Assessment of Potential Toxicity of Hyaluronic Acid-Coated Magnetic Nanoparticles on Maize (Zea mays) at Early Development Stages

The effectiveness of iron oxide nanoparticles in enhancing crop plant development depends on their stabilization. In this study, the effect of hyaluronic acid (HA), used both as a stabilizer for iron oxide nanoparticles (HA-MNP) and independently, was evaluated in maize seedlings. Different concentrations of HA-MNP (0.625-7.5 mg/L) were tested alongside a 0.01% HA solution. Growth parameters, antioxidant enzyme activities (peroxidase and polyphenol oxidase), photosynthetic pigments (chlorophyll and carotenoids), phenolic content, and genotoxicity were analyzed. While HA alone led to slight decreases in seedling length, pigment content, and polyphenol levels compared to the control, it increased peroxidase activity and mitotic index. Lower concentrations of HA-MNP (below 2.5 mg/L) enhanced seedling growth, likely due to improved iron uptake, whereas higher concentrations reduced pigment and phenolic content. All HA-MNP concentrations induced genotoxic effects, which was proven by an increased mitotic index and chromosomal aberrations, indicating both positive and defensive plant responses to oxidative stress. These findings suggest a complex interaction between HA, HA-MNP, and maize seedlings, where HA concentrations play a significant role in modulating growth and stress response, while higher concentrations may induce toxicity.