Synthesis and characterization of imidacloprid microspheres for controlled drug release study

Polypropylene carbonate (PPC) was synthesized by the alternating copolymerization of carbon dioxide with propylene oxide (PO). Imidacloprid microspheres were prepared by emulsion solvent evaporation, PPC as the drug-carrier material. The effect of the reaction conditions on drug loading (DL) and entrapment efficiency (EE) was examined. High DL of 45.03% was achieved at the methylene chloride and water volume ratio of 1:1, polyvinyl alcohol (PVA)-1788 concentration of 1%, imidacloprid and PPC mass ratio of 1:3, and shear rate of 10,000 r/min. When imidacloprid and PPC mass ratio was 2:3, high EE of 77.91% was obtained. Through the scanning electronic microscopy (SEM) the hollow structure of the microspheres was studied. The effects of shear rate on the diameter and morphology of microspheres were studied by the SEM. The perfect microspheres were obtained at the 10,000 r/min shear rate. The release behavior of imidacloprid encapsulated in the microspheres was studied. The experimental results indicated that the microspheres had a property of sustained drug release.