Multicomponent reactions (MCRs) have attracted considerable attention in the field of sustainable and green chemistry because of their excellent atom economy, versatility, and reproducibility. These reactions provide an efficient route for synthesizing novel organic compounds, as they minimize the need for multiple purification steps and allow the formation of the final product in a single one-pot process. One of the key challenges in MCRs is carrying out these reactions in an environmentally friendly manner, where the choice of solvent plays a crucial role. Water is often considered an ideal green solvent, as it can enhance both the selectivity and reactivity of chemical transformations, although it may pose limitations due to the poor solubility of many organic substrates. To overcome this issue, surfactants are commonly used to improve substrate solubility. Surfactants, which form micellar structures in solution, not only improve reaction rates and yields but also reduce the interfacial tension between organic and aqueous phases. Their role can be understood in two ways: first, they encapsulate the reactants within micelles, effectively bringing them closer together and facilitating interaction; second, the hydrophobic products tend to associate with the micellar core, which helps shift the reaction equilibrium toward product formation.
Rifampicin (RF) is a important pharmaceutical compounds that require sensitive and selective electrochemical detection. The increase in efficiency of the carbon paste electrode, followed by the modification of serine functionalization by electropolymerization to form synergistic effects of polymeric films with the carbon paste electrode to enhance electron–proton transfer and surface activity by electrocatalytic behaviour. Electrochemical studies, including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV), revealed optimisation of a pH of 6.5 with diffusion-controlled redox behaviour under optimisation of scan rate. The developed electrodes demonstrated excellent wide linear ranges for low detection limits. The calculated lower detection limits, corresponding to lower quantification limits, were 8 nM and 0.02 µM (CV), 7 nM and 0.017 µM (LSV), and 4 nM and 0.015 µM (DPV), and outstanding simultaneous hydraqunine selectivity and sensitivity through different interferents, with good recovery rates from pharmaceutical tablets. The overall study signifies stability, reproducibility, and repeatability, highlighting the potential of the serine functionalization carbon paste electrode (SFCPE) for reliable voltammetric determination of RF and its applicability in pharmaceutical formulations and clinical applications.
In this study, the photocatalytic degradation of methylene blue (MB) was investigated using graphene oxide (GO)/CuBi2O4/TiO2 catalysts under UV irradiation. The degradation kinetics were monitored as a function of GO loading in the system. It was observed that the optimal GO loading was 0.5 wt
A scalable and sustainable one-pot strategy is reported for the synthesis of a bio-functionalized graphene oxide hybrid (WT@FGO) using Wrightia tinctoria latex as a natural oxidizing and functionalizing agent. This integrated approach circumvents the conventional multi-step graphene oxide synthesis–reduction–functionalization process, thereby minimizing reaction time, solvent usage, and overall processing complexity. Unlike conventional graphene oxide, which predominantly contains oxygenated functionalities, the latex-assisted route enables the in-situ incorporation of heteroatom-rich bioactive moieties, yielding an O/N/S-enriched framework with enhanced surface polarity, abundant active sites, and improved interfacial accessibility. The as-prepared WT@FGO exhibits intrinsic fluorescence and demonstrates high selectivity toward Pb²⁺ ions, attributed to strong coordination interactions with surface nitrogen and oxygen donor sites, achieving a detection limit in the nanomolar range. The antibacterial activity of WT@FGO was compared with a standard antibiotic used as the positive control under identical experimental conditions. WT@FGO exhibited concentration-dependent antibacterial activity against Escherichia coli and Pseudomonas aeruginosa, demonstrating promising antibacterial efficacy and confirming its potential as a sustainable antimicrobial material. This work establishes W. Tinctoria latex as a sustainable and versatile platform for the fabrication of multifunctional graphene-based nanomaterials, offering promising potential in environmental sensing and antimicrobial applications.
Monitoring Mesalazine (MSZ) and Uric Acid (UA) levels is vital for managing inflammatory bowel disease (IBD) and preventing nephrolithiasis. Addressing this clinical need, we developed a novel poly(pyrazinamide) modified carbon paste electrode (poly(PYZ)MCPE) for the simultaneous, selective detection of MSZ and UA. The modifier PYZ was electropolymerized onto the electrode surface using cyclic voltammetry (CV) to enhance its electrochemical activity. The sensor’s electrochemical behaviour was characterised by using CV and differential pulse voltammetry (DPV). Density functional theory (DFT) calculations revealed the preferential interactions between PYZ and the targeted analytes, suggesting a dual-mode interaction mechanism involving π–π stacking and hydrogen bonding. The sensor demonstrated a linear response for MSZ and UA in the concentration range of 0.05 to 0.4 mM, with low detection limits of 0.0755 µM and 0.96 µM, respectively. Critically, poly(PYZ)MCPE demonstrated the capability to simultaneously detect MSZ and UA with good peak separation, highlighting its potential for multi-analyte sensing. High selectivity, good pH sensitivity, and successful application in pharmaceutical tablet analysis confirm the practical viability of the poly(PYZ)MCPE sensor. This work highlights the potential of PYZ as a promising and cost-effective electrode modifier for sensitive multi-analyte electrochemical sensing applications, which can be efficiently deployed for the real-time monitoring of inflammatory bowel disease and kidney stone patients.
Manganese dioxide is an earth-abundant and environmentally benign material with broad relevance to catalytic reactions. Here, we explore the preparation of crystalline MnO2-like planar model surfaces on Au(111) and Au(001) by molecular beam epitaxy (MBE), using O2 and NO2 as oxygen sources. The resulting MnOx structures depend jointly on substrate symmetry, oxygen chemical potential, and the Mn coverage. Under strongly oxidizing NO2 atmosphere, low nominal Mn coverage, defined here as less than 0.8 monolayer equivalent (MLE), produces a hexagonal oxygen-rich MnOx phase, whereas increasing the total Mn coverage to 1.2-2.0 MLE leads to the formation of a higher-coverage MnO2-like overlayer. High-resolution Scanning Tunneling Microscope (STM) and Scanning Tunneling Spectroscopy (STS) measurements, combined with DFT energetics, support oxygen-terminated O–Mn–O trilayer-related structures, with Au–O–Mn–O and Au–O–Mn–O–Mn–O as the most plausible models for the low- and high-coverage phases, respectively. These epitaxially stabilized phases provide atomically defined model surfaces for investigating manganese-oxide structure-property relationships.
The precise monitoring of dopamine (DA), serotonin (5-HT), and L-tryptophan (L-Trp) is a critical challenge for the early diagnosis and management of neurodegenerative disorders, such as Alzheimer’s and Parkinson’s diseases. This work describes the development of a high-performance electrochemical platform based on a carbon paste electrode modified with a novel nanocomposite of glassy carbon microspheres (GCMs) decorated with magnetite (Fe3O4) nanoparticles. The modifier was synthesized through a sustainable and efficient hydrothermal route, which ensured a uniform decoration of the GC surface and enhanced the material’s synergistic electrocatalytic properties. Under optimized conditions using square wave voltammetry (SWV) at pH 7.50, the sensor achieved wide linear response ranges: 0.04–10.00 µM for DA and 0.09–20.00 µM for 5-HT and L-Trp. Remarkably low limits of detection (LOD) were obtained for simultaneous determination: 2.8 nM for DA, 8.1 nM for 5-HT, and 6.7 nM for L-Trp. The proposed analytical method was successfully validated in complex biological matrices, including blood serum and synthetic urine, providing excellent recovery rates (near 100
The removal of ethylene - a phytohormone that promotes fruit ripening after harvesting can prolong the ripening time of the fruit. In this study, the TiO2 photocatalyst was modified to increase the catalytic efficiency by mechanical mixing with two types of zeolites which underwent the silver ion exchange process. Various analytical techniques, including XRD, N2 adsorption-desorption, SEM-EDS, were employed to evaluate the crystal structure, textural characteristics, morphology, and elemental distribution of the materials. This investigation examined two distinct aluminosilicate molecular sieve materials: zeolite ZSM-5 and zeolite P, which exhibit a framework type denoted as MFI and GIS, respectively. The TiO2 – Ag/ZSM-5 and TiO2 – Ag/ZP samples, gives 3- and 4.5-times better efficiency, respectively, compared to the use of parent TiO2 P25. Furthermore, the study assessed the effect of different types of zeolites in the dispersion of TiO2 on a fixed surface of the material. In all experiments, zeolite P showed better catalytic support effect than zeolite ZSM-5. Besides, the study investigated factors related to reaction conditions in a continuous flow reactor. The research findings serve as fundamental data for the practical development of utilizing photocatalysts to prolong the shelf life of agricultural products.
The development of rare-earth doped metal oxide graphene nanocomposites as electrochemical sensors for environmental and antimicrobial-related sensing applications is examined critically in this study, along with current developments and problems. These nanocomposites provide a potent platform for improved analyte adsorption, charge transport, and electrochemical signal generation by fusing the high electrical conductivity, mechanical flexibility, and large surface area of graphene derivatives with the defect-rich and catalytically active nature of rare-earth-doped metal oxides. Consequently, when compared to traditional metal oxide-based sensors, they showed enhanced sensitivity, selectivity and stability. Major synthesis techniques such as hydrothermal, sol-gel, solvothermal, and co-precipitation methods and important characterization techniques were analyzed for assessing the properties of the composites like, surface area, morphology, defect chemistry, mixed-valence redox behavior, rare-earth-induced, oxygen vacancies. And also discussed the graphene-assisted charge transport on electrochemical sensing efficiency, in contrast to previous reviews that concentrate independently on graphene-based sensors, rare-earth doped metal oxides, or wide hybrid nanocomposites only. In this review, we have analyzed the various electrochemical sensing parameters like detection limit, linear range, sensitivity, selectivity, stability and real-sample applicability of rare-earth doped metal oxide/graphene composites. We observed that rare earth metals like Pr, Yb, Gd etc. doped metals oxides like CuO, ZnO, V2O5 etc., with graphene composites shows promising sensing systems with other materials. The potential of rare earth doped metal oxide-graphene nanocomposites are promising for the next-generation sensing platforms that can monitor environmental pollutants and critical antimicrobial related targets in complex environments in real-time.
The orthogonal self-assembly of anchored molecular monolayers on chemically heterogeneous substrates offers a route for bottom-up chemical nanopatterning and area-selective deposition. Herein, we investigated the selective growth of self-assembled monolayers (SAMs) of n-decanethiol (DT) and 4,4'-biphenyldicarboxylic acid (BPDCA) on a pristine Au(111) surface and on CoO nanoislands on Au(111) by physical vapor deposition (PVD) under ultrahigh vacuum (UHV) conditions. We combined in situ infrared reflection-absorption spectroscopy (IRAS) applied during PVD and scanning tunneling microscopy (STM). At 300 K, DT formed a lying-down phase on Au(111), which evolved into a denser and slightly more upright adlayer upon heating to 400 K. On the Au(111) surface partially covered by CoO nanoislands, BPDCA preferentially binds to CoO. BPDCA adopts a tilted or upright orientation on CoO with one carboxylate group bound to the surface and a free carboxylic acid group pointing towards the vacuum. When DT is dosed onto BPDCA-precovered CoO/Au(111), the BPDCA SAM is preserved while a DT SAM grows on the Au regions between the CoO islands. This observation demonstrates that the oxide-bound carboxylate layer is sufficiently robust to confine DT to the Au regions. Our results provide a vacuum-based procedure for orthogonal functionalization of a metal/oxide nanostructure to synthesize a nanopatterned SAM with different terminating functional groups.
The study focuses on rutin by the voltammetric detection of rutin in an apple juice sample. The bare carbon paste electrode (BCPE) is modified with leucine as a functional modifier to improve film formation and enhance electrochemical performance. The modified electrodes reveal enhanced conductivity, increased electroactive surface area, and rapid electron-proton transfer during the redox reactions. Electrochemical investigation was carried out in a 0.1 M phosphate buffer solution (PBS) at pH 6.7 using a scan rate of 0.1 V/s (SR). Techniques of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and linear sweep voltammetry (LSV) were employed to assess the performance of the electrodes. The fabricated electrodes confirm excellent stability, reproducibility, selectivity, and sensitivity, showing high current response through diffusion-controlled behaviour and low detection limits of 0.017µM (CV), 0.016µM (LSV), and 0.007µM (DPV). Concentration variation and simultaneous analyses were conducted with hydroquinone, along with real sample testing for food formulations, offering a promising platform for the electrochemical detection of apple juice food components.
One of the best ways to deal with solid waste is microwave-assisted pyrolysis. Extraction of valuable oils from date seed (DS) and Chelly seeds (CS) by MW-assisted catalytic co-pyrolysis has demonstrated encouraging results in this field of study. The CaO Nano catalyst served as the susceptor, while graphite was employed as the catalyst. A 1:1 CS: DS ratio was used as the feedstock. The production yields of oil (37.04 to 50.20 wt
Airborne nitrogen oxides (NOₓ) are among the most persistent urban pollutants, contributing to ozone formation, acid rain, and respiratory health issues. Beyond emission control at the source, photocatalytic NOₓ oxidation and storage (PHONOS) has emerged as a promising strategy for sustainable environmental remediation. This review systematically discusses the fundamental mechanisms, material developments, and practical aspects of photocatalytic NOₓ abatement. We first summarize the reaction pathways governing NO and NO2 oxidation on TiO2 and related semiconductors, emphasizing the roles of photogenerated holes, hydroxyl radicals, and surface-bound intermediates in determining selectivity toward nitrate. Next, we highlight advances in material design, including single-atom catalysts, doped TiO2, g-C3N4 heterostructures, and oxygenate-modified surfaces that enhance visible-light activity and nitrate storage stability. The influence of environmental factors-such as humidity, reactant gas flow rate, and irradiation wavelength are also discussed. Existing scientific literature suggests that as a novel environmental airborne pollution abatement technology, PHONOS has the potential to evolve from a laboratory concept into a viable, sunlight-driven approach for actively improving urban air quality even far away from the point where pollution is generated.
Trans-ferulic acid (E-isomer) (FA), a vital phenolic compound widely used in food, pharmaceutical and biological matrices, demands a highly selective and sensitive method for quality control and biomedical applications. The present work demonstrates the successful development of ZnO Nanoparticles-modified carbon paste electrode (ZnO NPs/CPE) and surface-pretreated ZnO NPs/CPE for the detection of FA. Fabricated by green routes using the combustion method. XRD and SEM are used to analyse the morphological and structural properties of ZnO NP, which revealed a crystalline hexagonal structure with uniform morphology. The FA’s electrochemical behaviour was examined using CV and DPV. Pretreated ZnO NPs/CPE results show improved oxidation peak currents compared to ZnO/CPE, faster electron transfer rates (α = 0.545, ks=4.85 s⁻¹), adsorption-controlled reaction kinetics, sensitivity (4.087 µAµM−1cm−²), linear range (1–10 µM), and low detection limit (0.006µM). The sensor exhibits outstanding reproducibility (1.3
Electrocatalytic detection of biological substances using hybrid nanocomposites represents a promising frontier in electrochemical biosensors for clinical applications. This review article presents a comprehensive overview of recent advances in the development and application different electrodes modified with hybrid nanostructures—materials that combine synergistic properties of inorganic components (such as metallic nanoparticles, metal oxides, graphene, carbon nanotubes) and organic or biomolecular components—for the sensitive, selective, and rapid detection of clinically relevant biomarkers, such as glucose, dopamine, uric acid, DNA, cancer antigens, and other metabolites or pathogens.
Copper nanoparticles are widely studied for catalytic applications; however, controlling their aggregation during synthesis remains challenging due to the complex interplay of synthesis parameters. In this work, we systematically investigate the aggregation behavior of copper nanoparticles synthesized via a one-pot chemical reduction method at room temperature by independently varying key synthesis parameters, including copper precursor concentration, reducing agent concentration and injection rate, capping agent concentration, and overall component concentrations. Electron microscopy-based size analysis combined with statistical evaluation reveals that, under the studied conditions, the primary particle size remains largely insensitive to changes in copper precursor concentration, while aggregation is strongly promoted with increasing precursor concentration and total component concentrations. In contrast, the reducing agent plays a decisive role in both particle growth and aggregation. Increasing its concentration promotes the formation of larger primary particles and aggregates, whereas faster injection rates effectively suppress aggregation over a broad parameter window. The capping agent, poly(vinylpyrrolidone), exhibits a comparatively limited influence on aggregation and no pronounced effect on primary particle size under the conditions investigated. The direct impact of aggregation on catalytic performance is demonstrated using CO oxidation as a probe reaction, where a decrease in activity is observed with increasing aggregate size despite similar primary particle sizes. Overall, this study establishes aggregation as a highly sensitive and independently tunable outcome of copper nanoparticle synthesis, providing practical guidelines for controlling aggregate formation during scale-up and for the rational design of nanostructured copper catalysts where aggregate architecture is critical to performance.
This research describes the preparation of a poly (valine)-modified multiwalled carbon nanotube carbon paste electrode (PVL-MWCNT/CPE) via facile electro-polymerization and grinding methods. Surface morphology, elemental composition, functional groups, and surface area of the modified electrode were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and cyclic voltammetry (CV). The modified electrode exhibited a strong electrocatalytic effect towards caffeic acid (CA) sensing in a 0.1 M phosphate buffer solution (PBS, pH 6.0), with increased peak current and reduced overpotential. For the calibration curve, differential pulse voltammetry (DPV) offered an enhanced peak in a linear range from 4.0 µM to 20 µM, with a low detection limit of 0.072 µM, indicating high sensitivity. The sensor also demonstrated good repeatability, reproducibility, and stability. The practical applicability of the sensor was confirmed by direct detection of low concentration CA in green tea samples with satisfactory outcomes.
