Preparation of MSNs-Chitosan@Prochloraz Nanoparticles for Reducing Toxicity and Improving Release Properties of Prochloraz

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 MSNs-chitosan@prochloraz nanoparticles had potential as an environmentally friendly preharvest treatment agent in agricultural application.