A stable polyamine‐modified zein‐based nanoformulation with high foliar affinity and lowered toxicity for sustained avermectin release

Abstract BACKGROUND A large amount of pesticides that are not deposited on desired locations due to drift and rolling, endangering the ecological environment and human health. Therefore, it is urgent to develop environmentally friendly and foliar affinity formulations. The design and construction of pesticide nano‐delivery system is considered to be an effective way to solve this problem. RESULTS In this research, polyamine‐modified zein (AM‐zein) was synthesized by incorporating ethylenediamine‐terminated polyethyleneimine into zein to improve its stability as a nanocarrier, enhance electrostatic force between the carrier and pesticides and plant foliage. Avermectin (AVM)‐loaded nanoparticles, containing a high positive charge, were prepared by the anti‐solvent method using AM‐zein as carrier. The nanoparticles can be stored for 30 days without any significant change in the particle size and stably dispersed at pH 5–9. Compared to the commercial emulsifiable concentrate (EC), nanoparticles dispersions exhibited better leaf affinity, and the retention of dispersion increased from 7.82 to 13.86 mg/cm 2 . Interestingly, we have discovered for the first time that the ultraviolet (UV) barrier effect of zein increases while prolonging the UV exposure time; 30.47% of the encapsulated AVM remained intact after exposure to UV for 60 min, compared to only 17.13% for the EC. Insecticidal activity of AVM nanoparticles did not improve compared to EC, but they demonstrated significantly lower toxicity against zebrafish. CONCLUSION This research opens up a new idea for improving the stability of zein nanoparticles, providing a novel path to deliver pesticides efficiently and eco‐friendly. © 2021 Society of Chemical Industry.