cyclic voltammetry technique, RIB produced an irreversible anodic wave around +0.837 V and reversible signals around +0.278 V/+0.209 V on the PGE surface. Using the PGE sensor, the RIB compound gave a very distinct anodic signal at a potential of +0.77 V in PBS (pH 3.0). For this analytical signal, the limit of detection and limit of quantitation values of RIB in the concentration range of 0.0139 3 M–0.0973 3 M in PBS (pH 3.0) were determined as 2.84 nM and 9.46 nM, respectively. The interaction of RIB with DNA was studied by voltammetric, spectrophotometric and molecular docking techniques. In the evaluation of the results obtained with all three techniques, the interaction of the RIB molecule with DNA was determined to occur through minor groove binding.

Microwave-assisted rapid synthesis of GO/SnTe nanocomposite for electrochemical quantification of caffeine and pharmaceutical formulations

Microwave-assisted rapid synthesis of GO/SnTe nanocomposite for electrochemical quantification of caffeine and pharmaceutical formulations

Long-lasting copper carbon nanotubes for non-enzymatic electrochemical sensing of glyphosate

Accurate electrochemical detection of glyphosate (GLY) presents significant challenges due to its non-electroactive nature on conventional electrode materials. To address this challenge, copper-modified electrodes have been developed to form a complex with GLY, enhancing detection capabilities. In this study, we propose an innovative material: copper-modified carbon nanotubes on a glassy carbon electrode (Cu/CNT/GCE). The detection mechanism of GLY using Cu/CNT/GCE involves the formation of a copper-GLY complex, which inhibits the electrochemical response of copper, proportionally to the GLY concentration. This effect is enhanced by the synergistic interaction between copper and carbon nanotubes, increasing the electrochemical stability and detection capacity of the system. To evaluate the electrochemical performance of Cu/CNT/GCE, cyclic voltammetry was performed at different electrolyte concentrations and pH levels. Square wave voltammetry was employed for the electrochemical quantification of GLY, showing a linear correlation between GLY concentration and the inhibition of the copper response. The proposed sensor exhibited a low limit of detection (0.098 ppm) and a limit of quantification (0.326 ppm). Furthermore, the electrode demonstrated long-term stability, retaining 95 % of its signal after one year of storage. This stability is attributed to the carbon nanotube support, which prevents corrosion of copper particles. Recovery values ranged from 94 to 106 % for Citromax™ and Orium™ glyphosate with precision. The method showed excellent selectivity for GLY detection, even in the presence of other herbicides such as diuron and oryzalin. These properties suggest that Cu/CNT/GCE presents promising features for the electrochemical monitoring of GLY in diverse environmental samples.

An Electrochemical Strip to Evaluate and to Discriminate Drug Encapsulation in Lipid Nanovectors.

Lipid nanovectors (LNVs) represent potent and versatile tools in the field of drug delivery for a wide range of medical applications including cancer therapy and vaccines. With this Technical Note, we introduce a novel "portable", easy-to-use, and low-cost strategy for double use: (1) it allows one to both quantify the amount of cargo in LNV formulation and (2) classify the nature of formulation with the aim of chemometrics. In particular, an electrochemical strip, based on a screen-printed electrode, was exploited to detect methylene blue (MB) as the model cargo encapsulated in various liposomes (used as model LNV). The experimental setup, including release of the MB content and its electrochemical quantification were optimized through a multivariate design of experiment (DoE), obtaining a satisfactory 88-95% accuracy in comparison to standard methods. In addition, the use of principal component analysis-linear discriminant analysis (PCA-LDA) highlighted the satisfactory differentiation of liposomes. The combination of portable electroanalysis and multivariate analysis is a potent tool for enhancing quality control in the field of pharmaceutical technologies, and also in the field of diagnostics, this approach might be useful for application toward naturally occurring lipid nanoparticles, i.e., exosomes.

Iodide based electrochemical gold quantification method for lateral flow assays

The lateral flow assay (LFA) is an ideal technology for at-home medical diagnostic tests due to its ease of use, cost-effectiveness, and rapid results. Despite these advantages, only few LFAs, such as the pregnancy and COVID-19 tests, have been translated from the laboratory to the homes of patients. To date, the medical applicability of LFAs is limited by the fact that they only provide yes/no answers unless combined with optical readers that are too expensive for at-home applications. Furthermore, LFAs are unable to compete with the state-of-the-art technologies in centralized laboratories in terms of detection limits. To address those shortcomings, we have developed an electrochemical readout procedure to enable quantitative and sensitive LFAs. This technique is based on a voltage-triggered in-situ dissolution of gold nanoparticles, the conventional label used to visualize target-specific signals on the test line in LFAs. Following the dissolution, the amount of gold is measured by electroplating onto an electrode and subsequent electrochemical quantification of the deposited gold. The measured current has a low noise, which achieves superior detection limits compared to optical techniques where background light scattering is limiting the readout performance. In addition, the hardware for the readout was developed to demonstrate translatability towards low-cost electronics.

Electrochemical signal quantification in saliva: investigation of signal analysis methods

Electrochemical signal quantification in saliva: investigation of signal analysis methods

Design and Implementation of a Cost‐Effective, Portable Impedance Analyzer Device with AD5941

This study proposes a cost‐effective, small‐size, and portable impedance analyzer using the AD5941 Analog Front End (AFE) that makes frequency sweep measurement for various applications. The design utilizes a microcontroller and an AD5941 circuit for impedance measurement. The AD541 is a high precision impedance converter system that consists of a 16‐bit, 1.6 MSPS, analog to digital converter (ADC), an integrated waveform generator, and a digital signal processing (DSP) block. The AD5941 has many advantages over the AD5933 which was used in numerous studies in the past decade. Also, the device implements the four‐wire impedance method which is an impedance measuring technique that reduces the effect of electrodes to achieve higher accuracy. A supporting Graphic User Interface (GUI) software is employed to control the Impedance Analyzer device and to visualize the measurement. This impedance analyzer achieves a frequency resolution of 0.015 Hz and can generate sinusoid up to 200 kHz. In frequency range from 10 kHz to 150 kHz, the device can measure impedance in the range of 10 Ω–100 kΩ with less than 4.3% of error in comparison with benchtop impedance analyzer, Microtest 6632. Moreover, our impedance measurement device has undergone testing involving human calf measurements and electrochemical quantification, particularly for estimating Sodium Chlorite. The experimental outcomes demonstrate that our design not only fulfills the criteria of an impedance analyzer device but also performs effectively across diverse applications. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Highly sensitive electrochemical quantification of carbendazim via synergistic enhancement of ring-opening metathesis polymerization and polyethyleneimine modified graphene oxide.

Anovel aptamer-based sensor was developed using the signal amplification strategy of ring-opening metathesis polymerization (ROMP) and polyethyleneimine modified graphene oxide to achieve trace detection of carbendazim (CBZ). The dual identification of aptamer and antibody was used to avoid false positive results and improve the selectivity. Polyethyleneimine modified graphene oxide (GO-PEI), as a substrate material with excellent conductivity, was modified on the surface of aglassy carbon electrode (GCE) to increase the grafting amount of aptamer on the electrode surface. Moreover, a large number of cyclopentenyl ferrocene (CFc) was aggregated to form long polymer chains through ring-opening metathesis polymerization (ROMP), so as to significantly improve the detection sensitivity of the biosensor. The linear range of this sensor was 1 pg/mL-100 ng/mL with a detection limit as low as 7.80fg/mL. The sensorexhibited excellent reproducibility and stability, and also achieved satisfactory results in actual sample detection. The design principle of such a sensor could provide innovative ideas for sensors in the detection of other types of targets.

Laser-induced graphene decorated with Ni[sbnd]Pt alloy nanoparticles for non-enzymatic electrochemical quantification of glucose

Enzyme-free electrochemical glucose (Glu) sensors, adopting electrochemically active catalysts, are of vital significance to effectively monitoring and analyzing the blood Glu level in diabetes diagnosis. Meanwhile, developing novel electrode substrates have been the hot research pot to meet the demand for constructing flexible sensors. In this work, porous laser-induced graphene (LIG) was prepared through a facile one-step laser-engraving technique on a polyimide thin film, and then used directly as the electrode. Furthermore, NiPt alloyed nanoparticles (NPs) were electrodeposited on the LIG electrode surface to gain the NiPt/LIG composite electrode, which was applied to construct the nonenzymatic electrochemical Glu sensor. The morphology, element and electrochemical performance of NiPt/LIG composite was characterized through various techniques. NiPt alloyed NPs were homogeneously distributed on the LIG scaffolds, which possess plenty of porous structure, high surface area and many active sites. The cooperative effect between the outstanding electrocatalytic capacity of NiPt alloyed NPs, the extraordinary electroconductibility of LIG and the numerous exposed active sites endow the NiPt/LIG sensor outstanding electrocatalytic performance for electrochemical oxidation of Glu. Under the most appropriate conditions, the obtained NiPt/LIG sensor was adopted to detect Glu, showing a broad detection concentration range of 0.5 μM to 2.1 mM and 2.1 mM to 5.6 mM, good sensitivities of 1.824 and 0.467 μA μM−1 cm−2, a low detection limit of 0.03 μM. The as-fabricated nonenzymatic Glu sensor also displays high selectivity, stability considering ageing effects under different environment conditions and prominent reproducibility. Additionally, this novel NiPt/LIG nonenzymatic Glu sensor was applied to quantify Glu successfully in blood serum and food samples and the results were in good agreement with that by UV–vis spectrophotometer, demonstrating high precision and accuracy as well as excellent recovery, showing good application prospects in Glu monitoring. This research confirmed the potential of exploiting NiPt/LIG as a highly sensitive Glu nonenzymatic electrochemical sensor and provided a practicable and suitable approach for construction of novel electrochemical sensors.

Active Hydrogen for Electrochemical Ammonia Synthesis

AbstractElectrochemical ammonia synthesis (EAS) presents an attractive alternative to the Haber–Bosch process due to the benefits of energy saving, low carbon emission, environmental friendliness, and so on. However, the competing hydrogen evolution reaction (HER) severely limits the yield, selectivity, and current efficiency of NH3. Although the accumulation and self‐aggregation of active hydrogen (H*) are the primary causes of the competing HER, it also serves as the critical active species and intermediate for the multistep hydrogenation and deoxygenation processes. Therefore, the sensible regulation of the H* generation and consumption are essential for enhancing EAS performance. And it is significant to thoroughly review the current strategies for H* control. Herein, a comprehensive introduction of H* to provide a fundamental understanding of its role in electrochemical reactions, including generation, conversion, identification, and quantification protocols is first proposed. In addition, the role and control strategies of H* in EAS are carefully summarized with a particular focus on regulating H* generation and consumption to enhance the activity, selectivity, and Faradaic efficiency. Finally, the remaining challenges and perspectives are discussed. This critical review is intended to offer a profound understanding of the regulation of H* in electrochemical reactions and the development of EAS technology.