Search Results (172)

Monitoring dopamine (DA) in pork can provide useful information for assessing meat freshness and quality deterioration. In this work, an Fe@N-S-O-C nanocomposite was fabricated as an electrode modifier for DA determination. The Fe@N-S-O-C nanocomposite was synthesized via precipitation followed by calcination using melamine and ferrous sulfate as precursors. The crystal structure, surface chemical composition, and morphology were characterized by XRD, XPS, SEM, and TEM. The Fe@N-S-O-C-modified glassy carbon electrode (Fe@N-S-O-C/GCE) was then evaluated for its electrocatalytic performance toward DA. Under the optimized conditions (pH 6.0), the sensor showed linear responses to DA over 1–65 and 65–220 μM. The sensitivities for these two ranges were 4.357 and 1.685 μA μM⁻¹ cm⁻², respectively, with an LOD of 40 nM. In addition, the Fe@N-S-O-C/GCE showed excellent reproducibility, good repeatability, and strong anti-interference capability against common coexisting substances. After 30 days of storage, 82.74% of the initial current response was retained by the same electrode. Practical applicability of the sensor was verified in pork samples, with recoveries of 95.97–106.73%. These results demonstrate that the Fe@N-S-O-C/GCE sensor offers a reliable and effective platform for DA detection in complex food matrices. Full article

Hydrophilic osmium(Os)-based redox polymers were designed as electron-transfer mediators for fungal flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH)-based glucose sensors. Poly(vinylimidazole-co-hydroxyethyl acrylate) (PVI-HEA) copolymers with different HEA compositions were synthesized and coordinated with Os(dmo-bpy)₂Cl₂ to prepare PVI-HEA-Os(dmo-bpy)₂Cl₂ redox mediators. The synthesized mediator systems were characterized using ¹H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, field emission scanning electron microscopy/energy dispersive spectroscopy, zeta potential analysis, cyclic voltammetry, and electrochemical impedance spectroscopy. The results confirmed the successful formation of Os redox polymer structures and their immobilization on the electrode surface. The electrochemical behavior and glucose sensing performance strongly depended on the PVI-HEA composition. Among the compositions tested, PVI-HEA(3.5:1)-Os(dmo-bpy)₂Cl₂ showed the strongest redox current response, stable aqueous dispersion behavior, and relatively low interfacial charge-transfer resistance. Glucose-sensing measurements using FAD-GDH/mediator-modified electrodes showed linear current responses over the glucose concentration range of 1.25–20 mM. The PVI-HEA(3.5:1)-Os(dmo-bpy)₂Cl₂-based electrode showed the highest sensitivity of 16.18 μA cm⁻² mM⁻¹, which was significantly higher than those observed at lower-HEA compositions. The optimized mediator system also showed selective glucose responses against representative biological interferents, including ascorbic acid, uric acid, dopamine, and serotonin. Stable catalytic current responses were maintained under Human Plasma-Like Medium conditions, suggesting improved matrix tolerance compared to conventional PVI-based Os redox polymers. The improved sensing performance was attributed to the hydrophilic polymer environment introduced by the HEA units, which may facilitate favorable interfacial charge-transfer behavior within the enzyme–mediator layer. The results show that the hydrophilic copolymer composition plays an important role in the electrochemical behavior and glucose sensing performance of Os redox polymer mediators. The proposed PVI-HEA-Os(dmo-bpy)₂Cl₂ system may be a promising candidate for future enzymatic glucose sensing and continuous glucose monitoring-related applications. Full article

An electrochemical sensor based on a novel composite of electrochemically reduced graphene oxide, polypyrrole-coated magnetic nanoparticles (MNPs@PPy), and Nafion was developed for dopamine (DA) detection. The structural, thermal, and electrochemical properties of the composite were validated through a combination of advanced spectroscopic techniques, thermal profiling, electron microscopy, and impedance analyses. Under optimized conditions, differential pulse voltammetry (DPV) revealed a high sensitivity (1.573 A·M⁻¹·cm⁻², R² = 0.9874) and a limit of detection (LOD) of 5.4 × 10⁻⁹ M for DA. The sensor displayed excellent selectivity, showing minimal interference from ascorbic acid, uric acid, and acetaminophen. Repeatability and reproducibility were confirmed (coefficient of variation ~8%). Real-sample analysis of urine and blood demonstrated recovery rates between 75 and 116%. Full article

The precise spatiotemporal monitoring of dopamine is critical for understanding neurotransmission and neurodegenerative pathologies. While traditional electrochemical methods offer excellent temporal resolution, they lack the spatial resolution required to map network-wide dynamic events. To address this, we adapted a wide-field plasmonic electrochemical microscopy (PEM) platform to spatially image localized electrochemical reactions. Specifically, we leveraged the anodic electropolymerization of dopamine into a surface-confined polydopamine nanofilm to enable label-free, pixel-level optical quantification. Bulk solution testing demonstrated highly uniform sensor sensitivity, yielding an estimated single-pixel limit of detection of 14 pM. Furthermore, utilizing a custom injection system, we successfully imaged the real-time localized delivery of micromolar dopamine concentrations and demonstrated qualitative responsiveness of the integrated optical signal to delivered dopamine as a proof-of-concept for the platform. The platform functions as a spatially resolved mass integrator while simultaneously decoupling this chemical signal from transient hydrodynamic mechanical deformations caused by dopamine injection flow. Ultimately, this platform establishes the fundamental methodology required for future high-throughput spatial monitoring of complex neurotransmitter release dynamics across cellular networks. Full article

Simultaneous quantification of ascorbic acid, dopamine, and uric acid is crucial for clinical diagnostics. Here, an electrochemical sensor was developed by modifying a glassy carbon electrode with a ternary composite of multi-walled carbon nanotubes, graphene, and Vulcan XC72 carbon black via a simple mixing method. The synergistic interaction of these carbon materials significantly increases the electroactive surface area and introduces defect-driven catalytic sites, enhancing electron transfer kinetics. The sensor enables interference-free simultaneous detection, exhibiting linear ranges of 100–1000 μM ascorbic acid, 5–50 μM dopamine, and 10–100 μM uric acid with sensitivities of 0.044, 0.47, and 0.95 μA μM⁻¹, respectively, and corresponding limits of detection of 34.1, 4.23, and 11.1 μM. The platform also demonstrated excellent stability, reproducibility, and anti-interference performance, with satisfactory recoveries in human urine samples. These results highlight the ternary composite sensor as a reliable and practical tool for multiplexed monitoring in complex physiological matrices. Full article

Dopamine (DA) is essential for motor control, motivation, and cognition, and its dysregulation is associated with neurological and psychiatric disorders such as Parkinson’s disease, schizophrenia, and addiction. Accurate and selective DA quantification in complex biological matrices is important, but remains challenging because of coexisting interferents and the low physiological concentration of DA. Here, we report a disposable electrochemical DA sensor based on screen-printed carbon electrodes (SPCEs) modified with metal–organic framework-derived gold nanocomposites (MOFD-AuNCs). The optimal material, synthesized with a 60 min NaBH₄ reduction step (MOFD-AuNC-60), exhibited superior electron-transfer kinetics compared with materials prepared at other reduction times. A single coating of MOFD-AuNC-60 on SPCEs enabled DA oxidation at a low potential (~0.05 V) with high selectivity in the presence of ascorbic acid and uric acid. In undiluted porcine serum, the sensor exhibited a dynamic range of 2.5–500 nM with a calculated detection limit of 0.5 nM. In undiluted human serum, it exhibited a dynamic range of 5–100 nM with a calculated detection limit of 4.4 nM. The MOFD-AuNC-60/SPCEs further demonstrated excellent reproducibility (relative standard deviation, 3%) and stability (7.5% current loss over 7 days). These results demonstrate that the proposed sensor provides a disposable, robust, and reliable sensing platform for direct DA detection in undiluted serum, showing promise for practical applications. Full article

The rapid and reliable detection of dopamine (DA) is crucial for clinical diagnostics and neurochemical research. Here, we present an advanced electrochemical sensor fabricated by integrating 3D printing technology with bimetallic nanomaterials to achieve high sensitivity, selectivity, and reproducibility. A conductive polylactic acid (PLA) electrode was 3D-printed and subsequently activated to expose electroactive carbon domains. The surface was then modified with AgPt bimetallic nanoparticles (NPs), synthesized via a one-step solvothermal method, and coated with Nafion^TM 117 to form the AgPt@A-3DPE sensor platform. Morphological and structural characterization confirmed the formation of uniform, quasi-spherical AgPt nanoparticles with excellent dispersion. The sensor exhibited outstanding electrochemical performance, including a wide linear detection range for DA (0.5–100 µM), a low limit of detection (LOD) of 0.037 µM, and a significantly enhanced electroactive surface area (1.04 cm²). Furthermore, it demonstrates high selectivity in complex matrices, with minimal interference from common biomolecules such as ascorbic acid, uric acid, and glucose. Moreover, the practical applicability of the AgPt@A-3DPE sensor was successfully validated through the analysis of real human urine samples. This work demonstrates a low-cost, scalable, and highly efficient sensing approach, opening new avenues for personalized diagnostics and real-time monitoring of neurotransmitters in biomedical applications. Full article

In this study, an electrochemical sensor based on magnesium zirconate (MgZrO₃) synthesized using a deep eutectic solvent (DES)-assisted approach was developed for the detection of dopamine. The structural and morphological properties of MgZrO₃ were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive spectroscopy, and elemental mapping. The electrochemical performance of the MgZrO₃-modified glassy carbon electrode (GCE) was evaluated using cyclic voltammetry and differential pulse voltammetry. The MgZrO₃/GCE exhibited an enhanced redox response and a reduced oxidation potential for dopamine in phosphate-buffered solution (PBS, pH 7.0), indicating improved electrocatalytic activity compared to the bare electrode. This improvement is attributed to the material’s increased active surface area and facilitated charge transfer kinetics. Under optimized conditions, the sensor showed a linear response over a concentration range of 0.3–80 µM, with a detection limit of 127 nM and quantification limit of 423 nM. The MgZrO₃/GCE also demonstrated good selectivity in the presence of common interfering species and was successfully applied for dopamine detection in biological samples, with satisfactory recovery results. The findings presented here contribute to the growing body of knowledge in the field and open up new possibilities for the development of advanced electrochemical sensors for neurotransmitter detection in clinical and research settings related to Breast Cancer Treatment. Full article

Dopamine (DA) is a crucial catecholamine neurotransmitter, and its abnormal levels are closely associated with neurological disorders such as Parkinson’s disease. Electrochemical sensing technology offers a rapid and cost-effective platform for DA detection; however, it often suffers from interference from coexisting biomolecules such as ascorbic acid (AA) and uric acid (UA). In this study, we report a novel electrochemical biosensor based on PdMo bimetallene, a nanomaterial synthesized via a facile wet-chemical approach, aiming to enhance the detection performance and selectivity for DA. PdMo bimetallene is a highly curved, atomically thin two-dimensional nanosheet featuring abundant strained sites and a high density of active centers, enabling the selective and sensitive detection of DA. The results demonstrate that the as-prepared PdMo bimetallene-modified glassy carbon electrode (GCE) exhibits excellent electrocatalytic activity toward the oxidation of DA. The sensor displays a good linear response over the concentration range from 10 nM to 200 µM, with an ultrahigh sensitivity of 80 µA·µM⁻¹ cm⁻² and a low detection limit of 0.14 µM (S/N = 3). Owing to the synergistic electronic effect between Pd and Mo, the high density of exposed active sites, and the unique strained lattice structure of the bimetallene, the sensor enables accurate determination of DA concentrations even in the presence of interfering species such as AA and UA. In summary, the successfully fabricated PdMo bimetallene-based sensor offers the advantages of low cost, facile synthesis, a wide linear range, and high sensitivity, positioning it as a promising candidate for neurotransmitter detection applications. Full article

A nanostructured sensing platform based on electrospun functionalized multi-walled carbon nanotubes/poly(3-aminobenzylamine) (FMWCNTs/P3ABA) was developed for the electrochemical detection of dopamine (DA) on fluorine-doped tin oxide (FTO) glass substrate. The electrochemical characteristics of the electrodes were investigated by chronocoulometry (CC) and cyclic voltammetry (CV) in phosphate-buffered saline solution containing K₃[Fe(CN)₆] as a redox mediator. The zeta potential analysis confirmed the presence of a stable surface charge that favors electrostatic interaction with DA molecules. The DA detection was performed in human urine by differential pulse voltammetry (DPV) over a potential of −0.2 to 0.8 V and at scan rate of 5 mV s⁻¹, where the FMWCNTs/P3ABA nanofiber electrode exhibited a high sensitivity of 1.502 µA cm⁻² nM⁻¹, a linear detection range of 10–500 nM (R² = 0.992), and a limit of detection of 1.753 nM. The sensor exhibited stable and reproducible responses, and the fibrous composite effectively discriminated DA from common electroactive interferents, including ascorbic acid, uric acid, creatinine, and glucose. Furthermore, reliable dopamine quantification in human urine samples demonstrates the strong potential of the electrospun FMWCNTs/P3ABA composite nanofiber platform for practical bioanalytical and non-invasive sensing applications in the future. Full article

Dopamine is a key neurotransmitter and neuromodulator that regulates many critical brain functions. Accurate monitoring of its level is essential for neuroscience as well as the diagnosis and treatment of many brain diseases. In this work, we developed a new electrochemical sensor, comprising phosphorus-doped graphitic carbon nitride (P-g-C₃N₄) and zeolitic imidazolate framework 67 (ZIF-67), for dopamine detection. In this composite electrode material, ZIF-67 provides numerous adsorption and sensing sites, while P-g-C₃N₄ enhances overall electrical conductivity and stability. Cyclic voltammetry tests reveal the redox behavior of dopamine at the surface of the composite electrode across various pH values and scan rates. Using differential pulse voltammetry, the sensitivity and selectivity of this dopamine sensor were assessed, identifying a limit of detection of 0.39 nM. Further successful quantification of dopamine in urine samples suggests the potential practical use of this new composite electrochemical sensor for detecting dopamine and/or other neurotransmitters. Full article

The development of high-performance electrochemical sensors requires precise integration of electrode active materials that provide both superior electrocatalytic activity and long-term structural stability. Herein, we report a systematically optimized, one-pot electrochemical deposition approach for the fabrication of nanographenide-based nanoarchitectures, incorporating either a conducting polymer (PEDOT-NG) or Prussian blue (PB-NG). Derived from optimization-driven structural refinement—including applied potential, electrodeposition time, and precursor concentration—the robust nanoarchitecture exhibits a hierarchical morphology that provides an expanded electroactive surface area, accelerating charge transfer and enhancing electrochemical catalytic activity. The optimized PEDOT-NG exhibits exceptional sensitivity for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA), achieving wide linear ranges with low detection limits of 4.1, 0.12, and 0.18 μM, respectively. The PB-NG achieves a limit of detection of 4.39 μM, driven by highly reversible and stable redox kinetics. This performance is underpinned by narrowed peak-to-peak separations (ΔE) and reduced redox potentials. These results underscore the pivotal role of precise parametric control in developing high-performance electrochemical sensors. Furthermore, this work establishes a comprehensive strategy for designing resilient electrode active materials, thereby paving the way for next-generation electrochemical platforms tailored for diverse and robust sensing environments. Full article

Electrochemical sensors are user-friendly devices designed for the rapid and straightforward detection of target analytes. Serotonin (5-hydroxytryptamine, 5-HT) is a key neurotransmitter and neuromodulator that regulates diverse neuronal processes. Using a custom-designed screen-printed carbon electrode (SPCE) incorporating ordered mesoporous carbon–bimetal oxides of Cu and Ni (CuO–NiO–OMC), rapid and real-time detection of 5-HT was achieved. The CuO–NiO–OMC structure featured highly active CuO and NiO catalytic sites that effectively promoted the irreversible oxidation of 5-HT (vs. Ag/AgCl reference electrode). The CuO–NiO–OMC/SPCE sensor, connected to a portable potentiostat, exhibited exceptional electrocatalytic performance for the oxidation of 5-HT, with a detection limit of 42.5 nM. The sensitivity was 1.56 A M⁻¹ cm⁻², and the linear dynamic range was 0.0–80.0 µM. The CuO–NiO–OMC/SPCE sensor also demonstrated outstanding selectivity in the presence of competing neurochemicals, including norepinephrine, epinephrine, dopamine, and glutamate, as well as high concentrations of tested biomolecules and inorganic ions. Furthermore, the practicality of the sensor was demonstrated using human serum and urine samples, with recovery percentages ranging from 91.1% to 98.3%. Thus, the CuO–NiO–OMC/SPCE sensor offers an effective approach for 5-HT sensing, thereby permitting molecular-level understanding of brain function. Full article

Dopamine (DA) plays an extremely crucial role in the metabolic processes of the human body. Accurate detection of DA is of great significance for many major diseases. This study reports an innovative synthesis method for composite material in which sulfur (S) and nitrogen (N) are incorporated into multi-walled carbon nanotubes (MWCNTs), and platinum (Pt) nanoparticle sensors (Pt/CNTs-N-S) are loaded for the highly sensitive and selective electrochemical detection of DA. The linear range of this sensor is from 0.0078 to 2 mM, and the limit of detection (LOD) is 0.73 μM (S/N = 3) for DA detection. The outstanding detection performance exhibited by Pt/CNTs-N-S is mainly attributed to the co-doping of N and S, which improves the surface properties of MWCNTs, and the dispersion of Pt nanoparticles (5.22 nm), which significantly increases the electrochemically active surface area (ESCA). In addition, the Pt/CNTs-N-S sensor also exhibits excellent stability and anti-interference performance. Overall, this study provides a simple and practical strategy for the potential application of Pt-based sensors in the detection of DA. Full article

Herein, (Nafion-treated) (30 wt%) NiO_x/graphene (GP) were prepared at 250 °C and 450 °C and investigated as materials for dopamine electrochemical detection. Initially, characterization of the samples was performed using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. Subsequently, they underwent electrochemical evaluation using cyclic voltammetry, linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoamperometry (CA) techniques. All electrochemical measurements of the dopamine oxidation reaction (DOR) were performed in a 0.1 M phosphate buffer solution (PBS) at pH of 7.00 and at temperature of 36.6 °C. It was found that Nafion addition to the electrocatalysts surface facilitates access of the cationic dopamine molecule to their active centers being attributed to Nafion cation permeability. Nafion-NiO₂₅₀/GP exhibited higher activity towards the DOR reaction. The limit of detection (LOD) for the lower linear range of 0.5–10 μM was calculated to be 0.8 μM, with a sensitivity of 3.086 μA μM⁻¹cm⁻². Furthermore, the Nafion NiO₂₅₀/GP/GC electrode exhibited high selectivity towards DA, as well as good repeatability and reproducibility with an acceptable level of deviation, and excellent storage stability. The six electrodes produced from the Nafion-NiO₂₅₀/GP showed 8.28% reproducibility (RSD), indicating adequate behavior, while the same electrode after six measurements over a 30-day period showed an RSD of 5.50%, indicating a reliable electrode. Full article