Co3O4/fluoro-copolymer nanocomposite modified boron-doped diamond electrode non-enzymatic sensor for the determination of skeletal muscle relaxant drug cyclobenzaprine in biological fluids

Electrochemical sensors have revolutionized pharmaceutical analysis by providing enhanced speed, selectivity, and cost-effectiveness. This study presents the development of a highly sensitive, non-enzymatic electrochemical sensor for Cyclobenzaprine (CBZ) determination. The sensor features a boron-doped diamond electrode (BDDE) modified with a novel Cobalt Oxide/Nafion-based nanocomposite (Co₃O₄/Nafion), synthesized and optimized for superior performance. The electroactive surface was fabricated by drop-casting a Co₃O₄/Nafion suspension onto the BDDE. Characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), confirmed the crystallinity, morphology, and functional groups of the nanocomposite. Electrochemical analyses, comprising electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV), and cyclic voltammetry (CV), demonstrated enhanced charge transfer properties and a one-electron/proton oxidation mechanism for Cyclobenzaprine (CBZ) detection. The sensor demonstrated optimal performance in BR buffer at pH 5.6, with a linear response to CBZ concentrations ranging from 2.49 μg/L to 19.61 μg/L, achieving a LOD of 2.08 μg/L and LOQ of 6.96 μg/L. Practical applicability was established by successfully quantifying CBZ in various biological matrices, including human blood serum (37.8 %), artificial blood serum (35.6 %), artificial sweat (-28.9 %), and urine (-8.9 %), with excellent recovery rates in pharmaceutical formulations (99.75 %) and human blood serum (100.16 %). The sensor exhibited high specificity, unaffected by common interferents such as ions, carbohydrates, and heavy metals. This work introduces, for the first time, a Co₃O₄/Nafion-modified BDDE sensor for CBZ determination, offering rapid, selective, and interference-free analysis with potential applications in therapeutic drug monitoring and pharmaceutical quality control.

Fe3O4-Cu-BTC/MWCNTs modified electrodes for real-time chlorine monitoring in aqueous solution

A efficient sensor is presented for detecting free chlorine in water by decorating glassy carbon electrodes (GCE) via multi-walled carbon nanotubes (MWCNTs) and Fe3O4-Cu-BTC composite. After the characterization of prepared materials by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) techniques, and N2 adsorption-desorption isotherm, the electrochemical properties of Fe3O4-Cu-BTC/MWCNTs/GC-modified electrode were assessed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV and chronoamperometry measurement in phosphate buffer solution with pH 7.0 proved the capability of the designed sensor to detect free chlorine. With amperometric detection, the modified electrode exhibits a linear response in the 0.1 to 400.0 ppm range towards free chlorine with a detection limit (LOD) (S/N = 3) of 0.0044 ppm, sufficient to control swimming pool water. To assay the practicability of the designed sensor in real situations, interferences of common ions and dissolved oxygen were tested on free chlorine determination and showed admirable selectivity. The proposed sensor also provides satisfactory results of free chlorine measurement in different real samples of swimming pool waters. The results of this work affirmed that MOF composite could be a promising material in the architecture of free chlorine electrochemical sensors in aqueous media.

Ultrafine metal-organic framework @ graphitic carbon with MoS2-CNTs nanocomposites as carbon-based electrochemical sensor for ultrasensitive detection of catechin in beverages

GO/Co-MOF/PPy-350 (GPC-350) was synthesized by in situ growth of ultrafine Co-MOF on graphene oxide (GO), followed by encapsulation with polypyrrole (PPy) and calcination at 350.0℃. Meanwhile, MoS2-MWCNTs (MoS2-CNTs) were produced via the in situ synthesis of MoS2 within multi-walled carbon nanotubes (MWCNTs). The electrochemically superior GPC-350/MoS2-CNTs nanocomposite was then achieved by combining GPC-350 with MoS2-CNTs. The polypyrrole encapsulation serves to protect the ultrafine Co-MOF, preventing its degradation during the calcination process. The linear detection range of the GPC-350/MoS2-CNTs/GCE sensor for the determination of catechin (CA) in phosphate buffered saline (PBS) was from 5.0 to 1800.0 nM with a limit of detection of 1.78 nM. In addition, the materials were characterized using SEM, EDX, TEM, XRD, EIS, XPS, FTIR, and Raman. These results indicate that the synthesis of GPC-350/MoS2-CNTs nanocomposites is successful and CA in beverages samples can be effectively detected using electrochemical sensors. Additionally, the reaction mechanism of CA was explored through cyclic voltammetry. The application of GPC-350/MoS2-CNTs nanocomposites in sensor technology offers innovative approaches for the ultrasensitive detection of flavonoids.

Electrochemical detection of nalbuphine drug using oval-like ZnO nanostructure-based sensor

Monitoring pharmaceutical drugs in various mediums is crucial to mitigate adverse effects. This study presents a chemical sensor using an oval-like zinc oxide (ZnO) nanostructure for electrochemical detection of nalbuphine. The ZnO nanostructure, produced via an efficient sol-gel technique, was extensively characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible spectrophotometry, and fourier transform infrared spectroscopy (FTIR). A slurry of the ZnO nanostructure in a binder was applied to a glassy carbon electrode (GCE). The sensor's responsiveness to nalbuphine was assessed using linear sweep voltammetry (LSV), achieving optimal performance by fine-tuning the pH. The sensor demonstrated a proportional response to nalbuphine concentrations up to 150.0 nM with a good regression coefficient (R2) and a detection limit of 6.20 nM (S/N ratio of 3). Selectivity was validated against various interfering substances, and efficacy was confirmed through real sample analysis, highlighting the sensor's successful application for nalbuphine detection.

Motoc) S, Cretu C, Cseh L, Rastei M, Donnio B, Szerb EI, Manea F. Design of Nanostructured Hybrid Electrodes Based on a Liquid Crystalline Zn(II) Coordination Complex-Carbon Nanotubes Composition for the Specific Electrochemical Sensing of Uric Acid

A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc electrode demonstrated the superiority of the former, and its great potential for the development of advanced electrochemical detection of uric acid. Advanced electrochemical techniques, such as differential-pulsed voltammetry (DPV) and square-wave voltammetry (SWV), allowed for the highly sensitive detection of uric acid in aqueous alkaline solutions. In addition, a good and fast amperometric signal for uric acid detection was achieved by multiple-pulsed amperometry, which was validated by urine analysis.

Sensitivity Detection of Uric Acid and Creatinine in Human Urine Based on Nanoporous Gold

Given the significance of uric acid and creatinine in clinical diagnostic, disease prevention and treatment, a multifunctional electrochemical sensor was proposed for sensitive detection of uric acid and creatinine. The sensitive detection of uric acid was realized based on the unique electrochemical oxidation of nanoporous gold (NPG) towards uric acid, showing good linearity from 10 μM to 750 μM with a satisfactory sensitivity of 222.91 μA mM−1 cm−2 and a limit of detection (LOD) of 0.06 μM. Based on the Jaffé reaction between creatinine and picric acid, the sensitive detection of creatinine was indirectly achieved in a range from 10 to 2000 μM by determining the consumption of picric acid in the Jaffé reaction with a detection sensitivity of 195.05 μA mM−1 cm−2 and a LOD of 10 μM. For human urine detection using the proposed electrochemical sensor, the uric acid detection results were comparable to that of high-performance liquid chromatography (HPLC), with a deviation rate of less than 10.28% and the recoveries of uric acid spiked in urine samples were 89~118%. Compared with HPLC results, the deviation rate of creatinine detection in urine samples was less than 4.17% and the recoveries of creatinine spiked in urine samples ranged from 92.50% to 117.40%. The multifunctional electrochemical sensor exhibited many advantages in practical applications, including short detection time, high stability, simple operation, strong anti-interference ability, cost-effectiveness, and easy fabrication, which provided a promising alternative for urine analysis in clinical diagnosis.