Synthesis of ZnO nanoparticles with different morphology: Study of their antifungal effect on strains of Aspergillus niger and Botrytis cinerea

Highlights: • ZnO-NPs with spheroidal and acicular morphologies were synthesized. • The activity of ZnO-NPs against Aspergillus niger and Botrytis cinerea was studied. • The ZnO-NPs with acicular morphology showed greater antifungal activity. • The conidiophores and the hyphae in the fungi were altered by the ZnO-NPs. -- Abstract: Zinc oxide nanoparticles were synthesized using acetic acid and ethylene glycol as solvents. Their characteristics were determined using IR and UV–Vis absorption spectroscopies, X-ray diffraction and transmission electron and scanning microscopies. Each solvent was found to produce ZnO nanoparticles with a different morphology and not monodispersed: the acetic acid solvent (with a heat treatment at 400 °C) gave acicular (with a size of ∼40 nm × 500 nm) particles, while ethylene glycol (and a heat treatment of 600 °C) produced a spheroidal (∼40 nm) morphology. The antifungal action of the ZnO nanoparticles on Aspergillus niger and Botrytis cinerea fungal strains was then determined. Those with acicular morphology showed a more efficient antifungal activity for the concentrations considered. High resolution optical microscopy images of imprints of the cultures studied showed that when these two fungi were subjected to the action of nanoparticles, alterations in the reproductive structures (conidiophores) and hyphae could clearly be seen.