Mesotrione reacts with hydrazides or amines to form irreversible enamine linkages, that re potentially still active. We therefore conjugated mesotrione to the nucleophilic PEG derivatives before forming the final gel. Mesotrione was incubated with PEG-CDH, PEG-ADH, or PEG-NH2 at a ratio of 1:4 between mesotrione and PEG end groups. We observed nearly quantitative reaction efficiency between…