Phyto-optimised Ag, Sn, Pb, And Fe oxide nanoparticles from nine precursors: A comparative study of antimicrobial, antioxidant, and photocatalytic activities

The study details the primary comparative phyto-optimized green synthesis of four metal oxide nanoparticles—Ag₂O, SnO₂, PbO, and Fe₃O₄—using Hylocereus undatus (dragon fruit) extract as a natural reducing and stabilizing agent. The average crystallite sizes of the biosynthesized nanoparticles were found to range from 29 to 45 nm, as revealed by XRD and TEM analyses. FTIR spectra showed the presence of phytochemical functional groups, suggesting their role in the reduction and stabilization. The nanoparticles displayed considerable antibacterial action, inhibiting S. aureus and E. coli at MICs of 12.5–50 µg mL⁻¹, and exhibited a dose-dependent antioxidant effect, reaching a maximum of 90% DPPH scavenging with Ag₂O. Under UV light, the degradation of methyl orange reached 85% efficiency for SnO₂ within 5 hours, based on a pseudo-first-order kinetic model. Due to its smaller particle size and enhanced surface plasmon resonance, Ag₂O displayed superior multifunctional performance compared to the other four oxides. These findings show that using H. undatus for synthesis offers an environmentally friendly method to create high-performance metal oxide nanomaterials for various applications in the environment and healthcare sectors. Schematic of green synthesis of Hylocereus undatus -based metal oxide nanoparticles and Applications.