Search Results (770)

Hydrogen sulfide (H₂S) is a contaminant for water quality, which can affect the eyes, respiratory system, and central nervous system, and may also cause damage to multiple organs such as the heart. Therefore, rapid and sensitive detection of trace H₂S is of great importance. In this work, a novel gold nanoparticle/2D porphyrin metal–organic framework nanocomposite (Au NPs/2D Cu-TCPP MOF) was prepared, and a novel electrochemical sensing method was established for the rapid determination of H₂S by differential pulse voltammetry (DPV). In 0.1 M PBS (pH 7.0), the detection limit of H₂S is as low as 0.03 μM, the linear range is 0.1–10 μM, and the response time is about 7 s. In addition, this method exhibits good stability and reproducibility, which can be applied to the rapid detection of H₂S in mine water samples. This study provides a reference for the development of new detection methods for H₂S in various complex environments. Full article

Melamine, characterized by its high nitrogen content, has been illegally added to food and feed to falsely increase apparent protein levels. However, melamine and its metabolites pose serious risks to human and animal health, including kidney stones, renal failure, and even death, as well as potential carcinogenic effects. Therefore, accurate detection of trace melamine is of great importance and urgency. Electrochemical sensors based on nanomaterials have been widely used for melamine detection due to their high sensitivity, good selectivity, rapid response, and simple operation. In this work, a composite nanosheet-structured electrode was fabricated, and a dense layer of gold nanoparticles was modified on its surface to enhance electrochemical performance. Cyclic voltammetry and electrochemical impedance spectroscopy measurements indicated that this electrode exhibited highly sensitive electrochemical properties. In addition, differential pulse voltammetry was employed for melamine detection, and the results showed a wide linear range of 20–500 nM with an LOD of 4.7 nM. The proposed electrode enabled the detection of melamine in milk samples, exhibiting good anti-interference ability and long-term stability. Full article

Molecularly imprinted polymers (MIPs) have emerged as robust and versatile recognition elements for electrochemical sensing due to their high chemical and mechanical stability, cost-effective fabrication, and excellent selectivity toward target analytes. In recent years, MIP-based electrochemical sensors have gained significant attention for the detection of pharmaceutical contaminants in wastewater, addressing growing environmental and public health concerns. This review provides a comprehensive overview of the fundamental principles of molecular imprinting Emphasis is placed on fabrication strategies and electrochemical detection techniques, including cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Furthermore, it discusses imprinting mechanisms for different classes of contaminants, matrix effects, and other challenges. By critically analyzing recent applications, this work highlights key factors influencing sensor performance, such as sensitivity, selectivity, and detection limits. Finally, we touch on future perspectives, focusing on the development of more reliable, scalable, and environmentally sustainable sensing platforms for real-world wastewater monitoring. Full article

Acute respiratory diseases caused by viral pathogens such as Influenza A continue to represent a major global health challenge, emphasizing the need for rapid, sensitive, and accessible diagnostic tools. In this work, a carbon screen-printed electrode (SPCE)-based electrochemical immunosensor for the detection of an Influenza A (H1) antigen is reported, incorporating a comparative electrochemical evaluation of four electrode materials. Fe₃O₄ nanoparticles, Fe₃O₄@C nanoparticles, graphene quantum dots (GQDs), and gold nanoparticles (AuNPs) were systematically assessed by cyclic voltammetry to evaluate their electrocatalytic performance. The highest electrochemical response was selected for biosensor construction. The immunosensor was fabricated by immobilizing antibodies on a modified SPCE and characterized using differential pulse voltammetry (DPV). A concentration-dependent response was observed for H1 antigen concentrations ranging from 0 to 300 ng/mL, with a minimum detectable concentration (MDC) of 1 ng/mL and limit of detection (LOD) of 176 ng/mL and 45 ng/mL for serum and nasopharyngeal swabs, respectively. The biosensor performance was specifically evaluated in complex biological fluids, demonstrating reproducible performance and moderate selectivity against non-target influenza subtypes. Overall, this study highlights the critical role of electrode material selection in determining electrochemical immunosensor performance and supports the potential of SPCE-based platforms for the screening of an Influenza A (H1) antigen in point-of-care-oriented applications. Full article

In the present research, lanthanum ferrite nanoparticles (LaFeO₃ NPs) and lanthanum ferrite polypyrrole (LaFeO₃/PPy) nanocomposites were synthesized and evaluated for electrochemical sensing of TNZ in biological and pharmaceutical samples. LaFeO₃ NPs were synthesized using the sol–gel auto-combustion method, whereas LaFeO₃/PPy nanocomposites were produced through an in situ chemical oxidative polymerization process. The obtained materials were subjected to comprehensive characterization by multiple analytical techniques, including XRD, which confirms an orthorhombic crystal structure; SEM micrographs of LaFeO₃ NPs and LaFeO₃/PPy nanocomposites exhibit a highly agglomerated structure with non-uniform particle distribution and a more homogeneous, smoother surface morphology, respectively, with an average size of <70 nm. The LaFeO₃/PPy nanocomposites exhibited an electron-transfer process governed by diffusion, as evidenced by cyclic voltammetry (CV) analysis. Using differential pulse voltammetry (DPV), the sensor achieved quantitative detection across a linear concertation range of 0.1–230 µM (R² = 0.997), with a detection limit (0.023 µM). The developed sensor demonstrated excellent stability, remarkable sensitivity, and high reproducibility, confirming reliability and suitability (RSD% < 4.0) for the quantitative determination of TNZ in both biological and pharmaceutical matrices. Full article

C-reactive protein (CRP) is one of the most essential biomarkers for the early detection of inflammation and infection. In this study, we developed a sensitive and selective electrochemical immunosensor for CRP detection, leveraging the unique properties of gold nanoparticles (AuNPs). A nanostructured layer of AuNPs was deposited onto a screen-printed carbon electrode (SPCE), followed by the formation of a self-assembled monolayer (SAM) of L-cysteine and EDC/sulfo-NHS chemistry. The antibody was covalently immobilized onto the modified electrode through optimized dual-crosslinking chemistry. Detection conditions were systematically optimized, with pH 8.0 in Tris buffer providing the best electrochemical response. Electrochemical characterization was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] redox probe solution containing 0.1 M KCl. CRP detection was achieved by monitoring the increase in charge transfer resistance (Rct) upon specific binding of the target CRP antigen to the immobilized antibody. Spiked recovery experiments showed spiked recovery rates ranging from 98.01% to 107.14%, with a standard deviation below 4%. Regeneration studies demonstrated high efficiency, confirming the suitability of the sensor interface for repeated and reliable measurements. Under optimized conditions, the immunosensor exhibited excellent analytical performance, including a low limit of detection (LOD) of 0.16 µg/mL, a wide linear detection range of 5–100 µg/mL, high selectivity against 13 potential interferents (including inflammatory cytokines), and good reproducibility with a relative standard deviation (RSD) of 3.69%. The sensor also showed strong stability, retaining more than 95% of its signal after 15 days, and high regeneration efficiency of 97% over seven cycles. These results highlight the strong potential of the proposed immunosensor for point-of-care (POC) applications due to its simple fabrication, cost-effectiveness, user accessibility, and robust analytical performance. Full article

Pipecolic acid (PA) is an important biomarker associated with peroxisomal and neurological disorders, necessitating the development of rapid, selective, and cost-effective detection methods beyond conventional chromatographic techniques. In this study, a molecularly imprinted electrochemical sensor (PA-MIP/Au) was developed for the selective determination of PA. The sensor was fabricated by electropolymerizing pyrrole on a gold electrode in the presence of PA as a template, followed by template removal to create specific recognition cavities. The electrochemical behavior and analytical performance were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a ferri/ferrocyanide redox system. The sensor exhibited a linear response over 5–100 µM, with a detection limit of 1.05 µM. This range covers the reported physiological plasma concentrations of pipecolic acid (0.7–2.6 µM) and extends to elevated levels observed in pathological conditions, thereby demonstrating its suitability for clinical and biochemical monitoring applications. The sensor also demonstrated high selectivity against structurally similar amino acids, good repeatability, reproducibility, and stability, retaining over 87% of its initial response after 28 days. Recovery studies in spiked artificial plasma samples yielded values between 97.2% and 98.4%, confirming its applicability in complex matrices. Overall, the proposed sensor offers a simple, rapid, and cost-effective alternative for PA determination with potential for clinical and point-of-care 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

This study describes the development of an electrochemical sensor for quantitatively measuring acetaminophen (ACOP) in drug tablets. The sensor design is based on the modification of glassy carbon electrode (GCE) using zinc oxide nanoparticles (ZnONPs) embedded in a naturally occurring clay matrix (Sa) functionalized with phenylalanine (Phe). To ensure that the ZnONPs are homogeneously dispersed on the clay surface, the nanocomposite was synthesized using an impregnation approach and low-temperature heat treatment. The amino acid promotes specific interactions with ACOP through hydrogen bonding and π-π stacking, acting as both a stabilizing agent and a molecular recognition moiety. FTIR, UV-Vis, XRD, and FESEM/EDX mapping were employed to fully characterize the developed material (ZnONPs-Sa/Phe). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for the electrochemical determination of ACOP using the modified electrode GCE/ZnONPs-Sa/Phe. Parameters susceptible to affecting the sensitivity of the developed sensor were optimized, revealing that 5 µL of the suspension ZnONPs-Sa/Phe immobilized on GCE was ideal for the sensing of ACOP in a phosphate buffer solution at pH 2.0. The calibration curve obtained by plotting peak current intensity against ACOP concentration exhibited linear behavior within the concentration range between 0.02 µM and 0.28 µM, enabling determination of the limits of detection (LOD) and quantitation (LOQ) at 8.54 × 10⁻⁹ M and 2.84 × 10⁻⁸ M, respectively. The reproducibility, stability, and selectivity of the sensor were evaluated, followed by its application to the nano-sensing of ACOP in Africure and Doliprane tablets, yielding satisfactory results. The simplicity, affordability, and high analytical sensitivity of the developed sensor make this sensing platform a promising tool for pharmaceutical quality control 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

In this study, the rank of multifaceted activity of catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG) and epigallocatechin-3-gallate (EGCG) was addressed. Their antioxidant activity was determined by the differential pulse voltammetry (DPV), whereas their ability to inhibit angiotensin-converting enzyme (ACE) activity, acetylcholinesterase activity (AChE), and formation of the advanced glycation end-products (AGEs) was performed in a model system to show their importance against hypertension, Alzheimer-type dementia, and diabetic’s complication, respectively. The order of the antioxidant potential of catechins in comparision to gallic acid (GA) was EGCG > ECG > EC > EGC ≈ C > GA, whereas the order of the ACE inhibitory activity was EGCG > ECG > EGC > EC > C, thus indicating the importance of the structure–activity relationship. The correlation between IC₅₀ for ACE inhibition of catechins and their antioxidant activity had the value r = −0.60. The order of the AChE enzyme inhibitory activity was EGCG ≈ EGC > ECG > EC > C, and the weak positive correlation between IC₅₀ and the first anodic peak potential (E_pa1) values was noted (r = 0.67). The ranking of the anti-AGE activities was EGCG ≈ ECG > EGC > EC > C, and a negative correlation between the inhibitory activity of catechins against AGE formation and their antioxidant activity was r = −0.82, whereas a positive correlation (r = 0.88) was noted between their first anodic peak potential (E_pa1) values. The provided results expand our knowledge on the multifaceted activity of catechins, indicating EGCG and ECG as the most active antioxidants against inhibition of ACE and AChE as well as towards AGE formation. Full article

Short-chain fatty acids (SCFAs) are key biomarkers of gut microbiota activity; however, routine quantification in fecal samples relies largely on chromatography, which is instrument-intensive and throughput-limited chromatography techniques. Herein, we present a rapid machine-learning-assisted electroanalysis platform for SCFAs profiling that integrates a disposable three-electrode planar gold chip with voltammetric fingerprinting and artificial neural network (ANN)-based signal decoupling. To generate orthogonal chemical information and improve the discrimination of structurally similar species, a dual pretreatment strategy combining acid-catalyzed esterification and alkaline dissociation was employed prior to electrochemical analyses. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were employed to acquire high-dimensional fingerprints, from which current-, potential-, and area-based descriptors were extracted using a cross-information feature strategy. A hierarchical modeling framework improved total SCFAs prediction by incorporating ANN-predicted propionate and butyrate concentrations as auxiliary inputs. While linear calibration was achievable in standard mixtures, direct linear models performed poorly in real fecal matrices due to strong sample-dependent matrix interference. In contrast, the ANN captured nonlinear relationships among multifeature inputs and suppressed matrix effects. Validation against gas chromatography–mass spectrometry in an independent fecal test cohort (n = 30) demonstrated excellent agreement and low prediction errors, with mean absolute error/root mean square error values of 0.063/0.072 mM (propionic acid), 0.029/0.034 mM (butyric acid), and 0.135/0.202 mM (total SCFAs). The DPV/CV acquisition requires only minutes per sample, whereas pretreatment takes 1~3 h depending on the target route but can be performed in parallel for batch processing; thus, overall throughput is determined mainly by batch pretreatment rather than per-sample instrument time. This electrochemical–ANN workflow provides a portable, high-throughput alternative to chromatography for fecal SCFAs profiling in clinical screening and microbiome research. Full article

Campylobacter spp. is one of the most common pathogens responsible for gastroenteritis in developed countries and is raising public health concerns worldwide. This work optimized a label-free electrochemical genosensor based on screen-printed gold electrodes (SPAuEs) for the rapid detection of Campylobacter jejuni, C. coli, C. lari and C. upsaliensis. SPAuEs were functionalized with a specific thiolated DNA probe and tested with a ferrocyanide solution for signal production. The optimization of the conditions was obtained using DNA extracted from pure cultures of Campylobacter spp. and negative controls such as Escherichia coli, Listeria innocua, Salmonella spp., and Helicobacter pylori. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were compared to assess sensitivity and specificity. The relative change in intensity of the ferrocyanide anodic peak (Ipa) was proportional to the value of Campylobacter spp. DNA concentrations in the range of 1 pg/µL to 10⁴ pg/µL. The limit of detection of our optimized system was 1.06 pg/μL. After optimization, the method was applied to chicken meat samples from the market. The proposed electrochemical DNA biosensor was able to detect Campylobacter jejuni, C. coli, C. lari and C. upsaliensis after selective enrichment and DNA isolation within 60 min of DNA extraction, demonstrating its usefulness for routine analyses. Full article

Zinc deficiency is recognized as a global public health concern, affecting populations of all ages. This study aims to develop zinc supplements (nutraceuticals) based on by-products of the fruit and vegetable processing industry. Dehydrated apple and beetroot pomace powders were enriched with vitamin C and zinc via fluid-bed wet granulation, producing granules with substantially improved flowability (Carr’s index reduced by up to 45%, Hausner ratio by up to 25%, while the bulk and tapped density were reduced by up to 25% and 40%, respectively). Microbiological and long-term storage stability was demonstrated by low water activity (aw) (≤0.3), moisture content (<10%), and glass transition temperatures (T_g = 29–34 °C) that were well above standard storage conditions. The formulated nutraceuticals exhibited stronger antioxidant activity compared to the starting powders, as well as significant anti-hyperglycemic activity. Furthermore, the enhanced bioaccessibility of zinc was confirmed upon in vitro digestion of granulated samples, using atomic absorption spectrometry and differential pulse voltammetry. The present findings demonstrate that apple and beetroot pomaces can be successfully valorized as sustainable and functional matrices for zinc enrichment, being free of gluten, artificial sweeteners, colorants, preservatives, anti-caking agents, and anti-nutritional factors such as phytic acid. Full article