Single Cell Encapsulation via Pickering Emulsion for Biopesticide Applications

Abstract

A new approach for single cell microencapsulation in an oil-in-water (o/w) Pickering emulsion is presented. The water/paraffin emulsions were stabilized by amine-functionalized silica nanoparticles. The droplet size of the emulsions was highly tunable, and ranged from 1 to 30 μm in diameter. The controllable droplet size along with the high colloidal stability of the Pickering emulsionswas harnessed to obtain single cell microencapsulation. Successful encapsulation of the conidia entomopathogenic fungus <i>Metarhizium brunneum</i> by the studied Pickering emulsions was confirmed via confocal laser scanning microscopy. The resulting systems were implemented to develop a novel biopesticide formulation for arthropod pest control. The conidia incorporated in the emulsions were applied to <i>Ricinus communis</i> leaves by spray assay. After drying of the emulsion, a silica-based honeycomb-like structure with an ordered hierarchical porosity is formed. This structure preserves the individual cell encapsulation. The successful single cell encapsulation has led to a high distribution of conidia cells on the leaves. The Pickering emulsion-based formulation exhibited significantly higher pest control activity against <i>Spodoptera littoralis</i> larvae compared to the control systems, thus making it a promising, cost-effective, innovative approach for tackling the pest control challenge.