Enhancing Plant Immunity and Mitigating Environmental Risk: A Chitosan Oligosaccharide-Functionalized Nanoplatform for Targeted Delivery of Fluopyram.

To balance pesticide efficacy and ecological safety, a synergistic delivery system (FLU@MSNs/CMCO) was constructed by grafting chitosan oligosaccharide (COS) onto mesoporous silica nanoparticles (MSNs) to encapsulate the hydrophobic pesticide fluopyram (FLU). This cationic nanosystem (131 nm) achieved a 35.0% loading capacity and sustained release. It orchestrates a "dual-attack" mechanism, the cationic surface promotes electrostatic targeting on nematode cuticles and fungal cell walls, while the COS shell acts as an immune elicitor, enhancing plant root chitinase activity and vigor. Consequently, compared with free FLU, FLU@MSNs/CMCO reduced the lethal concentrations (LC50) against Meloidogyne incognitaChitwood by 65.0% and exhibited superior antifungal activity against Fusarium spp. Crucially, the system alleviated toxicity toward non-target earthworms, showing an 8.7-fold increase in LC50. Mechanistic studies revealed that the COS coating scavenged reactive oxygen species and maintained redox homeostasis, inhibiting lipid peroxidation and DNA damage. This nanosystem offers a promising and practical strategy for precise and eco-friendly crop protection.