Preparation And Performance Characteristics Of Dinotefuran Microcapsules Based On CS-co-PLA

Now the research of microcapsules with good biodegradable and biocompatible wall materials has caused widespread attention in the field of pesticide, and the CS-co-PLA grafted copolymers is widely used as drug carrier due to its good biological materials. Compared with some conventional pesticides, the dinotefuran shows many advantages: higher utilization ratio, lower toxicity, wide insecticide controlling spectrum, safer for humans and the crops and less pollution towards the environment, however, it has great solubility in the water. In the paper we focused on how the novel amphiphilic chitosan derivatives were synthesized; how the chemical structure and physical properties were characterized; and the preparation and performance charateristics of dinotefuran microcapsules along with investigating the effects of the experimental parameters related to the quality in order to provide theoretical basis for the microcapsules with water-soluble pesticides. Three sections of work were carried as follows:With chitosan as the raw material, the hydrophilic chitosan was prepared through oxidation-reduction method. Then a novel biodegradable amphiphilic copolymer with hydrophobic PLA moiety and a hydrophilic chitosan segment （CS-co-PLA） was synthesized through soluble chitosan and lactide by Ring-Opening method with triethylamine as catalyst in DMSO. The chemical structures of the copolymers were characterized by NMR (¹H NMR, ¹³C NMR), FT-IR, thermogravimetric analysis （TGA） and GPC, the experimental analysis showed was synthesized successfully, the molecular weight was 14KDa and the CS-co-PLA could be completely decomposed at 150℃.The dinotefuran microcapsules was prepared by nanoprecipitaion and double emulsion with CS-co-PLA as carrier. With encapsulation efficiency （EE） and particles size as important investigation index, the effects of the experimental parameters, such as [m（dinotefuran）:m（CS-co-PLA）],volume of external phase and poly（vinyl alcohol） concentration were investigated with single factor screening test. The optimum process parameters were as followed:the double emulsion method, m（dinotefuran）:m（CS-co-PLA） was 1:50-1:100, PVA concentration was 2%, the volume of external phase was 50mL. The sustained release behaviors of the dinotefuran microcapsules and dinotefuran water-soluble granule were studied. The research showed that the Particle size of the dinotefuran microcapsules was 1.48-3.34μm with good evenness, the entrapment efficiency was 82.18-90.49%, and showed obvious sustaioned release behavior.The prepared dinotefuran microcapsules was quantified with HPLC, the method showed wide linearity range and good linear relation, both the precision and accuracy met the industry standard analysis, the linear equation was Y=46814428.9 X-4265.8, R²=0.999996, the RSD and CV met the analytical requirement, the recovery rate was 98.28%-99.82% met the analytical standard.