Plant-Mediated Synthesis of ZnO Nanoparticles From Sonchus wightianus: Physicochemical Characterization and Evaluation of Photocatalytic, Antibiofilm, and Antioxidant Potential.

Zinc oxide nanoparticles (ZnO NPs) were successfully synthesized via an eco-friendly green route using aqueous leaf extract of Sonchus wightianus as a natural reducing and capping agent. UV-Vis spectroscopy revealed a characteristic absorption peak at 267 nm, with a direct optical band gap of 2.96 eV and an Urbach energy of 0.917 eV, indicating the contribution of surface defect states to the optical properties of the synthesized nanoparticles. FTIR analysis confirmed the active role of phytochemical constituents in the reduction and stabilization process. X-ray diffraction confirmed the formation of phase-pure hexagonal wurtzite ZnO with an average crystallite size of 21.38 nm. SEM analysis revealed a heterogeneous morphology comprising quasi-spherical and rod-like structures arranged in agglomerated assemblies. The synthesized ZnO NPs demonstrated remarkable solar-driven photocatalytic activity, achieving 99.2% degradation of Rose Bengal dye under natural sunlight within 120 min. Furthermore, the nanoparticles exhibited significant concentration-dependent antibiofilm activity against four clinically relevant pathogens, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. These findings demonstrate that Sonchus wightianus-mediated ZnO NPs represent a promising multifunctional nanomaterial with considerable potential for environmental remediation and biomedical applications.