Coordination of Antioxidant Repair and Photosynthetic Enhancement by the Mn-Based Prussian Blue Nanozyme for Drought Stress Alleviation

In this study, a Mn-based Prussian blue nanozyme (MnPBNz) was prepared using micronutrients essential for plant growth as raw materials. The MnPBNz possesses both multienzyme activity and photosynthesis-enhancing capacity, which enables multi-pathway alleviation of drought stress. This study reveals that 100 μg·mL–1 for MnPBNz eliminates reactive oxygen species (ROS) in plants under drought stress, restoring the elevated activities of SOD and POD enzymes by approximately 25.03% and 88.99%, respectively. Moreover, Mn and Fe facilitate the recovery of the PSII reaction center function, raising Fv/Fm from 0.62 to 0.78 and boosting photosynthetic electron transport. The coordinated action of antioxidant repair and photosynthetic enhancement resulted in a 51.89% decrease in the MDA content, along with reductions of 59.4% and 30.6% in soluble protein and soluble sugar levels, respectively, demonstrating effective mitigation of drought stress injury. This study validates the broad application prospects of the nanozyme in sustainable agriculture, but field-scale verification and long-term environmental safety evaluation remain necessary.