Nanozymes: An innovative approach to regulating heavy metal accumulation in plants and alleviating toxicity-A comprehensive review

Managing farmlands' heavy metal (HM) pollution is crucial for improving plant growth and ensuring agricultural product safety. While low to medium doses of HM exposure may not directly result in crop reduction, they can lead to HM accumulation in plants and potential food-chain risks, as well as trigger the accumulation of reactive oxygen species (ROS). Excessive ROS can cause oxidative stress and irreversible damage to plant cells. Nanozymes, cost-effective and stable artificial nanoparticles with enzyme-like activity, have been widely used in multiple fields. Over the past decade, research has confirmed certain nanozymes' effectiveness in plant systemic immunity during HM remediation. The activities of nanozymes hinge on their physicochemical properties, while the biological effects also depend on application methods, size, charge, coating, crop varieties, and growth stages. Therefore, it is crucial to understand the nanozyme-plant interactions and resistance mechanisms to HMs. This paper comprehensively reviews nanozyme-mediated ROS scavenging mechanisms across enzymology, metabolomics, proteomics, and transcriptomics. It also introduces the application pathways and effects, influencing factors, possible risks, and prospects. This review may provide a theoretical framework for nanozyme-mediated mitigation of HM stress along with other abiotic stresses in agriculture for sustainable "precision fertilization" with nanozymes.