Effect of ZnO-nanoparticles on Aspergillus flavus growth and aflatoxin accumulation both on a maize based medium and irradiated maize grains

Abstract Maize ( Zea mays L.) a main crop worldwide, is susceptible to fungal contamination specially by Aspergillus flavus which produces aflatoxins (AFs) AFB 1 and AFB 2 . These mycotoxins are carcinogenic and can cause significant economic losses due to contamination in food and feed chains. Climate change, leading to more frequent droughts, exacerbates this issue by potentially increasing AFs contamination. Nanotechnology offers a promising option for controlling fungal pathogens and mycotoxins. Zinc oxide nanoparticles (ZnO-NPs) are particularly interesting to for their antifungal properties. This study was aimed to synthesise and characterised ZnO-NPs and to evaluate their effectiveness on reducing the A. flavus growth and AFs accumulation under in vitro (maize based medium) and in situ (irradiated maize grains) assays. ZnO-NPs were synthesised and characterised, showing stability and effective antifungal properties. In vitro , ZnO-NPs significantly reduced A. flavus growth rates by a 40-78% and AFB 1 production by 93.6-100%. This also caused hyphal deformation and unusual bulges besides a decrease in the fungal conidiation. In situ , ZnO-NPs caused reduction in fungal growth rates by ∼40% at 2 g/kg. AFs reduction was observed in a wide range of percentages even at 99%, especially at low water activities. However, some treatments increased AFs production by 2-5-fold, due to probably not homogeneous nanoparticle distribution on grain surface, suggesting potential stress responses by the fungus. Overall, ZnO-NPs demonstrate strong potential for managing aflatoxin contamination in maize, though their application must be carefully controlled to avoid unintended effects. Further field studies and environmental impact assessments are needed to optimise their use.