Electrochemical Monitoring of Piroxicam by Using a Screen-Printed Carbon Electrode Modified With Yolk–Shell SiO₂@ MCM-41-Co₃O₄ Nanocomposite and Gold Nanoparticles

Considering that using piroxicam in high concentrations can lead to gastrointestinal diseases, its analysis is important to obtain the optimal therapeutic concentration and ensure quality in pharmaceutical formulations. Hence, a delicate electrochemical sensor constructed using a screen-printed carbon electrode (SPCE) boosted with SiO2@MCM-41-Co3O4 and gold nanoparticles was prepared with outstanding capabilities for piroxicam measurement. At first, the synthesized SiO2@MCM-41-Co3O4 was evaluated using X-ray diffraction (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy, and field-emission scanning electron microscopy analyses. The evaluations revealed that yolk–shell microspheres have a magnetic silica core microsphere of about 400 nm and a shell of about 100 nm thick containing cobalt oxide crystals. Then, piroxicam was measured using cyclic voltammetry (CV) and differential pulse voltammetry. The obtained detection and quantitative limits were 1.6–5 nM for the quantification range of 0.005– <tex-math notation="LaTeX">250~μ </tex-math> M with a sensitivity of <tex-math notation="LaTeX">0.33~μ </tex-math> A/ <tex-math notation="LaTeX">μ </tex-math> M and proper selectivity. The kinetic parameters, such as electron transfer coefficient, diffusion coefficient, and kinetic rate constants, were reported. The prepared sensor showed a very favorable selectivity and could detect piroxicam in real samples.