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 (NPs). The droplet size of the emulsions was highly tunable, and ranged from 0.2-30 µm in diameter. The controllable droplet size along with the high colloidal stability of the Pickering emulsions were harnessed to obtain single cell microencapsulation.
Single cell encapsulation via Pickering emulsion for biopesticide applications
The successful encapsulation of the conidia enthomopathogenic fungus Metarhizium brunneum by the studied Pickering emulsions was confirmed via fluorescent confocal 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 Ricinus communis leaves by spray assay. The resulting dried paraffin/silica films formed a silica based honeycomb-like structure with an ordered hierarchical porosity that preserve individual cell encapsulation. This successful single cell encapsulation system led to a significantly high distribution of conidia cells on the leaves. The Pickering emulsion based formulation exhibited significantly higher pest control against Spodoptera littoralis larvae compare to the control systems, thus making it a promising cost effective, innovative approach to tackling the pest control challenge.
ACS Omega, 2018, 3 (10), pp 14294–14301; doi: 10.1021/acsomega.8b02225
Figure 1. SEM micrographs of dried silica-NH2 Pickering emulsion with conidia. (scale bar 10µm)
Figure 2. Confocal microscopy images of single cell encapsulation of Metarhizium brunneum Ma7-GFP conidia in a silica-NH2 Pickering emulsion (o/w ratio, 20:80) with different NPs contents of (a) 2 wt%, (b) 3 wt% and (c) 5 wt%. (Scale bar is 10 µm)