嘧菌酯微囊的制备及其性能表征

以生物可降解的壳聚糖(CS)和DL-丙交酯为原料,利用开环聚合法合成了可降解的壳聚糖-聚乳酸接枝共聚物(CS-co-PLA),并以其为壁材,以嘧菌酯为芯材,以聚乙烯醇(PVA)为连续相稳定剂,采用乳化溶剂挥发法制备了不同粒径的嘧菌酯微囊,研究了芯壁材质量比、PVA质量分数、油水相比例、剪切速率及时间对微囊形态、粒径及分布、包封率和载药量的影响,测定了典型微囊的缓释性能,探讨了微囊制备工艺条件及粒径调控方法。结果表明:在PVA质量分数为1%,m(嘧菌酯):m(CS-co-PLA)=1∶4~1∶1,V(油相)∶V(水相)=1∶10,剪切乳化时间为5 min时,在3 000~18 000 r/min之间通过调节剪切速率,可制备出形状规则、粒径在280 nm~4.5μm之间并具有良好缓释性能的嘧菌酯微囊;其中剪切速率是影响微囊粒径的主要因素。

Preparation and performance characteristics of azoxystrobin microcapsules

The novel biodegradable amphiphilic copolymer (CS-co-PLA) was synthesized by ring-opening polymerization reaction of chitosan (CS) with DL-lactide. A series of azoxystrobin-loaded microcapsules with different particle sizes were prepared by emulsion/solvent evaporation method using CS-co-PLA as wall materials, azoxystrobin as core materials and PVA as continuous phase stabilizers. The effects of mass ratio of core materials and wall materials m(azoxystrobin):m(CS-co-PLA)], PVA concentration, V(oil phase):V(aqueous phase), shear rate and shear emulsification time on surface morphology, particle size and size distribution, entrapment rate and drug-loading rate of microcapsules were investigated. The sustained release performance of typical microcapsules, as well as the preparation process conditions and particle size controling methods of microcapsules were also studied. The results showed that when the conditions of PVA mass fraction (1%), m(azoxystrobin):m(CS-co-PLA)=1:4-1:1, V(oil phase):V(aqueous phase)=1:10 and shear emulsification time (5 min) were fixed,different sizes (from 280 nm to 4.5 μ m) of microcapsules could be prepared by adjusting different shear rate (3 000 r/min to 18 000 r/min). The azoxystrobin microcapsules dispersed as individual particles with a well-defined spherical shape and homogeneous distribution, and showed good sustained release performance. It could be concluded that shear rate was the main factor influencing particle size of the microcapsules.