Preparation of layered beta-cypermethrin-carrying microcapsules from Pickering emulsion of hollow mesoporous silica nanoparticles

Microcapsules may be viable carriers in sustained-release delivery system for pesticides due to their attractive core structures and diverse wall materials. However, previous research on microcapsules loaded with fat-soluble pesticides was mainly concentrated on the single shell and core structure. In our study, benefiting from the stabilization mechanism of solid particles in Pickering emulsions, hollow mesoporous silica nanoparticles (HMSNs) were fully utilized to serve as pesticides-carrying carriers and enrich the structure of microcapsules. An oil-in-water (O/W) Pickering emulsion composed of a dichloromethane/water system was obtained at a concentration of HMSNs above 0.2% (w/v). An O/W emulsion with better stability was formed by adding gelatin aqueous dispersion (1 wt%) for co-emulsification. A novel layered beta-cypermethrin-carrying microcapsule was successfully prepared, in which HMSNs pre-loaded with a small amount of beta-cypermethrin were covered the shell surface of the microcapsules. Furthermore, the as-prepared microcapsules have good sustained-release performance, and the release behavior of beta-cypermethrin could be explained by first-order kinetic model and Korsmeyer-Peppas model. Bioassay results indicated that the content of microcapsules reached at 5 wt%, the prepared film has a better mosquito repellent effect. Hence, this study provided a simple preparation of functionalized layered sustained-release microcapsules carrying fat-soluble pesticides, and the prepared microcapsules could be used as the anti-mosquito coating additives.