Encapsulation of anti‐viral active material for plant protection based on inverse Pickering emulsions

Abstract

AbstractThis study presents anti‐viral coating formulations based on Pickering emulsion. We used a versatile strategy to produce a stable Pickering emulsion by depletion interaction between an emulsion droplet and a particle using solvent‐soluble polymers as a depletant. This interaction facilitates the adsorption of particles onto the droplet interface and stabilizes the emulsions. The coating formulation is based on water‐in‐toluene emulsions stabilized using commercial hydrophobic silica, with polycaprolactone polymer as a depletant dissolved in toluene. The structure of the emulsions and their stability were characterized by confocal microscopy, centrifugal analysis using a LUMiSizer®, and cryogenic‐scanning electron microscopy (cryo‐SEM) used to confirm the depletion phenomenon. The active materials copper oxychloride and propionic acid were incorporated into the most stable water‐in‐toluene emulsion and applied to the polycarbonate surfaces after being oven‐dried to remove the toluene while leaving the colloidosomes template with the active ingredient needed to resist viral infections. The bio‐assay of the copper oxychloride and propionic acid encapsulated samples were carried out on Nicotiana tabaccum var Xanthi plants. At a 6–7 leaf stage, Young plants of Xanthi were subjected to inoculation with the 0.01 M sodium‐phosphate pH = 7.0 containing ToBRFV from each of the coated surfaces. The inoculated plants were dusted with carborundum to enhance virus infection, and three leaves above the two lowest leaves in each plant were rubbed. Local lesions were apparent at ~4 days post‐inoculation, indicating virus count. The formulation encapsulated with copper oxychloride gave 87% protection, whereas the one with propionic acid dissolved conferred 91% protection from infestation.