Exploring phytochemical composition, photocatalytic, antibacterial, and antifungal efficacies of Au NPs supported by Cymbopogon flexuosus essential oil

Biofabrication of gold nanoparticles (AuNPs) using the aromatic essential oils is highlighted due to its simple, economical, low toxicity, and eco-friendly nature. Essential oil of Cymbopogon flexuosus (CF), an economically valuable medicinal plant, exhibits anti-inflammatory, anti-tumor, antioxidant, and antimicrobial activities. For the first time, this research accounts for the biosynthesis, physicochemical, photocatalytic, antifungal, antibacterial properties of biogenic AuNPs, fabricated using CF essential oil collected from different altitudes (S1-Palampur, S2-Haryana, S3-Dehradun). The altitudinal disparity in the phytochemical composition of essential oils is highlighted. The average crystallite size ranged from 10 to 32 nm and was influenced by CF samples used in the synthesis. The spectroscopic outcomes revealed the involvement of bioactive reagents from CF essential oil in the fabrication and stabilization of AuNPs. The fabricated AuNPs exhibited excellent antimicrobial activities against all tested strains (Staphyloccucs aureus, Escherichia coli, Fusarium oxysporum), showing their efficacy as an antimicrobial agent to treat infectious diseases. Moreover, AuNPs exhibited excellent photocatalytic efficacy of around 91.8% for the degradation of methylene blue under exposure of direct sunlight for 3 h without the assistance of an external reducing agent. The outcomes highlight a potential economic and environmentally friendly strategy to fabricate biogenic AuNPs for diversified industrial applications where antimicrobial and photocatalytic efficacies are the key requirements.