Preparation And Properties Of Hydroxyecdysone Microcapsules By Complex Coacervation

The development of green pesticides and the pesticides preparation are research hotspot currently. That involves the research on the preparation of highly effective, low poisonous (nonpoisonous), low residual and pollution free chemical pesticide. And the steroids pesticide is an important research direction. As a protection techniques, microcapsule is often used in the preparation of new pesticide.This paper selected the best condition of preparation ofβ-Hydroxyecdysone(β-HE) microcapsules with complex coacervation method by orthogonal experiments. The shape ofβ-HE microcapsules was characterized by means of scanning of the electron microscope and optical microscope. The release behavior and photo-stability ofβ-HE microcapsules were also studied. The results were as follows:The optimal conditions were as follows:wall material concentration was 3%, core/wall mass ratio was 1:1, early pH value 4.6, terminal pH value 8.0. Under this condition, the smooth and uniform microcapsules have been prepared. The mean length of thoseβ-HE microcapsules was 5μm. The drug loading and encapsulation efficiency were 68.5% and 63.4% respectively.The studies of the release behavior of microcapsule in simulating the insects alimentary canal environmental conditions and field conditions have shown that comparing with bareβ-HE,β-HE microcapsules obviously behaved slowly releasing feature.The capsules prolonged the release time of the encapsulatedβ-HE and enhanced the photostability ofβ-HE.The toxicity experiments were obtained the toxicity regression equation after those larvae feeding on the artifical diet containingβ-HE microcapsules or bareβ-HE for more than 72hours.β-HE microcapsules:Y=11.1221+1.7053x; LC50=0.0024; Bareβ-HE crystal: Y=11.4260+1.7546x; LC50=0.0022. Opposed to the insecticidal effect of bareβ-HE crystal, the insecticidal effect ofβ-HE microcapsules reduced slowly and released longer time.