Harnessing <i>Aloe barbadensis</i> Miller ( <i>Aloe vera</i> ) gel extract for the green synthesis of <scp>ZnO</scp> and <scp> MnO ₂ </scp> nanoparticles: A phytochemical, statistical, and antibacterial study

Abstract Over the past decade, plant‐mediated synthesis of nanoparticles has garnered significant research interest owing to its biocompatibility, simplicity, non‐toxicity, and environmental friendliness. Likewise, plant‐derived phytochemicals have been recognized as efficient bio‐reductants and capping agents in the green synthesis of nanoparticles such as zinc oxide (ZnO) and manganese oxide (MnO 2 ). This study focused on the synthesis of manganese oxide (MnO 2 ) and zinc oxide nanoparticles (ZnO NPs) using Aloe vera gel extract (AVEx) and examined their antibacterial properties. The synthesized MnO 2 and ZnO nanoparticles were characterized through various techniques, including UV–Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), photoluminescence spectroscopy (PL), energy dispersive x‐ray (EDX) analysis, particle size analysis (PSA), and zeta potential measurement. The aggregated, rough morphology of MnO 2 and the presence of grain‐like ZnO nanoparticles, attributed to AVEx, were confirmed through SEM analysis. The crystalline sizes of MnO 2 and ZnO were calculated to be 1.15 and 3.05 nm, respectively, using the Scherrer equation. The antibacterial potential of ZnO and MnO 2 nanoparticles was examined using the micro broth dilution method against the Gram‐negative bacterium Escherichia coli ( E. coli ). The results indicate that the MIC values for ZnO and MnO 2 were 10 and 280 μg/mL, respectively, illustrating that ZnO NPs exhibit a significantly stronger antibacterial effect compared to MnO 2 NPs. The significant antibacterial potential of ZnO nanoparticles can be linked to their extensive surface area, diminutive size, and increased interaction with bacterial cells, resulting in oxidative stress and disruption of the cell membrane.