One‐pot method for instant nanoformulation via self‐assembling of alginate with quaternary ammonium for controlled release of emamectin benzoate

Abstract

To prompt the nanopesticides from laboratory investigation to agricultural application and reduce the use of pesticides and the impacts on the environment, sodium alginate (SA) was self‐assembled with cetyl trimethyl ammonium bromide (CTAB) into stable and uniform nanoparticle under mild conditions. The structure of the nanoparticle was investigated by dynamic light scattering (DLS), ζ‐potential measurement, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) and related to the loading and release properties. It was found that the nanoparticle size increased and ζ‐potential decreased with increasing concentration of SA, leading to higher loading efficiency and sustained release efficacy towards emamectin benzoate (EB). The amount of CTAB had little effects on the size of the nanoparticle, however made a competition to EB and reduced the loading and sustaining efficacy of the nanocarrier. The release of EB from SA‐CTAB nanoparticle was pH‐sensitive and was slower in the medium of higher pH value, due to the increased interaction with the nanocarrier. The entrapment into the nanoparticle greatly increased the insecticidal toxicity of EB due to the interaction between the carriers and cell membrane. The median lethal concentration of typical nanoformulation against Mythimna separata larvae was 30% of that of technical EB, after feeding to the insect for 48 h.