SUPERIOR ANTIBACTERIAL FEATURES OFZnONANOPARTICLES PREPARED BY Azadirachta indica: MEDIATED GREEN SYNTHESIS ROUTE
Zinc oxide nanoparticles exhibit size- and morphology-dependent properties strongly influenced by synthesis routes. We report ZnO nanoparticles prepared via chemical co-precipitation [ZnO(C)] and a green route using Azadirachtaindica leaf extract [ZnO(G)]. Furthermore, their structure–property correlations have been systematically studiedbyseveral characterization methods. Formation of a hexagonal wurtzite ZnO phase was confirmed by X-ray diffractionanalysis, revealing that ZnO(G) possessed comparatively smaller crystallite sizes, a result of the controllednucleation and growth imparted by phytochemicals present in the Azadirachta indica extract. FESEManalysisrevealed irregular agglomerates in ZnO(C), whereas ZnO(G) exhibited uniform spherical structures. UV–Vis spectrashowed strong near-UV absorption, with band gaps of ~3.60 eV (ZnO(C)) and ~3.63 eV (ZnO(G)), the latter slightlyredshifted by defect states and biomolecule interactions. Antibacterial tests against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) showed stronger inhibition for ZnO(G), attributed to residual phytoconstituents and altered surface chemistry. Overall, synthesis pathways dictate crystallite size, morphology, optical bandgap, and antimicrobial activity, highlighting Azadirachta indica-mediated green synthesis as asustainable route to prepare nano ZnO for biomedical use.
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