Rational design of acid-degradable polymeric micelles in response to root-mediated pH changes for site-specific herbicide delivery

The low utilization efficacy of conventional herbicide formulations greatly harms the environment and human health. Inspired by the fact that many drug delivery systems are designed to achieve targeted release triggered by the microenvironment of tumor tissues in cancer therapy, a tartaric acid-derived polyester with hydrophilic acid-degradable side chains was designed and synthesized for site-specific herbicide delivery by utilizing the acidic microenvironment in the rhizosphere . The amphiphilic polymer can spontaneously form polymeric micelles in the aqueous solution to load diuron. The diuron-loaded polymeric micelles can release diuron under acidic conditions, and the release rate increase with the reduction of pH value. The herbicidal effect of the diuron-loaded polymeric micelles is investigated using barnyard grass as the research object. The results reveal that the diuron-loaded polymeric micelles are able to kill barnyard grass effectively. Finally, the toxicity studies suggest that the polymer can mitigate toxicity to the non-target organisms. In view of its superior herbicidal activity, excellent biodegradability and biocompatibility, this site-specific herbicides release system has broad potential in agricultural applications.