Nanowarriors from Mentha: Unleashing Nature's Antimicrobial Arsenal with Cerium Oxide Nanoparticles

Medicinal plant-based cerium oxide nanoparticles (CeO₂NPs) possessed excellent antimicrobial properties against multiple strains of Gram-positive and Gram-negative bacteria. The CeO₂NPs are popular because their electropositive charged surface causes oxidation of plasma membrane and facilitates the penetration of CeO₂NPs inside the pathogen body. In the present research work, CeO₂NPs stabilized with Mentha leaf extract; as a result, nanoparticles surface-bonded with various functional groups of phytochemicals which enhanced the therapeutic potential of CeO₂NPs. The inhibition percentage of CeO₂NPs was evaluated against eight pathogenic Gram-positive bacteria Staphylococcus aureus and Streptococcus epidermidis; Gram-negative bacteria Escherichia coli, Stenotrophomonas maltophilia, Comamonas sp., Halobacterium sp., and Klebsiella pneumoniae; and plant bacteria Xanthomonas sp. The antifungal properties of CeO₂NPs were evaluated against three pathogenic fungal species Bipolaris sorokiniana, Aspergillus flavus, and Fusarium oxysporum via the streak plate method. The antimicrobial inhibitory activity of CeO₂NPs was good to excellent. The current research work clearly shows that three different medicinal plants Mentha royleana, Mentha longifolia, and Mentha arvensis based CeO₂NPs, variation in nanoparticle sizes, and surface-to-volume ratio of green CeO₂NPs are three factors responsible to generate and provoke antimicrobial activities of CeO₂NPs against human pathogenic bacteria and plant infecting fungi. The results show that CeO₂NPs possessed good antimicrobial properties and are effective to use for pharmaceutical applications and as a food preservative because of low toxicity, organic coating, and acceptable antimicrobial properties. This study showed a rapid and well-organized method to prepare stable phytochemical-coated CeO₂NPs with three different plants M. royleana, M. longifolia, and M. arvensis with remarkable antibacterial and antifungal characteristics.