Construction And Evaluation Of Three Pesticides Controlled Release Systems

In this paper, the nano-sized controlled release system was used in pesticide field for the safe and effective use of pesticide. The nano-sized controlled release system was one of the effective ways to resolve various problems that exited in the pesticide field. Mesoporous silica and amphiphilic polymer have been widely used as carriers in the pesticide controlled release system. Based on these two kinds of controlled release systems, three pesticides controlled release systems were constructed with nanotechnology. In addition, sustained impact on the target or non- target organisms was studied. This study will provide new methods and ideas for the novel pesticide formulation. The content was as follows:(1) The technology of co-delivery nanoparticles was used to prepare pesticide combination formulation, which could realize the co-delivery of hydrophilic pesticide and hydrophobic pesticide in the same nanaoparticles. The carrier amphiphilic copolymer methoxy poly(ethylene glycol)-poly(lactide-co-glycolide)(m PEG-PLGA) was synthesized with ring-opening method. The co-delivery NPs that could deliver both hydrophilic pesticide(validamycin) and hydrophobic pesticide(hexaconazole) was constructed with an improved double emulsion method. The co-delivery NPs held a sustained release property. Compared to the Vail?Hexa WP, the co-delivery NPs showed better lasting impact against Rhizoctonia cerealis.(2) Pesticides controlled release formulations with different sizes were prepared by the nanotechnology, and the size-dependent effect was further studied. The flexible copolymer m PEG-PLGA with suitable molecular weight(45 KDa) was selected as the carrier. Prochloraz-loaded m PEG-PLGA particles with different sizes were constructed by emulsion/solvent evaporation method, including nanoparticles, sub micro-particles and micro-particles. The size-dependent effect results showed that when the mass ratio of copolymer to prochloraz was constant, larger size prochloraz-loaded particles hold higher loading content and slower sustained-release speed. And smaller size prochloraz-loaded particles exhibited better germicidal efficacy against Fusarium graminearum in 14 d.(3) Based on the carrier of silica, nitenpyram controlled release system was constructed, which could reduce the nitenpyram exposure dose to bees. The MCM-41 silica was first dispersed in the nitenpyram aqueous solution with further sonication, aimed that the nitenpyram was well absorbed in the pore of the silica. The efficient positively charged polymer(quaternized chitosan, HACC) coating is realized by the phosphoramidate covalent bonding between the phosphonate groups on the silica nanoparticles and the amino groups of HACC. The nitenpyram-loaded nanoparticles hold a sustained release property. The results of toxicity to bees indicated that the acute toxicity of nitenpyram-loaded nanoparticles was reduced.