Microwave-Assisted Green Synthesis of Au-Ag Alloy Nanoparticles Using Melaleuca quinquenervia Leaf Extract and Their Pharmacological and Decontamination Activities

Au and Ag nanoparticles (NPs) exhibit distinct pharmacological activities, cytotoxicity profiles, and catalytic properties. This study sought to maximize the advantages of both metals while reducing the production of toxic byproducts and promoting the rapid synthesis of Au-Ag alloy NPs. For this, we used Melaleuca quinquenervia leaf extract (MQLE) as a reducing and capping agent alongside microwave-assisted green synthesis techniques. The physicochemical properties and biological activities of the synthesized Au-Ag alloy NPs were systematically evaluated. Our findings confirmed successful synthesis of nearly spherical Au-Ag alloy NPs with an average diameter of 37 nm, achieved within a 60 s irradiation period. Energy-dispersive spectroscopy (EDS) revealed a nearly uniform elemental composition, with Au and Ag constituting 43.56% and 40.21%, respectively, of the alloy. Thermogravimetric (TG) analysis confirmed the complete coating of the NPs with MQLE. Owing to these characteristics, the Au-Ag alloy NPs exhibited low cytotoxicity (half-maximal inhibitory concentration [IC50] > 110 mg/L), strong antioxidant activity (IC50 < 15 mg/L), reasonable antimicrobial efficacy (minimum inhibitory concentration: 2.5–10 mg/L), considerable anti-inflammatory potential (IC50: 9.45–35.41 mg/L), promising wound healing capacity (72.5% in 24 h), and excellent catalytic performance (apparent rate constant: 0.254–0.654 min−1). In conclusion, the rapid, efficient, and environmentally friendly synthesis of Au-Ag alloy NPs demonstrated in this study holds promise for various industrial applications, particularly in pharmaceutical and therapeutic development.