Nanoencapsulation-based fabrication of eco-friendly pH-responsive pyraclostrobin formulations with enhanced photostability and adhesion to leaves

The development of pesticide-loaded nanocapsules responding to environmental stimuli holds great promise for sustainable disease control and may help to reduce pesticide usage while making it more efficient. Herein, pH-responsive nanocapsules containing pyraclostrobin (Pyr) were constructed by the rapid interfacial assembly of tannic acid (TA), ethylene oxide-propylene oxide block copolymer, and Cu2+ ions using a fine reversed-phase emulsion as a template. Under acidic conditions similar to those caused by Rhizoctonia solani infestation, these nanocapsules released Pyr to achieve its intelligent delivery and, hence, efficient R. solani control. Nanoencapsulation significantly increased the photostability of Pyr, and the half-life increased by 10 times compared with the Pyr-technical (Pyr-TC). In addition, the introduction of TA enhanced its spreading performance and rainfall resistance in crops, and contact angle drops to 2.2° ± 0.1° in 100 s. Its toxicity to non-target organisms (Daphnia magna and humans) was reduced. The fabricated nanocapsules exhibited a high antifungal activity superior to that of commercially available agents and exerted no significant adverse effects on crop growth and soil microbial communities. Thus, our work highlights the potential of nanoencapsulation for the intelligent delivery of fungicides to target crops, thus providing an effective strategy for improving the efficiency of pesticide usage and promoting sustainable pesticide development.