Preparation And Biological Activity Of Nano-based Controlled Release Formulations Of Cyantraniliprole And Pyraclostrobin

Pesticides play an irreplaceable role in ensuring the global food production due to their efficient,fast,economical,and easily implementation.Nano-based pesticide formulations can prevent the off-target loss of active ingredients and reduce the amount of pesticides exposed to the environment,thereby reducing the threats to environment and human health.Mesoporous silica nanoparticles have attracted tremendous attention in the field of medicine as well as controlled release of pesticides,due to their adjustable porous structure,large surface area,coupled with the excellent biocompatibility.In this thesis,multi-functional nano-based pesticide formulations based on hollow mesoporous silica nanoparticles was studied to overcome the disadvantages of traditional pesticide formulations.The results were described as follow:1.HMS was fabricated using polystyrene?PS?spheres?400 nm?as a hard template,ethylsilicate as the silicon source,hexadecyl trimethyl ammonium bromide as a surfactant.After the silica was functionalized with 3-aminopropyltriethoxysilane and 2-bromoisobutyryl bromide,an adhesive organic-inorganic hybrid material?HMS-PDAAM?with an outer layer of poly?diacetone acrylamide?and an inner layer of HMS was synthsised using surface-initiated atom transfer radical polymerization.Finally,cyantraniliprole?CNAP?utilized as a model pesticide was incorporated into hybrid material to prepare controlled release formulation?CNAP-HMS-PDAAM?.CNAP-HMS-PDAAM were characterized by transmission electron microscopy?TEM?,scanning electron microscopy?SEM?,Fourier-transform infrared spectroscopy?FT-IR?,thermogravimetric analysis?TGA?,and Brunauer-Emmett-Teller?BET?.The results suggested that HMS-PDAAM nanoparticles with uniform particle size and excellent dispersibility have been successfully prepared and had a large load capacity for CNAP?50%w/w?.Kinetic studies of CNAP release demonstrated that CNAP-loaded HMS-PDAAM exhibited a sustained release property for at least 25 days.The stability test identified that CNAP-loaded HMS-PDAAM were much more stable under UV irradiation and thermal conditions than CNAP technical.Tests of the adhesive properties showed that HMS-PDAAM have strong rainfastness property on rice leaves.More importantly,field experiment results suggested that the efficacies of CNAP-HMS-PDAAM in controlling Cnaphalocrocis medinalis?Guénee?after 28 days and Chilo suppressalis?Walker?were better than CNAP oil-based suspension concentrate?Benevia?after 21 days.2.The amino-functionalized HMS?HMS-NH₂?were synthesized by a one-step method using polystyrene latex?130 nm?as a hard-template as well as TEOS and APTES as the sources of the silica shells.HMS-NH₂ was modified with succinic anhydride to prepare carboxyl-functionalized HMS?HMS-COOH?.Pyraclostrobin?PYR?was loaded into HMS-COOH by impregnation method,and then hydroxypropyl cellulose?HPC?was capped on the surface of HMS using ester linkage to prepare dual stimuli-responsive release formulation?PYR-HMS-HPC?.PYR-HMS-HPC were characterized by TEM,SEM,FT-IR,TGA,and BET.The results demonstrated that HMS-HPC nanoparticles with regular spherical structure and good dispersibility had a high loading efficiency of PYR?13.3%w/w?.Moreover,PYR-HMS-HPC,which could effectively protect PYR against degradation under UV irradiation and reduce genotoxicity of PYR,displayed excellent cellulase and acid dual stimuli-responsive properties.The bioassay results showed that the germicidal efficacy of PYR-HMS-HPC against Magnaporthe oryzae was better than PYR-technical and PYR aqueous suspension concentrates?Seltima?after 7 days.