The Preparation Of Pyraclostrobin PLGA Microsphere And Research On Its Property

In this artical, we will utilize PLGA as vector, preparing pyraclostrosbin microsphere, and test its properties with sigle factor experiment, investigating its physicochemical properties with DSC, FI-IR, SEM, light stability experiment, and controlled release experiment. And take indoor toxicity measurement of strains of Fusari wilt of cotton.we prepared pyraclostrosbin microspheres with PLGA through ultrasonic emulsification-solvent evaporation method.It was estimated by the quality of microsphere with drug loading capacity, entrapment efficiency and diameter of particles. Some fators would be studied,such as PLGA concentration, PVA concentration, drug concentration, o/w ratio, ultrasound time and ultrasound power on the quality of microspheres. The process conditions were as followed:PVA concentration was1%(m/V), PLGA concentration was20mg/mL, drug concentration was5mg/mL, o/w ratio was one to four, ultrasound99W for54s, we get microspheres,diameter was0.59μm, drug-loading rate was17.9%(W/W), encapsulation efficiency was89.74%.Drug loading capacity, encapsulation efficiency, and diameters are all important properties measurements. In order to investigate the drug distribution, status and micromorphology, a series of measurement undertook. SEM analysis show that pyraclostrosbin microspheres are intact round balls without adhesion. DSC results show that the edothermic peak disappeared, indicating that pyraclostrosbin encapsulated in the microsphere successfully. FI-IR atlas analysis show a few wave number of characteristic functional group absorption peak shifted, suggesting the tangling between drug and vectors. No new absorption peak or existed peak disppear, indicating that microsphere formation is a physical process. Compared to the active compound, pyraclostrosbin microspheres is insensitive to UV, and its half-life period prolonged by at least50%.Sustained-release preparation become a new pesticide formulation for its controlled release characteristics, thus, it is an essential work for establishing dynamic release model. In this artical, we utilize semipermeable membrane to measure its controlled release property, establishing frequently-used dynamical model to match our data. We also surveyed the influence of diameter, pH, temperature and shock mode on the drug release of pyraclostrosbin microspheres. Statics show that microspheres with bigger grain size release slower, and microspheres in basic and acid environment release faster than that of in neutral conditions;35℃release faster than25℃; shocking faster than standing. When matching with0.6μm microsphere, we found that first order kinetics model is more suitable for pyraclostrosbin PLGA microsphere release curve.And the release data was fitted with four model equations:Higuchi Release Equation, First Order Release Equation,Zero Order Release Equation and Weibull Release Equation. The release of PLGA pyraclostrosbin microspheres better obeyed the First Order Release Equation and Weibull Release Equation comparing with Zero Order Equation and Higuchi Equation.The result of efficacy indoor of pyraclostrosbin PLGA microspheres and pyraclostrosbin EC against cotton fusari wilt showed that:the rapid effect of pyraclostrosbin PLGA microspheres was less than pyraclostrosbin EC and the controlled release properties of pyraclostrosbin PLGA microspheres was better than pyraclostrosbin EC.