Avermectin loaded nanosphere prepared from acylated alkali lignin showed anti-photolysis property and controlled release performance

Abstract Acetylated lignin (ACAL) and benzoylated lignin (BZAL) were obtained from the chemical modification of alkali lignin with acetyl chloride and benzoyl chloride, respectively. The results showed that the introduction of alkyl chain can increase the hydrophobicity of AL evidently. The ACAL and BZAL were used as shell materials for the preparation of nanospheres to encapsulate photosensitive pesticide avermectin (AVM). The prepared AVM-loaded nanospheres showed good controlled release and anti-photolysis properties. The highest encapsulation efficiency of AVM-loaded nanospheres prepared by ACAL (AVM@ACAL) and BZAL (AVM@BZAL) were 90.7% and 97.5%, respectively, which exhibit remarkable controlled release performance compared to control group. After 50 h UV irradiation, the highest AVM retention rates of AVM@ACAL and AVM@BZAL were 67.6% and 77.0% respectively, while the retention rate of control group was only 27%. The acylation degree of acylated alkali lignin had great effect on the anti-photolysis performance of AVM-loaded nanospheres, and the higher acylation degree will reduce the retention rate of AVM by 15˜20%.