Cellulose-based nanocarrier for on-demand release and reduced aquatic toxicity of pyraclostrobin in fungal disease management

Achieving precise and environmentally safe delivery of fungicides remains a critical challenge in the development of pesticide nanocarriers. Here, we developed a pathogen-responsive nanocarrier for efficient and safe release of pyraclostrobin (Pyr). Pyraclostrobin-loaded ethyl cellulose (EC) nanoparticles were prepared via solvent evaporation, which were subsequently coated with a tannic acid–Cu 2+ (TCu) coordination network, denoted as Pyr@EC-TCu. This system exhibited multi-stimuli responsiveness, primarily triggered by cellulase, with pH and temperature acting as secondary cues. Upon exposure to cellulase, a cumulative 92 % of pyraclostrobin was released within 60 h, while the release remained below 51 % without enzymatic stimulus. This release mechanism enabled on-demand fungicide delivery at infection sites and reduced unintended environmental exposure. Moreover, the system exhibited high resistance to UV photodegradation and superior rainfastness. Compared with conventional formulations, the nanocarrier demonstrated superior control of rice sheath blight in greenhouse trials, with 88.9 % efficacy at 7 days and 81.0 % at 14 days. It also reduced acute toxicity to zebrafish by 7.7-fold and caused no observable phytotoxicity. This bioresponsive platform offers a promising strategy for precision agriculture by enabling targeted, eco-safe, and sustainable fungicide delivery.