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The main aim of this study was to characterize the molecular interaction between sulfadoxine and the major transport protein in the blood plasma, human serum albumin using fluorescence, absorption,...

A nanocomposite from a green nanomaterial (nanocellulose) and f-MWCNTs was modified onto glassy carbon (GC) electrode for the detection of diclofenac sodium (DCF), a non-steroidal anti-inflammatory drug (NSAID) and widely used electroactive painkiller. The presence of OH groups in the nanocellulose provides more binding sites for different analytes. This ensures an axial modulus rearrangement and the incorporation of f-MWCNTs which provides larger surface area, high mechanical strength and improved electrical conductivity. On the other hand, the synergy between both compounds enhances the electrochemical detection of DCF in human blood and urine. Under optimum conditions, the modified electrode exhibited a remarkable improvement in the anodic peak current (41.6 μA) for 50 μM DCF at 0.677 V peak potential. The newly fabricated electrode showed two linear dynamic ranges from 0.05 to 1.00 μM and 2–250 μM DCF with low detection limit of 0.012 μM. In addition, differential pulse voltammetry (DPV) and cyclic voltammetry (CV) showed good sensitivity and selectivity for the determination of DCF. With this technique, the modified electrode was very effective and suitable for DCF determination from commercial tablets, ampoules (pharmaceutical preparations) and also from clinical preparations (human blood serum and urine sample) with good recoveries.

An electrochemical sensor for the determination of acetaminophen (AC) was fabricated on glassy carbon electrode (GCE) modified with platinum nitrogen-doped graphene (Pt/NGr) nanocomposite. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square-wave voltammetry (SWV) were performed to investigate the electrochemical behaviour of AC. From the electrochemical results, the synergy between platinum nanoparticles and nitrogen-doped graphene improved the interfacial electron transfer process, thus exhibited a higher catalytic performance towards the electrochemical oxidation of AC. A linear range between 0.05–90 μmol L−1 for the determination of AC was achieved with a limit of detection of 0.008 μmol L−1. The prepared sensor demonstrated acceptable reproducibility, stability and good selectivity in the presence of interferences such as ascorbic acid, p-aminophenol and dopamine. In addition, this method showed satisfactory results in commercial tablets.

This work reports a biosensor based on tri-metallic organic framework (MOF) for the determination of an anticancer therapeutic agent, nilutamide (NLM). The tri-metallic Co-Ni-Cu-MOF and the single metal MOFs Co-MOF, Ni-MOF and Cu-MOF were grown onto nickel foam (NF) substrate by a solvothermal method. The crystal, chemical structure, morphology and surface area of the MOFs were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical sensing of NLM by the Co-Ni-Cu-MOF/NF and the single metal MOFs grown onto NF were studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The CV of the Co-Ni-Cu-MOF/NF shows a redox couple between -0.4 V and 0.3 V in phosphate buffer solution at pH 7.0. The Co-Ni-Cu-MOF/NF sensor shows a strong electrocatalytic activity towards the redox reaction of NLM with a broad concentration range from 0.5–70 μM and 70–900 μM with high sensitivity of 10.712 μA μM−1 cm-2 and a low limit of detection of 0.48 ± 0.02 nM. These results confirm that the tri-metallic MOF possesses high selectivity and sensitivity for the determination of NLM from human serum specimen and pharmaceutical tablet dosage forms.

A platinum–silver graphene (Pt–Ag/Gr) nanocomposite modified electrode was fabricated for the electrochemical detection of dopamine (DA). Electrochemical studies of the Pt–Ag/Gr nanocomposite towards DA detection were performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV analysis showed that Pt–Ag/Gr/GCE had enhanced electrocatalytic activity towards DA oxidation due to the synergistic effects between the platinum–silver nanoparticles and graphene. The DPV results showed that the modified sensor demonstrated a linear concentration range between 0.1 and 60 μM with a limit of detection of 0.012 μM. The Pt–Ag/Gr/GCE presented satisfactory results for reproducibility, stability and selectivity. The prepared sensor also showed acceptable recoveries for a real sample study.

In the present study, a nanocomposite of f-MWCNTs-chitosan-Co was prepared by the immobilization of Co(II) on f-MWCNTs-chitosan by a self-assembly method and used for the quantitative determination of paracetamol (PR). The composite was characterized by field emission scanning electron microscopy (FESEM) and energy dispersive x-ray analysis (EDX). The electroactivity of cobalt immobilized on f-MWCNTs-chitosan was assessed during the electro-oxidation of paracetamol. The prepared GCE modified f-MWCNTs/CTS-Co showed strong electrocatalytic activity towards the oxidation of PR. The electrochemical performances were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under favorable experimental conditions, differential pulse voltammetry showed a linear dynamic range between 0.1 and 400 μmol L−1 with a detection limit of 0.01 μmol L−1 for the PR solution. The fabricated sensor exhibited significant selectivity towards PR detection. The fabricated sensor was successfully applied for the determination of PR in commercial tablets and human serum sample.

Multiwalled carbon nanotubes (CNT) supported cobalt oxide was prepared as a catalyst by strong electrostatic adsorption (SEA) method. The CNT support was initially acid- and thermal-treated in order to functionalize the support to uptake more Co clusters. The Co/CNT were characterized by a range of analytical methods including transmission electron microscopy (TEM), temperature programmed reduction with hydrogen (H2-TPR), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic absorption spectroscopy (AAS), Zeta sizer particle size analysis and Brunauer&ndash, Emmett&ndash, Teller (BET) surface area analysis. TEM images showed cobalt particles were highly dispersed and impregnated at both exterior and interior walls of the CNT support with a narrow particle size distribution of 6&ndash, 8 nm. In addition, the performance of the synthesized Co/CNT catalyst was tested using Fischer&ndash, Tropsch synthesis (FTS) reaction which was carried out in a fixed-bed micro-reactor. H2-TPR profiles indicated the lower reduction temperature of 420 &deg, C was required for the FTS reaction. The study revealed that cobalt is an effective metal for Co/CNT catalysts at pH 14 and at 900 &deg, C calcination temperature. Furthermore, FTS reaction results showed that CO conversion and C5+ selectivity were recorded at 58.7% and 83.2% respectively, which were higher than those obtained using a Co/CNT catalyst which pre-treated at a lower thermal treatment temperature and pH.