Antibacterial and antioxidant activity of gamma star-like MnO2 nanostructure with and without coating with iron oxide nanoparticles

Abstract

Bacterial resistance caused by antibiotic misuse has garnered substantial attention, prompting numerous researchers to develop materials that can combat these resistant pathogens. The hydrothermal method is employed to produce γ-MnO₂ nanostars and to coat them with Fe₂O₃ nanoparticles. The materials are characterized using XRD, FE-SEM, EDX, and UV-vis spectrophotometry, as well as antioxidant and antibacterial activities. The nano γ-MnO₂ star shapes are coated with tiny spherical Fe₂O₃ nanoparticles with diameters of 35-47 nm. The peaks located at the crystal planes (120), (031), (131), (230), (300), (160), (421), and (003) are represented by the values of 2θ = 22.36º, 34.36º, 37.22º, 38.78º, 42.56º, 56.14º, 65.48º and 68.82º, respectively, and no additional peaks for any more materials showing pure γ-MnO₂. The SEM descriptions of the star shapes of γ-MnO₂ nanostructure in three different magnifications. The diameters of the six-branched star-shaped γ-MnO₂ are about 140 nm close to the star's center, 55–70 nm close to its tips, and 1.5–4 μm in length. The EDX analysis of the γ-MnO₂ nanostars are coated with Fe₂O₃ nanoparticles. It clearly shows the elemental composition that includes Mn, O, and Fe. The radical scavenging performance of the γ-MnO₂ nanostars coated with Fe₂O₃ nanoparticles is showed substantial enhancement compared to bare γ-MnO₂ nanostars. The prepared materials exhibit comparable antibacterial properties, with noticeable activity against Gram-negative strains (Salmonella and Escherichia coli), but no effectiveness against Gram-positive strains (Bacillus subtilis and Staphylococcus aureus).