Nadir S.E. Osman

NiO–ZrO2 nanocomposite modified electrode for the sensitive and selective determination of efavirenz, an anti-HIV drug

The present study reports the synthesis of NiO–ZrO2 nanocomposites followed by their characterization using X-ray powder diffraction, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. A new chemically modified glassy carbon electrode was fabricated based on the synthesized nanocomposite and used as a highly sensitive electrochemical sensor for the determination of efavirenz, an anti-HIV drug. The modification increased the effective surface area of the sensor ten times in comparison to the bare glassy carbon electrode. Cyclic voltammograms revealed that the modified electrode exhibits excellent electrocatalytic activity towards oxidation of the drug. The current displayed a wide linear response ranging from 0.01 to 10 μM with a detection limit of 1.36 nM. The effect of interferents on the peak current response was studied. The electrode displayed advantages such as simple preparation, appreciable stability, reproducibility and high sensitivity. The feasibility of the proposed method was successfully demonstrated by determining efavirenz in commercial pharmaceutical formulations and human urine samples.

Investigation of magnetic and electrochemical sensing properties of novel Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles

Novel Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles were successfully synthesized using the glycol thermal route. The X-ray diffraction study confirmed a well defined spinel phase structure of the sample. The microstrain was investigated based on the Williamson–Hall plot. Crystallinity, shape and size of the nanoparticles were studied using high resolution transmission electron microscopy and high resolution scanning electron microscopy. Brunauer–Emmet–Teller measurement revealed that the sample has a high surface area of 116 m2 g−1. The Barrett–Joyner–Halenda test showed that the sample is mesoporous. The magnetization was found to increase from 66.5 ± 0.3 emu g−1 at 300 K to 84.4 ± 0.5 emu g−1 at 4 K. Furthermore, the electrochemical sensing properties of Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles were investigated using cyclic voltammetry. A glassy carbon electrode was modified using the synthesized Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles. The modified electrode demonstrated excellent electrocatalytic activity towards didanosine, an anti-HIV drug. A linear response to the drug concentration was obtained in the range from 0.001 to 5.0 μM with a detection limit of 1.0 nM. The electrode was highly stable, reproducible and was successfully used to determine trace amounts of didanosine in human urine samples.