Three-in-One Diblock Copolymer Nanoparticles for a Sprayable Pickering Emulsion-Based Avermectin Delivery Platform

Abstract In this study, diblock copolymer nanoparticles featuring amino-functionalized poly(N,N-dimethylacrylamide) (PDMA) shells and cinnamaldehyde (CA)-loaded poly(diacetone acrylamide) (PDAAM) cores, denoted as NH2-D86D80/CA, were fabricated through RAFT-mediated aqueous polymerization induced self-assembly (PISA). The resultant NH2-D86D80/CA nanoparticles possessed excellent emulsifying performance, prominent antioxidant activity, and tunable surface charge properties. Sprayable oil-in-water Pickering emulsions were subsequently constructed employing the synthesized NH2-D86D80/CA as Pickering emulsifiers. Relative to Pickering emulsions stabilized by non-aminated D86D80/CA counterparts, NH2-D86D80/CA-stabilized Pickering emulsions showed improved foliar retention. Furthermore, NH2-D86D80/CA-stabilized oil-in-water Pickering emulsions were developed as a delivery system for avermectin (Avm). The formulated Avm delivery platform demonstrated superior oxidative stability and excellent insecticidal activity against Rhopalosiphum padi. Bioassay results indicated that the developed formulation demonstrated concentration-dependent insecticidal efficacy while maintaining favorable crop safety at optimal application concentrations.