Green-Synthesized ZnO Nanoparticles from Neem: Multifunctional Bioactivity Study

Zinc oxide (ZnO) nanoparticles were synthesized in aqueous extract of leaf of Azadirachta indica (neem) which acts as a reducing and stabilizing agent in this study. Precursor used were zinc acetate dihydrate under optimized conditions (pH 8, 70 °C) and the precipitate was oven dried. The high crystallinity of the nanoparticles was further confirmed by using the UV– Visible spectroscopy with its distinct absorbance peak at 370–380 nm. The antifungal, plant growth promoting and synergistic antibacterial activities of ZnO nanoparticles were evaluated at 2, 5 and 10 mg/mL. Antifungal testing was performed on fungal strains from rotten jackfruit. Nigella sativa and Trigonella foenum-graecum were used for plant assays and antibacterial synergy was evaluated in combination with chloramphenicol with E. coli R28 and ATCC 10536 bacteria. The findings reveal that the bio-engineered nanoparticles are highly effective in inhibiting the growth of fungus and also increase seedling vigor in both the plant models (Chikkanna et al., 2018; Golipalle et al., 2025). The 5 mg/mL concentration was the most effective with the best biological response, including maximum fungal inhibition, seed germination, root elongation and enhanced antibacterial activity. There was minimal effect from the lower concentration, but it was less effective at 10 mg/mL, perhaps because of aggregation of the nanoparticles or phytotoxicity. These findings indicate that the neem-mediated ZnO nanoparticles are potential candidates in plant biotechnology and antimicrobial application as sustainable means.

Green synthesis, Azadirachta indica, ZnO nanoparticles, antifungal activity, plant growth, chloramphenicol synergy, nanobiotechnology.

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