Enhanced Antibacterial Activity and Structural Characterization of ZnO-Doped MgO Nanocomposites Synthesized via Sol-Gel Technique

Abstract In this study, nanocomposites of Mg1 − xZnxO (x = 0, 0.1, 0.2, and 0.3) were synthesized using the sol-gel technique. The structural, surface morphological, and antibacterial effects of pure MgO and MgO doped with ZnO were investigated. For structural and morphological evaluations, X-ray diffraction (XRD) and Field emission scanning electron microscopy (FE-SEM) were used. The Rietveld refinement software analysis of XRD data revealed that the phase fraction of MgO exhibits a direct and linear relationship with increasing zinc nitrate concentration. In contrast, the ZnO phase shows an inverse correlation. It was also observed that, as the concentration of ZnO increased, the crystal sizes of the MgO and ZnO phases decreased from 35.87 to 31.29 nm and 46.16 to 41.41 nm, respectively, while their lattice constants increased. The FE-SEM images demonstrated that the particle morphologies of all the samples were similar, with no discernible distinctions. In general, the particles exhibited a small spherical appearance, and their sizes ranged from 73.771 to 76 nm, with irregular agglomeration influenced by the concentration of ZnO. In addition, the synthesized MgO/ZnO nanocomposite exhibited a synergistic antibacterial effect, inhibiting the growth of both Gram-positive Staphylococcus aureus and gram-negative bacteria Escherichia coli. Notably, the rate of Gram-positive and Gram-negative bacterial growth inhibition increased as the concentration of ZnO in the MgO nanocomposite increased.