关键词: 聚乳酸, 纳米微球, 乳化-溶剂挥发法, 嘧菌酯

Abstract: Polylactic acid (PLA) has been widely used in the medical field，because of its good bio-compatibility and bio-degradablity. The preparation of pesticide delivery system with PLA as carrier can effectively prevent the degradation of sensitive drugs and prolong the duration of pesticide. This experiment prepared poly lactic acid nano-microspheres by emulsion solvent evaporation method (O/W); investigated the effects of surfactant kind and concentration, volume ratio of  organic phase to aqueous phase, concentration of PLA, etc. factors on the size of nano-microsphere; characterized its morphology by scanning electron microscopy and transmission electron microscopy; and also characterized the particle size and polydispersity index by particle size analyzer. The results indicated that choosing Tween20 as surfactant, when Tween20 concentration was 0.01~0.03 g/mL, PLA concentration was 0.02 g/mL and ratio of V(oil phase)∶V(aqueous phase) = 1∶10, the nano-microsphere with 230~250 nm particle size could be prepared by ultrasonic emulsification. These nano-microspheres had better dispersibility and spheronization. The PLA-azoxystrobin nano-microspheres were further prepared. The results showed that the surfactant concentration was a key factor affecting the particle size. When the concentration of Tween20 was 0.03 g/mL, nano-microspheres with 236 nm particle size could be obtained. The entrapment efficiency and drug-loading rate were 81.38% and 27.11%, respectively. This study provided technical and parameter support for the preparation of environmental-friendly PLA sustainable release nano-microspheres for pesticide.

Key words: polylactic acid (PLA), nano-microsphere, emulsion-solvent evaporation method, azoxystrobin