Antibody‐Targeted Phytohormone Delivery Using Foliar Sprayed Silk Fibroin Pickering Emulsions

Abstract

Efficient delivery systems based on biopolymers offer new solutions to enhance food security by boosting crop yield and quality while decreasing agrochemical input and mitigating environmental impact. Herein, a novel Pickering emulsion fabrication method that utilizes antibody‐functionalized silk fibroin to enhance foliar adhesion upon application for efficient agrochemicals delivery is reported. Silk fibroin microparticles (SFMPs) stabilize both nonpolar and polar oil‐in‐water Pickering emulsions, revealing the cooperative function of both oil phase polarity and aqueous media pH in stabilization, where phytohormones addition influenced the stability and oil‐water contact angle. Phytohormone‐containing Pickering emulsions are functionalized with anti‐pectic polysaccharide (alpha‐1,5‐arabinan) antibody labeled SFMPs through adsorption, to enhance droplet adhesion to leaf cuticle surface. As a proof‐of‐concept, Pickering emulsion containing 0.1 mM jasmonic acid (JA) is applied to Arabidopsis thaliana via foliar spraying. Following washing, treatment with antibody‐functionalized Pickering emulsion increased trichome numbers on young leaves by 20% and 3%, when compared to nonencapsulated JA and nonfunctionalized emulsions, respectively. The functionalized Pickering emulsion stabilized by SFMPs exhibited no plant toxicity and biodegraded 50 wt.% in 7 days, catalyzed by Streptomyces griseus protease. Results highlight the potential of SFMP‐stabilized oleic acid‐in‐water Pickering emulsion as a sustainable and biodegradable solution to precisely deliver agrochemicals through foliar spray.