Unlocking the Hidden Potential of Agave tequilana for the Green Synthesis of Antibacterial ZnO Nanomaterials: A Waste-to-Value Nanotechnology Approach

Traditional nanoparticle synthesis methods often rely on hazardous chemicals, raising concerns about their environmental impact. This study reports the green synthesis of zinc oxide (ZnO) nanoparticles using aqueous extracts from three distinct parts of <i>Agave tequilana</i>: the stalk (ZnO-S), heart (ZnO-H), and leaves (ZnO-L). The aim was to explore the influence of the different plant parts, each with their respective phytochemical profile, on the structural, optical, and antibacterial properties of the resulting nanoparticles. The synthesized ZnO-NPs were extensively characterized using UV-Vis spectroscopy, ATR-FTIR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The results revealed that ZnO-S exhibited the smallest particle size (~18.3 nm), the highest crystallinity, and the most uniform morphology. Optical analysis showed bandgap energies of 3.13 eV (ZnO-S), 2.99 eV (ZnO-H), and 3.02 eV (ZnO-L), with ZnO-S demonstrating enhanced UV absorption and reactive oxygen species (ROS) generation potential. Antibacterial assays against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> confirmed strong bactericidal activity for all samples, with ZnO-S showing the largest inhibition zones, approaching the efficacy of the reference antibiotic kanamycin. This work highlights the fundamental roles of plant-derived phytochemicals as natural reducing and capping agents and emphasizes the valorization of agave stalk and leaves, traditionally treated as agricultural waste for cost-effective and eco-friendly nanomaterial production. The findings reveal the untapped potential of <i>Agave tequilana</i> as a sustainable source for high-performance nanomaterials, paving the way for green innovations in antimicrobial and environmental applications.