Multistimuli-Responsive Nanoformulation Based on Polydopamine-Modified Alginate for the Controlled Release of Emamectin Benzoate with Enhanced Foliar Retention, UV Stability, and Insecticidal Activity

Abstract Polydopamine-functionalized sodium alginate nanoparticles (SA-PDAs) were fabricated through self-assembly of dopamine-modified sodium alginate with cetyltrimethylammonium bromide and Tween 80, followed by in situ oxidative polymerization. The nanoparticle served as an excellent carrier for the controlled release of emamectin benzoate (EB) with enhanced photostability and foliar adhesion. The release of EB from nanoparticles, dominated by interactions between the active ingredient and the matrix, was sensitive to the pH of the medium, near-infrared irradiation, and protease hydrolysis. The encapsulation to nanoparticles significantly improved the insecticidal efficacy of EB while alleviating acute toxicity to the growth of cucumber seeds and the survival of earthworms and zebrafish. The median lethal concentration of the EB@SA-PDA nanosuspension against Mythimna separata larvae was only 34.7% of that of the commercial EB emulsifiable concentrate. The results illustrated a straightforward and effective strategy for constructing an intelligent platform to translate nanopesticides from laboratory investigations into field applications.