Preparation And Biological Efficacy Evaluation Of Stimuli-responsive Controlled Release Formulation Of Pesticide

Controlled release formulation of pesticides is highly desirable for maximising the utilization of the pesticide, as well as remarkably reducing the negative impact of the pesticide on agricultural products and ecological environment. Stimuli-responsive controlled release formulation can intelligently respond to the external stimuli and trigger the release of the active ingredients to control pests effectively. In this dissertation, novel stimuli-responsive controlled release formulation of pesticides was developed to solve the current problem about low utilization ratio of conventional pesticide formulation, and pesticide residue and worsening agricultural ecological environment caused by traditional formulation. Stimuli-responsive controlled release formulations of pesticides were prepared using emamectin benzoate, kasugamycin, pendimethalin and indolebutyric acid as model pesticides and characterized. The preparation conditions, controlled release kinetics, stability, bioactivity, and genotoxicity of the stimuli-responsive controlled release formulation of pesticides were investigated to provide scientific basis for the preparation of stimuli-responsive controlled release formulation of pesticides and ascertain the effective approach to increase the utilization of the pesticide and reduce environmental pollution. The expected results of this study will provide new methods and pathways for the development of high efficient pesticide formulations and is of great significance for agricultural sustainable development and agricultural and ecological environment security. Through experimental research, the thesis has obtained the following main results:1. Emamectin benzoate was wrapped into the porous silica formed through the hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) by an emulsion polymerization method using TEOS as the silica precursor. Then the silica shell was modified with 3-aminopropyltriethoxysilane to obtain amino-functionalized silica microspheres, while epichlorohydrin modified carboxymethylcellulose was synthesized. Finally, the epichlorohydrin modified carboxymethylcellulose was conjugated on the surface of the silica microspheres, resulting in novel cellulase and pH dual responsive emamectin benzoate microcapsules. The resulting microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and particle size analysis (PSA). The results showed that the obtained microcapsules had a remarkable loading ability for emamectin benzoate (about 35% w/w) and could improve the light and thermal stability of emamectin benzoate effectively. The silica-epichlorohydrin-carboxymethylcellulose microcapsules displayed excellent cellulase and pH dual stimuli-responsive properties and a sustained insecticidal efficacy against Myzus persicae. Allium cepa chromosome aberration assays demonstrated that the microcapsules had less genotoxicity than the technical.2. Kasugamycin was wrapped into the porous silica formed through the hydrolysis and polycondensation of TEOS by the reversed-phase microemulsion method using TEOS as the silica precursor. Subsequently, the silica shell was modified with 3-mercaptopropyltrimethoxysilane to obtain thiol-functionalized silica microspheres, and then reacted with mercaptoethylamine to synthesize silica-SS-NH2 microspheres. Finally, pectin was conjugated on the surface of the silica microspheres, resulting in novel pectinase and glutathione dual responsive kasugamycin microcapsules. The resulting microcapsules were characterized by FT-IR, SEM, TGA, and PSA. The results showed that the obtained microcapsules had a remarkable loading ability for kasugamycin (about 20% w/w) and could improve the light and thermal stability of kasugamycin effectively. The silica-SS-pectin microcapsules displayed excellent pectinase and glutathione dual stimuli-responsive properties and a sustained bactericidal efficacy against Erwinia carotovora. A. cepa chromosome aberration assays demonstrated that the microcapsules had less genotoxicity than the technical.3. The silica microspheres were prepared using an improved Stober method, and then were modified with 3-isocyanatopropyltriethoxysilane (IPTS) to obtain isocyanate-functionalized silica microspheres. Finally, polyethyleneimine was conjugated on the surface of the silica microspheres with pendimethalin, resulting in novel urease responsive pendimethalin microcapsules. The resulting microcapsules were characterized by FT-IR, SEM, TGA, and PSA. The results showed that the obtained microcapsules had a remarkable loading ability for pendimethalin (about 30% w/w) and could improve the light and thermal stability of pendimethalin effectively. The silica-IPTS-polyethyleneimine microcapsules displayed excellent urease stimuli-responsive properties and a sustained herbicidal efficacy against Echinochloa crusgalli and Amaranthus retroflexus. A. cepa chromosome aberration assays demonstrated that the microcapsules had less genotoxicity than the technical.4. The indolebutyric acid (IBA) and 3-glycidyloxypropyltrimethoxysilane (GPTMS) conjugate was prepared through a covalent cross-linking reaction and subsequent hydrolyzation and polycondensation to synthesize novel esterase and pH dual responsive IBA-silica nanospheres. The resulting nanospheres were characterized by FT-IR, ultraviolet spectrophotometry (UV-vis), SEM, and TGA. The results showed that the obtained nanospheres had a remarkable loading ability for indolebutyric acid (about 43% w/w) and could improve the light and thermal stability of indolebutyric acid effectively. The IBA-silica nanospheres displayed excellent esterase and pH dual stimuli-responsive properties and a sustained promoting roots formation efficacy against Pisum sativum. A. cepa chromosome aberration assays demonstrated that the nanospheres had less genotoxicity than the technical.