Preparation of avermectin microcapsules with anti-photodegradation and slow-release by the assembly of lignin derivatives

Avermectin (Av) is a highly efficient pesticide against a variety of nematodes and is widely used in agriculture. However, it is susceptible to oxidation and photolysis, resulting in instability under UV irradiation and a short half-life. Herein, a rapid and low-cost approach was reported on preparing alkyl chain-coupled lignosulfonate-based polymer coated Av (Av@ALS) microcapsules by the self-assembly of natural and environmentally friendly lignin derivatives. The morphology and UV-shielding of Av@ALS microcapsules were investigated by SEM, EDX, TEM, DLS, FTIR and UV-vis spectroscopy. The self-assembly process and release kinetics of Av@ALS microcapsules were also studied in detail. The results show Av@ALS microcapsules have remarkable avermectin loading ability (up to 57.01% (w/w)), excellent slow-release properties and especially superior UV-shielding properties. The ease and low cost of the assembly process, combined with the natural materials, allows the coating method to open a new avenue for the field of efficient utilization of pesticide.