A brief study on the kinetic of the voltammetric behavior of the modified carbon paste electrode with NiO nanoparticles towards loratadine as a carboxylate-amidic drug compound

Detection of paracetamol by a montmorillonite-modified carbon paste sensor: A study combining MC simulation, DFT computation and electrochemical investigations

This study aims to develop a suitable electrochemical electrode through the incorporation of potassium montmorillonite (MMTK10)clay into the carbon matrix for the direct and sensitive determination of paracetamol (PAR) in pharmaceutical formulations. Electrochemical characterization of the electrodes involves the use of techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The results reveal that the voltammetric response of PAR is linear over a wide concentration range (1.0-15 μM), with a low detection limit of 0.46 μM. Analytically, PAR recovery results were around 94%, indicating that the developed electrode is highly suitable for PAR detection in pharmaceutical formulation. Additionally, density functional theory (DFT) is employed to investigate the reactivity of PAR and explain the interaction process of PAR on the electrode surface at different pH values. A Monte Carlo simulations model is developed to provide a deeper understanding of the adsorption mechanism, particularly to comprehend molecular interactions and preferential orientations of PAR with MMT fractions at the electrode surface. Reduced Density Gradient is calculated and discussed using techniques such as Multiwfn and Visualization of Molecular Dynamics. The developed CPE-MMTK10 sensor provided a simple preparation method, rapid response, high sensitivity, reproducibility, strong selectivity, and extended stability. Moreover, there is a good correlation between most parameters calculated by DFT and experimental results, thereby reinforcing the validity of the theoretical approach in this study.

Toward an Improved Electrocatalytic Determination of Immunomodulator COVID Medication Baricitinib Using Multiwalled Carbon Nanotube Nickel Hybrid

The study presents a first electrochemical method for the determination of the immunomodulator drug Baricitinib (BARI), crucial in managing COVID-19 patients requiring oxygen support. A unique electrode was developed by modifying graphite carbon nickel nanoparticles (NiNPs) with functionalized multiwalled carbon nanotubes (f.MWCNTs), resulting in nanohybrids tailored for highly sensitive BARI detection. Comparative analysis revealed the superior electrocatalytic performance of the nanohybrid-modified electrode over unmodified counterparts and other modifications, attributed to synergistic interactions between f.MWCNTs and nickel nanoparticles. Under optimized conditions, the sensors exhibited linear detection within a concentration range from 4.00 × 10-8 to 5.56 × 10-5 M, with a remarkably low detection limit of 9.65 × 10-9 M. Notably, the modified electrode displayed minimal interference from common substances and demonstrated high precision in detecting BARI in plasma and medicinal formulations, underscoring its clinical relevance and potential impact on COVID-19 treatment strategies.

An electrochemical microfluidic device for non-enzymatic cholesterol determination using a lab-made disposable electrode

Cholesterol is an important steroid and hormone precursor, and its levels in the blood are associated with risk factors for cardiovascular diseases. In this work, a non-enzymatic methodology for cholesterol determination in serum samples is described. First, a working electrode was constructed using homemade ink and a plastic substrate by a simple dunking process. Next, the dunked electrode (DWE) was modified with nickel ions (Ni-DWE) and combined with a low-cost microfluidic platform, resulting in a thread-based electroanalytical device (μTED). The arrangement of μTED consists of two coupled electrodes (one reference in the inlet reservoir and an auxiliary electrode against the outlet reservoir) and a mobile support for facile working electrode exchange. After optimization of construction parameters, the system was applied for non-enzymatic determination of cholesterol under alkaline conditions using the redox pair Ni(II)/Ni(III) as a mediator. Under the best analytical conditions, a calibration curve was constructed with a linear dynamic range (LDR) from 0.25 to 25.0 μmol L^-1, and the calculated limits of detection (LOD) and quantification (LOQ) were 0.074 and 0.24 μmol L^-1, respectively. No effects of possible interferents on electrochemical response were found in the presence of ascorbic acid, uric acid, dopamine, cysteine, and glucose, suggesting that the proposed device can be used for the determination of cholesterol without significant matrix effects of human plasma. Finally, cholesterol analysis was carried out using spiked plasma samples, and good recovery values were achieved.

Dimensionality effects of g-C3N4 from wettability to solar light assisted self-cleaning and electrocatalytic oxygen evolution reaction

Unique interfacial properties of 2D materials make them more functional than their bulk counterparts in a catalytic application. In the present study, bulk and 2D graphitic carbon nitride nanosheet (bulk g-C₃N₄ and 2D-g-C₃N₄ NS) coated cotton fabrics and nickel foam electrode interfaces have been applied for solar light-driven self-cleaning of methyl orange (MO) dye and electrocatalytic oxygen evolution reaction (OER), respectively. Compared to bulk, 2D-g-C₃N₄ coated interfaces show higher surface roughness (1.094 > 0.803) and enhanced hydrophilicity (θ ∼ 32° < 62° for cotton fabric and θ ∼ 25° < 54° for Ni foam substrate) due to oxygen defect induction as confirmed from morphological (HR-TEM and AFM) and interfacial (XPS) characterizations. The self-remediation efficiencies for blank and bulk/2D-g-C₃N₄ coated cotton fabrics are estimated through colorimetric absorbance and average intensity changes. The self-cleaning efficiency for 2D-g-C₃N₄ NS coated cotton fabric is 87%, whereas the blank and bulk-coated fabric show 31% and 52% efficiency. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis determines the reaction intermediates for MO cleaning. 2D-g-C₃N₄ shows lower overpotential (108 mV) and onset potential (1.30 V) vs. RHE for 10 mA cm^-2 OER current density in 0.1 M KOH. Also, the decreased charge transfer resistance (R_CT = 12 Ω) and lower Tafel's slope (24 mV dec^-1) of 2D-g-C₃N₄ make it the most efficient OER catalyst over bulk-g-C₃N₄ and state-of-the-art material RuO₂. The pseudocapacitance behavior of OER governs the kinetics of electrode-electrolyte interaction through the electrical double layer (EDL) mechanism. The 2D electrocatalyst demonstrates long-term stability (retention ∼94%) and efficacy compared to commercial electrocatalysts.

Preparation of new hydrogels by visible light cross-linking of dextran methacrylate and poly(ethylene glycol)-maleic acid copolymer

In this work, a series of new biodegradable and biocompatible hydrogels were synthesized by photopolymerization of dextran-methacrylate (DXM) with poly(ethylene glycol)-maleic acid copolymer (poly(PEG-co-MA, PEGMA)) using (-)-riboflavin as a visible light photoinitiator and L-arginine as a co-photoinitiator. DXM was prepared by acylation of dextran (DX) with methacryloyl chloride (MAC), and PEGMA was synthesized by polycondensation of poly(ethylene glycol) (PEG) and maleic acid (MA). The DXM and PEGMA were characterized by FT-IR and ¹HNMR spectroscopy. Different types of hydrogels from various ratios of DXM and PEGMA were prepared and characterized by SEM. The results showed that the prepared hydrogel by photo-cross-linking of DXM (DPHG0) was transparent and flexible, and its physical shape was excellent, but it was sticky. The stickiness was reduced by increasing the PEGMA contents, and different types of DXM/PEGMA hydrogels (DPHG1-4) with various properties were prepared. For example, DPHG2 (PEGMA content was 0.25 g) was transparent and flexible, its physical shape was excellent, and it was not sticky. The prepared hydrogels showed excellent cytocompatibility, and their tensile and compressive strength were also evaluated. Additionally, the in vitro degradation and swelling ratios of the prepared hydrogels were studied in buffer solution at different pHs.

Recent advances in the electrochemical applications of Ni-based metal organic frameworks (Ni-MOFs) and their derivatives

Nickel-based metal-organic skeletal materials (Ni-MOFs) are a new class of inorganic materials that have aroused attention of investigators during past couple of years. They offer advantages such as high specific surface area, structural diversity, tunable framework etc. This assorted class of materials exhibited catalytic activity and electrochemical properties and display wide range of applications in the fields of electrochemical sensing, electrical energy storage and electrocatalysis. In this context, the presented review focuses on strategies to improve the electrochemical performance and stability of Ni-MOFs through the optimization of synthesis conditions, the construction of composite materials, and the preparation of derivatives of precursors. The review also presents the applications of Ni-MOFs and their derivatives as electrochemical sensors, energy storage devices, and electrocatalysts. In addition, the challenges and further electrochemical development prospects of Ni-MOFs have been discussed.

Cyclic and Linear Sweep Voltammetric Studies of a Modified Carbon Paste Electrode with Nickel Oxide Nanoparticles toward Tamoxifen: Effects of Surface Modification on Electrode Response Kinetics

Due to the serious adverse futures of some anticancer drugs, the determination of trace amounts of these drugs by simple analytical techniques is of great interest. In this regard, knowing about the mechanism of the analyte with the sensing material plays an important role. Nickel oxide nanoparticles (NiO NPs) modified by a carbon paste electrode (NiO-CPE) showed an irreversible cyclic voltammetric (CV) behavior in the NaOH (pH 13) supporting electrolyte based on the peak separation of 311 mV. Its peak current was decreased by adding tamoxifen (TAM), confirming that TAM molecules can consume NiO before participating in the electrode reaction. For this goal, TAM can be oxidized or reduced, and the corresponding mechanisms are schematically illustrated in the text. This study focused on the kinetic aspects of the process. Based on the CV results, a surface coverage (Γ) value of 2.72 × 10^-5 mol NiO per cm² was obtained with charge transfer coefficients α_a and α_c of 0.317 and 0.563, respectively. α_a and α_c values were changed to 0.08 and 0.72 in the presence of TAM. Further, the rate constant (k _s) value was 0.021 ± 0.01 s^-1 in the presence of TAM. In linear sweep voltammetry (LSV), an α value of about 0.636 ± 0.023 and an exchange rate constant (k _o) value of about 0.097 ± 0.031 s^-1 were obtained in the absence of TAM, which changed to 0.62 ± 0.081 and 0.089 ± 0.021 s^-1 in the presence of TAM, respectively. Despite more published papers, when the TAM analyte was added to the NaOH supporting electrolyte, both anodic and cathodic peak currents of the modified NiO-CPE decreased. We suggested some reasons for this decreased peak current, and four mechanisms were illustrated for the electrode response in the presence of TAM.

Step-doped disulfide vacancies and functional groups synergistically enhance photocatalytic activity of S-scheme Cu3SnS4/L-BiOBr towards ciprofloxacin degradation

Development of efficient photocatalysts for efficient recalcitrant organic pollutants degradation is of great significance. Herein, the step-doped disulfide vacancies S-scheme Cu₃SnS₄/L-BiOBr (CTS/L-BiOBr) heterojunction photocatalyst was prepared for ciprofloxacin (CIP) degradation. X-ray photoelectron spectroscopy (XPS) analysis, ultraviolet photo-electron spectroscopy (UPS) analysis, band structure and dominant radicals' identification together verified that the transfer of photogenerated carriers conformed to the S-scheme mechanism. Benefited from the interfacial electric field (IEF) of the S-scheme heterojunction and incorporation of L-cysteine with introducing S-vacancies and surface functional groups (-NH₂, -COO^-), photogenerated charges generation and separation of the CTS/L-BiOBr₍₁₀₎ were greatly improved. With ·OH and h⁺ as dominant reactive species, CIP removal reached 93% using CTS/L-BiOBr₍₁₀₎ within 180 min of visible light irradiation, which was 3.5 times and 2.6 times of pristine Cu₃SnS₄ and L-BiOBr, respectively. Moreover, possible CIP degradation pathways were proposed and the degradation intermediates ecotoxicity were evaluated. This study could provide reference for designing efficient S-scheme photocatalysts for recalcitrant wastewater treatment.

Biopolymer-Modified Carbon Paste Electrode for the Electrochemical Detection of Pb(II) in Water

During the present study, biopolymer lignin was extracted, in particular, from sugar beet pulp (molasses) from the Tadla region (224 km from Marrakech, Morocco). The lignin was characterized by infrared spectroscopy (FTIR) and thermogravimetric TG/DTA analysis and then used as a modifier to enhance the electroanalytical detection of heavy metal ion traces. The performance of the lignin/CPE sensor to detect lead (II) was studied by cyclic voltammetry (CV) and square-wave voltammetry in 0.3 mol L^-1 NaCl. With optimized experimental parameters, the lignin/CPE sensor developed has a minimum detection limit of 2.252.10^-11 M for Pb (II). The proposed working electrode has been successfully applied for the coanalysis of Pb (II) in tap water with good results.

Covalent immobilization of lipase from Candida rugosa on epoxy-activated cloisite 30B as a new heterofunctional carrier and its application in the synthesis of banana flavor and production of biodiesel

In this paper, an epoxy-activated cloisite (ECL) was prepared as a new heterofunctional carrier via a reaction between cloisite 30B (CL) and epichlorohydrin and utilized for covalent immobilization of lipase from Candida rugosa. The lipase immobilized on the ECL (LECL) was successfully used in the olive oil hydrolysis, synthesis of isoamyl acetate (banana flavor), and biodiesel production. The TGA, FT-IR, SEM, and XRD were used to characterize CL, ECL, and LECL. The influences of temperature, pH, thermal stability, and storage capacity were examined in the olive oil hydrolysis. The effects of solvent, temperature, time, water content, and substrates molar ratio on the yields of ester and biodiesel were also investigated. In the optimized conditions, the hydrolytic activity of LECL was 1.85 ± 0.05 U/ mg, and the maximum yield of ester and biodiesel was 91.6% and 95.4%, respectively. The LECL showed good thermal stability and storage capacity compared to the free lipase. Additionally, LECL was reusable for both esterification and transesterification after being used for nine cycles.