Comparative antibacterial efficacy of metal oxide nanoparticles against Gram negative bacteria

The antibacterial efficacy of metal oxide nanoparticles (MONs) derived from selected precursors of zinc, titanium and silver was assessed comparatively through in vitro assays. The synthesized MONs were screened against four selected Gram negative test strains: Pseudomonas aeruginosa C1, Escherichia coli RGR13, Enterobacter sp. Lna3 and Sphingobacterium sp. GB2 with reference to zinc oxide nanoparticles as a positive control. For this purpose, the MONs were synthesized chemically and characterized through Fourier transform infrared spectroscopy, X-ray diffraction spectra and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis. The antibacterial efficiency of MONs, as confirmed by agar diffusion and bacterial count reduction assays, indicates the highest potential bactericidal action against test strains of silver oxide nanoparticles, followed by zinc and titanium oxide nanoparticles. Moreover, the minimum bactericidal concentrations (MBC) of the respective MONs for each test bacteria reveals their dose-dependent antibacterial properties. Among all the synthesized MONs, silver oxide nanoparticles show the highest antibacterial potency even at much lower doses (7.5 μg mL−1). Therefore, synthesized MONs could be more efficient than existing antibiotic treatments, especially to inhibit certain antibiotic-resistant Gram negative bacteria.