Preparation And Characterization Of Three Sustained-release Nano-pesticides

Pesticides play an important role in the prevention and control of pests and diseases,However the effective utilization rate of pesticides is low and environmental pollution is serious.Nanomaterials have potential advantages in the improvement of pesticide formulations due to small size and modification.Three nano-sustained nanoparticles were successfully constructed based on organic polymer material poly（lactic-co-glycolic acid）（PLGA）and inorganic mesoporous silica materials SBA-15,FDU-12 and BMMs which respectively containing fungicide Fluazinam（Flu）,Boscalid（Bos）and the insecticide Thiamethoxam（Thi）,which physical and chemical properties and Biological activities were evaluated separately.This study provides a theoretical basis for improving the effective utilization rate of pesticides and developing efficient and environmentally friendly green new pesticide formulations.The main result of research contents are summarized:（1）Two kinds of nano-drugs Flu-PLGA-PVA and Flu-PLGA-SDS which fluazinam-coated and surfactant PVA（Polyvinyl alcohol,PVA）and SDS（Sodium dodecyl sulfate,SDS）added were constructed by SPG membrane emulsification method.The nanoparticles are spherical in shape and uniform in size distribution,the particle sizes of Flu-PLGA-SDS and Flu-PLGA-PVA nanoparticles are 314.1 nm and612.8 nm,respectively,The nanoparticles showed excellent anti-photolysis and storage stability,wettability and sustained release,and the release rates at 24 h reach79.2%and 73.4%,respectively.The EC₅₀values were reduced by 46.4% and 39.5% on day 8 compared to the commercial formulations,respectively.（2）Bos was assembled into the pores of inorganic mesoporous materials SBA-15and FDU-12 by solution adsorption method,and the new nanocomposite pesticides Bos-SBA-15 and Bos-FDU-12 carrying Bos were successfully prepared.The two nano-drugs were distributed in a rod shape and a granular shape with average particle sizes of 680.3 nm and 870.6 nm,respectively.XRD detection and thermogravimetric analysis confirmed Bos has been successfully loaded into two kinds of mesoporous materials,SBA-15 and FDU-12.The loading of pestcide did not have a large impact on the mesoporous structure,and the load rates were 31.49% and 22.44%,respectively.Nano drug showed excellent thermal stability,sustained release and antibacterial activity.（3）Firstly,the mesoporous material BMMs of the double model were synthesized and modified by amino group.Then,Thi been loaded and the surface grafting method was used to coat the surface of the drug carrier with polyacrylic acid PAA based on the principle of free radical polymerization.Finally,a p H-sensitive composite nano drug is obtained.The drug has a size of 891.7 nm,a uniform structure distribution,and a loading ratio of 25.2%.The study also found that the nanocomposite P/Thi-NN-BMMs have a certain p H sensitivity,and the cumulative release in alkaline environment is significantly higher than in neutral and acidic environments.Compared with the unmodified nanomedicine and the commercially available preparation,it has stronger insecticidal properties,the relative toxicity of nanomedicine is 1.44 times that of Thi wettable powder.