Preparation And Properties Of Benzoyl Urea Pesticide Microcapsules In Sustained Release

With the developing of scientific technology of modern society, the control methods of pests are becoming more and more various, and their negative effects are also becoming serious.Recently, the researches and developments of pesticides with ultra performance and low residue are becoming the focus of most scientific researchers.Among these, research on the development of controlled-release microcrystals pesticide is an main direction of the research.This paper provides the preparation technology of microcrystals pesticide carrier, using nature chitosan (CHI) and sodium alginate(ALG) as the materials, and using fipronil (FPN), chlorbenzuron (CBZ), triflumuron (TFM), buprofezin (BPF) as the core materials respectively to prepare microcrystals through layer-by-layer (LbL) self-assembly. To observe the dispersed state and surface character of microcrystals by confocal laser scanning microscopy and scanning electron microscopy (SEM), and determination of electric potential change of microcrystals by zeta in different assembled times.In addition, we use the orthogonal experiments to optimize the preparing technology the according to four factors: concentration of chitosan, the concentration of sodium alginate, the dosage and the concentration of the medicine and calcium chloride. To understand the releasing function by in-vitro release experiments and finally to conduct virulence test and to compare with the original drug in order to research on the activity of insect disinfestation of microcrystals pesticide. The results of the study are as follows:Four kinds of recrystallized BPUs pesticides were prepared and characterized through layer-by-layer (LbL) self-assembly. CLSM displayed that:four kinds of microcrystals were encapsulated uniformly, individual and dispersed without aggregation; their surfaces are regular and without dissolution of medicine.In the orthogonal optimizational experiments, we draw a conclusion that the concentration of chitosan,sodium alginate,medicine and calcium chloride have different effects to the preparation system. To chlorbenzuron,buprofezin,triflumuron and fipronil, the most influential factors are the concentration of chitosan,sodium alginate,medicine and calcium chloride respectively. By using the optimizational preparation system,the Zeta results show that, as the capsule wall, CHI and ALG are both deposit in the four pesticides through layer-by-layer self-assembles electrostatic adsorption. The average grain sizes of chlorbenzuron,buprofezin,triflumuron and fipronil which are determined by laser particle analyzer are 10μm,1.5μm,6μm,4μm respectively. The entrapment rate and drug-loading rate of this four microcrystals are respectively: chlorbenzuron are 69.1±0.86% and 68.8±0.86%,buprofezin are 67.2±0.73% and 66.7± 0.31％,triflumuron are 71.1±0.51％and 67.4±0.33％,fipronil are 62.1±0.44％and 53.1±0.15％,self-assembly.