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Nanotechnology-based pesticide formulations can improve the utilization rate of pesticides and reduce their negative effects on the environment. In this work, prochloraz was encapsulated within the pores of mesoporous silica nanoparticles (MSNs) attached covalently chitosan on the surface as gatekeepers via a silane coupling agent to prepare MSNs-chitosan@prochloraz nanoparticles. The results demonstrated that the obtained nanoparticles had a relatively high loading efficiency of prochloraz (25.4% w/w) and enhanced the light stability of prochloraz effectively. The nanoparticles showed excellent esterase and pH dual-responsive properties with controlled release behavior. The biological activity survey confirmed that the acid and enzyme produced by infected fruit can easily open the "gate" guarded by chitosan to achieve esterase and pH triggered on-demand pesticide release. Compared with prochloraz emulsifiable concentrate, preharvest application of MSNs-chitosan@prochloraz nanoparticles possessed a longer duration and a better antifungal activity against citrus diseases. The toxicity of the nanoparticles to zebrafish was reduced more than 6-fold compared with that of prochloraz technical. These results demonstrated that the MSNschitosan@prochloraz nanoparticles had potential as an environmentally friendly preharvest treatment agent in agricultural application.

Microcapsules are highly desirable for attaining the most effective utilization of the pesticide as well as reducing environmental pollution. In this work, a novel urease-responsive system was prepared using isocyanate-functionalized silica cross-linked with polyethylenimine (silica–IPTS–PEI) via urea bonds. The results demonstrated that the silica–IPTS–PEI microcapsules had a high pendimethalin loading efficiency (approximately 30% w/w) and could effectively enhance the thermal and light stability of pendimethalin. The release curves agreed with the Ritger and Peppas equation, and the release of pendimethalin was diffusion-controlled. The release rates of synthesized silica-IPTS-PEI microcapsules showed positive correlation with the temperature. In weak acid and base conditions, the pendimethalin release rates were higher than under neutral conditions, and the silica–IPTS–PEI microcapsules displayed excellent urease-responsive property with controlled release performance. Compared with pendimethalin emulsifiable concentration, the silica-IPTS-PEI microcapsules had a longer duration and higher herbicidal activity against weeds in a greenhouse experiment. Allium cepa chromosome aberration assays showed that the microcapsules had lower genotoxicity than pendimethalin technical. Thus, the urease-responsive silica–IPTS–PEI microcapsules have a great potential application as an environmentally friendly herbicide formulation.

No abstract

Stimulus-responsive release systems for site-specific pesticide delivery are one of the promising strategies to improve the use efficiency of pesticides as well as decrease environmental damage. Herein, a plant disease microenvironment-responsive nanosystem using disulfide-bridged mesoporous organosilica nanoparticles (MONs) as the porous support and calcium carbonate (CaC) as the capping agent was constructed to deliver prochloraz (PRO) for management of Sclerotinia disease. The obtained PRO-MON-CaC had high loading capacity and could effectively enhance the light stability of PRO. This delivery system could respond to different biological stimuli associated with Sclerotinia disease and release PRO intelligently. Compared with PRO emulsion in water, PRO-MON-CaC provided a longer Sclerotinia disease protection window on potted rapeseed plants. The acute toxicity of PRO-MON-CaC to zebrafish was reduced more than 4-fold compared with that of PRO technical. Additionally, MON-CaC nanocarriers had no obvious influence on the growth of rapeseed plants. This study represents a promising approach for sustainable plant disease management and precision farming.