Probing the effect of Ni, Co and Fe doping concentrations on the antibacterial behaviors of MgO nanoparticles.

The divalent transition metal ions (Ni, Co, and Fe)-doped MgO nanoparticles were synthesized via the sol-gel method. X-ray diffraction showed the MgO pure, single cubic phase of samples at 600 °C. Field emission electron microscope showed the uniform spherical shape of samples. The magnetic behavior of Ni, Co, Fe-doped MgO system were varied with Ni, Co, Fe content (0.00, 0.01, 0.03, 0.05, 0.07). The magnetic nature of pure had changed from paramagnetic to ferromagnetic. The number of oxygen vacancies increases with increasing amounts of dopant ions that lead to an ionic charge imbalance between Ni/Co/Fe and Mg, leading to increase magnetic properties of the samples. The magnetic nature of prepared samples makes them suitable for biomedical applications. A comparative study of the antibacterial activity of nanoparticles against the Gram-negative (E. coli) and Gram-positive bacteria (S. aureus) was performed by disc diffusion, pour plate techniques, and study surface morphology of untreated and treated bacterial cell wall. An investigation of the antibacterial activity of doped MgO nanoparticles reveals that the doped MgO nanoparticles show effective antibacterial activity against the Gram-negative (E. coli) and Gram-positive (S. aureus) bacterium. The minimum inhibitory concentration of the synthesized nanoparticles against microorganisms was recorded with 40 μg/ml, while the maximum inhibitory concentration was observed with 80 μg/ml. At a concentration of 80 μg/ml, the complete growth inhibition of the E. coli was achieved with 7% Co-doped MgO and 7% Fe-doped MgO, while bacterial growth of S. aureus was inhibited by 100% in the presence of 7% Fe-doped MgO. The present work is promising for using nanomaterials as a novel antibiotic instead of the conventional antibiotics for the treatment of infectious diseases which are caused by tested bacteria.