Studies on the influence of the physicochemical characteristics of nanostructured copper, zinc and magnesium oxides on their antibacterial activities

The influence of the physicochemical characteristics of nanostructured metal oxides on their antibacterial activities have been investigated. In this work, different shapes of copper, zinc and magnesium oxides nanoparticles have been synthesized. Type, purity and crystal properties of the prepared metal oxides were tested using the x-ray diffraction analyses. The shape and particle sizes were investigated using TEM measurements. Surface characteristics of the prepared metal oxides were also studied. The antibacterial studies on the prepared metal oxides were conducted on Gram positive (Bacillussubtilis and Staphylococcus aureus) and Gram negative (Escherichia coll.) bacteria by agar diffusion method. Overall, both CuO and ZnO showed high antibacterial activities. However, the antibacterial performance of MgO was significantly low. The physicochemical characteristics of CuO and ZnO nanoparticles significantly affect their antibacterial performance. For example, thin CuO nanorods (CuOnr1) showed higher antibacterial activities than the thick rods (CuOnr2). Thin polar facets of CuOnr1 probably easily penetrated into bacterial membranes. In addition, hexagonal ZnO sample (ZnOh2) possesses the highest total pore volume and the lowest particle size compared to the other ZnO samples. Consequently, ZnOh2 shows the highest antibacterial activities toward all bacteria under investigation. Contrary, the antibacterial activity of MgO does not significantly affected by the criteria of the prepared nanoparticles. It seems that the ability of MgO to launch the antibacterial process is quite low so the impact of their physical properties could not be detected.