In Vitro Photocatalytic, Antioxidant, and Antibacterial Activity of Biogenically Synthesized Zinc Oxide Nanoparticles via Plantago lanceolata Leaf Extract

Objective The study aimed to synthesize zinc oxide nanoparticles (ZnO-NPs) using zinc acetate as the raw material and leaf extract of Plantago lanceolata both as reducing and stabilizing agent, and to evaluate their antibacterial, photocatalytic, as well as antioxidant activities. Methods ZnO-NPs were biosynthesized with zinc acetate and P. lanceolata leaf extract. This is the first report on the green synthesis of ZnO-NPs using P. lanceolata leaf extract as a bio-reductant and stabilizer. Characterization involved UV-Vis spectroscopy, zeta potential measurements, TEM, XRD, and FTIR. Photocatalytic activity was assessed via methylene blue degradation under UV light. Antioxidant activity was evaluated using the DPPH assay. Antibacterial testing was conducted against S. aureus , K.pneumoniae , S. epidermidis , and E. coli . Results UV-Vis absorption peak were observed at 370 for biosynthesis of ZnO-NPs nm, indicating nanoparticles formation, with an optical band gap energy ranging from 3.57 to 3.61 eV. Zeta potential was −30.5 mV, confirming good colloidal stability. TEM showed irregularly shaped nanoparticles averaging 23 nm, and XRD confirmed a hexagonal wurtzite crystal structure, with an average crystallite size of 23 nm. FTIR verified the presence of flavonoids and polyphenols as capping agents. Photocatalytic degradation of MB reached 76.65% efficiency after 75 min at 500 µg/mL concentration, with degradation increasing from 14.09% at 100 µg/mL to 60.27% at 75 min. Antioxidant activity showed concentration-dependent radical scavenging, with an IC 5 0 of 76.24 µg/mL and inhibition percentages ranging from 50.23 ± 1.74% at 100 µg/mL to 90.31 ± 0.51% at 500 µg/mL. Antibacterial assays revealed notable zones of inhibition, with K. pneumoniae showing the highest (30.1 ± 1.11 mm), surpassing the control (28.00 mm), and values for other strains including E. coli (21.21 ± 1.15 mm), S. aureus (28.11 ± 1.08 mm), and S. epidermidis (25.34 ± 1.15 mm) at 500 µg/mL. Conclusion These findings shows that P. lanceolata -mediated ZnO-NPs possess excellent photocatalytic, antibacterial as well as antioxidant activities, highlighting their potential for eco-friendly applications in wastewater treatment and biomedical fields.