Coprecipitation-based synchronous pesticide encapsulation with chitosan for controlled spinosad release

Controlled release pesticide formulation with long-term efficacy is highly desirable for improving pesticide utilization and reducing adverse effects. In this study, an environment-friendly controlled release formulation of biological insecticide spinosad was fabricated through the coprecipitation-based synchronous encapsulation with chitosan. The resulted spinosad/chitosan formulation showed an excellent encapsulation efficiency of 60 %, obvious pH and temperature sensitivity, and outstanding ultraviolet shielding ability. The in vitro release tests displayed long sustained-release time (> 18 d) and high cumulative release (> 80 %) under neutral and weakly alkaline conditions. The primary interaction between spinosad and chitosan has been found to be physical adsorption and adhesion, with the release dynamics following Fickian diffusion mechanism of Ritger-Peppas model. This work contributes to the development of pesticide carrier system of natural polymer materials, with a great potential for insect pest control.