Efficient Mitigation of Copper Induced Cellular Dysfunction Using Chitosan Based Iron Oxide Nanoparticles

Copper is an essential redox-active micronutrient, but agricultural soils are increasingly contaminated by copper from mining, industrial discharge, and intensive agrochemical use, pushing concentrations beyond levels plants can tolerate. Excess copper triggers Fenton-like reactive oxygen species (ROS) generation, mitochondrial dysfunction, and impaired growth. Existing mitigation strategies, such as soil amendments, phytoremediation, antioxidants, and different chelators, have been explored to reduce copper toxicity, but their effectiveness can be limited by immobilization, poor specificity, and environmental persistence. The present work introduces a nanoparticle-based strategy for the direct sequestration of excess copper coupled with protection against the oxidative damage caused by copper stress. Here, we report MPA-iron oxide nanoparticles (MIONPs), sequentially functionalized with chitosan, glutathione, and 3-mercaptopropionic acid, designed to simultaneously scavenge ROS, restore redox homeostasis, and chelate copper via surface thiol groups. MIONPs showed a significant increase in copper binding capacity over bare iron oxide nanoparticles (BIONPs) and, in copper-stressed Solanum lycopersicum seedlings, significantly improved germination and root/shoot growth, reduced intracellular ROS, restored mitochondrial membrane potential, and preserved nuclear integrity. This integrated design establishes MIONPs as a promising, dual-function nanoplatform for sustainable copper stress management in agriculture.