Green synthesis of zinc oxide nanoparticles using Pulicaria undulata extract: Evaluation of antibacterial and larvicidal efficacy against Aedes aegypti

The present study reports the green synthesis and characterization of zinc oxide nanoparticles (ZnO NPs) using Pulicaria undulata extract and evaluates their larvicidal and antibacterial potential. UV–Visible spectroscopy confirmed ZnO NP formation by a sharp peak at 294 nm, indicating surface plasmon resonance and nanoparticle stability. Scanning electron microscopy (SEM) revealed irregular, agglomerated nanoparticles with heterogeneous morphology, while X-ray diffraction (XRD) confirmed a crystalline wurtzite hexagonal structure with high purity and crystallinity. Fourier-transform infrared spectroscopy (FTIR) identified hydroxyl, carboxylic, and Zn—O functional groups, highlighting the role of plant phytochemicals in nanoparticle stabilization. Histopathological analysis demonstrated significant tissue damage in Aedes aegypti larvae treated with ZnO NPs, including midgut disruption and muscular degeneration, suggesting strong larvicidal activity. Antibacterial assays against Escherichia coli and Staphylococcus aureus showed concentration-dependent zones of inhibition, with S. aureus exhibiting higher susceptibility. SEM images of bacterial cells post-treatment revealed severe morphological damage, including membrane rupture and shrinkage, confirming the antibacterial mechanism via structural disruption. Overall, the biosynthesized ZnO NPs exhibit promising eco-friendly properties with effective larvicidal and antibacterial activity, indicating their potential applications in mosquito vector control and antimicrobial therapeutics.