Electrochemical Detection Of Dopamine Research Articles

Carbon Nitride‐Supported Zinc Oxide Nanocomposite for the Electrochemical Detection of Dopamine and the Development of Disposable Sensors

AbstractThe carbon nitride‐supported zinc oxide (CNZO) nanocomposite was synthesized through a high‐temperature synthesis method, resulting in zinc oxide nanoparticles with an average size of ~44 nm, dispersed on a carbon nitride matrix. X‐ray diffraction confirmed the formation of the hexagonal wurtzite phase of zinc oxide, with a space group of P63mc. X‐ray photoelectron spectroscopy and Fourier‐transform infrared analysis further verified the presence of both zinc oxide and carbon nitride. The CNZO nanocomposite served as a catalyst for the electrochemical detection of dopamine, achieving limit of detection and sensitivity of 2.66 μM and 6.23 μA μM−1 cm−2 respectively, using square wave voltammetry technique. Cyclic voltammetry experiments demonstrated excellent electroactivity of the CNZO nanocomposite in a neutral pH environment. An electrochemical paper‐based analytical device (EPAD) was designed and successfully employed for the electrochemical analysis of dopamine in pharmaceutical samples using CNZO nanocomposites. Additionally, CNZO was used as an active material in the development of a disposable dopamine sensor based on an extended gate field‐effect transistor (EG‐FET). This sensor exhibited a sensitivity and limit of detection 18.22 μA μM−1 cm−2 and 0.36 μM, respectively, with a correlation coefficient of 0.99.

Tailoring phases of ferrihydrite/α-Fe2O3@C nanocomposites using syringyl and guaiacyl-rich biomass-derived carbon nanodots for electrochemical application

Biomass-derived carbon nanodots (CNDs) hold promise as effective reducing agents for metal oxide nanoparticles yet understanding the intricate interplay with CND structure remains challenging. This study explores the impact of lignin types, specifically syringyl (S), and guaiacyl (G) units in CNDs on metal oxide phases and their electrochemical activity toward dopamine oxidation. We design phases of ferrihydrite/α-Fe2O3@C nanocomposites, using hazelnut carbon nanodots (HS-CNDs (S-rich)) and beetroot carbon nanodots (BS-CNDs (G-rich)) via a one-pot hydrothermal technique. Our findings show S units in HS-CNDs promote α-FeOOH/α-Fe2O3@CHS, while G units in BS-CNDs favor α (β)-FeOOH/α-Fe2O3@CBS. In contrast to α(β)-FeOOH/α-Fe2O3@CBS, α-FeOOH/α-Fe2O3@CHS exhibits superior electrochemical performance in dopamine oxidation due to its larger electrochemical active surface area, higher absorbance capacity, and shortened electron transfer length. Moreover, α-FeOOH/α-Fe2O3@CHS nanocomposites demonstrate remarkable dopamine selectivity, achieving rapid detection response in 10 s with a low LOD of 4 nM within a broad linear range (0.05–0.3 μM), demonstrating impressive reproducibility (97.5 %), stability (96.4 %), and works in real-time human urine detection with a recovery rate of ranging from 94.57 % and 102.2 %. Therefore, the utilization of biomass-derived CNDs, particularly S and G units-rich CNDs, in tailoring the phases of ferrihydrite/α-Fe2O3@C nanocomposites for electrochemical dopamine detection is promising.

Air plasma fast-induced defect-enriched carbon cloth for simultaneous electrochemical detection of dopamine and uric acid

Herein, we report a fast (10 min) and simple surface treatment of pure carbon cloth (CC) only by an air plasma. The structural characterizations indicate that the air plasma process brings out higher rugosity, more defects, and increased oxygen-related groups on CC surfaces than Ar- or N2-plasma, which can offer abundant capture sites, large electroactive area, and superhydrophilic interface for analytes. As a result, the air-treated CC (CC−PAir) electrode achieves a pronounced improvement of electrocatalytic activity for the [Fe(CN)6]3-/[Fe(CN)6]4- probe evidenced by increased peak currents, decreased peak-to-peak separation, and the lowered resistance of charge transfer. It is also demonstrated that the self-supported CC−PAir electrode possesses excellent sensing performance toward dopamine (DA) and uric acid (UA). The feasibility of the simultaneous electrochemical detection of DA and UA can be verified by their large peak potential gap (∼112 mV) for differential pulse voltammetry. The chronoamperometric sensor yields wide linear ranges of 0.05–100 μM for DA and 0.5–300 μM for UA. The corresponding detection limits are estimated to be 2.6 and 20.4 nM for DA and UA, respectively. The sensor also displays satisfactory selectivity, stability, and reproducibility. Due to good flexibility, the CC−PAir electrode presents great potential for manufacturing wearable and soft electronics for human health monitoring.

Synthesis of Starfish-Shaped ZnS Nanostructures by Hydrothermal Method and Their Electrochemical Sensing of Dopamine.

Introduction Dopamine serves an essential function as a neurotransmitter, influencing the regulation of movement, cognitive processes, and emotional states. The identification of abnormal dopamine levels is critical for clinical diagnoses and scientific research, given its links to various disorders, including depression, schizophrenia, and Parkinson's disease. The distinctive electrochemical characteristics, stability, and broad bandgap of zinc sulfide (ZnS) nanostructures render them particularly fascinating. The hydrothermal method is recognized as an effective and economical approach for the fabrication of ZnS nanostructures, exhibiting a range of morphologies. Utilizing this method to create ZnS nanostructures leads to the formation of structures characterized by extensive surface areas, hierarchical designs, and improved electrochemical properties. Aim The objective is to examine the electrochemical characteristics of ZnS starfish-shaped nanostructures produced through the hydrothermal technique and to assess their viability as a sensing platform for dopamine detection. Materials and methods To synthesize ZnS nanoflowers, stoichiometric amounts of transition metal salts were prepared: 10 mM of Zn(NO3)2•3H2O and 30 mM of sodium thiosulfate (Na2S2O3•5H2O) were dissolved in 30 mL of deionized water and stirred for 20 minutes. The solutions were then combined and transferred into a 100 mL Teflon autoclave reactor, which was heated at 200 °C for 12 hours in a furnace. This process utilized the hydrothermal technique to produce the desired ZnS nanoflowers. Result The crystalline arrangement of ZnS was validated by X-ray diffraction (XRD) analysis, aligning with the Joint Committee on Powder Diffraction Standards (JCPDS). Moreover, field emission scanning electron microscopy (FE-SEM) illustrated the particle morphology of ZnS, showing a range between 200 and 500 nm size. Additionally, the cyclic voltammetry results indicated that the modified electrode produced a greater current response than the bare electrode, highlighting its improved sensitivity to dopamine molecules. Conclusion ZnSnanoparticles were synthesized via a hydrothermal method and characterized using XRDand FE-SEM. These nanoparticles were used for electrochemical dopamine detection, showing potential for advanced sensing platforms. Integrating ZnS into microfluidic devices enables real-time dopamine monitoring, opening new possibilities for healthcare and neurochemical research. Exploring surface engineering techniques could further enhance the electrochemical performance of ZnS-based sensors.

Intercalation of multilayered Ti3C2Txelectrode doped with vanadium for highly sensitive electrochemical detection of dopamine in biological samples.

Theelectrochemical detection characteristics of the layered Ti3C2Tx materialwere enhanced by modifying its surface. Ti3C2Tx is used as the Ti - F chemical bond weakens with increasing pH levels. Ti3C2Tx is alkalinized by KOH, and F is substituted for - OH. The surface hydroxyl groups can be eliminated by intercalating K+. This study elaborates on the hydrothermal production of vanadium-doped layered Ti3C2Tx nanosheets intercalated with K+. Thedevelopment of a sensitive dopamine electrochemical sensor is outlinedby intercalating a vanadium-doped multilayered K+ Ti3C2Tx electrode. The chemical, surface, and structural composition of the synthesized electrode for dopamine detection was investigated and confirmed. The sensor exhibits a linear range (1-10 µM), a low detection limit (8.4 nM), and a high sensitivity of 2.746 µAµM-1cm-2 under optimal electrochemical testing conditions. The sensor also demonstrates exceptional anti-interference capabilities and stability. The sensor was applied todetection of dopamine in (spiked) rat brains, human serum, and urine samples. This study introduces a novel approach by utilizing K+ intercalation of vanadium-doped Ti3C2Tx-based electrochemical sensors and an innovative method for dopamine detection. The dopamine detection revealed the potential of (V0.05) K+ Ti3C2Tx-GCE for practical application in pharmaceutical sample analysis.

A Novel Ferrocene-Linked Thionine as a Dual Redox Mediator for the Electrochemical Detection of Dopamine and Hydrogen Peroxide.

We introduce a novel dual redox mediator synthesized by covalently linking ferrocene dicarboxylic acid (FcDA) and thionine (TH) onto a pre-treated glassy carbon electrode. This unique structure significantly enhances the electro-oxidation of dopamine (DA) and the reduction of hydrogen peroxide (H2O2), offering a sensitive detection method for both analytes. The electrode exhibits exceptional sensitivity, selectivity, and stability, demonstrating potential for practical applications in biosensing. It facilitates rapid electron transfer between the analyte and the electrode surface, detecting H2O2 concentrations ranging from 1.5 to 60 µM with a limit of detection (LoD) of 0.49 µM and DA concentrations from 0.3 to 230 µM with an LoD of 0.07 µM. The electrode's performance was validated through real-sample analyses, yielding satisfactory results.

Adjusting Paper Device Properties for Bioelectrochemical Analysis and 3D Cell Culture

Context- Paper is an innovative material for cell culture due to its biocompatibility, its inert chemical properties and its low-cost. Paper is already used in many biomedical applications such as immunoassays and, more recently, as affordable electrochemical sensors. In this context, tuning the properties of paper devices can achieve better, more efficient and user-friendly assays for biomedical applications. Here, and by modifying the electrochemical properties of paper electrochemical devices, it is possible to create electrodes that can detect neurotransmitters, a critical type of biomolecules involved in neuronal communication. Dopamine is a neurotransmitter involved in reward and addiction and a molecule of considerable scientific interest. Dopamine is secreted in the brain by dopaminergic neurons. However, the fine chemical mechanisms of neuron networks are still obscure. Being able to spatially measure dopamine secretion, in response to activation of precise neuronal regions in a unique system, can lead to a better understanding of neuronal dynamics, as well as their response to drug alterations. Proposing a research model describing neuronal chemical function in a network will therefore help shining light on their mechanisms and testing new neuropharmacological solutions. Developing new tools for the analytical electrochemistry of the brain will make quantitative neuro-analysis more accessible, thus paving the way for a better understanding of the chemical mechanisms of the brain. Tuning paper electrode for neurochemical analysis- Conductive inks, i.e. conductive polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and carbon nanotubes (CNT) suspensions, were used to improve the detection of dopamine at paper-based electrodes. The physical and chemical properties of different preparations and mixtures of inks were considered. Solvent secondary doping, a common technique for PEDOT-PSS based electrode, was used to improve the electrical properties of the electrodes. Ferrocyanide electroanalysis was used to benchmark 10 different electrode preparations, revealing that combining CNT and PEDOT-PSS improves the electroactivity of the surface of the sensor. Interestingly, it was found that CNT has a doping effect on PEDOT-PSS, leading to improved electrochemical properties. Finally, these electrodes were tested for dopamine detection. It was found that combining PEDOT-PSS and CNT in the surface layer of ink deposited on the paper electrode allows for lower capacitance, higher anodic current as well as better fouling resistance. Figure 1 presents a CV voltammogram for Dopamine obtained with a paper electrode. Overall, this strategy improves the sensitivity of the assay. Growing neurons on paper- Paper-based devices can also be used for cell culture. Cell on paper constructs are 3D cell culture models that are more suitable to study cell in a biomimetic 3D environment, thus better recapitulating their functions and biology. By carefully modifying the surface of the paper devices, it is possible to adjust their biocompatible properties to ameliorate the survival rate of cell culture on paper. This opens the possibility to achieve neuronal cell culture on paper. We will present different paper preparations compatible with murine dopaminergic maintenance. The neurons were maintained alive for several days of culture. We were able to effectively observe and study neurons in a 3D paper environment and quantify the growth of their processes. Figure 1 : Electrochemical detection of Dopamine for 20 cycles. Working electrode is a paper electrode with PEDOT:PSS and CNT conductive inks, shown on the right, scale is 1 cm. The reference electrode is an Ag/AgCl electrode, and the counter electrode is a platinum electrode. Scan rate is 0.02 Vs-1. Figure 1

MoSe2 nanosheets-based sensor for electrochemical detection of dopamine, ascorbic acid, and uric acid

There has been a growing interest in the field of transition metal dichalcogenide (TMD) materials and their potential applications in the field of electrochemical sensors. In the present work, molybdenum diselenide (MoSe2), as a typical representative of TMD, was prepared using a facile hydrothermal method and characterized in terms of its morphological and structural properties. Then, the obtained MoSe2 was dispersed in various solvents to investigate its electrocatalytic properties towards dopamine (DA), ascorbic acid (AA), and uric acid (UA). The electrochemical measurements revealed that deionized water is an effective solvent to disperse the MoSe2 and modify electrodes with the MoSe2 for electrochemical applications. Furthermore, the glassy carbon electrode (GCE) modified with the MoSe2, referred as GCE-MoSe2, was used as an electrochemical sensor to simultaneously detect the DA, AA, and UA. The GCE-MoSe2 exhibited wide linear detection with concentration ranges of 1–333 µM for DA, 50–3440 µM for AA, and 5–1146 µM for UA in phosphate buffer solution and low detection limits (LODs) of 0.57 µM, 13.7 µM, and 1.75 µM, respectively. The electrode further displayed good selectivity, reproducibility, and stability. This work provides valuable insights on constructing electrochemical sensing devices with high analytical performance using the important two-dimensional (2D) TMD materials.

SIMULTANEOUS DETERMINATION OF ASCORBIC ACID, URIC ACID, AND DOPAMINE ON CARBON NANOTUBE PASTE ELECTRODE

Background: Ascorbic acid (AA), uric acid (UA), and dopamine (DA) play crucial roles in human metabolism. These substances coexist in biological fluids, and their levels are directly associated with various pathologies. A significant problem encountered in the direct and simultaneous electrochemical detection of AA, UA, and DA is that these species present very close oxidation potentials on most electrode materials, leading to an overlap in the voltammetric response. Aim: The main goal of this work was to determine the concentration of AA, UA, and DA in a natural water sample on a carbon nanotube paste electrode (CNTPE). Methods: All voltammetric measurements were performed on a µAutolab potentiostat/galvanostat (Metrohm) connected to an electrochemical cell of three electrodes: working, reference (Ag/AgCl, KCl3.0M), and auxiliary (platinum). The working electrode was handmade in our laboratory. The following proportions were used to prepare the paste: 50% CNT + 50% mineral oil and 65% CNT + 35% mineral oil. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for the electroanalytical study. Results: The linear ranges for the simultaneous determination of AA, DA, and UA by DPV were: 0.45 – 1.0 mM, 50 – 200 ?M, and 10 – 90 ?M, respectively. The LODs of the proposed method for AA, DA, and UA were: 7.97 mM; 8.57 ?M, and 5.96 ?M, respectively. The relative standard deviations (RSD) were 4.6, 2.8, and 1.6% for 0.45 mM of AA, 50 ?M of DA, and 50 ?M of UA. Discussion: The oxidation mechanism of: AA, UA, and DA is a process that involves two electrons and 2 protons. Electrochemical detection of DA in the presence of high levels of AA on carbon-based electrodes becomes difficult due to the catalytic oxidation of AA by DA. For the three molecules, AA, UA, and DA, it is observed that the oxidation peak currents increased with increasing concentration. Conclusions: CNTPE allowed the separation of the oxidation peaks of the ternary mixture of AA, UA, and DA by cyclic voltammetry and, when associated with DPV allowed the simultaneous quantitative determination of AA, UA, and DA.

Pd nanoparticles supported on Fe3O4 particles grafted with poly(acrylamide) gel brush for simultaneous electrochemical‐sensing of dopamine and paracetamol

AbstractIn the present study, a glassy carbon electrode (GCE) modified with Pd nanoparticles deposited on poly(acrylamide) gel brush‐grafted magnetic particles (Pd/PAAmGB@Fe3O4) with core‐shell structure was fabricated for simultaneous electrochemical detection of dopamine (DA) and paracetamol (PA). Electrochemical performance of Pd/PAAmGB@Fe3O4/GCE was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The fabricated sensor exhibited voltammetric sensing with a satisfactory linear determination range from 0.4–41 μM for DA and from 0.5–95 μM for PA. The limit of detection (LOD) was 0.1 μM for DA and 0.17 μM for PA based on signal to noise ratio of 3. The proposed sensor also had excellent reusability and selectivity, good reproducibility and stability, and satisfactory recovery in biomedical examples. It is believed that metal nanoparticles deposited on polymer gel brush composites may offer promising new horizons for sensor growth.

Label-Free Electrochemical Dopamine Biosensor Based on Electrospun Nanofibers of Polyaniline/Carbon Nanotube Composites.

The development of conducting polymer incorporated with carbon materials-based electrochemical biosensors has been intensively studied due to their excellent electrical, optical, thermal, physical and chemical properties. In this work, a label-free electrochemical dopamine (DA) biosensor based on polyaniline (PANI) and its aminated derivative, i.e., poly(3-aminobenzylamine) (PABA), composited with functionalized multi-walled carbon nanotubes (f-CNTs), was developed to utilize a conducting polymer as a transducing material. The electrospun nanofibers of the composites were fabricated on the surface of fluorine-doped tin oxide (FTO)-coated glass substrate under the optimized condition. The PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which confirmed the existence of f-CNTs in the composites. The electroactivity of the electrospun nanofibers was investigated in phosphate buffer saline solution using cyclic voltammetry (CV) before being employed for label-free electrochemical detection of DA using differential pulse voltammetry (DPV). The sensing performances including sensitivity, selectivity, stability, repeatability and reproducibility of the fabricated electrospun nanofiber films were also electrochemically evaluated. The electrochemical DA biosensor based on PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers exhibited a sensitivity of 6.88 µA·cm-2·µM-1 and 7.27 µA·cm-2·µM-1 in the linear range of 50-500 nM (R2 = 0.98) with a limit of detection (LOD) of 0.0974 µM and 0.1554 µM, respectively. The obtained DA biosensor showed great stability, repeatability and reproducibility with precious selectivity under the common interferences, i.e., glucose, ascorbic acid and uric acid. Moreover, the developed electrochemical DA biosensor also showed the good reliability under detection of DA in artificial urine.

Electrochemical Detection of Dopamine: Use of Covalently Bonded Ag (Silver) - Au (Gold) Bimetallic Nanoparticles

Dopamine (DA) is a crucial neurotransmitter that is generated by dopaminergic neurons in the central nervous system. We have produced and studied aspartic acid-capped gold nanoparticles and thioctic acid-capped silver nanoparticles, and we have covalently linked them via EDC-NHS coupling. The heightened stability and reproducibility of the Ag-Au-Nafion modified glassy carbon electrode (GCE) allowed for the sensitive and accurate detection of dopamine in PBS buffer at pH 6. The electrode modification approach’s selectivity and sensitivity as well as the possible interference of other compounds present in complicated biological samples, require more study. The creation of more precise and sensitive electrochemical sensors for dopamine detection is aided by this discovery, which has broad implications for medical diagnostics.

A Machine Learning Approach for Simultaneous Electrochemical Detection of Dopamine and Serotonin in an Optimized Carbon Thread-Based Miniaturized Device

A Machine Learning Approach for Simultaneous Electrochemical Detection of Dopamine and Serotonin in an Optimized Carbon Thread-Based Miniaturized Device

Synergetic effect of optimized β-Zn(OH)2/ZnO heterostructure towards electrochemical dopamine detection

In this study, we have synthesized β-Zn(OH)2/ZnO heterostructures via a simple one-pot hydrothermal method followed by calcination at different temperatures under air for electrochemical dopamine (DA) detection. We found that the synergetic effect between optimized β-Zn(OH)2 and ZnO phases in β-Zn(OH)2/ZnO heterostructures boosts electrocatalytic activity. Moreover, β-Zn(OH)2/ZnO heterostructures calcined at 300 °C (i.e.,β-Zn(OH)2/ZnO300) showed enhanced electrochemical activity towards DA oxidation due to its larger electrochemical active surface area and higher adsorption capacity compared to other β-Zn(OH)2/ZnO heterostructures and ZnO. Additionally, β-Zn(OH)2/ZnO300 heterostructures demonstrated remarkable DA selectivity in the presence of over eight biomolecules, achieving rapid detection response in less than 10 seconds with a low detection limit of 0.17 nM and 1.0 nM within a linear range of (1.75–263 nM) and (263–1300 nM), respectively. Moreover, β-Zn(OH)2/ZnO300 heterostructures showed remarkable reproducibility (98.8 %), high stability (98.1 %), and real-time DA detection in human urine samples with a recovery rate ranging from 95.9 % to 103.2 %. Therefore, β-Zn(OH)2/ZnO heterostructures, especially those optimized under 300 °C, possess great potential for electrochemical applications, particularly in DA detection.

Tailored multi-layer graphene arrays for precision detection of neurotransmitter

The development of sensitive dopamine (DA) sensors has significantly contributed to our understanding of DA-related disorders and has enabled advancements in medical diagnostics and neuroscience research. Therefore, in the present work, a novel electrochemical sensing platform was developed using multi-layer graphene arrays (MGA) modified electrodes for the selective detection of DA. The preparation of high-quality MGA was achieved using the plasma-enhanced chemical vapor deposition (PCVD) method and was confirmed using various physiochemical techniques such as transmission electron microscopy and Raman spectroscopy. The modified electrode, made of MGA, was utilized for the electrochemical detection of DA using cyclic voltammetry and amperometry i-t methods. DA’s electrochemical oxidation response and sensitivity at the MGA electrode were ≈9 and 3 times higher than observed with unmodified and commercially available multi-layer graphene-modified electrodes. The MGA sensor exhibited excellent analytical parameters for DA detection, including a wide linear range of up to 172.1 μM and a low detection limit of 1.3 nM. The sensor also demonstrated remarkable sensitivity, storage stability, and selectivity for DA detection, making it highly suitable for accurately detecting DA in medical diagnostics and neuroscience research. Furthermore, the practical application of the MGA sensor for DA detection was demonstrated in various real samples.

Thiourea‐Modified Multiwalled Carbon Nanotubes as Electrochemical Biosensor for Ultra‐Precise Detection of Dopamine

AbstractFunctionalized multi‐walled carbon nanotubes (MWCNTs) have enticed remarkable attention in the field of electrochemical sensing applications. Dopamine (DA) is a monoamine neurotransmitter released in the brain acting as a chemical messenger that communicates messages between nerve cells and rest of the body. Therefore, there is a significant technological urge for the development of electrochemical sensors for DA in body fluids. In this context, nitrogen‐functionalized MWCNTs (TM‐CNT600) were fabricated by thermal annealing of carboxylic acid functionalized MWCNTs with thiourea at 600 °C under N2 atmosphere. The XPS spectrum reveals the presence of nitrogen‐containing functionalities in the as‐prepared TM‐CNT600. FTIR results show the presence of −OH, C−N and C−S functional groups. XPS further corroborates the FTIR results and quantifies the predominant functional groups in as‐prepared material. The material was investigated as a potential electrochemical sensor for the detection of dopamine (DA). In the case of TM‐CNT600/GCE, a linear relationship for DA concentration was observed in the range of 10.7–24.2 μM with the limit of detection (LOD) of 1.42 μM using linear sweep voltammetry (LSV). These results highlight the potential of TM‐CNT600 modified GCE as an efficient sensor for the electrochemical detection of DA in body fluids.

Innovative use of shrimp shell powder in carbon paste electrode for the electrochemical detection of dopamine and paracetamol: Valorization, characterization and application

The present study outlines the design of an innovative, cost-effective, and environmentally friendly electrochemical sensor, based on a carbon paste electrode (CPE) modified by shrimp shell waste (SSW). The developed electrode was used to facilitate the electrocatalytic detection of two compounds, namely dopamine (DA) and paracetamol (PAR). The use of SSW as an electrode material is ground breaking. The results have shown that the addition of shrimp shell (SS) in the CPE has led to a significant increase in the active surface area (0.504 cm2) and has improved electron transfer by decreasing the charge transfer resistance (17.45 Ω.cm2) at the electrode/solution interface. The SSW was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and fourier transform infra-red (FTIR). The results show a fibrous and porous structure with high calcium content and other chemical elements including carbon, oxygen, sulphur, phosphorus and nitrogen. The electrochemical behavior of DA and PAR on the CPE-SS electrode was studied using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) techniques. Additionally, CPE and CPE-SS electrodes were examined by SEM/EDS and FTIR. The effect of scan rate shows that the electrochemical process is diffusion controlled for DA and PAR. The CPE-SS electrode provide a wide linear range, good selectivity, repeatability, precision (≤5%), and low detection limits 3.6 µM and 5.54 µM for DA and PAR, respectively. In addition, the developed sensor was applied to detect DA and PAR in urine, tap water, and pharmaceutical tablets with apparent recoveries.

Electrochemical and quantum chemical approaches to the study of dopamine sensing using bentonite and l-cysteine modified carbon paste electrode

This work presents a significant investigation involving both electrochemical experiment and quantum chemical simulation approaches. The objective was to characterize the electrochemical detection of dopamine (DA). The detection was carried out using a modified carbon paste electrode (CPE) incorporating bentonite (Bent) and l-cysteine (CySH) (named as CySH/Bent/CPE). To understand and explain the oxidation mechanism of DA on the CySH/Bent modified electrode surface, the coupling of the two approaches were exploited. The CySH/Bent/CPE showed excellent electroactivity toward DA such as good sensibility, selectivity, stability, and regenerative ability. The developed sensor shows a dynamic linear range from 0.8 to 80 μM with a limit of detection and quantification of 0.5 μM and 1.5 μM, respectively. During the quantitative analysis of DA in presence of ascorbic acid (AA) and uric acid (UA) the electrochemical oxidation signals of AA, DA, and UA distinctly appear as three separate peaks. The potential differences between the peaks are 190 mv, 150 mv, and 340 mV for the AA–DA, DA–UA, and AA–UA oxidation pairs, respectively. These observations stem from square wave voltammetry (SWV) studies, along with the corresponding redox peak potential separations. The developed sensor is simple and accurate to monitor DA in human serum samples. On the other hand, CySH acts as an electrocatalyst on the CySH/Bent/CPE surface by increasing its active electron transfer sites, as suggested by the quantum chemical modeling with analytical results of Fukui. Furthermore, the voltammetric results obtained agree well with the theoretical calculations.

Biofouling and performance of boron-doped diamond electrodes for detection of dopamine and serotonin in neuron cultivation media

Boron doped diamond has been considered as a fouling-resistive electrode material for in vitro and in vivo detection of neurotransmitters. In this study, its performance in electrochemical detection of dopamine and serotonin in neuron cultivation media Neurobasal™ before and after cultivation of rat neurons was investigated. For differential pulse voltammetry the limits of detection in neat Neurobasal™ medium of 2 µM and 0.2 µM for dopamine and serotonin, respectively, were achieved on the polished surface, which is comparable with physiological values. On oxidized surface twofold higher values, but increased repeatabilities of the signals were obtained. However, in Neurobasal™ media with peptides-containing supplements necessary for cell cultivation, the voltammograms were notably worse shaped due to biofouling, especially in the medium isolated after neuron growth. In these complex media, the amperometric detection mode at +0.75 V (vs. Ag/AgCl) allowed to detect portion-wise additions of dopamine and serotonin (as low as 1–2 µM), mimicking neurotransmitter release from vesicles despite the lower sensitivity in comparison with neat NeurobasalTM. The results indicate substantial differences in detection on boron doped diamond electrode in the presence and absence of proteins, and the necessity of studies in real media for successful implementation to neuron-electrode interfaces.

Ultrasound assisted synthesis of CoFe-LDH for the simultaneous electrochemical detection of dopamine and acetaminophen

Herein, CoFe layered double hydroxide composites (CoFe-LDH) were synthesised by a simple ultrasound assisted synthesis method. It has been characterized by scanning electron microscopy (SEM), X-ray diffraction and X-ray photoelectron spectroscopy. CoFe-LDH modified glass carbon electrode was used as dual-function sensors for DA and AP detection. The sensor exhibits a wide detection linear range for DA and AP (2 μM-900 μM), low detection limits (DA: 0.08 μM; AP: 0.37 μM) (S/N = 3). The sensitivity of CoFe-LDH/GCE for DA and AP were 0.54 μA μM−1 cm−2 and 0.55 μA μM−1 cm−2. And it shows good reproducibility, selectivity, and stability. In addition, the sensor demonstrated good recovery rates for the detection of DA and AP in human serum samples.