Biogenic Synthesis of Selenium–Zinc Oxide Nanocomposites Using <i>Moringa oleifera</i> Extract with Enhanced Antibacterial Activity against <i>Staphylococcus aureus</i>

Skin infections caused by Gram-positive bacteria, particularly Staphylococcus aureus, remain a significant health concern. Although current treatments is effective, topical therapies often contain chemical agents that can induce inflammation or irritation, potentially worsening skin conditions and delaying wound healing. Furthermore, over 10% of patients receiving topical treatment develop allergic contact dermatitis from exposure to irritant, phototoxic, or photoallergic compounds. These limitations highlight the need for safer antibacterial alternatives. One promising strategy involves nanomaterials with antibacterial properties, such as selenium nanoparticles (SeNPs), have emerged as promising candidates. This study aimed to biologically synthesize SeNPs using Moringa oleifera leaf extract as a natural bioreductant and subsequently composite them with zinc oxide (ZnO) to form SeNPs-ZnO nanocomposites. SeNPs were synthesized with two concentrations of Moringa extract (1.5% and 2.5% w/v) and combined with varying ZnO masses (300, 600, and 1200 mg). The nanocomposites were characterized using UV-Vis spectroscopy, FTIR, XRD, and particle size analysis (PSA). The antibacterial activity of the SeNPs-ZnO nanocomposites was evaluated against Staphylococcus aureus using the disc diffusion assay. The formation of a nanocomposite was confirmed by a red shift in the UV-Vis absorbance spectrum. PSA results showed that SeNPs prepared with 1.5% extract had an average size of 441.9 nm, while those prepared with 2.5% MO extract reached 780.25 nm. Antibacterial evaluation revealed that nanocomposite sample (SZN1) exhibited higher antibacterial activity than SeNPs alone, indicating synergistic antibacterial activity. SeNPs-ZnO nanocomposites show promising antibacterial properties and may serve as safer alternatives to conventional topical therapies for Gram-positive skin infections.